Merge pull request #578 from rod-hynes/conjure

Integrate Conjure

README.md

@@ -198,6 +198,7 @@ Psiphon Tunnel Core uses:
 * [wader/filtertransport](https://github.com/wader/filtertransport)
 * [Yawning/chacha20](https://github.com/Yawning/chacha20)
 * [Yawning/goptlib](https://github.com/Yawning/goptlib)
+* [yawning/obfs4](https://gitlab.com/yawning/obfs4)
 * [zach-klippenstein/goregen](https://github.com/zach-klippenstein/goregen)
 * [zap](https://go.uber.org/zap)
 

psiphon/TCPConn.go

@@ -46,7 +46,7 @@ type TCPConn struct {
 // Note: do not set an UpstreamProxyURL in the config when using NewTCPDialer
 // as a custom dialer for NewProxyAuthTransport (or http.Transport with a
 // ProxyUrl), as that would result in double proxy chaining.
-func NewTCPDialer(config *DialConfig) Dialer {
+func NewTCPDialer(config *DialConfig) common.Dialer {
 	return func(ctx context.Context, network, addr string) (net.Conn, error) {
 		if network != "tcp" {
 			return nil, errors.Tracef("%s unsupported", network)

psiphon/common/net.go

@@ -33,6 +33,9 @@ import (
 	"github.com/wader/filtertransport"
 )
 
+// Dialer is a custom network dialer.
+type Dialer func(context.Context, string, string) (net.Conn, error)
+
 // NetDialer mimicks the net.Dialer interface.
 type NetDialer interface {
 	Dial(network, address string) (net.Conn, error)

psiphon/common/parameters/parameters.go

@@ -222,6 +222,8 @@ const (
 	ReplayHostname                                   = "ReplayHostname"
 	ReplayQUICVersion                                = "ReplayQUICVersion"
 	ReplayObfuscatedQUIC                             = "ReplayObfuscatedQUIC"
+	ReplayConjureRegistration                        = "ReplayConjureRegistration"
+	ReplayConjureTransport                           = "ReplayConjureTransport"
 	ReplayLivenessTest                               = "ReplayLivenessTest"
 	ReplayUserAgent                                  = "ReplayUserAgent"
 	ReplayAPIRequestPadding                          = "ReplayAPIRequestPadding"
@@ -269,6 +271,8 @@ const (
 	ClientBurstUpstreamTargetBytes                   = "ClientBurstUpstreamTargetBytes"
 	ClientBurstDownstreamDeadline                    = "ClientBurstDownstreamDeadline"
 	ClientBurstDownstreamTargetBytes                 = "ClientBurstDownstreamTargetBytes"
+	ConjureDecoyRegistrarWidth                       = "ConjureDecoyRegistrarWidth"
+	ConjureTransportObfs4Probability                 = "ConjureTransportObfs4Probability"
 )
 
 const (
@@ -502,6 +506,8 @@ var defaultParameters = map[string]struct {
 	ReplayHostname:                         {value: true},
 	ReplayQUICVersion:                      {value: true},
 	ReplayObfuscatedQUIC:                   {value: true},
+	ReplayConjureRegistration:              {value: true},
+	ReplayConjureTransport:                 {value: true},
 	ReplayLivenessTest:                     {value: true},
 	ReplayUserAgent:                        {value: true},
 	ReplayAPIRequestPadding:                {value: true},
@@ -558,6 +564,9 @@ var defaultParameters = map[string]struct {
 	ClientBurstUpstreamDeadline:      {value: time.Duration(0), minimum: time.Duration(0)},
 	ClientBurstDownstreamTargetBytes: {value: 0, minimum: 0},
 	ClientBurstDownstreamDeadline:    {value: time.Duration(0), minimum: time.Duration(0)},
+
+	ConjureDecoyRegistrarWidth:       {value: 5, minimum: 1},
+	ConjureTransportObfs4Probability: {value: 0.0, minimum: 0.0},
 }
 
 // IsServerSideOnly indicates if the parameter specified by name is used

psiphon/common/protocol/protocol.go

@@ -78,6 +78,9 @@ const (
 	RANDOM_STREAM_CHANNEL_TYPE = "[email protected]"
 
 	PSIPHON_API_HANDSHAKE_AUTHORIZATIONS = "authorizations"
+
+	CONJURE_TRANSPORT_MIN_OSSH   = "Min-OSSH"
+	CONJURE_TRANSPORT_OBFS4_OSSH = "Obfs4-OSSH"
 )
 
 type TunnelProtocols []string
@@ -187,12 +190,16 @@ func TunnelProtocolUsesMarionette(protocol string) bool {
 	return protocol == TUNNEL_PROTOCOL_MARIONETTE_OBFUSCATED_SSH
 }
 
-func TunnelProtocolUsesTapdance(protocol string) bool {
+func TunnelProtocolUsesRefractionNetworking(protocol string) bool {
 	return protocol == TUNNEL_PROTOCOL_TAPDANCE_OBFUSCATED_SSH ||
 		protocol == TUNNEL_PROTOCOL_CONJURE_OBFUSCATED_SSH
 }
 
-func TunnelProtocolUsesDarkDecoys(protocol string) bool {
+func TunnelProtocolUsesTapDance(protocol string) bool {
+	return protocol == TUNNEL_PROTOCOL_TAPDANCE_OBFUSCATED_SSH
+}
+
+func TunnelProtocolUsesConjure(protocol string) bool {
 	return protocol == TUNNEL_PROTOCOL_CONJURE_OBFUSCATED_SSH
 }
 
@@ -200,7 +207,7 @@ func TunnelProtocolIsResourceIntensive(protocol string) bool {
 	return TunnelProtocolUsesMeek(protocol) ||
 		TunnelProtocolUsesQUIC(protocol) ||
 		TunnelProtocolUsesMarionette(protocol) ||
-		TunnelProtocolUsesTapdance(protocol)
+		TunnelProtocolUsesRefractionNetworking(protocol)
 }
 
 func TunnelProtocolIsCompatibleWithFragmentor(protocol string) bool {
@@ -210,7 +217,8 @@ func TunnelProtocolIsCompatibleWithFragmentor(protocol string) bool {
 		protocol == TUNNEL_PROTOCOL_UNFRONTED_MEEK_HTTPS ||
 		protocol == TUNNEL_PROTOCOL_UNFRONTED_MEEK_SESSION_TICKET ||
 		protocol == TUNNEL_PROTOCOL_FRONTED_MEEK ||
-		protocol == TUNNEL_PROTOCOL_FRONTED_MEEK_HTTP
+		protocol == TUNNEL_PROTOCOL_FRONTED_MEEK_HTTP ||
+		protocol == TUNNEL_PROTOCOL_CONJURE_OBFUSCATED_SSH
 }
 
 func TunnelProtocolRequiresTLS12SessionTickets(protocol string) bool {

psiphon/common/protocol/serverEntry.go

@@ -55,7 +55,8 @@ type ServerEntry struct {
 	SshHostKey                    string   `json:"sshHostKey"`
 	SshObfuscatedPort             int      `json:"sshObfuscatedPort"`
 	SshObfuscatedQUICPort         int      `json:"sshObfuscatedQUICPort"`
-	SshObfuscatedTapdancePort     int      `json:"sshObfuscatedTapdancePort"`
+	SshObfuscatedTapDancePort     int      `json:"sshObfuscatedTapdancePort"`
+	SshObfuscatedConjurePort      int      `json:"sshObfuscatedConjurePort"`
 	SshObfuscatedKey              string   `json:"sshObfuscatedKey"`
 	Capabilities                  []string `json:"capabilities"`
 	Region                        string   `json:"region"`
@@ -468,7 +469,7 @@ func (serverEntry *ServerEntry) SupportsProtocol(protocol string) bool {
 type ConditionallyEnabledComponents interface {
 	QUICEnabled() bool
 	MarionetteEnabled() bool
-	TapdanceEnabled() bool
+	RefractionNetworkingEnabled() bool
 }
 
 // GetSupportedProtocols returns a list of tunnel protocols supported
@@ -503,7 +504,8 @@ func (serverEntry *ServerEntry) GetSupportedProtocols(
 
 		if (TunnelProtocolUsesQUIC(protocol) && !conditionallyEnabled.QUICEnabled()) ||
 			(TunnelProtocolUsesMarionette(protocol) && !conditionallyEnabled.MarionetteEnabled()) ||
-			(TunnelProtocolUsesTapdance(protocol) && !conditionallyEnabled.TapdanceEnabled()) {
+			(TunnelProtocolUsesRefractionNetworking(protocol) &&
+				!conditionallyEnabled.RefractionNetworkingEnabled()) {
 			continue
 		}
 

psiphon/common/protocol/serverEntry_test.go

@@ -180,7 +180,8 @@ func testServerEntryListSignatures(t *testing.T, setExplicitTag bool) {
 		SshHostKey:                    prng.HexString(n),
 		SshObfuscatedPort:             prng.Intn(n),
 		SshObfuscatedQUICPort:         prng.Intn(n),
-		SshObfuscatedTapdancePort:     prng.Intn(n),
+		SshObfuscatedTapDancePort:     prng.Intn(n),
+		SshObfuscatedConjurePort:      prng.Intn(n),
 		SshObfuscatedKey:              prng.HexString(n),
 		Capabilities:                  []string{prng.HexString(n)},
 		Region:                        prng.HexString(n),

psiphon/common/tapdance/tapdance.go → psiphon/common/refraction/refraction.go

@@ -1,4 +1,4 @@
-// +build PSIPHON_ENABLE_TAPDANCE
+// +build PSIPHON_ENABLE_REFRACTION_NETWORKING
 
 /*
  * Copyright (c) 2018, Psiphon Inc.
@@ -21,14 +21,15 @@
 
 /*
 
-Package tapdance wraps github.com/refraction-networking/gotapdance with net.Listener
-and net.Conn types that provide drop-in integration with Psiphon.
+Package refraction wraps github.com/refraction-networking/gotapdance with
+net.Listener and net.Conn types that provide drop-in integration with Psiphon.
 
 */
-package tapdance
+package refraction
 
 import (
 	"context"
+	"crypto/sha256"
 	"io/ioutil"
 	"net"
 	"os"
@@ -39,15 +40,17 @@ import (
 
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/errors"
+	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/protocol"
 	"github.com/armon/go-proxyproto"
-	refraction_networking_tapdance "github.com/refraction-networking/gotapdance/tapdance"
+	refraction_networking_proto "github.com/refraction-networking/gotapdance/protobuf"
+	refraction_networking_client "github.com/refraction-networking/gotapdance/tapdance"
 )
 
 const (
 	READ_PROXY_PROTOCOL_HEADER_TIMEOUT = 5 * time.Second
 )
 
-// Enabled indicates if Tapdance functionality is enabled.
+// Enabled indicates if Refraction Networking functionality is enabled.
 func Enabled() bool {
 	return true
 }
@@ -57,15 +60,21 @@ type Listener struct {
 	net.Listener
 }
 
-// Listen creates a new Tapdance listener on top of an existing TCP listener.
+// Listen creates a new Refraction Networking listener.
 //
-// The Tapdance station will send the original client address via the HAProxy
-// proxy protocol v1, https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt.
-// The original client address is read and returned by accepted conns'
-// RemoteAddr. RemoteAddr _must_ be called non-concurrently before calling Read
-// on accepted conns as the HAProxy proxy protocol header reading logic sets
+// The Refraction Networking station (TapDance or Conjure) will send the
+// original client address via the HAProxy proxy protocol v1,
+// https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt. The original
+// client address is read and returned by accepted conns' RemoteAddr.
+// RemoteAddr _must_ be called non-concurrently before calling Read on
+// accepted conns as the HAProxy proxy protocol header reading logic sets
 // SetReadDeadline and performs a Read.
-func Listen(tcpListener net.Listener) (net.Listener, error) {
+func Listen(address string) (net.Listener, error) {
+
+	tcpListener, err := net.Listen("tcp", address)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
 
 	// Setting a timeout ensures that reading the proxy protocol
 	// header completes or times out and RemoteAddr will not block. See:
@@ -83,15 +92,14 @@ func Listen(tcpListener net.Listener) (net.Listener, error) {
 }
 
 // stationListener uses the proxyproto.Listener SourceCheck callback to
-// capture and record the direct remote address, the Tapdance station address,
-// and wraps accepted conns to provide station address metrics via GetMetrics.
+// capture and record the direct remote address, the station address, and
+// wraps accepted conns to provide station address metrics via GetMetrics.
 // These metrics enable identifying which station fronted a connection, which
 // is useful for network operations and troubleshooting.
 //
 // go-proxyproto.Conn.RemoteAddr reports the originating client IP address,
 // which is geolocated and recorded for metrics. The underlying conn's remote
-// address, the Tapdance station address, is not accessible via the
-// go-proxyproto API.
+// address, the station address, is not accessible via the go-proxyproto API.
 //
 // stationListener is not safe for concurrent access.
 type stationListener struct {
@@ -162,16 +170,231 @@ func (c *stationConn) GetMetrics() common.LogFields {
 	return logFields
 }
 
+// DialTapDance establishes a new TapDance connection to a TapDance station
+// specified in the config assets and forwarding through to the Psiphon server
+// specified by address.
+//
+// The TapDance station config assets (which are also the Conjure station
+// assets) are read from dataDirectory/"refraction-networking". When no config
+// is found, default assets are paved.
+//
+// The input ctx is expected to have a timeout for the dial.
+//
+// Limitation: the parameters emitLogs and dataDirectory are used for one-time
+// initialization and are ignored after the first DialTapDance/Conjure call.
+func DialTapDance(
+	ctx context.Context,
+	emitLogs bool,
+	dataDirectory string,
+	dialer common.NetDialer,
+	address string) (net.Conn, error) {
+
+	return dial(
+		ctx,
+		emitLogs,
+		dataDirectory,
+		dialer,
+		false,
+		nil,
+		0,
+		"",
+		address)
+}
+
+// DialConjure establishes a new Conjure connection to a Conjure station.
+//
+// See DialTapdance comment.
+func DialConjure(
+	ctx context.Context,
+	emitLogs bool,
+	dataDirectory string,
+	dialer common.NetDialer,
+	conjureDecoyRegistrarDialer common.NetDialer,
+	conjureDecoyRegistrarWidth int,
+	conjureTransport string,
+	address string) (net.Conn, error) {
+
+	return dial(
+		ctx,
+		emitLogs,
+		dataDirectory,
+		dialer,
+		true,
+		conjureDecoyRegistrarDialer,
+		conjureDecoyRegistrarWidth,
+		conjureTransport,
+		address)
+}
+
+func dial(
+	ctx context.Context,
+	emitLogs bool,
+	dataDirectory string,
+	dialer common.NetDialer,
+	useConjure bool,
+	conjureDecoyRegistrarDialer common.NetDialer,
+	conjureDecoyRegistrarWidth int,
+	conjureTransport string,
+	address string) (net.Conn, error) {
+
+	err := initRefractionNetworking(emitLogs, dataDirectory)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+
+	if _, ok := ctx.Deadline(); !ok {
+		return nil, errors.TraceNew("dial context has no timeout")
+	}
+
+	manager := newDialManager()
+
+	refractionDialer := &refraction_networking_client.Dialer{
+		TcpDialer:      manager.makeManagedDialer(dialer.DialContext),
+		UseProxyHeader: true,
+	}
+
+	if useConjure {
+
+		refractionDialer.DarkDecoy = true
+
+		refractionDialer.DarkDecoyRegistrar = refraction_networking_client.DecoyRegistrar{
+			TcpDialer: manager.makeManagedDialer(conjureDecoyRegistrarDialer.DialContext),
+		}
+		refractionDialer.Width = conjureDecoyRegistrarWidth
+
+		switch conjureTransport {
+		case protocol.CONJURE_TRANSPORT_MIN_OSSH:
+			refractionDialer.Transport = refraction_networking_proto.TransportType_Min
+			refractionDialer.TcpDialer = newMinTransportDialer(refractionDialer.TcpDialer)
+		case protocol.CONJURE_TRANSPORT_OBFS4_OSSH:
+			refractionDialer.Transport = refraction_networking_proto.TransportType_Obfs4
+		default:
+			return nil, errors.Tracef("invalid Conjure transport: %s", conjureTransport)
+		}
+	}
+
+	// If the dial context is cancelled, use dialManager to interrupt
+	// refractionDialer.DialContext. See dialManager comment explaining why
+	// refractionDialer.DialContext may block even when the input context is
+	// cancelled.
+	dialComplete := make(chan struct{})
+	go func() {
+		select {
+		case <-ctx.Done():
+		case <-dialComplete:
+		}
+		select {
+		// Prioritize the dialComplete case.
+		case <-dialComplete:
+			return
+		default:
+		}
+		manager.close()
+	}()
+
+	conn, err := refractionDialer.DialContext(ctx, "tcp", address)
+	close(dialComplete)
+	if err != nil {
+		manager.close()
+		return nil, errors.Trace(err)
+	}
+
+	manager.startUsingRunCtx()
+
+	return &refractionConn{
+		Conn:    conn,
+		manager: manager,
+	}, nil
+}
+
+// minTransportConn buffers the first 32-byte random HMAC write performed by
+// Conjure TransportType_Min, and prepends it to the subsequent first write
+// made by OSSH. The purpose is to avoid a distinct fingerprint consisting of
+// the initial TCP data packet always containing exactly 32 bytes of payload.
+// The first write by OSSH will be a variable length multi-packet-sized
+// sequence of random bytes.
+type minTransportConn struct {
+	net.Conn
+
+	mutex  sync.Mutex
+	state  int
+	buffer []byte
+	err    error
+}
+
+const (
+	stateMinTransportInit = iota
+	stateMinTransportBufferedHMAC
+	stateMinTransportWroteHMAC
+	stateMinTransportFailed
+)
+
+func newMinTransportConn(conn net.Conn) *minTransportConn {
+	return &minTransportConn{
+		Conn:  conn,
+		state: stateMinTransportInit,
+	}
+}
+
+func (conn *minTransportConn) Write(p []byte) (int, error) {
+	conn.mutex.Lock()
+	defer conn.mutex.Unlock()
+
+	switch conn.state {
+	case stateMinTransportInit:
+		if len(p) != sha256.Size {
+			conn.state = stateMinTransportFailed
+			conn.err = errors.TraceNew("unexpected HMAC write size")
+			return 0, conn.err
+		}
+		conn.buffer = make([]byte, sha256.Size)
+		copy(conn.buffer, p)
+		conn.state = stateMinTransportBufferedHMAC
+		return sha256.Size, nil
+	case stateMinTransportBufferedHMAC:
+		conn.buffer = append(conn.buffer, p...)
+		n, err := conn.Conn.Write(conn.buffer)
+		if n < sha256.Size {
+			conn.state = stateMinTransportFailed
+			conn.err = errors.TraceNew("failed to write HMAC")
+			if err == nil {
+				// As Write must return an error when failing to write the entire buffer,
+				// we don't expect to hit this case.
+				err = conn.err
+			}
+		} else {
+			conn.state = stateMinTransportWroteHMAC
+		}
+		n -= sha256.Size
+		// Do not wrap Conn.Write errors, and do not return conn.err here.
+		return n, err
+	case stateMinTransportWroteHMAC:
+		return conn.Conn.Write(p)
+	case stateMinTransportFailed:
+		return 0, conn.err
+	default:
+		return 0, errors.TraceNew("unexpected state")
+	}
+}
+
+func newMinTransportDialer(dialer common.Dialer) common.Dialer {
+	return func(ctx context.Context, network, address string) (net.Conn, error) {
+		conn, err := dialer(ctx, network, address)
+		if err != nil {
+			return nil, errors.Trace(err)
+		}
+		return newMinTransportConn(conn), nil
+	}
+}
+
 // dialManager tracks all dials performed by and dialed conns used by a
-// refraction_networking_tapdance client. dialManager.close interrupts/closes
+// refraction_networking_client conn. dialManager.close interrupts/closes
 // all pending dials and established conns immediately. This ensures that
-// blocking calls within refraction_networking_tapdance, such as tls.Handhake,
+// blocking calls within refraction_networking_client, such as tls.Handhake,
 // are interrupted:
 // E.g., https://github.com/refraction-networking/gotapdance/blob/4d84655dad2e242b0af0459c31f687b12085dcca/tapdance/conn_raw.go#L307
 // (...preceeding SetDeadline is insufficient for immediate cancellation.)
 type dialManager struct {
-	tcpDialer func(ctx context.Context, network, address string) (net.Conn, error)
-
 	ctxMutex       sync.Mutex
 	useRunCtx      bool
 	initialDialCtx context.Context
@@ -181,36 +404,43 @@ type dialManager struct {
 	conns *common.Conns
 }
 
-func newDialManager(
-	tcpDialer func(ctx context.Context, network, address string) (net.Conn, error)) *dialManager {
-
+func newDialManager() *dialManager {
 	runCtx, stopRunning := context.WithCancel(context.Background())
-
 	return &dialManager{
-		tcpDialer:   tcpDialer,
 		runCtx:      runCtx,
 		stopRunning: stopRunning,
 		conns:       common.NewConns(),
 	}
 }
 
-func (manager *dialManager) dial(ctx context.Context, network, address string) (net.Conn, error) {
+func (manager *dialManager) makeManagedDialer(dialer common.Dialer) common.Dialer {
+
+	return func(ctx context.Context, network, address string) (net.Conn, error) {
+		return manager.dialWithDialer(dialer, ctx, network, address)
+	}
+}
+
+func (manager *dialManager) dialWithDialer(
+	dialer common.Dialer,
+	ctx context.Context,
+	network string,
+	address string) (net.Conn, error) {
 
 	if network != "tcp" {
 		return nil, errors.Tracef("unsupported network: %s", network)
 	}
 
 	// The context for this dial is either:
-	// - ctx, during the initial tapdance.DialContext, when this is Psiphon tunnel
-	//   establishment.
-	// - manager.runCtx after the initial tapdance.Dial completes, in which case
-	//   this is a Tapdance protocol reconnection that occurs periodically for
-	//   already established tunnels.
+	// - ctx, during the initial refraction_networking_client.DialContext, when
+	//   this is Psiphon tunnel establishment.
+	// - manager.runCtx after the initial refraction_networking_client.Dial
+	//   completes, in which case this is a TapDance protocol reconnection that
+	//   occurs periodically for already established tunnels.
 
 	manager.ctxMutex.Lock()
 	if manager.useRunCtx {
 
-		// Preserve the random timeout configured by the tapdance client:
+		// Preserve the random timeout configured by the TapDance client:
 		// https://github.com/refraction-networking/gotapdance/blob/4d84655dad2e242b0af0459c31f687b12085dcca/tapdance/conn_raw.go#L263
 		deadline, ok := ctx.Deadline()
 		if !ok {
@@ -222,14 +452,14 @@ func (manager *dialManager) dial(ctx context.Context, network, address string) (
 	}
 	manager.ctxMutex.Unlock()
 
-	conn, err := manager.tcpDialer(ctx, network, address)
+	conn, err := dialer(ctx, network, address)
 	if err != nil {
 		return nil, errors.Trace(err)
 	}
 
 	// Fail immediately if CloseWrite isn't available in the underlying dialed
 	// conn. The equivalent check in managedConn.CloseWrite isn't fatal and
-	// tapdance will run in a degraded state.
+	// TapDance will run in a degraded state.
 	// Limitation: if the underlying conn _also_ passes through CloseWrite, this
 	// check may be insufficient.
 	if _, ok := conn.(common.CloseWriter); !ok {
@@ -267,7 +497,7 @@ type managedConn struct {
 }
 
 // CloseWrite exposes the net.TCPConn.CloseWrite() functionality
-// required by tapdance.
+// required by TapDance.
 func (conn *managedConn) CloseWrite() error {
 	if closeWriter, ok := conn.Conn.(common.CloseWriter); ok {
 		return closeWriter.CloseWrite()
@@ -282,103 +512,35 @@ func (conn *managedConn) Close() error {
 	return conn.Conn.Close()
 }
 
-type tapdanceConn struct {
+type refractionConn struct {
 	net.Conn
 	manager  *dialManager
 	isClosed int32
 }
 
-func (conn *tapdanceConn) Close() error {
+func (conn *refractionConn) Close() error {
 	conn.manager.close()
 	err := conn.Conn.Close()
 	atomic.StoreInt32(&conn.isClosed, 1)
 	return err
 }
 
-func (conn *tapdanceConn) IsClosed() bool {
+func (conn *refractionConn) IsClosed() bool {
 	return atomic.LoadInt32(&conn.isClosed) == 1
 }
 
-// Dial establishes a new Tapdance session to a Tapdance station specified in
-// the config assets and forwarding through to the Psiphon server specified by
-// address.
-//
-// The Tapdance station config assets are read from dataDirectory/"tapdance".
-// When no config is found, default assets are paved. ctx is expected to have
-// a timeout for the dial.
-//
-// Limitation: the parameters emitLogs and dataDirectory are used for one-time
-// initialization and are ignored after the first Dial call.
-func Dial(
-	ctx context.Context,
-	emitLogs bool,
-	dataDirectory string,
-	netDialer common.NetDialer,
-	address string) (net.Conn, error) {
-
-	err := initTapdance(emitLogs, dataDirectory)
-	if err != nil {
-		return nil, errors.Trace(err)
-	}
-
-	if _, ok := ctx.Deadline(); !ok {
-		return nil, errors.TraceNew("dial context has no timeout")
-	}
-
-	manager := newDialManager(netDialer.DialContext)
-
-	tapdanceDialer := &refraction_networking_tapdance.Dialer{
-		TcpDialer: manager.dial,
-	}
-
-	// If the dial context is cancelled, use dialManager to interrupt
-	// tapdanceDialer.DialContext. See dialManager comment explaining why
-	// tapdanceDialer.DialContext may block even when the input context is
-	// cancelled.
-	dialComplete := make(chan struct{})
-	go func() {
-		select {
-		case <-ctx.Done():
-		case <-dialComplete:
-		}
-		select {
-		// Prioritize the dialComplete case.
-		case <-dialComplete:
-			return
-		default:
-		}
-		manager.close()
-	}()
-
-	conn, err := tapdanceDialer.DialContext(ctx, "tcp", address)
-	close(dialComplete)
-	if err != nil {
-		manager.close()
-		return nil, errors.Trace(err)
-	}
-
-	manager.startUsingRunCtx()
-
-	return &tapdanceConn{
-		Conn:    conn,
-		manager: manager,
-	}, nil
-}
-
-var initTapdanceOnce sync.Once
+var initRefractionNetworkingOnce sync.Once
 
-func initTapdance(emitLogs bool, dataDirectory string) error {
+func initRefractionNetworking(emitLogs bool, dataDirectory string) error {
 
 	var initErr error
-	initTapdanceOnce.Do(func() {
+	initRefractionNetworkingOnce.Do(func() {
 
 		if !emitLogs {
-			refraction_networking_tapdance.Logger().Out = ioutil.Discard
+			refraction_networking_client.Logger().Out = ioutil.Discard
 		}
 
-		refraction_networking_tapdance.EnableProxyProtocol()
-
-		assetsDir := filepath.Join(dataDirectory, "tapdance")
+		assetsDir := filepath.Join(dataDirectory, "refraction-networking")
 
 		err := os.MkdirAll(assetsDir, 0700)
 		if err != nil {
@@ -396,7 +558,7 @@ func initTapdance(emitLogs bool, dataDirectory string) error {
 			return
 		}
 
-		refraction_networking_tapdance.AssetsSetDir(assetsDir)
+		refraction_networking_client.AssetsSetDir(assetsDir)
 	})
 
 	return initErr

psiphon/common/tapdance/tapdance_disabled.go → psiphon/common/refraction/refraction_disabled.go

@@ -1,4 +1,4 @@
-// +build !PSIPHON_ENABLE_TAPDANCE
+// +build !PSIPHON_ENABLE_REFRACTION_NETWORKING
 
 /*
  * Copyright (c) 2018, Psiphon Inc.
@@ -19,7 +19,7 @@
  *
  */
 
-package tapdance
+package refraction
 
 import (
 	"context"
@@ -29,7 +29,7 @@ import (
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/errors"
 )
 
-// Enabled indicates if Tapdance functionality is enabled.
+// Enabled indicates if Refraction Networking functionality is enabled.
 func Enabled() bool {
 	return false
 }
@@ -39,12 +39,17 @@ type Listener struct {
 	net.Listener
 }
 
-// Listen creates a new Tapdance listener.
-func Listen(_ net.Listener) (net.Listener, error) {
+// Listen creates a new Refraction Networking listener.
+func Listen(_ string) (net.Listener, error) {
 	return nil, errors.TraceNew("operation is not enabled")
 }
 
-// Dial establishes a new Tapdance session to a Tapdance station.
-func Dial(_ context.Context, _ bool, _ string, _ common.NetDialer, _ string) (net.Conn, error) {
+// DialTapDance establishes a new Tapdance connection to a Tapdance station.
+func DialTapDance(_ context.Context, _ bool, _ string, _ common.NetDialer, _ string) (net.Conn, error) {
+	return nil, errors.TraceNew("operation is not enabled")
+}
+
+// DialConjure establishes a new Conjure connection to a Conjure station.
+func DialConjure(_ context.Context, _ bool, _ string, _, _ common.NetDialer, _ int, _, _ string) (net.Conn, error) {
 	return nil, errors.TraceNew("operation is not enabled")
 }

psiphon/config.go

@@ -158,11 +158,12 @@ type Config struct {
 	NetworkLatencyMultiplier float64
 
 	// LimitTunnelProtocols indicates which protocols to use. Valid values
-	// include:
-	// "SSH", "OSSH", "UNFRONTED-MEEK-OSSH", "UNFRONTED-MEEK-HTTPS-OSSH",
-	// "UNFRONTED-MEEK-SESSION-TICKET-OSSH", "FRONTED-MEEK-OSSH",
-	// "FRONTED-MEEK-HTTP-OSSH", "QUIC-OSSH", "MARIONETTE-OSSH", and
-	// "TAPDANCE-OSSH".
+	// include: "SSH", "OSSH", "UNFRONTED-MEEK-OSSH",
+	// "UNFRONTED-MEEK-HTTPS-OSSH", "UNFRONTED-MEEK-SESSION-TICKET-OSSH",
+	// "FRONTED-MEEK-OSSH", "FRONTED-MEEK-HTTP-OSSH", "QUIC-OSSH",
+	// "FRONTED-MEEK-QUIC-OSSH", "MARIONETTE-OSSH", "TAPDANCE-OSSH", and
+	// "CONJURE-OSSH".
+
 	// For the default, an empty list, all protocols are used.
 	LimitTunnelProtocols []string
 
@@ -451,10 +452,10 @@ type Config struct {
 	// and testing only.
 	EmitSLOKs bool
 
-	// EmitTapdanceLogs indicates whether to emit gotapdance log messages
-	// to stdout. Note that gotapdance log messages do not conform to the
-	// Notice format standard. Default is off.
-	EmitTapdanceLogs bool
+	// EmitRefractionNetworkingLogs indicates whether to emit gotapdance log
+	// messages to stdout. Note that gotapdance log messages do not conform to
+	// the Notice format standard. Default is off.
+	EmitRefractionNetworkingLogs bool
 
 	// EmitServerAlerts indicates whether to emit notices for server alerts.
 	EmitServerAlerts bool
@@ -978,15 +979,6 @@ func (config *Config) Commit(migrateFromLegacyFields bool) error {
 		}
 	}
 
-	// Create tapdance directory
-	tapdanceDirectoryPath := config.GetTapdanceDirectory()
-	if !common.FileExists(tapdanceDirectoryPath) {
-		err := os.Mkdir(tapdanceDirectoryPath, os.ModePerm)
-		if err != nil {
-			return errors.Tracef("failed to create tapdance directory %s with error: %s", tapdanceDirectoryPath, err.Error())
-		}
-	}
-
 	if config.ClientVersion == "" {
 		config.ClientVersion = "0"
 	}
@@ -1331,12 +1323,6 @@ func (config *Config) GetUpgradeDownloadFilename() string {
 	return filepath.Join(config.GetPsiphonDataDirectory(), UpgradeDownloadFilename)
 }
 
-// GetTapdanceDirectory returns the directory under which tapdance will create
-// and manage files.
-func (config *Config) GetTapdanceDirectory() string {
-	return filepath.Join(config.GetPsiphonDataDirectory(), "tapdance")
-}
-
 // UseUpstreamProxy indicates if an upstream proxy has been
 // configured.
 func (config *Config) UseUpstreamProxy() bool {
@@ -1902,11 +1888,6 @@ func migrationsFromLegacyFilePaths(config *Config) ([]common.FileMigration, erro
 			OldPath: filepath.Join(config.MigrateDataStoreDirectory, "psiphon.boltdb.lock"),
 			NewPath: filepath.Join(config.GetDataStoreDirectory(), "psiphon.boltdb.lock"),
 		},
-		{
-			OldPath: filepath.Join(config.MigrateDataStoreDirectory, "tapdance"),
-			NewPath: filepath.Join(config.GetTapdanceDirectory(), "tapdance"),
-			IsDir:   true,
-		},
 	}
 
 	if config.MigrateRemoteServerListDownloadFilename != "" {

psiphon/config_test.go

@@ -299,17 +299,6 @@ func LoadConfigMigrateTest(oslDirChildrenPreMigration []FileTree, oslDirChildren
 					{
 						Name: "psiphon.boltdb.lock",
 					},
-					{
-						Name: "tapdance",
-						Children: []FileTree{
-							{
-								Name: "file1",
-							},
-							{
-								Name: "file2",
-							},
-						},
-					},
 					{
 						Name: "non_tunnel_core_file_should_not_be_migrated",
 					},
@@ -454,22 +443,6 @@ func LoadConfigMigrateTest(oslDirChildrenPreMigration []FileTree, oslDirChildren
 									},
 								},
 							},
-							{
-								Name: "tapdance",
-								Children: []FileTree{
-									{
-										Name: "tapdance",
-										Children: []FileTree{
-											{
-												Name: "file1",
-											},
-											{
-												Name: "file2",
-											},
-										},
-									},
-								},
-							},
 							{
 								Name: "upgrade",
 							},

psiphon/dialParameters.go

@@ -113,6 +113,9 @@ type DialParameters struct {
 	QUICDialSNIAddress        string
 	ObfuscatedQUICPaddingSeed *prng.Seed
 
+	ConjureDecoyRegistrarWidth int
+	ConjureTransport           string
+
 	LivenessTestSeed *prng.Seed
 
 	APIRequestPaddingSeed *prng.Seed
@@ -168,6 +171,8 @@ func MakeDialParameters(
 	replayHostname := p.Bool(parameters.ReplayHostname)
 	replayQUICVersion := p.Bool(parameters.ReplayQUICVersion)
 	replayObfuscatedQUIC := p.Bool(parameters.ReplayObfuscatedQUIC)
+	replayConjureRegistration := p.Bool(parameters.ReplayConjureRegistration)
+	replayConjureTransport := p.Bool(parameters.ReplayConjureTransport)
 	replayLivenessTest := p.Bool(parameters.ReplayLivenessTest)
 	replayUserAgent := p.Bool(parameters.ReplayUserAgent)
 	replayAPIRequestPadding := p.Bool(parameters.ReplayAPIRequestPadding)
@@ -498,6 +503,22 @@ func MakeDialParameters(
 		}
 	}
 
+	if (!isReplay || !replayConjureRegistration) &&
+		protocol.TunnelProtocolUsesConjure(dialParams.TunnelProtocol) {
+
+		dialParams.ConjureDecoyRegistrarWidth = p.Int(parameters.ConjureDecoyRegistrarWidth)
+	}
+
+	if (!isReplay || !replayConjureTransport) &&
+		protocol.TunnelProtocolUsesConjure(dialParams.TunnelProtocol) {
+
+		dialParams.ConjureTransport = protocol.CONJURE_TRANSPORT_MIN_OSSH
+		if p.WeightedCoinFlip(
+			parameters.ConjureTransportObfs4Probability) {
+			dialParams.ConjureTransport = protocol.CONJURE_TRANSPORT_OBFS4_OSSH
+		}
+	}
+
 	if !isReplay || !replayLivenessTest {
 
 		// TODO: initialize only when LivenessTestMaxUp/DownstreamBytes > 0?
@@ -526,7 +547,10 @@ func MakeDialParameters(
 		dialParams.DirectDialAddress = fmt.Sprintf("%s:%d", serverEntry.IpAddress, serverEntry.SshObfuscatedPort)
 
 	case protocol.TUNNEL_PROTOCOL_TAPDANCE_OBFUSCATED_SSH:
-		dialParams.DirectDialAddress = fmt.Sprintf("%s:%d", serverEntry.IpAddress, serverEntry.SshObfuscatedTapdancePort)
+		dialParams.DirectDialAddress = fmt.Sprintf("%s:%d", serverEntry.IpAddress, serverEntry.SshObfuscatedTapDancePort)
+
+	case protocol.TUNNEL_PROTOCOL_CONJURE_OBFUSCATED_SSH:
+		dialParams.DirectDialAddress = fmt.Sprintf("%s:%d", serverEntry.IpAddress, serverEntry.SshObfuscatedConjurePort)
 
 	case protocol.TUNNEL_PROTOCOL_QUIC_OBFUSCATED_SSH:
 		dialParams.DirectDialAddress = fmt.Sprintf("%s:%d", serverEntry.IpAddress, serverEntry.SshObfuscatedQUICPort)

psiphon/dialParameters_test.go

@@ -519,8 +519,9 @@ func makeMockServerEntries(tunnelProtocol string, count int) []*protocol.ServerE
 			SshPort:                    1,
 			SshObfuscatedPort:          2,
 			SshObfuscatedQUICPort:      3,
-			SshObfuscatedTapdancePort:  4,
-			MeekServerPort:             5,
+			SshObfuscatedTapDancePort:  4,
+			SshObfuscatedConjurePort:   5,
+			MeekServerPort:             6,
 			MeekFrontingHosts:          []string{"www1.example.org", "www2.example.org", "www3.example.org"},
 			MeekFrontingAddressesRegex: "[a-z0-9]{1,64}.example.org",
 			LocalSource:                protocol.SERVER_ENTRY_SOURCE_EMBEDDED,

psiphon/interrupt_dials_test.go

@@ -29,33 +29,34 @@ import (
 	"testing"
 	"time"
 
+	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/parameters"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/prng"
 )
 
 func TestInterruptDials(t *testing.T) {
 
-	makeDialers := make(map[string]func(string) Dialer)
+	makeDialers := make(map[string]func(string) common.Dialer)
 
-	makeDialers["TCP"] = func(string) Dialer {
+	makeDialers["TCP"] = func(string) common.Dialer {
 		return NewTCPDialer(&DialConfig{})
 	}
 
-	makeDialers["SOCKS4-Proxied"] = func(mockServerAddr string) Dialer {
+	makeDialers["SOCKS4-Proxied"] = func(mockServerAddr string) common.Dialer {
 		return NewTCPDialer(
 			&DialConfig{
 				UpstreamProxyURL: "socks4a://" + mockServerAddr,
 			})
 	}
 
-	makeDialers["SOCKS5-Proxied"] = func(mockServerAddr string) Dialer {
+	makeDialers["SOCKS5-Proxied"] = func(mockServerAddr string) common.Dialer {
 		return NewTCPDialer(
 			&DialConfig{
 				UpstreamProxyURL: "socks5://" + mockServerAddr,
 			})
 	}
 
-	makeDialers["HTTP-CONNECT-Proxied"] = func(mockServerAddr string) Dialer {
+	makeDialers["HTTP-CONNECT-Proxied"] = func(mockServerAddr string) common.Dialer {
 		return NewTCPDialer(
 			&DialConfig{
 				UpstreamProxyURL: "http://" + mockServerAddr,
@@ -74,7 +75,7 @@ func TestInterruptDials(t *testing.T) {
 		t.Fatalf("NewSeed failed: %s", err)
 	}
 
-	makeDialers["TLS"] = func(string) Dialer {
+	makeDialers["TLS"] = func(string) common.Dialer {
 		return NewCustomTLSDialer(
 			&CustomTLSConfig{
 				Parameters:               params,
@@ -104,7 +105,7 @@ func TestInterruptDials(t *testing.T) {
 func runInterruptDials(
 	t *testing.T,
 	doTimeout bool,
-	makeDialer func(string) Dialer,
+	makeDialer func(string) common.Dialer,
 	dialGoroutineFunctionNames []string) {
 
 	t.Logf("Test timeout: %+v", doTimeout)

psiphon/meekConn.go

@@ -434,7 +434,7 @@ func DialMeek(
 
 		scheme = "http"
 
-		var dialer Dialer
+		var dialer common.Dialer
 
 		// For HTTP, and when the meekConfig.DialAddress matches the
 		// meekConfig.HostHeader, we let http.Transport handle proxying.
@@ -573,13 +573,13 @@ func DialMeek(
 type cachedTLSDialer struct {
 	usedCachedConn int32
 	cachedConn     net.Conn
-	dialer         Dialer
+	dialer         common.Dialer
 
 	mutex      sync.Mutex
 	requestCtx context.Context
 }
 
-func newCachedTLSDialer(cachedConn net.Conn, dialer Dialer) *cachedTLSDialer {
+func newCachedTLSDialer(cachedConn net.Conn, dialer common.Dialer) *cachedTLSDialer {
 	return &cachedTLSDialer{
 		cachedConn: cachedConn,
 		dialer:     dialer,

psiphon/net.go

@@ -35,6 +35,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/errors"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/fragmentor"
 	"github.com/miekg/dns"
@@ -105,6 +106,19 @@ type DialConfig struct {
 	UpstreamProxyErrorCallback func(error)
 }
 
+// WithoutFragmentor returns a copy of the DialConfig with any fragmentor
+// configuration disabled. The return value is not a deep copy and may be the
+// input DialConfig; it should not be modified.
+func (config *DialConfig) WithoutFragmentor() *DialConfig {
+	if config.FragmentorConfig == nil {
+		return config
+	}
+	newConfig := new(DialConfig)
+	*newConfig = *config
+	newConfig.FragmentorConfig = nil
+	return newConfig
+}
+
 // NetworkConnectivityChecker defines the interface to the external
 // HasNetworkConnectivity provider, which call into the host application to
 // check for network connectivity.
@@ -159,13 +173,10 @@ type NetworkIDGetter interface {
 	GetNetworkID() string
 }
 
-// Dialer is a custom network dialer.
-type Dialer func(context.Context, string, string) (net.Conn, error)
-
 // NetDialer implements an interface that matches net.Dialer.
 // Limitation: only "tcp" Dials are supported.
 type NetDialer struct {
-	dialTCP Dialer
+	dialTCP common.Dialer
 }
 
 // NewNetDialer creates a new NetDialer.
@@ -176,13 +187,21 @@ func NewNetDialer(config *DialConfig) *NetDialer {
 }
 
 func (d *NetDialer) Dial(network, address string) (net.Conn, error) {
-	return d.DialContext(context.Background(), network, address)
+	conn, err := d.DialContext(context.Background(), network, address)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+	return conn, nil
 }
 
 func (d *NetDialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
 	switch network {
 	case "tcp":
-		return d.dialTCP(ctx, "tcp", address)
+		conn, err := d.dialTCP(ctx, "tcp", address)
+		if err != nil {
+			return nil, errors.Trace(err)
+		}
+		return conn, nil
 	default:
 		return nil, errors.Tracef("unsupported network: %s", network)
 	}

psiphon/notice.go

@@ -510,6 +510,10 @@ func noticeWithDialParameters(noticeType string, dialParams *DialParameters) {
 			args = append(args, "networkLatencyMultiplier", dialParams.NetworkLatencyMultiplier)
 		}
 
+		if dialParams.ConjureTransport != "" {
+			args = append(args, "conjureTransport", dialParams.ConjureTransport)
+		}
+
 		if dialParams.DialConnMetrics != nil {
 			metrics := dialParams.DialConnMetrics.GetMetrics()
 			for name, value := range metrics {

psiphon/server/api.go

@@ -860,6 +860,7 @@ var baseDialParams = []requestParamSpec{
 	{"network_latency_multiplier", isFloatString, requestParamOptional | requestParamLogStringAsFloat},
 	{"client_bpf", isAnyString, requestParamOptional},
 	{"network_type", isAnyString, requestParamOptional},
+	{"conjure_transport", isAnyString, requestParamOptional},
 }
 
 // baseSessionAndDialParams adds baseDialParams to baseSessionParams.

psiphon/server/tunnelServer.go

@@ -48,8 +48,8 @@ import (
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/prng"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/protocol"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/quic"
+	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/refraction"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/tactics"
-	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/tapdance"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/tun"
 	"github.com/marusama/semaphore"
 	cache "github.com/patrickmn/go-cache"
@@ -173,13 +173,19 @@ func (server *TunnelServer) Run() error {
 				support.Config.ServerIPAddress,
 				support.Config.MarionetteFormat)
 
+		} else if protocol.TunnelProtocolUsesRefractionNetworking(tunnelProtocol) {
+
+			listener, err = refraction.Listen(localAddress)
+
+		} else if protocol.TunnelProtocolUsesFrontedMeek(tunnelProtocol) {
+
+			listener, err = net.Listen("tcp", localAddress)
+
 		} else {
 
+			// Only direct, unfronted protocol listeners use TCP BPF circumvention
+			// programs.
 			listener, BPFProgramName, err = newTCPListenerWithBPF(support, localAddress)
-
-			if protocol.TunnelProtocolUsesTapdance(tunnelProtocol) {
-				listener, err = tapdance.Listen(listener)
-			}
 		}
 
 		if err != nil {

psiphon/serverApi.go

@@ -996,6 +996,10 @@ func getBaseAPIParameters(
 				fmt.Sprintf("%f", dialParams.NetworkLatencyMultiplier)
 		}
 
+		if dialParams.ConjureTransport != "" {
+			params["conjure_transport"] = dialParams.ConjureTransport
+		}
+
 		if dialParams.DialConnMetrics != nil {
 			metrics := dialParams.DialConnMetrics.GetMetrics()
 			for name, value := range metrics {

psiphon/tlsDialer.go

@@ -81,7 +81,7 @@ type CustomTLSConfig struct {
 
 	// Dial is the network connection dialer. TLS is layered on
 	// top of a new network connection created with dialer.
-	Dial Dialer
+	Dial common.Dialer
 
 	// DialAddr overrides the "addr" input to Dial when specified
 	DialAddr string
@@ -363,7 +363,7 @@ func IsTLSConnUsingHTTP2(conn net.Conn) bool {
 }
 
 // NewCustomTLSDialer creates a new dialer based on CustomTLSDial.
-func NewCustomTLSDialer(config *CustomTLSConfig) Dialer {
+func NewCustomTLSDialer(config *CustomTLSConfig) common.Dialer {
 	return func(ctx context.Context, network, addr string) (net.Conn, error) {
 		return CustomTLSDial(ctx, network, addr, config)
 	}

psiphon/tunnel.go

@@ -42,8 +42,8 @@ import (
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/prng"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/protocol"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/quic"
+	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/refraction"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/tactics"
-	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/tapdance"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/transferstats"
 )
 
@@ -742,18 +742,40 @@ func dialTunnel(
 			return nil, errors.Trace(err)
 		}
 
-	} else if protocol.TunnelProtocolUsesTapdance(dialParams.TunnelProtocol) {
+	} else if protocol.TunnelProtocolUsesTapDance(dialParams.TunnelProtocol) {
 
-		dialConn, err = tapdance.Dial(
+		dialConn, err = refraction.DialTapDance(
 			ctx,
-			config.EmitTapdanceLogs,
-			config.GetTapdanceDirectory(),
+			config.EmitRefractionNetworkingLogs,
+			config.GetPsiphonDataDirectory(),
 			NewNetDialer(dialParams.GetDialConfig()),
 			dialParams.DirectDialAddress)
 		if err != nil {
 			return nil, errors.Trace(err)
 		}
 
+	} else if protocol.TunnelProtocolUsesConjure(dialParams.TunnelProtocol) {
+
+		// The Conjure "phantom" connection is compatible with fragmentation, but
+		// the decoy registrar connection, like Tapdance, is not, so force it off.
+		// Any tunnel fragmentation metrics will refer to the "phantom" connection
+		// only.
+		decoyRegistrarDialer := NewNetDialer(
+			dialParams.GetDialConfig().WithoutFragmentor())
+
+		dialConn, err = refraction.DialConjure(
+			ctx,
+			config.EmitRefractionNetworkingLogs,
+			config.GetPsiphonDataDirectory(),
+			NewNetDialer(dialParams.GetDialConfig()),
+			decoyRegistrarDialer,
+			dialParams.ConjureDecoyRegistrarWidth,
+			dialParams.ConjureTransport,
+			dialParams.DirectDialAddress)
+		if err != nil {
+			return nil, errors.Trace(err)
+		}
+
 	} else {
 
 		dialConn, err = DialTCP(

psiphon/utils.go

@@ -39,8 +39,8 @@ import (
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/errors"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/marionette"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/quic"
+	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/refraction"
 	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/stacktrace"
-	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/tapdance"
 )
 
 // MakePsiphonUserAgent constructs a User-Agent value to use for web service
@@ -277,6 +277,6 @@ func (c conditionallyEnabledComponents) MarionetteEnabled() bool {
 	return marionette.Enabled()
 }
 
-func (c conditionallyEnabledComponents) TapdanceEnabled() bool {
-	return tapdance.Enabled()
+func (c conditionallyEnabledComponents) RefractionNetworkingEnabled() bool {
+	return refraction.Enabled()
 }

vendor/git.torproject.org/pluggable-transports/goptlib.git/COPYING

@@ -0,0 +1,121 @@
+Creative Commons Legal Code
+
+CC0 1.0 Universal
+
+    CREATIVE COMMONS CORPORATION IS NOT A LAW FIRM AND DOES NOT PROVIDE
+    LEGAL SERVICES. DISTRIBUTION OF THIS DOCUMENT DOES NOT CREATE AN
+    ATTORNEY-CLIENT RELATIONSHIP. CREATIVE COMMONS PROVIDES THIS
+    INFORMATION ON AN "AS-IS" BASIS. CREATIVE COMMONS MAKES NO WARRANTIES
+    REGARDING THE USE OF THIS DOCUMENT OR THE INFORMATION OR WORKS
+    PROVIDED HEREUNDER, AND DISCLAIMS LIABILITY FOR DAMAGES RESULTING FROM
+    THE USE OF THIS DOCUMENT OR THE INFORMATION OR WORKS PROVIDED
+    HEREUNDER.
+
+Statement of Purpose
+
+The laws of most jurisdictions throughout the world automatically confer
+exclusive Copyright and Related Rights (defined below) upon the creator
+and subsequent owner(s) (each and all, an "owner") of an original work of
+authorship and/or a database (each, a "Work").
+
+Certain owners wish to permanently relinquish those rights to a Work for
+the purpose of contributing to a commons of creative, cultural and
+scientific works ("Commons") that the public can reliably and without fear
+of later claims of infringement build upon, modify, incorporate in other
+works, reuse and redistribute as freely as possible in any form whatsoever
+and for any purposes, including without limitation commercial purposes.
+These owners may contribute to the Commons to promote the ideal of a free
+culture and the further production of creative, cultural and scientific
+works, or to gain reputation or greater distribution for their Work in
+part through the use and efforts of others.
+
+For these and/or other purposes and motivations, and without any
+expectation of additional consideration or compensation, the person
+associating CC0 with a Work (the "Affirmer"), to the extent that he or she
+is an owner of Copyright and Related Rights in the Work, voluntarily
+elects to apply CC0 to the Work and publicly distribute the Work under its
+terms, with knowledge of his or her Copyright and Related Rights in the
+Work and the meaning and intended legal effect of CC0 on those rights.
+
+1. Copyright and Related Rights. A Work made available under CC0 may be
+protected by copyright and related or neighboring rights ("Copyright and
+Related Rights"). Copyright and Related Rights include, but are not
+limited to, the following:
+
+  i. the right to reproduce, adapt, distribute, perform, display,
+     communicate, and translate a Work;
+ ii. moral rights retained by the original author(s) and/or performer(s);
+iii. publicity and privacy rights pertaining to a person's image or
+     likeness depicted in a Work;
+ iv. rights protecting against unfair competition in regards to a Work,
+     subject to the limitations in paragraph 4(a), below;
+  v. rights protecting the extraction, dissemination, use and reuse of data
+     in a Work;
+ vi. database rights (such as those arising under Directive 96/9/EC of the
+     European Parliament and of the Council of 11 March 1996 on the legal
+     protection of databases, and under any national implementation
+     thereof, including any amended or successor version of such
+     directive); and
+vii. other similar, equivalent or corresponding rights throughout the
+     world based on applicable law or treaty, and any national
+     implementations thereof.
+
+2. Waiver. To the greatest extent permitted by, but not in contravention
+of, applicable law, Affirmer hereby overtly, fully, permanently,
+irrevocably and unconditionally waives, abandons, and surrenders all of
+Affirmer's Copyright and Related Rights and associated claims and causes
+of action, whether now known or unknown (including existing as well as
+future claims and causes of action), in the Work (i) in all territories
+worldwide, (ii) for the maximum duration provided by applicable law or
+treaty (including future time extensions), (iii) in any current or future
+medium and for any number of copies, and (iv) for any purpose whatsoever,
+including without limitation commercial, advertising or promotional
+purposes (the "Waiver"). Affirmer makes the Waiver for the benefit of each
+member of the public at large and to the detriment of Affirmer's heirs and
+successors, fully intending that such Waiver shall not be subject to
+revocation, rescission, cancellation, termination, or any other legal or
+equitable action to disrupt the quiet enjoyment of the Work by the public
+as contemplated by Affirmer's express Statement of Purpose.
+
+3. Public License Fallback. Should any part of the Waiver for any reason
+be judged legally invalid or ineffective under applicable law, then the
+Waiver shall be preserved to the maximum extent permitted taking into
+account Affirmer's express Statement of Purpose. In addition, to the
+extent the Waiver is so judged Affirmer hereby grants to each affected
+person a royalty-free, non transferable, non sublicensable, non exclusive,
+irrevocable and unconditional license to exercise Affirmer's Copyright and
+Related Rights in the Work (i) in all territories worldwide, (ii) for the
+maximum duration provided by applicable law or treaty (including future
+time extensions), (iii) in any current or future medium and for any number
+of copies, and (iv) for any purpose whatsoever, including without
+limitation commercial, advertising or promotional purposes (the
+"License"). The License shall be deemed effective as of the date CC0 was
+applied by Affirmer to the Work. Should any part of the License for any
+reason be judged legally invalid or ineffective under applicable law, such
+partial invalidity or ineffectiveness shall not invalidate the remainder
+of the License, and in such case Affirmer hereby affirms that he or she
+will not (i) exercise any of his or her remaining Copyright and Related
+Rights in the Work or (ii) assert any associated claims and causes of
+action with respect to the Work, in either case contrary to Affirmer's
+express Statement of Purpose.
+
+4. Limitations and Disclaimers.
+
+ a. No trademark or patent rights held by Affirmer are waived, abandoned,
+    surrendered, licensed or otherwise affected by this document.
+ b. Affirmer offers the Work as-is and makes no representations or
+    warranties of any kind concerning the Work, express, implied,
+    statutory or otherwise, including without limitation warranties of
+    title, merchantability, fitness for a particular purpose, non
+    infringement, or the absence of latent or other defects, accuracy, or
+    the present or absence of errors, whether or not discoverable, all to
+    the greatest extent permissible under applicable law.
+ c. Affirmer disclaims responsibility for clearing rights of other persons
+    that may apply to the Work or any use thereof, including without
+    limitation any person's Copyright and Related Rights in the Work.
+    Further, Affirmer disclaims responsibility for obtaining any necessary
+    consents, permissions or other rights required for any use of the
+    Work.
+ d. Affirmer understands and acknowledges that Creative Commons is not a
+    party to this document and has no duty or obligation with respect to
+    this CC0 or use of the Work.

vendor/git.torproject.org/pluggable-transports/goptlib.git/ChangeLog

@@ -0,0 +1,60 @@
+== v1.1.0
+
+Added the Log function.
+https://bugs.torproject.org/28940
+
+== v1.0.0
+
+Changed the tag naming scheme to work better with Go modules.
+https://github.com/golang/go/wiki/Modules#semantic-import-versioning
+
+== 0.7
+
+Fixed the ProxyError function; previously it would always panic.
+
+Repeated transport names in TOR_PT_SERVER_BINDADDR now result in an
+ENV-ERROR.
+https://bugs.torproject.org/21261
+
+== 0.6
+
+Remove all support for the "*" transport specification. The argument to
+the ClientSetup and ServerSetup functions is now unused.
+https://bugs.torproject.org/15612
+
+Replaced SOCKS4a with SOCKS5.
+https://bugs.torproject.org/12535
+
+== 0.5
+
+The AcceptSocks function no longer reports non-permanent errors, such as
+those caused by a faulty SOCKS handshake.
+
+Added support for an upstream proxy (TOR_PT_PROXY). The two new
+functions are ProxyError and ProxyDone. The ClientInfo struct has a new
+ProxyURL member.
+https://bugs.torproject.org/12125
+
+== 0.4
+
+Read the ExtORPort cookie file on every call to DialOr, instead of
+reading it once and caching the result. This is to work around a tor bug
+where tor doesn't ensure a new cookie file is written before starting
+pluggable transports.
+https://bugs.torproject.org/15240
+
+== 0.3
+
+Made output functions panic intead of backslash-escaping. Escaping of
+invalid bytes is not specified by pt-spec, and backslashes conflicted
+with the specified escaping of SMETHOD ARGS.
+https://bugs.torproject.org/13370
+
+== 0.2
+
+Added the MakeStateDir function.
+
+== 0.1
+== 0.0
+
+Initial release.

vendor/git.torproject.org/pluggable-transports/goptlib.git/README

@@ -0,0 +1,27 @@
+goptlib is a library for writing Tor pluggable transports in Go.
+
+https://spec.torproject.org/pt-spec
+https://gitweb.torproject.org/torspec.git/tree/proposals/196-transport-control-ports.txt
+https://gitweb.torproject.org/torspec.git/tree/proposals/217-ext-orport-auth.txt
+https://gitweb.torproject.org/torspec.git/tree/proposals/232-pluggable-transports-through-proxy.txt
+
+To download a copy of the library into $GOPATH:
+	go get git.torproject.org/pluggable-transports/goptlib.git
+
+See the included example programs for examples of how to use the
+library. To build them, enter their directory and run "go build".
+	examples/dummy-client/dummy-client.go
+	examples/dummy-server/dummy-server.go
+The recommended way to start writing a new transport plugin is to copy
+dummy-client or dummy-server and make changes to it.
+
+There is browseable documentation here:
+https://godoc.org/git.torproject.org/pluggable-transports/goptlib.git
+
+Report bugs to the [email protected] mailing list or to the
+bug tracker at https://trac.torproject.org/projects/tor.
+
+To the extent possible under law, the authors have dedicated all
+copyright and related and neighboring rights to this software to the
+public domain worldwide. This software is distributed without any
+warranty. See COPYING.

vendor/git.torproject.org/pluggable-transports/goptlib.git/args.go

@@ -0,0 +1,219 @@
+package pt
+
+import (
+	"bytes"
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// Key–value mappings for the representation of client and server options.
+
+// Args maps a string key to a list of values. It is similar to url.Values.
+type Args map[string][]string
+
+// Get the first value associated with the given key. If there are any values
+// associated with the key, the value return has the value and ok is set to
+// true. If there are no values for the given key, value is "" and ok is false.
+// If you need access to multiple values, use the map directly.
+func (args Args) Get(key string) (value string, ok bool) {
+	if args == nil {
+		return "", false
+	}
+	vals, ok := args[key]
+	if !ok || len(vals) == 0 {
+		return "", false
+	}
+	return vals[0], true
+}
+
+// Append value to the list of values for key.
+func (args Args) Add(key, value string) {
+	args[key] = append(args[key], value)
+}
+
+// Return the index of the next unescaped byte in s that is in the term set, or
+// else the length of the string if no terminators appear. Additionally return
+// the unescaped string up to the returned index.
+func indexUnescaped(s string, term []byte) (int, string, error) {
+	var i int
+	unesc := make([]byte, 0)
+	for i = 0; i < len(s); i++ {
+		b := s[i]
+		// A terminator byte?
+		if bytes.IndexByte(term, b) != -1 {
+			break
+		}
+		if b == '\\' {
+			i++
+			if i >= len(s) {
+				return 0, "", fmt.Errorf("nothing following final escape in %q", s)
+			}
+			b = s[i]
+		}
+		unesc = append(unesc, b)
+	}
+	return i, string(unesc), nil
+}
+
+// Parse a name–value mapping as from an encoded SOCKS username/password.
+//
+// "First the '<Key>=<Value>' formatted arguments MUST be escaped, such that all
+// backslash, equal sign, and semicolon characters are escaped with a
+// backslash."
+func parseClientParameters(s string) (args Args, err error) {
+	args = make(Args)
+	if len(s) == 0 {
+		return
+	}
+	i := 0
+	for {
+		var key, value string
+		var offset, begin int
+
+		begin = i
+		// Read the key.
+		offset, key, err = indexUnescaped(s[i:], []byte{'=', ';'})
+		if err != nil {
+			return
+		}
+		i += offset
+		// End of string or no equals sign?
+		if i >= len(s) || s[i] != '=' {
+			err = fmt.Errorf("no equals sign in %q", s[begin:i])
+			return
+		}
+		// Skip the equals sign.
+		i++
+		// Read the value.
+		offset, value, err = indexUnescaped(s[i:], []byte{';'})
+		if err != nil {
+			return
+		}
+		i += offset
+		if len(key) == 0 {
+			err = fmt.Errorf("empty key in %q", s[begin:i])
+			return
+		}
+		args.Add(key, value)
+		if i >= len(s) {
+			break
+		}
+		// Skip the semicolon.
+		i++
+	}
+	return args, nil
+}
+
+// Parse a transport–name–value mapping as from TOR_PT_SERVER_TRANSPORT_OPTIONS.
+//
+// "...a semicolon-separated list of <key>:<value> pairs, where <key> is a PT
+// name and <value> is a k=v string value with options that are to be passed to
+// the transport. Colons, semicolons, equal signs and backslashes must be
+// escaped with a backslash."
+// Example: scramblesuit:key=banana;automata:rule=110;automata:depth=3
+func parseServerTransportOptions(s string) (opts map[string]Args, err error) {
+	opts = make(map[string]Args)
+	if len(s) == 0 {
+		return
+	}
+	i := 0
+	for {
+		var methodName, key, value string
+		var offset, begin int
+
+		begin = i
+		// Read the method name.
+		offset, methodName, err = indexUnescaped(s[i:], []byte{':', '=', ';'})
+		if err != nil {
+			return
+		}
+		i += offset
+		// End of string or no colon?
+		if i >= len(s) || s[i] != ':' {
+			err = fmt.Errorf("no colon in %q", s[begin:i])
+			return
+		}
+		// Skip the colon.
+		i++
+		// Read the key.
+		offset, key, err = indexUnescaped(s[i:], []byte{'=', ';'})
+		if err != nil {
+			return
+		}
+		i += offset
+		// End of string or no equals sign?
+		if i >= len(s) || s[i] != '=' {
+			err = fmt.Errorf("no equals sign in %q", s[begin:i])
+			return
+		}
+		// Skip the equals sign.
+		i++
+		// Read the value.
+		offset, value, err = indexUnescaped(s[i:], []byte{';'})
+		if err != nil {
+			return
+		}
+		i += offset
+		if len(methodName) == 0 {
+			err = fmt.Errorf("empty method name in %q", s[begin:i])
+			return
+		}
+		if len(key) == 0 {
+			err = fmt.Errorf("empty key in %q", s[begin:i])
+			return
+		}
+		if opts[methodName] == nil {
+			opts[methodName] = make(Args)
+		}
+		opts[methodName].Add(key, value)
+		if i >= len(s) {
+			break
+		}
+		// Skip the semicolon.
+		i++
+	}
+	return opts, nil
+}
+
+// Escape backslashes and all the bytes that are in set.
+func backslashEscape(s string, set []byte) string {
+	var buf bytes.Buffer
+	for _, b := range []byte(s) {
+		if b == '\\' || bytes.IndexByte(set, b) != -1 {
+			buf.WriteByte('\\')
+		}
+		buf.WriteByte(b)
+	}
+	return buf.String()
+}
+
+// Encode a name–value mapping so that it is suitable to go in the ARGS option
+// of an SMETHOD line. The output is sorted by key. The "ARGS:" prefix is not
+// added.
+//
+// "Equal signs and commas [and backslashes] MUST be escaped with a backslash."
+func encodeSmethodArgs(args Args) string {
+	if args == nil {
+		return ""
+	}
+
+	keys := make([]string, 0, len(args))
+	for key := range args {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+
+	escape := func(s string) string {
+		return backslashEscape(s, []byte{'=', ','})
+	}
+
+	var pairs []string
+	for _, key := range keys {
+		for _, value := range args[key] {
+			pairs = append(pairs, escape(key)+"="+escape(value))
+		}
+	}
+
+	return strings.Join(pairs, ",")
+}

vendor/git.torproject.org/pluggable-transports/goptlib.git/pt.go

@@ -0,0 +1,1033 @@
+// Package pt implements the Tor pluggable transports specification.
+//
+// Sample client usage:
+// 	var ptInfo pt.ClientInfo
+// 	...
+// 	func handler(conn *pt.SocksConn) error {
+// 		defer conn.Close()
+// 		remote, err := net.Dial("tcp", conn.Req.Target)
+// 		if err != nil {
+// 			conn.Reject()
+// 			return err
+// 		}
+// 		defer remote.Close()
+// 		err = conn.Grant(remote.RemoteAddr().(*net.TCPAddr))
+// 		if err != nil {
+// 			return err
+// 		}
+// 		// do something with conn and remote.
+// 		return nil
+// 	}
+// 	func acceptLoop(ln *pt.SocksListener) error {
+// 		defer ln.Close()
+// 		for {
+// 			conn, err := ln.AcceptSocks()
+// 			if err != nil {
+// 				if e, ok := err.(net.Error); ok && e.Temporary() {
+// 					pt.Log(pt.LogSeverityError, "accept error: " + err.Error())
+// 					continue
+// 				}
+// 				return err
+// 			}
+// 			go handler(conn)
+// 		}
+// 		return nil
+// 	}
+// 	...
+// 	func main() {
+// 		var err error
+// 		ptInfo, err = pt.ClientSetup(nil)
+// 		if err != nil {
+// 			os.Exit(1)
+// 		}
+// 		if ptInfo.ProxyURL != nil {
+// 			// you need to interpret the proxy URL yourself
+// 			// call pt.ProxyDone instead if it's a type you understand
+// 			pt.ProxyError(fmt.Sprintf("proxy %s is not supported", ptInfo.ProxyURL))
+// 			os.Exit(1)
+// 		}
+// 		for _, methodName := range ptInfo.MethodNames {
+// 			switch methodName {
+// 			case "foo":
+// 				ln, err := pt.ListenSocks("tcp", "127.0.0.1:0")
+// 				if err != nil {
+// 					pt.CmethodError(methodName, err.Error())
+// 					break
+// 				}
+// 				go acceptLoop(ln)
+// 				pt.Cmethod(methodName, ln.Version(), ln.Addr())
+// 			default:
+// 				pt.CmethodError(methodName, "no such method")
+// 			}
+// 		}
+// 		pt.CmethodsDone()
+// 	}
+//
+// Sample server usage:
+// 	var ptInfo pt.ServerInfo
+// 	...
+// 	func handler(conn net.Conn) error {
+// 		defer conn.Close()
+// 		or, err := pt.DialOr(&ptInfo, conn.RemoteAddr().String(), "foo")
+// 		if err != nil {
+// 			return
+// 		}
+// 		defer or.Close()
+// 		// do something with or and conn
+// 		return nil
+// 	}
+// 	func acceptLoop(ln net.Listener) error {
+// 		defer ln.Close()
+// 		for {
+// 			conn, err := ln.Accept()
+// 			if err != nil {
+// 				if e, ok := err.(net.Error); ok && e.Temporary() {
+// 					continue
+// 				}
+// 				pt.Log(pt.LogSeverityError, "accept error: " + err.Error())
+// 				return err
+// 			}
+// 			go handler(conn)
+// 		}
+// 		return nil
+// 	}
+// 	...
+// 	func main() {
+// 		var err error
+// 		ptInfo, err = pt.ServerSetup(nil)
+// 		if err != nil {
+// 			os.Exit(1)
+// 		}
+// 		for _, bindaddr := range ptInfo.Bindaddrs {
+// 			switch bindaddr.MethodName {
+// 			case "foo":
+// 				ln, err := net.ListenTCP("tcp", bindaddr.Addr)
+// 				if err != nil {
+// 					pt.SmethodError(bindaddr.MethodName, err.Error())
+// 					break
+// 				}
+// 				go acceptLoop(ln)
+// 				pt.Smethod(bindaddr.MethodName, ln.Addr())
+// 			default:
+// 				pt.SmethodError(bindaddr.MethodName, "no such method")
+// 			}
+// 		}
+// 		pt.SmethodsDone()
+// 	}
+//
+// Some additional care is needed to handle signals and shutdown properly. See
+// the example programs dummy-client and dummy-server.
+//
+// Tor pluggable transports specification:
+// https://spec.torproject.org/pt-spec
+//
+// Extended ORPort:
+// https://gitweb.torproject.org/torspec.git/tree/proposals/196-transport-control-ports.txt
+//
+// Extended ORPort Authentication:
+// https://gitweb.torproject.org/torspec.git/tree/proposals/217-ext-orport-auth.txt
+//
+// Pluggable Transport through SOCKS proxy:
+// https://gitweb.torproject.org/torspec.git/tree/proposals/232-pluggable-transports-through-proxy.txt
+//
+// The package implements a SOCKS5 server sufficient for a Tor client transport
+// plugin.
+//
+// https://www.ietf.org/rfc/rfc1928.txt
+// https://www.ietf.org/rfc/rfc1929.txt
+package pt
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"crypto/subtle"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"net"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// This type wraps a Write method and calls Sync after each Write.
+type syncWriter struct {
+	*os.File
+}
+
+// Call File.Write and then Sync. An error is returned if either operation
+// returns an error.
+func (w syncWriter) Write(p []byte) (n int, err error) {
+	n, err = w.File.Write(p)
+	if err != nil {
+		return
+	}
+	err = w.Sync()
+	return
+}
+
+// Writer to which pluggable transports negotiation messages are written. It
+// defaults to a Writer that writes to os.Stdout and calls Sync after each
+// write.
+//
+// You may, for example, log pluggable transports messages by defining a Writer
+// that logs what is written to it:
+// 	type logWriteWrapper struct {
+// 		io.Writer
+// 	}
+//
+// 	func (w logWriteWrapper) Write(p []byte) (int, error) {
+// 		log.Print(string(p))
+// 		return w.Writer.Write(p)
+// 	}
+// and then redefining Stdout:
+// 	pt.Stdout = logWriteWrapper{pt.Stdout}
+var Stdout io.Writer = syncWriter{os.Stdout}
+
+// Represents an error that can happen during negotiation, for example
+// ENV-ERROR. When an error occurs, we print it to stdout and also pass it up
+// the return chain.
+type ptErr struct {
+	Keyword string
+	Args    []string
+}
+
+// Implements the error interface.
+func (err *ptErr) Error() string {
+	return formatline(err.Keyword, err.Args...)
+}
+
+func getenv(key string) string {
+	return os.Getenv(key)
+}
+
+// Returns an ENV-ERROR if the environment variable isn't set.
+func getenvRequired(key string) (string, error) {
+	value := os.Getenv(key)
+	if value == "" {
+		return "", envError(fmt.Sprintf("no %s environment variable", key))
+	}
+	return value, nil
+}
+
+// Returns true iff keyword contains only bytes allowed in a PT→Tor output line
+// keyword.
+// <KeywordChar> ::= <any US-ASCII alphanumeric, dash, and underscore>
+func keywordIsSafe(keyword string) bool {
+	for _, b := range []byte(keyword) {
+		switch {
+		case '0' <= b && b <= '9':
+			continue
+		case 'A' <= b && b <= 'Z':
+			continue
+		case 'a' <= b && b <= 'z':
+			continue
+		case b == '-' || b == '_':
+			continue
+		default:
+			return false
+		}
+	}
+	return true
+}
+
+// Returns true iff arg contains only bytes allowed in a PT→Tor output line arg.
+// <ArgChar> ::= <any US-ASCII character but NUL or NL>
+func argIsSafe(arg string) bool {
+	for _, b := range []byte(arg) {
+		if b >= '\x80' || b == '\x00' || b == '\n' {
+			return false
+		}
+	}
+	return true
+}
+
+func formatline(keyword string, v ...string) string {
+	var buf bytes.Buffer
+	if !keywordIsSafe(keyword) {
+		panic(fmt.Sprintf("keyword %q contains forbidden bytes", keyword))
+	}
+	buf.WriteString(keyword)
+	for _, x := range v {
+		if !argIsSafe(x) {
+			panic(fmt.Sprintf("arg %q contains forbidden bytes", x))
+		}
+		buf.WriteString(" " + x)
+	}
+	return buf.String()
+}
+
+// Print a pluggable transports protocol line to Stdout. The line consists of a
+// keyword followed by any number of space-separated arg strings. Panics if
+// there are forbidden bytes in the keyword or the args (pt-spec.txt 2.2.1).
+func line(keyword string, v ...string) {
+	fmt.Fprintln(Stdout, formatline(keyword, v...))
+}
+
+// Emit and return the given error as a ptErr.
+func doError(keyword string, v ...string) *ptErr {
+	line(keyword, v...)
+	return &ptErr{keyword, v}
+}
+
+// Emit an ENV-ERROR line with explanation text. Returns a representation of the
+// error.
+func envError(msg string) error {
+	return doError("ENV-ERROR", msg)
+}
+
+// Emit a VERSION-ERROR line with explanation text. Returns a representation of
+// the error.
+func versionError(msg string) error {
+	return doError("VERSION-ERROR", msg)
+}
+
+// Emit a CMETHOD-ERROR line with explanation text. Returns a representation of
+// the error.
+func CmethodError(methodName, msg string) error {
+	return doError("CMETHOD-ERROR", methodName, msg)
+}
+
+// Emit an SMETHOD-ERROR line with explanation text. Returns a representation of
+// the error.
+func SmethodError(methodName, msg string) error {
+	return doError("SMETHOD-ERROR", methodName, msg)
+}
+
+// Emit a PROXY-ERROR line with explanation text. Returns a representation of
+// the error.
+func ProxyError(msg string) error {
+	return doError("PROXY-ERROR", msg)
+}
+
+// Emit a CMETHOD line. socks must be "socks4" or "socks5". Call this once for
+// each listening client SOCKS port.
+func Cmethod(name string, socks string, addr net.Addr) {
+	line("CMETHOD", name, socks, addr.String())
+}
+
+// Emit a CMETHODS DONE line. Call this after opening all client listeners.
+func CmethodsDone() {
+	line("CMETHODS", "DONE")
+}
+
+// Emit an SMETHOD line. Call this once for each listening server port.
+func Smethod(name string, addr net.Addr) {
+	line("SMETHOD", name, addr.String())
+}
+
+// Emit an SMETHOD line with an ARGS option. args is a name–value mapping that
+// will be added to the server's extrainfo document.
+//
+// This is an example of how to check for a required option:
+// 	secret, ok := bindaddr.Options.Get("shared-secret")
+// 	if ok {
+// 		args := pt.Args{}
+// 		args.Add("shared-secret", secret)
+// 		pt.SmethodArgs(bindaddr.MethodName, ln.Addr(), args)
+// 	} else {
+// 		pt.SmethodError(bindaddr.MethodName, "need a shared-secret option")
+// 	}
+// Or, if you just want to echo back the options provided by Tor from the
+// TransportServerOptions configuration,
+// 	pt.SmethodArgs(bindaddr.MethodName, ln.Addr(), bindaddr.Options)
+func SmethodArgs(name string, addr net.Addr, args Args) {
+	line("SMETHOD", name, addr.String(), "ARGS:"+encodeSmethodArgs(args))
+}
+
+// Emit an SMETHODS DONE line. Call this after opening all server listeners.
+func SmethodsDone() {
+	line("SMETHODS", "DONE")
+}
+
+// Emit a PROXY DONE line. Call this after parsing ClientInfo.ProxyURL.
+func ProxyDone() {
+	fmt.Fprintf(Stdout, "PROXY DONE\n")
+}
+
+// Unexported type to represent log severities, preventing external callers from
+// inventing new severity strings that may violate quoting rules.
+//
+// pt-spec.txt section 3.3.4 specifies quoting for MESSAGE, but not for
+// SEVERITY, and the example shows an unquoted "SEVERITY=debug". While we know
+// tor's parser permits quoting of SEVERITY, it's not actually specified.
+// Therefore we we need to guard against callers passing a string that violates
+// the global protocol constraint of "any US-ASCII character but NUL or NL." So
+// here, we instantiate exactly the five supported severities, using a type that
+// cannot be constructed outside the package.
+type logSeverity struct {
+	string
+}
+
+// Severity levels for the Log function.
+var (
+	LogSeverityError   = logSeverity{"error"}
+	LogSeverityWarning = logSeverity{"warning"}
+	LogSeverityNotice  = logSeverity{"notice"}
+	LogSeverityInfo    = logSeverity{"info"}
+	LogSeverityDebug   = logSeverity{"debug"}
+)
+
+// Encode a string according to the CString rules of section 2.1.1 in
+// control-spec.txt.
+// 	CString = DQUOTE *qcontent DQUOTE
+// "...in a CString, the escapes '\n', '\t', '\r', and the octal escapes '\0'
+// ... '\377' represent newline, tab, carriage return, and the 256 possible
+// octet values respectively."
+// RFC 2822 section 3.2.5 in turn defines what byte values we need to escape:
+// everything but
+// 	NO-WS-CTL /     ; Non white space controls
+// 	%d33 /          ; The rest of the US-ASCII
+// 	%d35-91 /       ;  characters not including "\"
+// 	%d93-126        ;  or the quote character
+// Technically control-spec.txt requires us to escape the space character (32),
+// but it is an error in the spec: https://bugs.torproject.org/29432.
+//
+// We additionally need to ensure that whatever we return passes argIsSafe,
+// because strings encoded by this function are printed verbatim by Log.
+func encodeCString(s string) string {
+	result := bytes.NewBuffer([]byte{})
+	result.WriteByte('"')
+	for _, c := range []byte(s) {
+		if c == 32 || c == 33 || (35 <= c && c <= 91) || (93 <= c && c <= 126) {
+			result.WriteByte(c)
+		} else {
+			fmt.Fprintf(result, "\\%03o", c)
+		}
+	}
+	result.WriteByte('"')
+	return result.String()
+}
+
+// Emit a LOG message with the given severity (one of LogSeverityError,
+// LogSeverityWarning, LogSeverityNotice, LogSeverityInfo, or LogSeverityDebug).
+func Log(severity logSeverity, message string) {
+	// "<Message> contains the log message which can be a String or CString..."
+	// encodeCString always makes the string safe to emit; i.e., it
+	// satisfies argIsSafe.
+	line("LOG", "SEVERITY="+severity.string, "MESSAGE="+encodeCString(message))
+}
+
+// Get a pluggable transports version offered by Tor and understood by us, if
+// any. The only version we understand is "1". This function reads the
+// environment variable TOR_PT_MANAGED_TRANSPORT_VER.
+func getManagedTransportVer() (string, error) {
+	const transportVersion = "1"
+	managedTransportVer, err := getenvRequired("TOR_PT_MANAGED_TRANSPORT_VER")
+	if err != nil {
+		return "", err
+	}
+	for _, offered := range strings.Split(managedTransportVer, ",") {
+		if offered == transportVersion {
+			return offered, nil
+		}
+	}
+	return "", versionError("no-version")
+}
+
+// Return the directory name in the TOR_PT_STATE_LOCATION environment variable,
+// creating it if it doesn't exist. Returns non-nil error if
+// TOR_PT_STATE_LOCATION is not set or if there is an error creating the
+// directory.
+func MakeStateDir() (string, error) {
+	dir, err := getenvRequired("TOR_PT_STATE_LOCATION")
+	if err != nil {
+		return "", err
+	}
+	err = os.MkdirAll(dir, 0700)
+	return dir, err
+}
+
+// Get the list of method names requested by Tor. This function reads the
+// environment variable TOR_PT_CLIENT_TRANSPORTS.
+func getClientTransports() ([]string, error) {
+	clientTransports, err := getenvRequired("TOR_PT_CLIENT_TRANSPORTS")
+	if err != nil {
+		return nil, err
+	}
+	return strings.Split(clientTransports, ","), nil
+}
+
+// Get the upstream proxy URL. Returns nil if no proxy is requested. The
+// function ensures that the Scheme and Host fields are set; i.e., that the URL
+// is absolute. It additionally checks that the Host field contains both a host
+// and a port part. This function reads the environment variable TOR_PT_PROXY.
+//
+// This function doesn't check that the scheme is one of Tor's supported proxy
+// schemes; that is, one of "http", "socks5", or "socks4a". The caller must be
+// able to handle any returned scheme (which may be by calling ProxyError if
+// it doesn't know how to handle the scheme).
+func getProxyURL() (*url.URL, error) {
+	rawurl := os.Getenv("TOR_PT_PROXY")
+	if rawurl == "" {
+		return nil, nil
+	}
+	u, err := url.Parse(rawurl)
+	if err != nil {
+		return nil, err
+	}
+	if u.Scheme == "" {
+		return nil, fmt.Errorf("missing scheme")
+	}
+	if u.Host == "" {
+		return nil, fmt.Errorf("missing authority")
+	}
+	host, port, err := net.SplitHostPort(u.Host)
+	if err != nil {
+		return nil, err
+	}
+	if host == "" {
+		return nil, fmt.Errorf("missing host")
+	}
+	if port == "" {
+		return nil, fmt.Errorf("missing port")
+	}
+	return u, nil
+}
+
+// This structure is returned by ClientSetup. It consists of a list of method
+// names and the upstream proxy URL, if any.
+type ClientInfo struct {
+	MethodNames []string
+	ProxyURL    *url.URL
+}
+
+// Check the client pluggable transports environment, emitting an error message
+// and returning a non-nil error if any error is encountered. Returns a
+// ClientInfo struct.
+//
+// If your program needs to know whether to call ClientSetup or ServerSetup
+// (i.e., if the same program can be run as either a client or a server), check
+// whether the TOR_PT_CLIENT_TRANSPORTS environment variable is set:
+// 	if os.Getenv("TOR_PT_CLIENT_TRANSPORTS") != "" {
+// 		// Client mode; call pt.ClientSetup.
+// 	} else {
+// 		// Server mode; call pt.ServerSetup.
+// 	}
+//
+// Always pass nil for the unused single parameter. In the past, the parameter
+// was a list of transport names to use in case Tor requested "*". That feature
+// was never implemented and has been removed from the pluggable transports
+// specification.
+// https://bugs.torproject.org/15612
+func ClientSetup(_ []string) (info ClientInfo, err error) {
+	ver, err := getManagedTransportVer()
+	if err != nil {
+		return
+	}
+	line("VERSION", ver)
+
+	info.MethodNames, err = getClientTransports()
+	if err != nil {
+		return
+	}
+
+	info.ProxyURL, err = getProxyURL()
+	if err != nil {
+		return
+	}
+
+	return info, nil
+}
+
+// A combination of a method name and an address, as extracted from
+// TOR_PT_SERVER_BINDADDR.
+type Bindaddr struct {
+	MethodName string
+	Addr       *net.TCPAddr
+	// Options from TOR_PT_SERVER_TRANSPORT_OPTIONS that pertain to this
+	// transport.
+	Options Args
+}
+
+func parsePort(portStr string) (int, error) {
+	port, err := strconv.ParseUint(portStr, 10, 16)
+	return int(port), err
+}
+
+// Resolve an address string into a net.TCPAddr. We are a bit more strict than
+// net.ResolveTCPAddr; we don't allow an empty host or port, and the host part
+// must be a literal IP address.
+func resolveAddr(addrStr string) (*net.TCPAddr, error) {
+	ipStr, portStr, err := net.SplitHostPort(addrStr)
+	if err != nil {
+		// Before the fixing of bug #7011, tor doesn't put brackets around IPv6
+		// addresses. Split after the last colon, assuming it is a port
+		// separator, and try adding the brackets.
+		// https://bugs.torproject.org/7011
+		parts := strings.Split(addrStr, ":")
+		if len(parts) <= 2 {
+			return nil, err
+		}
+		addrStr := "[" + strings.Join(parts[:len(parts)-1], ":") + "]:" + parts[len(parts)-1]
+		ipStr, portStr, err = net.SplitHostPort(addrStr)
+	}
+	if err != nil {
+		return nil, err
+	}
+	if ipStr == "" {
+		return nil, net.InvalidAddrError(fmt.Sprintf("address string %q lacks a host part", addrStr))
+	}
+	if portStr == "" {
+		return nil, net.InvalidAddrError(fmt.Sprintf("address string %q lacks a port part", addrStr))
+	}
+	ip := net.ParseIP(ipStr)
+	if ip == nil {
+		return nil, net.InvalidAddrError(fmt.Sprintf("not an IP string: %q", ipStr))
+	}
+	port, err := parsePort(portStr)
+	if err != nil {
+		return nil, err
+	}
+	return &net.TCPAddr{IP: ip, Port: port}, nil
+}
+
+// Return a new slice, the members of which are those members of addrs having a
+// MethodName in methodNames.
+func filterBindaddrs(addrs []Bindaddr, methodNames []string) []Bindaddr {
+	var result []Bindaddr
+
+	for _, ba := range addrs {
+		for _, methodName := range methodNames {
+			if ba.MethodName == methodName {
+				result = append(result, ba)
+				break
+			}
+		}
+	}
+
+	return result
+}
+
+// Return an array of Bindaddrs, being the contents of TOR_PT_SERVER_BINDADDR
+// with keys filtered by TOR_PT_SERVER_TRANSPORTS. Transport-specific options
+// from TOR_PT_SERVER_TRANSPORT_OPTIONS are assigned to the Options member.
+func getServerBindaddrs() ([]Bindaddr, error) {
+	var result []Bindaddr
+
+	// Parse the list of server transport options.
+	serverTransportOptions := getenv("TOR_PT_SERVER_TRANSPORT_OPTIONS")
+	optionsMap, err := parseServerTransportOptions(serverTransportOptions)
+	if err != nil {
+		return nil, envError(fmt.Sprintf("TOR_PT_SERVER_TRANSPORT_OPTIONS: %q: %s", serverTransportOptions, err.Error()))
+	}
+
+	// Get the list of all requested bindaddrs.
+	serverBindaddr, err := getenvRequired("TOR_PT_SERVER_BINDADDR")
+	if err != nil {
+		return nil, err
+	}
+	seenMethods := make(map[string]bool)
+	for _, spec := range strings.Split(serverBindaddr, ",") {
+		var bindaddr Bindaddr
+
+		parts := strings.SplitN(spec, "-", 2)
+		if len(parts) != 2 {
+			return nil, envError(fmt.Sprintf("TOR_PT_SERVER_BINDADDR: %q: doesn't contain \"-\"", spec))
+		}
+		bindaddr.MethodName = parts[0]
+		// Check for duplicate method names: "Applications MUST NOT set
+		// more than one <address>:<port> pair per PT name."
+		if seenMethods[bindaddr.MethodName] {
+			return nil, envError(fmt.Sprintf("TOR_PT_SERVER_BINDADDR: %q: duplicate method name %q", spec, bindaddr.MethodName))
+		}
+		seenMethods[bindaddr.MethodName] = true
+		addr, err := resolveAddr(parts[1])
+		if err != nil {
+			return nil, envError(fmt.Sprintf("TOR_PT_SERVER_BINDADDR: %q: %s", spec, err.Error()))
+		}
+		bindaddr.Addr = addr
+		bindaddr.Options = optionsMap[bindaddr.MethodName]
+		result = append(result, bindaddr)
+	}
+
+	// Filter by TOR_PT_SERVER_TRANSPORTS.
+	serverTransports, err := getenvRequired("TOR_PT_SERVER_TRANSPORTS")
+	if err != nil {
+		return nil, err
+	}
+	result = filterBindaddrs(result, strings.Split(serverTransports, ","))
+
+	return result, nil
+}
+
+func readAuthCookie(f io.Reader) ([]byte, error) {
+	authCookieHeader := []byte("! Extended ORPort Auth Cookie !\x0a")
+	buf := make([]byte, 64)
+
+	n, err := io.ReadFull(f, buf)
+	if err != nil {
+		return nil, err
+	}
+	// Check that the file ends here.
+	n, err = f.Read(make([]byte, 1))
+	if n != 0 {
+		return nil, fmt.Errorf("file is longer than 64 bytes")
+	} else if err != io.EOF {
+		return nil, fmt.Errorf("did not find EOF at end of file")
+	}
+	header := buf[0:32]
+	cookie := buf[32:64]
+	if subtle.ConstantTimeCompare(header, authCookieHeader) != 1 {
+		return nil, fmt.Errorf("missing auth cookie header")
+	}
+
+	return cookie, nil
+}
+
+// Read and validate the contents of an auth cookie file. Returns the 32-byte
+// cookie. See section 4.2.1.2 of 217-ext-orport-auth.txt.
+func readAuthCookieFile(filename string) (cookie []byte, err error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		closeErr := f.Close()
+		if err == nil {
+			err = closeErr
+		}
+	}()
+
+	return readAuthCookie(f)
+}
+
+// This structure is returned by ServerSetup. It consists of a list of
+// Bindaddrs, an address for the ORPort, an address for the extended ORPort (if
+// any), and an authentication cookie (if any).
+type ServerInfo struct {
+	Bindaddrs      []Bindaddr
+	OrAddr         *net.TCPAddr
+	ExtendedOrAddr *net.TCPAddr
+	AuthCookiePath string
+}
+
+// Check the server pluggable transports environment, emitting an error message
+// and returning a non-nil error if any error is encountered. Resolves the
+// various requested bind addresses, the server ORPort and extended ORPort, and
+// reads the auth cookie file. Returns a ServerInfo struct.
+//
+// If your program needs to know whether to call ClientSetup or ServerSetup
+// (i.e., if the same program can be run as either a client or a server), check
+// whether the TOR_PT_CLIENT_TRANSPORTS environment variable is set:
+// 	if os.Getenv("TOR_PT_CLIENT_TRANSPORTS") != "" {
+// 		// Client mode; call pt.ClientSetup.
+// 	} else {
+// 		// Server mode; call pt.ServerSetup.
+// 	}
+//
+// Always pass nil for the unused single parameter. In the past, the parameter
+// was a list of transport names to use in case Tor requested "*". That feature
+// was never implemented and has been removed from the pluggable transports
+// specification.
+// https://bugs.torproject.org/15612
+func ServerSetup(_ []string) (info ServerInfo, err error) {
+	ver, err := getManagedTransportVer()
+	if err != nil {
+		return
+	}
+	line("VERSION", ver)
+
+	info.Bindaddrs, err = getServerBindaddrs()
+	if err != nil {
+		return
+	}
+
+	orPort := getenv("TOR_PT_ORPORT")
+	if orPort != "" {
+		info.OrAddr, err = resolveAddr(orPort)
+		if err != nil {
+			err = envError(fmt.Sprintf("cannot resolve TOR_PT_ORPORT %q: %s", orPort, err.Error()))
+			return
+		}
+	}
+
+	info.AuthCookiePath = getenv("TOR_PT_AUTH_COOKIE_FILE")
+
+	extendedOrPort := getenv("TOR_PT_EXTENDED_SERVER_PORT")
+	if extendedOrPort != "" {
+		if info.AuthCookiePath == "" {
+			err = envError("need TOR_PT_AUTH_COOKIE_FILE environment variable with TOR_PT_EXTENDED_SERVER_PORT")
+			return
+		}
+		info.ExtendedOrAddr, err = resolveAddr(extendedOrPort)
+		if err != nil {
+			err = envError(fmt.Sprintf("cannot resolve TOR_PT_EXTENDED_SERVER_PORT %q: %s", extendedOrPort, err.Error()))
+			return
+		}
+	}
+
+	// Need either OrAddr or ExtendedOrAddr.
+	if info.OrAddr == nil && info.ExtendedOrAddr == nil {
+		err = envError("need TOR_PT_ORPORT or TOR_PT_EXTENDED_SERVER_PORT environment variable")
+		return
+	}
+
+	return info, nil
+}
+
+// See 217-ext-orport-auth.txt section 4.2.1.3.
+func computeServerHash(authCookie, clientNonce, serverNonce []byte) []byte {
+	h := hmac.New(sha256.New, authCookie)
+	io.WriteString(h, "ExtORPort authentication server-to-client hash")
+	h.Write(clientNonce)
+	h.Write(serverNonce)
+	return h.Sum([]byte{})
+}
+
+// See 217-ext-orport-auth.txt section 4.2.1.3.
+func computeClientHash(authCookie, clientNonce, serverNonce []byte) []byte {
+	h := hmac.New(sha256.New, authCookie)
+	io.WriteString(h, "ExtORPort authentication client-to-server hash")
+	h.Write(clientNonce)
+	h.Write(serverNonce)
+	return h.Sum([]byte{})
+}
+
+func extOrPortAuthenticate(s io.ReadWriter, info *ServerInfo) error {
+	// Read auth types. 217-ext-orport-auth.txt section 4.1.
+	var authTypes [256]bool
+	var count int
+	for count = 0; count < 256; count++ {
+		buf := make([]byte, 1)
+		_, err := io.ReadFull(s, buf)
+		if err != nil {
+			return err
+		}
+		b := buf[0]
+		if b == 0 {
+			break
+		}
+		authTypes[b] = true
+	}
+	if count >= 256 {
+		return fmt.Errorf("read 256 auth types without seeing \\x00")
+	}
+
+	// We support only type 1, SAFE_COOKIE.
+	if !authTypes[1] {
+		return fmt.Errorf("server didn't offer auth type 1")
+	}
+	_, err := s.Write([]byte{1})
+	if err != nil {
+		return err
+	}
+
+	clientNonce := make([]byte, 32)
+	clientHash := make([]byte, 32)
+	serverNonce := make([]byte, 32)
+	serverHash := make([]byte, 32)
+
+	_, err = io.ReadFull(rand.Reader, clientNonce)
+	if err != nil {
+		return err
+	}
+	_, err = s.Write(clientNonce)
+	if err != nil {
+		return err
+	}
+
+	_, err = io.ReadFull(s, serverHash)
+	if err != nil {
+		return err
+	}
+	_, err = io.ReadFull(s, serverNonce)
+	if err != nil {
+		return err
+	}
+
+	// Work around tor bug #15240 where the auth cookie is generated after
+	// pluggable transports are launched, leading to a stale cookie getting
+	// cached forever if it is only read once as part of ServerSetup.
+	// https://bugs.torproject.org/15240
+	authCookie, err := readAuthCookieFile(info.AuthCookiePath)
+	if err != nil {
+		return fmt.Errorf("error reading TOR_PT_AUTH_COOKIE_FILE %q: %s", info.AuthCookiePath, err.Error())
+	}
+
+	expectedServerHash := computeServerHash(authCookie, clientNonce, serverNonce)
+	if subtle.ConstantTimeCompare(serverHash, expectedServerHash) != 1 {
+		return fmt.Errorf("mismatch in server hash")
+	}
+
+	clientHash = computeClientHash(authCookie, clientNonce, serverNonce)
+	_, err = s.Write(clientHash)
+	if err != nil {
+		return err
+	}
+
+	status := make([]byte, 1)
+	_, err = io.ReadFull(s, status)
+	if err != nil {
+		return err
+	}
+	if status[0] != 1 {
+		return fmt.Errorf("server rejected authentication")
+	}
+
+	return nil
+}
+
+// See section 3.1.1 of 196-transport-control-ports.txt.
+const (
+	extOrCmdDone      = 0x0000
+	extOrCmdUserAddr  = 0x0001
+	extOrCmdTransport = 0x0002
+	extOrCmdOkay      = 0x1000
+	extOrCmdDeny      = 0x1001
+)
+
+func extOrPortSendCommand(s io.Writer, cmd uint16, body []byte) error {
+	var buf bytes.Buffer
+	if len(body) > 65535 {
+		return fmt.Errorf("body length %d exceeds maximum of 65535", len(body))
+	}
+	err := binary.Write(&buf, binary.BigEndian, cmd)
+	if err != nil {
+		return err
+	}
+	err = binary.Write(&buf, binary.BigEndian, uint16(len(body)))
+	if err != nil {
+		return err
+	}
+	err = binary.Write(&buf, binary.BigEndian, body)
+	if err != nil {
+		return err
+	}
+	_, err = s.Write(buf.Bytes())
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Send a USERADDR command on s. See section 3.1.2.1 of
+// 196-transport-control-ports.txt.
+func extOrPortSendUserAddr(s io.Writer, addr string) error {
+	return extOrPortSendCommand(s, extOrCmdUserAddr, []byte(addr))
+}
+
+// Send a TRANSPORT command on s. See section 3.1.2.2 of
+// 196-transport-control-ports.txt.
+func extOrPortSendTransport(s io.Writer, methodName string) error {
+	return extOrPortSendCommand(s, extOrCmdTransport, []byte(methodName))
+}
+
+// Send a DONE command on s. See section 3.1 of 196-transport-control-ports.txt.
+func extOrPortSendDone(s io.Writer) error {
+	return extOrPortSendCommand(s, extOrCmdDone, []byte{})
+}
+
+func extOrPortRecvCommand(s io.Reader) (cmd uint16, body []byte, err error) {
+	var bodyLen uint16
+	data := make([]byte, 4)
+
+	_, err = io.ReadFull(s, data)
+	if err != nil {
+		return
+	}
+	buf := bytes.NewBuffer(data)
+	err = binary.Read(buf, binary.BigEndian, &cmd)
+	if err != nil {
+		return
+	}
+	err = binary.Read(buf, binary.BigEndian, &bodyLen)
+	if err != nil {
+		return
+	}
+	body = make([]byte, bodyLen)
+	_, err = io.ReadFull(s, body)
+	if err != nil {
+		return
+	}
+
+	return cmd, body, err
+}
+
+// Send USERADDR and TRANSPORT commands followed by a DONE command. Wait for an
+// OKAY or DENY response command from the server. If addr or methodName is "",
+// the corresponding command is not sent. Returns nil if and only if OKAY is
+// received.
+func extOrPortSetMetadata(s io.ReadWriter, addr, methodName string) error {
+	var err error
+
+	if addr != "" {
+		err = extOrPortSendUserAddr(s, addr)
+		if err != nil {
+			return err
+		}
+	}
+	if methodName != "" {
+		err = extOrPortSendTransport(s, methodName)
+		if err != nil {
+			return err
+		}
+	}
+	err = extOrPortSendDone(s)
+	if err != nil {
+		return err
+	}
+	cmd, _, err := extOrPortRecvCommand(s)
+	if err != nil {
+		return err
+	}
+	if cmd == extOrCmdDeny {
+		return fmt.Errorf("server returned DENY after our USERADDR and DONE")
+	} else if cmd != extOrCmdOkay {
+		return fmt.Errorf("server returned unknown command 0x%04x after our USERADDR and DONE", cmd)
+	}
+
+	return nil
+}
+
+func extOrPortSetup(s net.Conn, timeout time.Duration,
+	info *ServerInfo, addr, methodName string) error {
+	err := s.SetDeadline(time.Now().Add(5 * time.Second))
+	if err != nil {
+		return err
+	}
+	err = extOrPortAuthenticate(s, info)
+	if err != nil {
+		return err
+	}
+	err = extOrPortSetMetadata(s, addr, methodName)
+	if err != nil {
+		return err
+	}
+	err = s.SetDeadline(time.Time{})
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// Dial info.ExtendedOrAddr if defined, or else info.OrAddr, and return an open
+// *net.TCPConn. If connecting to the extended OR port, extended OR port
+// authentication à la 217-ext-orport-auth.txt is done before returning; an
+// error is returned if authentication fails.
+//
+// The addr and methodName arguments are put in USERADDR and TRANSPORT ExtOrPort
+// commands, respectively. If either is "", the corresponding command is not
+// sent.
+func DialOr(info *ServerInfo, addr, methodName string) (*net.TCPConn, error) {
+	if info.ExtendedOrAddr == nil || info.AuthCookiePath == "" {
+		return net.DialTCP("tcp", nil, info.OrAddr)
+	}
+
+	s, err := net.DialTCP("tcp", nil, info.ExtendedOrAddr)
+	if err != nil {
+		return nil, err
+	}
+	err = extOrPortSetup(s, 5*time.Second, info, addr, methodName)
+	if err != nil {
+		s.Close()
+		return nil, err
+	}
+
+	return s, nil
+}

vendor/git.torproject.org/pluggable-transports/goptlib.git/socks.go

@@ -0,0 +1,507 @@
+package pt
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"net"
+	"time"
+)
+
+const (
+	socksVersion = 0x05
+
+	socksAuthNoneRequired        = 0x00
+	socksAuthUsernamePassword    = 0x02
+	socksAuthNoAcceptableMethods = 0xff
+
+	socksCmdConnect = 0x01
+	socksRsv        = 0x00
+
+	socksAtypeV4         = 0x01
+	socksAtypeDomainName = 0x03
+	socksAtypeV6         = 0x04
+
+	socksAuthRFC1929Ver     = 0x01
+	socksAuthRFC1929Success = 0x00
+	socksAuthRFC1929Fail    = 0x01
+
+	socksRepSucceeded = 0x00
+	// "general SOCKS server failure"
+	SocksRepGeneralFailure = 0x01
+	// "connection not allowed by ruleset"
+	SocksRepConnectionNotAllowed = 0x02
+	// "Network unreachable"
+	SocksRepNetworkUnreachable = 0x03
+	// "Host unreachable"
+	SocksRepHostUnreachable = 0x04
+	// "Connection refused"
+	SocksRepConnectionRefused = 0x05
+	// "TTL expired"
+	SocksRepTTLExpired = 0x06
+	// "Command not supported"
+	SocksRepCommandNotSupported = 0x07
+	// "Address type not supported"
+	SocksRepAddressNotSupported = 0x08
+)
+
+// Put a sanity timeout on how long we wait for a SOCKS request.
+const socksRequestTimeout = 5 * time.Second
+
+// SocksRequest describes a SOCKS request.
+type SocksRequest struct {
+	// The endpoint requested by the client as a "host:port" string.
+	Target string
+	// The userid string sent by the client.
+	Username string
+	// The password string sent by the client.
+	Password string
+	// The parsed contents of Username as a key–value mapping.
+	Args Args
+}
+
+// SocksConn encapsulates a net.Conn and information associated with a SOCKS request.
+type SocksConn struct {
+	net.Conn
+	Req SocksRequest
+}
+
+// Send a message to the proxy client that access to the given address is
+// granted. Addr is ignored, and "0.0.0.0:0" is always sent back for
+// BND.ADDR/BND.PORT in the SOCKS response.
+func (conn *SocksConn) Grant(addr *net.TCPAddr) error {
+	return sendSocks5ResponseGranted(conn)
+}
+
+// Send a message to the proxy client that access was rejected or failed.  This
+// sends back a "General Failure" error code.  RejectReason should be used if
+// more specific error reporting is desired.
+func (conn *SocksConn) Reject() error {
+	return conn.RejectReason(SocksRepGeneralFailure)
+}
+
+// Send a message to the proxy client that access was rejected, with the
+// specific error code indicating the reason behind the rejection.
+func (conn *SocksConn) RejectReason(reason byte) error {
+	return sendSocks5ResponseRejected(conn, reason)
+}
+
+// SocksListener wraps a net.Listener in order to read a SOCKS request on Accept.
+//
+// 	func handleConn(conn *pt.SocksConn) error {
+// 		defer conn.Close()
+// 		remote, err := net.Dial("tcp", conn.Req.Target)
+// 		if err != nil {
+// 			conn.Reject()
+// 			return err
+// 		}
+// 		defer remote.Close()
+// 		err = conn.Grant(remote.RemoteAddr().(*net.TCPAddr))
+// 		if err != nil {
+// 			return err
+// 		}
+// 		// do something with conn and remote
+// 		return nil
+// 	}
+// 	...
+// 	ln, err := pt.ListenSocks("tcp", "127.0.0.1:0")
+// 	if err != nil {
+// 		panic(err.Error())
+// 	}
+// 	for {
+// 		conn, err := ln.AcceptSocks()
+// 		if err != nil {
+// 			log.Printf("accept error: %s", err)
+// 			if e, ok := err.(net.Error); ok && e.Temporary() {
+// 				continue
+// 			}
+// 			break
+// 		}
+// 		go handleConn(conn)
+// 	}
+type SocksListener struct {
+	net.Listener
+}
+
+// Open a net.Listener according to network and laddr, and return it as a
+// SocksListener.
+func ListenSocks(network, laddr string) (*SocksListener, error) {
+	ln, err := net.Listen(network, laddr)
+	if err != nil {
+		return nil, err
+	}
+	return NewSocksListener(ln), nil
+}
+
+// Create a new SocksListener wrapping the given net.Listener.
+func NewSocksListener(ln net.Listener) *SocksListener {
+	return &SocksListener{ln}
+}
+
+// Accept is the same as AcceptSocks, except that it returns a generic net.Conn.
+// It is present for the sake of satisfying the net.Listener interface.
+func (ln *SocksListener) Accept() (net.Conn, error) {
+	return ln.AcceptSocks()
+}
+
+// Call Accept on the wrapped net.Listener, do SOCKS negotiation, and return a
+// SocksConn. After accepting, you must call either conn.Grant or conn.Reject
+// (presumably after trying to connect to conn.Req.Target).
+//
+// Errors returned by AcceptSocks may be temporary (for example, EOF while
+// reading the request, or a badly formatted userid string), or permanent (e.g.,
+// the underlying socket is closed). You can determine whether an error is
+// temporary and take appropriate action with a type conversion to net.Error.
+// For example:
+//
+// 	for {
+// 		conn, err := ln.AcceptSocks()
+// 		if err != nil {
+// 			if e, ok := err.(net.Error); ok && e.Temporary() {
+// 				log.Printf("temporary accept error; trying again: %s", err)
+// 				continue
+// 			}
+// 			log.Printf("permanent accept error; giving up: %s", err)
+// 			break
+// 		}
+// 		go handleConn(conn)
+// 	}
+func (ln *SocksListener) AcceptSocks() (*SocksConn, error) {
+retry:
+	c, err := ln.Listener.Accept()
+	if err != nil {
+		return nil, err
+	}
+	conn := new(SocksConn)
+	conn.Conn = c
+	err = conn.SetDeadline(time.Now().Add(socksRequestTimeout))
+	if err != nil {
+		conn.Close()
+		goto retry
+	}
+	conn.Req, err = socks5Handshake(conn)
+	if err != nil {
+		conn.Close()
+		goto retry
+	}
+	err = conn.SetDeadline(time.Time{})
+	if err != nil {
+		conn.Close()
+		goto retry
+	}
+	return conn, nil
+}
+
+// Returns "socks5", suitable to be included in a call to Cmethod.
+func (ln *SocksListener) Version() string {
+	return "socks5"
+}
+
+// socks5handshake conducts the SOCKS5 handshake up to the point where the
+// client command is read and the proxy must open the outgoing connection.
+// Returns a SocksRequest.
+func socks5Handshake(s io.ReadWriter) (req SocksRequest, err error) {
+	rw := bufio.NewReadWriter(bufio.NewReader(s), bufio.NewWriter(s))
+
+	// Negotiate the authentication method.
+	var method byte
+	if method, err = socksNegotiateAuth(rw); err != nil {
+		return
+	}
+
+	// Authenticate the client.
+	if err = socksAuthenticate(rw, method, &req); err != nil {
+		return
+	}
+
+	// Read the command.
+	err = socksReadCommand(rw, &req)
+	return
+}
+
+// socksNegotiateAuth negotiates the authentication method and returns the
+// selected method as a byte.  On negotiation failures an error is returned.
+func socksNegotiateAuth(rw *bufio.ReadWriter) (method byte, err error) {
+	// Validate the version.
+	if err = socksReadByteVerify(rw, "version", socksVersion); err != nil {
+		return
+	}
+
+	// Read the number of methods.
+	var nmethods byte
+	if nmethods, err = socksReadByte(rw); err != nil {
+		return
+	}
+
+	// Read the methods.
+	var methods []byte
+	if methods, err = socksReadBytes(rw, int(nmethods)); err != nil {
+		return
+	}
+
+	// Pick the most "suitable" method.
+	method = socksAuthNoAcceptableMethods
+	for _, m := range methods {
+		switch m {
+		case socksAuthNoneRequired:
+			// Pick Username/Password over None if the client happens to
+			// send both.
+			if method == socksAuthNoAcceptableMethods {
+				method = m
+			}
+
+		case socksAuthUsernamePassword:
+			method = m
+		}
+	}
+
+	// Send the negotiated method.
+	var msg [2]byte
+	msg[0] = socksVersion
+	msg[1] = method
+	if _, err = rw.Writer.Write(msg[:]); err != nil {
+		return
+	}
+
+	if err = socksFlushBuffers(rw); err != nil {
+		return
+	}
+	return
+}
+
+// socksAuthenticate authenticates the client via the chosen authentication
+// mechanism.
+func socksAuthenticate(rw *bufio.ReadWriter, method byte, req *SocksRequest) (err error) {
+	switch method {
+	case socksAuthNoneRequired:
+		// Straight into reading the connect.
+
+	case socksAuthUsernamePassword:
+		if err = socksAuthRFC1929(rw, req); err != nil {
+			return
+		}
+
+	case socksAuthNoAcceptableMethods:
+		err = fmt.Errorf("SOCKS method select had no compatible methods")
+		return
+
+	default:
+		err = fmt.Errorf("SOCKS method select picked a unsupported method 0x%02x", method)
+		return
+	}
+
+	if err = socksFlushBuffers(rw); err != nil {
+		return
+	}
+	return
+}
+
+// socksAuthRFC1929 authenticates the client via RFC 1929 username/password
+// auth.  As a design decision any valid username/password is accepted as this
+// field is primarily used as an out-of-band argument passing mechanism for
+// pluggable transports.
+func socksAuthRFC1929(rw *bufio.ReadWriter, req *SocksRequest) (err error) {
+	sendErrResp := func() {
+		// Swallow the write/flush error here, we are going to close the
+		// connection and the original failure is more useful.
+		resp := []byte{socksAuthRFC1929Ver, socksAuthRFC1929Fail}
+		rw.Write(resp[:])
+		socksFlushBuffers(rw)
+	}
+
+	// Validate the fixed parts of the command message.
+	if err = socksReadByteVerify(rw, "auth version", socksAuthRFC1929Ver); err != nil {
+		sendErrResp()
+		return
+	}
+
+	// Read the username.
+	var ulen byte
+	if ulen, err = socksReadByte(rw); err != nil {
+		return
+	}
+	if ulen < 1 {
+		sendErrResp()
+		err = fmt.Errorf("RFC1929 username with 0 length")
+		return
+	}
+	var uname []byte
+	if uname, err = socksReadBytes(rw, int(ulen)); err != nil {
+		return
+	}
+	req.Username = string(uname)
+
+	// Read the password.
+	var plen byte
+	if plen, err = socksReadByte(rw); err != nil {
+		return
+	}
+	if plen < 1 {
+		sendErrResp()
+		err = fmt.Errorf("RFC1929 password with 0 length")
+		return
+	}
+	var passwd []byte
+	if passwd, err = socksReadBytes(rw, int(plen)); err != nil {
+		return
+	}
+	if !(plen == 1 && passwd[0] == 0x00) {
+		// tor will set the password to 'NUL' if there are no arguments.
+		req.Password = string(passwd)
+	}
+
+	// Mash the username/password together and parse it as a pluggable
+	// transport argument string.
+	if req.Args, err = parseClientParameters(req.Username + req.Password); err != nil {
+		sendErrResp()
+	} else {
+		resp := []byte{socksAuthRFC1929Ver, socksAuthRFC1929Success}
+		_, err = rw.Write(resp[:])
+	}
+	return
+}
+
+// socksReadCommand reads a SOCKS5 client command and parses out the relevant
+// fields into a SocksRequest.  Only CMD_CONNECT is supported.
+func socksReadCommand(rw *bufio.ReadWriter, req *SocksRequest) (err error) {
+	sendErrResp := func(reason byte) {
+		// Swallow errors that occur when writing/flushing the response,
+		// connection will be closed anyway.
+		sendSocks5ResponseRejected(rw, reason)
+		socksFlushBuffers(rw)
+	}
+
+	// Validate the fixed parts of the command message.
+	if err = socksReadByteVerify(rw, "version", socksVersion); err != nil {
+		sendErrResp(SocksRepGeneralFailure)
+		return
+	}
+	if err = socksReadByteVerify(rw, "command", socksCmdConnect); err != nil {
+		sendErrResp(SocksRepCommandNotSupported)
+		return
+	}
+	if err = socksReadByteVerify(rw, "reserved", socksRsv); err != nil {
+		sendErrResp(SocksRepGeneralFailure)
+		return
+	}
+
+	// Read the destination address/port.
+	// XXX: This should probably eventually send socks 5 error messages instead
+	// of rudely closing connections on invalid addresses.
+	var atype byte
+	if atype, err = socksReadByte(rw); err != nil {
+		return
+	}
+	var host string
+	switch atype {
+	case socksAtypeV4:
+		var addr []byte
+		if addr, err = socksReadBytes(rw, net.IPv4len); err != nil {
+			return
+		}
+		host = net.IPv4(addr[0], addr[1], addr[2], addr[3]).String()
+
+	case socksAtypeDomainName:
+		var alen byte
+		if alen, err = socksReadByte(rw); err != nil {
+			return
+		}
+		if alen == 0 {
+			err = fmt.Errorf("SOCKS request had domain name with 0 length")
+			return
+		}
+		var addr []byte
+		if addr, err = socksReadBytes(rw, int(alen)); err != nil {
+			return
+		}
+		host = string(addr)
+
+	case socksAtypeV6:
+		var rawAddr []byte
+		if rawAddr, err = socksReadBytes(rw, net.IPv6len); err != nil {
+			return
+		}
+		addr := make(net.IP, net.IPv6len)
+		copy(addr[:], rawAddr[:])
+		host = fmt.Sprintf("[%s]", addr.String())
+
+	default:
+		sendErrResp(SocksRepAddressNotSupported)
+		err = fmt.Errorf("SOCKS request had unsupported address type 0x%02x", atype)
+		return
+	}
+	var rawPort []byte
+	if rawPort, err = socksReadBytes(rw, 2); err != nil {
+		return
+	}
+	port := int(rawPort[0])<<8 | int(rawPort[1])<<0
+
+	if err = socksFlushBuffers(rw); err != nil {
+		return
+	}
+
+	req.Target = fmt.Sprintf("%s:%d", host, port)
+	return
+}
+
+// Send a SOCKS5 response with the given code. BND.ADDR/BND.PORT is always the
+// IPv4 address/port "0.0.0.0:0".
+func sendSocks5Response(w io.Writer, code byte) error {
+	resp := make([]byte, 4+4+2)
+	resp[0] = socksVersion
+	resp[1] = code
+	resp[2] = socksRsv
+	resp[3] = socksAtypeV4
+
+	// BND.ADDR/BND.PORT should be the address and port that the outgoing
+	// connection is bound to on the proxy, but Tor does not use this
+	// information, so all zeroes are sent.
+
+	_, err := w.Write(resp[:])
+	return err
+}
+
+// Send a SOCKS5 response code 0x00.
+func sendSocks5ResponseGranted(w io.Writer) error {
+	return sendSocks5Response(w, socksRepSucceeded)
+}
+
+// Send a SOCKS5 response with the provided failure reason.
+func sendSocks5ResponseRejected(w io.Writer, reason byte) error {
+	return sendSocks5Response(w, reason)
+}
+
+func socksFlushBuffers(rw *bufio.ReadWriter) error {
+	if err := rw.Writer.Flush(); err != nil {
+		return err
+	}
+	if rw.Reader.Buffered() > 0 {
+		return fmt.Errorf("%d bytes left after SOCKS message", rw.Reader.Buffered())
+	}
+	return nil
+}
+
+func socksReadByte(rw *bufio.ReadWriter) (byte, error) {
+	return rw.Reader.ReadByte()
+}
+
+func socksReadBytes(rw *bufio.ReadWriter, n int) ([]byte, error) {
+	ret := make([]byte, n)
+	if _, err := io.ReadFull(rw.Reader, ret); err != nil {
+		return nil, err
+	}
+	return ret, nil
+}
+
+func socksReadByteVerify(rw *bufio.ReadWriter, descr string, expected byte) error {
+	val, err := socksReadByte(rw)
+	if err != nil {
+		return err
+	}
+	if val != expected {
+		return fmt.Errorf("SOCKS message field %s was 0x%02x, not 0x%02x", descr, val, expected)
+	}
+	return nil
+}
+
+var _ net.Listener = (*SocksListener)(nil)

vendor/git.torproject.org/pluggable-transports/goptlib.git/test_authcookie

@@ -0,0 +1,2 @@
+! Extended ORPort Auth Cookie !
+this file is used in test code.

vendor/github.com/dchest/siphash/LICENSE

@@ -0,0 +1,121 @@
+Creative Commons Legal Code
+
+CC0 1.0 Universal
+
+    CREATIVE COMMONS CORPORATION IS NOT A LAW FIRM AND DOES NOT PROVIDE
+    LEGAL SERVICES. DISTRIBUTION OF THIS DOCUMENT DOES NOT CREATE AN
+    ATTORNEY-CLIENT RELATIONSHIP. CREATIVE COMMONS PROVIDES THIS
+    INFORMATION ON AN "AS-IS" BASIS. CREATIVE COMMONS MAKES NO WARRANTIES
+    REGARDING THE USE OF THIS DOCUMENT OR THE INFORMATION OR WORKS
+    PROVIDED HEREUNDER, AND DISCLAIMS LIABILITY FOR DAMAGES RESULTING FROM
+    THE USE OF THIS DOCUMENT OR THE INFORMATION OR WORKS PROVIDED
+    HEREUNDER.
+
+Statement of Purpose
+
+The laws of most jurisdictions throughout the world automatically confer
+exclusive Copyright and Related Rights (defined below) upon the creator
+and subsequent owner(s) (each and all, an "owner") of an original work of
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vendor/github.com/dchest/siphash/README.md

@@ -0,0 +1,69 @@
+SipHash (Go)
+============
+
+[![Build Status](https://travis-ci.org/dchest/siphash.svg)](https://travis-ci.org/dchest/siphash)
+
+Go implementation of SipHash-2-4, a fast short-input PRF created by
+Jean-Philippe Aumasson and Daniel J. Bernstein (http://131002.net/siphash/).
+
+
+## Installation
+
+    $ go get github.com/dchest/siphash
+
+## Usage
+
+    import "github.com/dchest/siphash"
+
+There are two ways to use this package.
+The slower one is to use the standard hash.Hash64 interface:
+
+    h := siphash.New(key)
+    h.Write([]byte("Hello"))
+    sum := h.Sum(nil) // returns 8-byte []byte
+
+or
+
+    sum64 := h.Sum64() // returns uint64
+
+The faster one is to use Hash() function, which takes two uint64 parts of
+16-byte key and a byte slice, and returns uint64 hash:
+
+    sum64 := siphash.Hash(key0, key1, []byte("Hello"))
+
+The keys and output are little-endian.
+
+
+## Functions
+
+### func Hash(k0, k1 uint64, p []byte) uint64
+
+Hash returns the 64-bit SipHash-2-4 of the given byte slice with two
+64-bit parts of 128-bit key: k0 and k1.
+
+### func Hash128(k0, k1 uint64, p []byte) (uint64, uint64)
+
+Hash128 returns the 128-bit SipHash-2-4 of the given byte slice with two
+64-bit parts of 128-bit key: k0 and k1.
+
+Note that 128-bit SipHash is considered experimental by SipHash authors at this time.
+
+### func New(key []byte) hash.Hash64
+
+New returns a new hash.Hash64 computing SipHash-2-4 with 16-byte key.
+
+### func New128(key []byte) hash.Hash
+
+New128 returns a new hash.Hash computing SipHash-2-4 with 16-byte key and 16-byte output.
+
+Note that 16-byte output is considered experimental by SipHash authors at this time.
+
+
+## Public domain dedication
+
+Written by Dmitry Chestnykh and Damian Gryski.
+
+To the extent possible under law, the authors have dedicated all copyright
+and related and neighboring rights to this software to the public domain
+worldwide. This software is distributed without any warranty.
+http://creativecommons.org/publicdomain/zero/1.0/

vendor/github.com/dchest/siphash/blocks.go

@@ -0,0 +1,148 @@
+// +build !arm,!amd64 appengine gccgo
+
+package siphash
+
+func once(d *digest) {
+	blocks(d, d.x[:])
+}
+
+func finalize(d *digest) uint64 {
+	d0 := *d
+	once(&d0)
+
+	v0, v1, v2, v3 := d0.v0, d0.v1, d0.v2, d0.v3
+	v2 ^= 0xff
+
+	// Round 1.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 2.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 3.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 4.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	return v0 ^ v1 ^ v2 ^ v3
+}
+
+func blocks(d *digest, p []uint8) {
+	v0, v1, v2, v3 := d.v0, d.v1, d.v2, d.v3
+
+	for len(p) >= BlockSize {
+		m := uint64(p[0]) | uint64(p[1])<<8 | uint64(p[2])<<16 | uint64(p[3])<<24 |
+			uint64(p[4])<<32 | uint64(p[5])<<40 | uint64(p[6])<<48 | uint64(p[7])<<56
+
+		v3 ^= m
+
+		// Round 1.
+		v0 += v1
+		v1 = v1<<13 | v1>>(64-13)
+		v1 ^= v0
+		v0 = v0<<32 | v0>>(64-32)
+
+		v2 += v3
+		v3 = v3<<16 | v3>>(64-16)
+		v3 ^= v2
+
+		v0 += v3
+		v3 = v3<<21 | v3>>(64-21)
+		v3 ^= v0
+
+		v2 += v1
+		v1 = v1<<17 | v1>>(64-17)
+		v1 ^= v2
+		v2 = v2<<32 | v2>>(64-32)
+
+		// Round 2.
+		v0 += v1
+		v1 = v1<<13 | v1>>(64-13)
+		v1 ^= v0
+		v0 = v0<<32 | v0>>(64-32)
+
+		v2 += v3
+		v3 = v3<<16 | v3>>(64-16)
+		v3 ^= v2
+
+		v0 += v3
+		v3 = v3<<21 | v3>>(64-21)
+		v3 ^= v0
+
+		v2 += v1
+		v1 = v1<<17 | v1>>(64-17)
+		v1 ^= v2
+		v2 = v2<<32 | v2>>(64-32)
+
+		v0 ^= m
+
+		p = p[BlockSize:]
+	}
+
+	d.v0, d.v1, d.v2, d.v3 = v0, v1, v2, v3
+}

vendor/github.com/dchest/siphash/blocks_amd64.s

@@ -0,0 +1,86 @@
+// +build amd64,!appengine,!gccgo
+
+#define ROUND(v0, v1, v2, v3) \
+	ADDQ v1, v0; \
+	RORQ $51, v1; \
+	ADDQ v3, v2; \
+	XORQ v0, v1; \
+	RORQ $48, v3; \
+	RORQ $32, v0; \
+	XORQ v2, v3; \
+	ADDQ v1, v2; \
+	ADDQ v3, v0; \
+	RORQ $43, v3; \
+	RORQ $47, v1; \
+	XORQ v0, v3; \
+	XORQ v2, v1; \
+	RORQ $32, v2
+
+// blocks(d *digest, data []uint8)
+TEXT ·blocks(SB),4,$0-32
+	MOVQ d+0(FP), BX
+	MOVQ 0(BX), R9		// R9 = v0
+	MOVQ 8(BX), R10		// R10 = v1
+	MOVQ 16(BX), R11	// R11 = v2
+	MOVQ 24(BX), R12	// R12 = v3
+	MOVQ p_base+8(FP), DI	// DI = *uint64
+	MOVQ p_len+16(FP), SI	// SI = nblocks
+	XORL DX, DX		// DX = index (0)
+	SHRQ $3, SI 		// SI /= 8
+body:
+	CMPQ DX, SI
+	JGE  end
+	MOVQ 0(DI)(DX*8), CX	// CX = m
+	XORQ CX, R12
+	ROUND(R9, R10, R11, R12)
+	ROUND(R9, R10, R11, R12)
+	XORQ CX, R9
+	ADDQ $1, DX
+	JMP  body
+end:
+	MOVQ R9, 0(BX)
+	MOVQ R10, 8(BX)
+	MOVQ R11, 16(BX)
+	MOVQ R12, 24(BX)
+	RET
+
+// once(d *digest)
+TEXT ·once(SB),4,$0-8
+	MOVQ d+0(FP), BX
+	MOVQ 0(BX), R9		// R9 = v0
+	MOVQ 8(BX), R10		// R10 = v1
+	MOVQ 16(BX), R11	// R11 = v2
+	MOVQ 24(BX), R12	// R12 = v3
+	MOVQ 48(BX), CX		// CX = d.x[:]
+	XORQ CX, R12
+	ROUND(R9, R10, R11, R12)
+	ROUND(R9, R10, R11, R12)
+	XORQ CX, R9
+	MOVQ R9, 0(BX)
+	MOVQ R10, 8(BX)
+	MOVQ R11, 16(BX)
+	MOVQ R12, 24(BX)
+	RET
+
+// finalize(d *digest) uint64
+TEXT ·finalize(SB),4,$0-16
+	MOVQ d+0(FP), BX
+	MOVQ 0(BX), R9		// R9 = v0
+	MOVQ 8(BX), R10		// R10 = v1
+	MOVQ 16(BX), R11	// R11 = v2
+	MOVQ 24(BX), R12	// R12 = v3
+	MOVQ 48(BX), CX		// CX = d.x[:]
+	XORQ CX, R12
+	ROUND(R9, R10, R11, R12)
+	ROUND(R9, R10, R11, R12)
+	XORQ CX, R9
+	NOTB R11
+	ROUND(R9, R10, R11, R12)
+	ROUND(R9, R10, R11, R12)
+	ROUND(R9, R10, R11, R12)
+	ROUND(R9, R10, R11, R12)
+	XORQ R12, R11
+	XORQ R10, R9
+	XORQ R11, R9
+	MOVQ R9, ret+8(FP)
+	RET

vendor/github.com/dchest/siphash/blocks_arm.s

@@ -0,0 +1,140 @@
+#include "textflag.h"
+
+#define ROUND()\
+	ADD.S	R2,R0,R0;\
+	ADC	R3,R1,R1;\
+	EOR	R2<<13,R0,R8;\
+	EOR	R3>>19,R8,R8;\
+	EOR	R2>>19,R1,R11;\
+	EOR	R3<<13,R11,R11;\
+	ADD.S	R6,R4,R4;\
+	ADC	R7,R5,R5;\
+	EOR	R6<<16,R4,R2;\
+	EOR	R7>>16,R2,R2;\
+	EOR	R6>>16,R5,R3;\
+	EOR	R7<<16,R3,R3;\
+	ADD.S	R2,R1,R1;\
+	ADC	R3,R0,R0;\
+	EOR	R2<<21,R1,R6;\
+	EOR	R3>>11,R6,R6;\
+	EOR	R2>>11,R0,R7;\
+	EOR	R3<<21,R7,R7;\
+	ADD.S	R8,R4,R4;\
+	ADC	R11,R5,R5;\
+	EOR	R8<<17,R4,R2;\
+	EOR	R11>>15,R2,R2;\
+	EOR	R8>>15,R5,R3;\
+	EOR	R11<<17,R3,R3;\
+	ADD.S	R2,R1,R1;\
+	ADC	R3,R0,R0;\
+	EOR	R2<<13,R1,R8;\
+	EOR	R3>>19,R8,R8;\
+	EOR	R2>>19,R0,R11;\
+	EOR	R3<<13,R11,R11;\
+	ADD.S	R6,R5,R5;\
+	ADC	R7,R4,R4;\
+	EOR	R6<<16,R5,R2;\
+	EOR	R7>>16,R2,R2;\
+	EOR	R6>>16,R4,R3;\
+	EOR	R7<<16,R3,R3;\
+	ADD.S	R2,R0,R0;\
+	ADC	R3,R1,R1;\
+	EOR	R2<<21,R0,R6;\
+	EOR	R3>>11,R6,R6;\
+	EOR	R2>>11,R1,R7;\
+	EOR	R3<<21,R7,R7;\
+	ADD.S	R8,R5,R5;\
+	ADC	R11,R4,R4;\
+	EOR	R8<<17,R5,R2;\
+	EOR	R11>>15,R2,R2;\
+	EOR	R8>>15,R4,R3;\
+	EOR	R11<<17,R3,R3;
+
+// once(d *digest)
+TEXT ·once(SB),NOSPLIT,$4-4
+	MOVW	d+0(FP),R8
+	MOVM.IA	(R8),[R0,R1,R2,R3,R4,R5,R6,R7]
+	MOVW	48(R8),R12
+	MOVW	52(R8),R14
+	EOR	R12,R6,R6
+	EOR	R14,R7,R7
+	ROUND()
+	EOR	R12,R0,R0
+	EOR	R14,R1,R1
+	MOVW	d+0(FP),R8
+	MOVM.IA [R0,R1,R2,R3,R4,R5,R6,R7],(R8)
+	RET
+
+// finalize(d *digest) uint64
+TEXT ·finalize(SB),NOSPLIT,$4-12
+	MOVW	d+0(FP),R8
+	MOVM.IA	(R8),[R0,R1,R2,R3,R4,R5,R6,R7]
+	MOVW	48(R8),R12
+	MOVW	52(R8),R14
+	EOR	R12,R6,R6
+	EOR	R14,R7,R7
+	ROUND()
+	EOR	R12,R0,R0
+	EOR	R14,R1,R1
+	EOR	$255,R4
+	ROUND()
+	ROUND()
+	EOR	R2,R0,R0
+	EOR	R3,R1,R1
+	EOR	R6,R4,R4
+	EOR	R7,R5,R5
+	EOR	R4,R0,R0
+	EOR	R5,R1,R1
+	MOVW	R0,ret_lo+4(FP)
+	MOVW	R1,ret_hi+8(FP)
+	RET
+
+// blocks(d *digest, data []uint8)
+TEXT ·blocks(SB),NOSPLIT,$4-16
+	MOVW	d+0(FP),R8
+	MOVM.IA	(R8),[R0,R1,R2,R3,R4,R5,R6,R7]
+	MOVW	p+4(FP),R9
+	MOVW	p_len+8(FP),R11
+	ADD	R9,R11,R11
+	MOVW	R11,endp-4(SP)
+	AND.S   $3,R9,R8
+	BNE     blocksunaligned
+blocksloop:
+	MOVM.IA.W (R9),[R12,R14]
+	EOR	R12,R6,R6
+	EOR	R14,R7,R7
+	ROUND()
+	EOR	R12,R0,R0
+	EOR	R14,R1,R1
+	MOVW	endp-4(SP),R11
+	CMP	R11,R9
+	BLO	blocksloop
+	MOVW	d+0(FP),R8
+	MOVM.IA [R0,R1,R2,R3,R4,R5,R6,R7],(R8)
+	RET
+blocksunaligned:
+	MOVBU.P   8(R9),R12
+	MOVBU    -7(R9),R11
+	ORR     R11<<8,R12,R12
+	MOVBU    -6(R9),R11
+	ORR     R11<<16,R12,R12
+	MOVBU    -5(R9),R11
+	ORR     R11<<24,R12,R12
+	MOVBU    -4(R9),R14
+	MOVBU    -3(R9),R11
+	ORR     R11<<8,R14,R14
+	MOVBU    -2(R9),R11
+	ORR     R11<<16,R14,R14
+	MOVBU    -1(R9),R11
+	ORR     R11<<24,R14,R14
+	EOR     R12,R6,R6
+	EOR     R14,R7,R7
+	ROUND()
+	EOR     R12,R0,R0
+	EOR     R14,R1,R1
+	MOVW    endp-4(SP),R11
+	CMP     R11,R9
+	BLO     blocksunaligned
+	MOVW    d+0(FP),R8
+	MOVM.IA [R0,R1,R2,R3,R4,R5,R6,R7],(R8)
+	RET

vendor/github.com/dchest/siphash/blocks_asm.go

@@ -0,0 +1,21 @@
+// +build arm amd64,!appengine,!gccgo
+
+// Written in 2012 by Dmitry Chestnykh.
+//
+// To the extent possible under law, the author have dedicated all copyright
+// and related and neighboring rights to this software to the public domain
+// worldwide. This software is distributed without any warranty.
+// http://creativecommons.org/publicdomain/zero/1.0/
+
+// This file contains a function definition for use with assembly implementations of Hash()
+
+package siphash
+
+//go:noescape
+func blocks(d *digest, p []uint8)
+
+//go:noescape
+func finalize(d *digest) uint64
+
+//go:noescape
+func once(d *digest)

vendor/github.com/dchest/siphash/hash.go

@@ -0,0 +1,216 @@
+// +build !arm,!amd64 appengine gccgo
+
+// Written in 2012 by Dmitry Chestnykh.
+//
+// To the extent possible under law, the author have dedicated all copyright
+// and related and neighboring rights to this software to the public domain
+// worldwide. This software is distributed without any warranty.
+// http://creativecommons.org/publicdomain/zero/1.0/
+
+package siphash
+
+// Hash returns the 64-bit SipHash-2-4 of the given byte slice with two 64-bit
+// parts of 128-bit key: k0 and k1.
+func Hash(k0, k1 uint64, p []byte) uint64 {
+	// Initialization.
+	v0 := k0 ^ 0x736f6d6570736575
+	v1 := k1 ^ 0x646f72616e646f6d
+	v2 := k0 ^ 0x6c7967656e657261
+	v3 := k1 ^ 0x7465646279746573
+	t := uint64(len(p)) << 56
+
+	// Compression.
+	for len(p) >= BlockSize {
+		m := uint64(p[0]) | uint64(p[1])<<8 | uint64(p[2])<<16 | uint64(p[3])<<24 |
+			uint64(p[4])<<32 | uint64(p[5])<<40 | uint64(p[6])<<48 | uint64(p[7])<<56
+		v3 ^= m
+
+		// Round 1.
+		v0 += v1
+		v1 = v1<<13 | v1>>(64-13)
+		v1 ^= v0
+		v0 = v0<<32 | v0>>(64-32)
+
+		v2 += v3
+		v3 = v3<<16 | v3>>(64-16)
+		v3 ^= v2
+
+		v0 += v3
+		v3 = v3<<21 | v3>>(64-21)
+		v3 ^= v0
+
+		v2 += v1
+		v1 = v1<<17 | v1>>(64-17)
+		v1 ^= v2
+		v2 = v2<<32 | v2>>(64-32)
+
+		// Round 2.
+		v0 += v1
+		v1 = v1<<13 | v1>>(64-13)
+		v1 ^= v0
+		v0 = v0<<32 | v0>>(64-32)
+
+		v2 += v3
+		v3 = v3<<16 | v3>>(64-16)
+		v3 ^= v2
+
+		v0 += v3
+		v3 = v3<<21 | v3>>(64-21)
+		v3 ^= v0
+
+		v2 += v1
+		v1 = v1<<17 | v1>>(64-17)
+		v1 ^= v2
+		v2 = v2<<32 | v2>>(64-32)
+
+		v0 ^= m
+		p = p[BlockSize:]
+	}
+
+	// Compress last block.
+	switch len(p) {
+	case 7:
+		t |= uint64(p[6]) << 48
+		fallthrough
+	case 6:
+		t |= uint64(p[5]) << 40
+		fallthrough
+	case 5:
+		t |= uint64(p[4]) << 32
+		fallthrough
+	case 4:
+		t |= uint64(p[3]) << 24
+		fallthrough
+	case 3:
+		t |= uint64(p[2]) << 16
+		fallthrough
+	case 2:
+		t |= uint64(p[1]) << 8
+		fallthrough
+	case 1:
+		t |= uint64(p[0])
+	}
+
+	v3 ^= t
+
+	// Round 1.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 2.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	v0 ^= t
+
+	// Finalization.
+	v2 ^= 0xff
+
+	// Round 1.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 2.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 3.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 4.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	return v0 ^ v1 ^ v2 ^ v3
+}

vendor/github.com/dchest/siphash/hash128.go

@@ -0,0 +1,302 @@
+// +build !arm,!amd64 appengine gccgo
+// Written in 2012 by Dmitry Chestnykh.
+// Modifications 2014 for 128-bit hash function by Damian Gryski.
+//
+// To the extent possible under law, the authors have dedicated all copyright
+// and related and neighboring rights to this software to the public domain
+// worldwide. This software is distributed without any warranty.
+// http://creativecommons.org/publicdomain/zero/1.0/
+
+package siphash
+
+// Hash returns the 128-bit SipHash-2-4 of the given byte slice with two 64-bit
+// parts of 128-bit key: k0 and k1.
+//
+// Note that 128-bit SipHash is considered experimental by SipHash authors at this time.
+func Hash128(k0, k1 uint64, p []byte) (uint64, uint64) {
+	// Initialization.
+	v0 := k0 ^ 0x736f6d6570736575
+	v1 := k1 ^ 0x646f72616e646f6d
+	v2 := k0 ^ 0x6c7967656e657261
+	v3 := k1 ^ 0x7465646279746573
+	t := uint64(len(p)) << 56
+
+	v1 ^= 0xee
+
+	// Compression.
+	for len(p) >= BlockSize {
+		m := uint64(p[0]) | uint64(p[1])<<8 | uint64(p[2])<<16 | uint64(p[3])<<24 |
+			uint64(p[4])<<32 | uint64(p[5])<<40 | uint64(p[6])<<48 | uint64(p[7])<<56
+		v3 ^= m
+
+		// Round 1.
+		v0 += v1
+		v1 = v1<<13 | v1>>(64-13)
+		v1 ^= v0
+		v0 = v0<<32 | v0>>(64-32)
+
+		v2 += v3
+		v3 = v3<<16 | v3>>(64-16)
+		v3 ^= v2
+
+		v0 += v3
+		v3 = v3<<21 | v3>>(64-21)
+		v3 ^= v0
+
+		v2 += v1
+		v1 = v1<<17 | v1>>(64-17)
+		v1 ^= v2
+		v2 = v2<<32 | v2>>(64-32)
+
+		// Round 2.
+		v0 += v1
+		v1 = v1<<13 | v1>>(64-13)
+		v1 ^= v0
+		v0 = v0<<32 | v0>>(64-32)
+
+		v2 += v3
+		v3 = v3<<16 | v3>>(64-16)
+		v3 ^= v2
+
+		v0 += v3
+		v3 = v3<<21 | v3>>(64-21)
+		v3 ^= v0
+
+		v2 += v1
+		v1 = v1<<17 | v1>>(64-17)
+		v1 ^= v2
+		v2 = v2<<32 | v2>>(64-32)
+
+		v0 ^= m
+		p = p[BlockSize:]
+	}
+
+	// Compress last block.
+	switch len(p) {
+	case 7:
+		t |= uint64(p[6]) << 48
+		fallthrough
+	case 6:
+		t |= uint64(p[5]) << 40
+		fallthrough
+	case 5:
+		t |= uint64(p[4]) << 32
+		fallthrough
+	case 4:
+		t |= uint64(p[3]) << 24
+		fallthrough
+	case 3:
+		t |= uint64(p[2]) << 16
+		fallthrough
+	case 2:
+		t |= uint64(p[1]) << 8
+		fallthrough
+	case 1:
+		t |= uint64(p[0])
+	}
+
+	v3 ^= t
+
+	// Round 1.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 2.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	v0 ^= t
+
+	// Finalization.
+	v2 ^= 0xee
+
+	// Round 1.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 2.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 3.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 4.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	r0 := v0 ^ v1 ^ v2 ^ v3
+
+	v1 ^= 0xdd
+
+	// Round 1.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 2.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 3.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 4.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	r1 := v0 ^ v1 ^ v2 ^ v3
+
+	return r0, r1
+}

vendor/github.com/dchest/siphash/hash128_amd64.s

@@ -0,0 +1,292 @@
+// +build amd64,!appengine,!gccgo
+
+// This is a translation of the gcc output of FloodyBerry's pure-C public
+// domain siphash implementation at https://github.com/floodyberry/siphash
+
+// This assembly code has been modified from the 64-bit output to the experiment 128-bit output.
+
+// SI = v0
+// AX = v1
+// CX = v2
+// DX = v3
+
+// func Hash128(k0, k1 uint64, b []byte) (r0 uint64, r1 uint64)
+TEXT	·Hash128(SB),4,$0-56
+	MOVQ	k0+0(FP),CX
+	MOVQ	$0x736F6D6570736575,R9
+	MOVQ	k1+8(FP),DI
+	MOVQ	$0x6C7967656E657261,BX
+	MOVQ	$0x646F72616E646F6D,AX
+	MOVQ	b_len+24(FP),DX
+	XORQ	$0xEE,AX
+	MOVQ	DX,R11
+	MOVQ	DX,R10
+	XORQ	CX,R9
+	XORQ	CX,BX
+	MOVQ	$0x7465646279746573,CX
+	XORQ	DI,AX
+	XORQ	DI,CX
+	SHLQ	$0x38,R11
+	XORQ	DI,DI
+	MOVQ	b_base+16(FP),SI
+	ANDQ	$0xFFFFFFFFFFFFFFF8,R10
+	JE	afterLoop
+	XCHGQ	AX,AX
+loopBody:
+	MOVQ	0(SI)(DI*1),R8
+	ADDQ	AX,R9
+	RORQ	$0x33,AX
+	XORQ	R9,AX
+	RORQ	$0x20,R9
+	ADDQ	$0x8,DI
+	XORQ	R8,CX
+	ADDQ	CX,BX
+	RORQ	$0x30,CX
+	XORQ	BX,CX
+	ADDQ	AX,BX
+	RORQ	$0x2F,AX
+	ADDQ	CX,R9
+	RORQ	$0x2B,CX
+	XORQ	BX,AX
+	XORQ	R9,CX
+	RORQ	$0x20,BX
+	ADDQ	AX,R9
+	ADDQ	CX,BX
+	RORQ	$0x33,AX
+	RORQ	$0x30,CX
+	XORQ	R9,AX
+	XORQ	BX,CX
+	RORQ	$0x20,R9
+	ADDQ	AX,BX
+	ADDQ	CX,R9
+	RORQ	$0x2F,AX
+	RORQ	$0x2B,CX
+	XORQ	BX,AX
+	RORQ	$0x20,BX
+	XORQ	R9,CX
+	XORQ	R8,R9
+	CMPQ	R10,DI
+	JA	loopBody
+afterLoop:
+	SUBQ	R10,DX
+
+	CMPQ	DX,$0x7
+	JA	afterSwitch
+
+	// no support for jump tables
+
+	CMPQ	DX,$0x7
+	JE	sw7
+
+	CMPQ	DX,$0x6
+	JE	sw6
+
+	CMPQ	DX,$0x5
+	JE	sw5
+
+	CMPQ	DX,$0x4
+	JE	sw4
+
+	CMPQ	DX,$0x3
+	JE	sw3
+
+	CMPQ	DX,$0x2
+	JE	sw2
+
+	CMPQ	DX,$0x1
+	JE	sw1
+
+	JMP	afterSwitch
+
+sw7:	MOVBQZX	6(SI)(DI*1),DX
+	SHLQ	$0x30,DX
+	ORQ	DX,R11
+sw6:	MOVBQZX	0x5(SI)(DI*1),DX
+	SHLQ	$0x28,DX
+	ORQ	DX,R11
+sw5:	MOVBQZX	0x4(SI)(DI*1),DX
+	SHLQ	$0x20,DX
+	ORQ	DX,R11
+sw4:	MOVBQZX	0x3(SI)(DI*1),DX
+	SHLQ	$0x18,DX
+	ORQ	DX,R11
+sw3:	MOVBQZX	0x2(SI)(DI*1),DX
+	SHLQ	$0x10,DX
+	ORQ	DX,R11
+sw2:	MOVBQZX	0x1(SI)(DI*1),DX
+	SHLQ	$0x8,DX
+	ORQ	DX,R11
+sw1:	MOVBQZX	0(SI)(DI*1),DX
+	ORQ	DX,R11
+afterSwitch:
+	LEAQ	(AX)(R9*1),SI
+	XORQ	R11,CX
+	RORQ	$0x33,AX
+	ADDQ	CX,BX
+	MOVQ	CX,DX
+	XORQ	SI,AX
+	RORQ	$0x30,DX
+	RORQ	$0x20,SI
+	LEAQ	0(BX)(AX*1),CX
+	XORQ	BX,DX
+	RORQ	$0x2F,AX
+	ADDQ	DX,SI
+	RORQ	$0x2B,DX
+	XORQ	CX,AX
+	XORQ	SI,DX
+	RORQ	$0x20,CX
+	ADDQ	AX,SI
+	RORQ	$0x33,AX
+	ADDQ	DX,CX
+	XORQ	SI,AX
+	RORQ	$0x30,DX
+	RORQ	$0x20,SI
+	XORQ	CX,DX
+	ADDQ	AX,CX
+	RORQ	$0x2F,AX
+	ADDQ	DX,SI
+	XORQ	CX,AX
+	RORQ	$0x2B,DX
+	RORQ	$0x20,CX
+	XORQ	SI,DX
+	XORQ	R11,SI
+	XORB	$0xEE,CL
+	ADDQ	AX,SI
+	RORQ	$0x33,AX
+	ADDQ	DX,CX
+	RORQ	$0x30,DX
+	XORQ	SI,AX
+	XORQ	CX,DX
+	RORQ	$0x20,SI
+	ADDQ	AX,CX
+	ADDQ	DX,SI
+	RORQ	$0x2F,AX
+	RORQ	$0x2B,DX
+	XORQ	CX,AX
+	XORQ	SI,DX
+	RORQ	$0x20,CX
+	ADDQ	AX,SI
+	ADDQ	DX,CX
+	RORQ	$0x33,AX
+	RORQ	$0x30,DX
+	XORQ	SI,AX
+	RORQ	$0x20,SI
+	XORQ	CX,DX
+	ADDQ	AX,CX
+	RORQ	$0x2F,AX
+	ADDQ	DX,SI
+	RORQ	$0x2B,DX
+	XORQ	CX,AX
+	XORQ	SI,DX
+	RORQ	$0x20,CX
+	ADDQ	AX,SI
+	ADDQ	DX,CX
+	RORQ	$0x33,AX
+	RORQ	$0x30,DX
+	XORQ	CX,DX
+	XORQ	SI,AX
+	RORQ	$0x20,SI
+	ADDQ	DX,SI
+	ADDQ	AX,CX
+	RORQ	$0x2F,AX
+	XORQ	CX,AX
+	RORQ	$0x2B,DX
+	RORQ	$0x20,CX
+	XORQ	SI,DX
+
+	// gcc optimized the tail end of this function differently.  However,
+	// we need to preserve out registers to carry out the second stage of
+	// the finalization.  This is a duplicate of an earlier finalization
+	// round.
+
+	ADDQ	AX,SI
+	RORQ	$0x33,AX
+	ADDQ	DX,CX
+	RORQ	$0x30,DX
+	XORQ	SI,AX
+	XORQ	CX,DX
+	RORQ	$0x20,SI
+	ADDQ	AX,CX
+	ADDQ	DX,SI
+	RORQ	$0x2F,AX
+	RORQ	$0x2B,DX
+	XORQ	CX,AX
+	XORQ	SI,DX
+	RORQ	$0x20,CX
+
+	// Stuff the result into BX instead of AX as gcc had done
+
+	MOVQ	SI,BX
+	XORQ	AX,BX
+	XORQ	DX,BX
+	XORQ	CX,BX
+	MOVQ	BX,ret+40(FP)
+
+	// Start the second finalization round
+
+	XORB	$0xDD,AL
+	ADDQ	AX,SI
+	RORQ	$0x33,AX
+	ADDQ	DX,CX
+	RORQ	$0x30,DX
+	XORQ	SI,AX
+	XORQ	CX,DX
+	RORQ	$0x20,SI
+	ADDQ	AX,CX
+	ADDQ	DX,SI
+	RORQ	$0x2F,AX
+	RORQ	$0x2B,DX
+	XORQ	CX,AX
+	XORQ	SI,DX
+	RORQ	$0x20,CX
+	ADDQ	AX,SI
+	ADDQ	DX,CX
+	RORQ	$0x33,AX
+	RORQ	$0x30,DX
+	XORQ	SI,AX
+	RORQ	$0x20,SI
+	XORQ	CX,DX
+	ADDQ	AX,CX
+	RORQ	$0x2F,AX
+	ADDQ	DX,SI
+	RORQ	$0x2B,DX
+	XORQ	CX,AX
+	XORQ	SI,DX
+	RORQ	$0x20,CX
+	ADDQ	AX,SI
+	ADDQ	DX,CX
+	RORQ	$0x33,AX
+	RORQ	$0x30,DX
+	XORQ	CX,DX
+	XORQ	SI,AX
+	RORQ	$0x20,SI
+	ADDQ	DX,SI
+	ADDQ	AX,CX
+	RORQ	$0x2F,AX
+	XORQ	CX,AX
+	RORQ	$0x2B,DX
+	RORQ	$0x20,CX
+	XORQ	SI,DX
+
+	ADDQ	AX,SI
+	RORQ	$0x33,AX
+	ADDQ	DX,CX
+	RORQ	$0x30,DX
+	XORQ	SI,AX
+	XORQ	CX,DX
+	RORQ	$0x20,SI
+	ADDQ	AX,CX
+	ADDQ	DX,SI
+	RORQ	$0x2F,AX
+	RORQ	$0x2B,DX
+	XORQ	CX,AX
+	XORQ	SI,DX
+	RORQ	$0x20,CX
+
+	MOVQ	SI,BX
+	XORQ	AX,BX
+	XORQ	DX,BX
+	XORQ	CX,BX
+	MOVQ	BX,ret1+48(FP)
+
+	RET

vendor/github.com/dchest/siphash/hash_amd64.s

@@ -0,0 +1,201 @@
+// +build amd64,!appengine,!gccgo
+
+// This is a translation of the gcc output of FloodyBerry's pure-C public
+// domain siphash implementation at https://github.com/floodyberry/siphash
+// func Hash(k0, k1 uint64, b []byte) uint64
+TEXT	·Hash(SB),4,$0-48
+	MOVQ	k0+0(FP),CX
+	MOVQ	$0x736F6D6570736575,R9
+	MOVQ	k1+8(FP),DI
+	MOVQ	$0x6C7967656E657261,BX
+	MOVQ	$0x646F72616E646F6D,AX
+	MOVQ	b_len+24(FP),DX
+	MOVQ	DX,R11
+	MOVQ	DX,R10
+	XORQ	CX,R9
+	XORQ	CX,BX
+	MOVQ	$0x7465646279746573,CX
+	XORQ	DI,AX
+	XORQ	DI,CX
+	SHLQ	$0x38,R11
+	XORQ	DI,DI
+	MOVQ	b_base+16(FP),SI
+	ANDQ	$0xFFFFFFFFFFFFFFF8,R10
+	JE	afterLoop
+	XCHGQ	AX,AX
+loopBody:
+	MOVQ	0(SI)(DI*1),R8
+	ADDQ	AX,R9
+	RORQ	$0x33,AX
+	XORQ	R9,AX
+	RORQ	$0x20,R9
+	ADDQ	$0x8,DI
+	XORQ	R8,CX
+	ADDQ	CX,BX
+	RORQ	$0x30,CX
+	XORQ	BX,CX
+	ADDQ	AX,BX
+	RORQ	$0x2F,AX
+	ADDQ	CX,R9
+	RORQ	$0x2B,CX
+	XORQ	BX,AX
+	XORQ	R9,CX
+	RORQ	$0x20,BX
+	ADDQ	AX,R9
+	ADDQ	CX,BX
+	RORQ	$0x33,AX
+	RORQ	$0x30,CX
+	XORQ	R9,AX
+	XORQ	BX,CX
+	RORQ	$0x20,R9
+	ADDQ	AX,BX
+	ADDQ	CX,R9
+	RORQ	$0x2F,AX
+	RORQ	$0x2B,CX
+	XORQ	BX,AX
+	RORQ	$0x20,BX
+	XORQ	R9,CX
+	XORQ	R8,R9
+	CMPQ	R10,DI
+	JA	loopBody
+afterLoop:
+	SUBQ	R10,DX
+
+	CMPQ	DX,$0x7
+	JA	afterSwitch
+
+	// no support for jump tables
+
+	CMPQ	DX,$0x7
+	JE	sw7
+
+	CMPQ	DX,$0x6
+	JE	sw6
+
+	CMPQ	DX,$0x5
+	JE	sw5
+
+	CMPQ	DX,$0x4
+	JE	sw4
+
+	CMPQ	DX,$0x3
+	JE	sw3
+
+	CMPQ	DX,$0x2
+	JE	sw2
+
+	CMPQ	DX,$0x1
+	JE	sw1
+
+	JMP	afterSwitch
+
+sw7:	MOVBQZX	6(SI)(DI*1),DX
+	SHLQ	$0x30,DX
+	ORQ	DX,R11
+sw6:	MOVBQZX	0x5(SI)(DI*1),DX
+	SHLQ	$0x28,DX
+	ORQ	DX,R11
+sw5:	MOVBQZX	0x4(SI)(DI*1),DX
+	SHLQ	$0x20,DX
+	ORQ	DX,R11
+sw4:	MOVBQZX	0x3(SI)(DI*1),DX
+	SHLQ	$0x18,DX
+	ORQ	DX,R11
+sw3:	MOVBQZX	0x2(SI)(DI*1),DX
+	SHLQ	$0x10,DX
+	ORQ	DX,R11
+sw2:	MOVBQZX	0x1(SI)(DI*1),DX
+	SHLQ	$0x8,DX
+	ORQ	DX,R11
+sw1:	MOVBQZX	0(SI)(DI*1),DX
+	ORQ	DX,R11
+afterSwitch:
+	LEAQ	(AX)(R9*1),SI
+	XORQ	R11,CX
+	RORQ	$0x33,AX
+	ADDQ	CX,BX
+	MOVQ	CX,DX
+	XORQ	SI,AX
+	RORQ	$0x30,DX
+	RORQ	$0x20,SI
+	LEAQ	0(BX)(AX*1),CX
+	XORQ	BX,DX
+	RORQ	$0x2F,AX
+	ADDQ	DX,SI
+	RORQ	$0x2B,DX
+	XORQ	CX,AX
+	XORQ	SI,DX
+	RORQ	$0x20,CX
+	ADDQ	AX,SI
+	RORQ	$0x33,AX
+	ADDQ	DX,CX
+	XORQ	SI,AX
+	RORQ	$0x30,DX
+	RORQ	$0x20,SI
+	XORQ	CX,DX
+	ADDQ	AX,CX
+	RORQ	$0x2F,AX
+	ADDQ	DX,SI
+	XORQ	CX,AX
+	RORQ	$0x2B,DX
+	RORQ	$0x20,CX
+	XORQ	SI,DX
+	XORQ	R11,SI
+	XORB	$0xFF,CL
+	ADDQ	AX,SI
+	RORQ	$0x33,AX
+	ADDQ	DX,CX
+	RORQ	$0x30,DX
+	XORQ	SI,AX
+	XORQ	CX,DX
+	RORQ	$0x20,SI
+	ADDQ	AX,CX
+	ADDQ	DX,SI
+	RORQ	$0x2F,AX
+	RORQ	$0x2B,DX
+	XORQ	CX,AX
+	XORQ	SI,DX
+	RORQ	$0x20,CX
+	ADDQ	AX,SI
+	ADDQ	DX,CX
+	RORQ	$0x33,AX
+	RORQ	$0x30,DX
+	XORQ	SI,AX
+	RORQ	$0x20,SI
+	XORQ	CX,DX
+	ADDQ	AX,CX
+	RORQ	$0x2F,AX
+	ADDQ	DX,SI
+	RORQ	$0x2B,DX
+	XORQ	CX,AX
+	XORQ	SI,DX
+	RORQ	$0x20,CX
+	ADDQ	AX,SI
+	ADDQ	DX,CX
+	RORQ	$0x33,AX
+	RORQ	$0x30,DX
+	XORQ	CX,DX
+	XORQ	SI,AX
+	RORQ	$0x20,SI
+	ADDQ	DX,SI
+	ADDQ	AX,CX
+	RORQ	$0x2F,AX
+	XORQ	CX,AX
+	RORQ	$0x2B,DX
+	RORQ	$0x20,CX
+	XORQ	SI,DX
+	ADDQ	AX,SI
+	RORQ	$0x33,AX
+	ADDQ	DX,CX
+	XORQ	SI,AX
+	RORQ	$0x30,DX
+	XORQ	CX,DX
+	ADDQ	AX,CX
+	RORQ	$0x2F,AX
+	XORQ	CX,AX
+	RORQ	$0x2B,DX
+	RORQ	$0x20,CX
+	XORQ	DX,AX
+	XORQ	CX,AX
+	MOVQ	AX,ret+40(FP)
+	RET

vendor/github.com/dchest/siphash/hash_arm.go

@@ -0,0 +1,27 @@
+// +build arm
+
+package siphash
+
+// NB: ARM implementation of forgoes extra speed for Hash()
+// and Hash128() by simply reusing the same blocks() implementation
+// in assembly used by the streaming hash.
+
+func Hash(k0, k1 uint64, p []byte) uint64 {
+	var d digest
+	d.size = Size
+	d.k0 = k0
+	d.k1 = k1
+	d.Reset()
+	d.Write(p)
+	return d.Sum64()
+}
+
+func Hash128(k0, k1 uint64, p []byte) (uint64, uint64) {
+	var d digest
+	d.size = Size128
+	d.k0 = k0
+	d.k1 = k1
+	d.Reset()
+	d.Write(p)
+	return d.sum128()
+}

vendor/github.com/dchest/siphash/hash_asm.go

@@ -0,0 +1,24 @@
+// +build amd64,!appengine,!gccgo
+
+// Written in 2012 by Dmitry Chestnykh.
+//
+// To the extent possible under law, the author have dedicated all copyright
+// and related and neighboring rights to this software to the public domain
+// worldwide. This software is distributed without any warranty.
+// http://creativecommons.org/publicdomain/zero/1.0/
+
+// This file contains a function definition for use with assembly implementations of Hash()
+
+package siphash
+
+//go:noescape
+
+// Hash returns the 64-bit SipHash-2-4 of the given byte slice with two 64-bit
+// parts of 128-bit key: k0 and k1.
+func Hash(k0, k1 uint64, b []byte) uint64
+
+//go:noescape
+
+// Hash128 returns the 128-bit SipHash-2-4 of the given byte slice with two
+// 64-bit parts of 128-bit key: k0 and k1.
+func Hash128(k0, k1 uint64, b []byte) (uint64, uint64)

vendor/github.com/dchest/siphash/siphash.go

@@ -0,0 +1,318 @@
+// Written in 2012-2014 by Dmitry Chestnykh.
+//
+// To the extent possible under law, the author have dedicated all copyright
+// and related and neighboring rights to this software to the public domain
+// worldwide. This software is distributed without any warranty.
+// http://creativecommons.org/publicdomain/zero/1.0/
+
+// Package siphash implements SipHash-2-4, a fast short-input PRF
+// created by Jean-Philippe Aumasson and Daniel J. Bernstein.
+package siphash
+
+import "hash"
+
+const (
+	// BlockSize is the block size of hash algorithm in bytes.
+	BlockSize = 8
+
+	// Size is the size of hash output in bytes.
+	Size = 8
+
+	// Size128 is the size of 128-bit hash output in bytes.
+	Size128 = 16
+)
+
+type digest struct {
+	v0, v1, v2, v3 uint64  // state
+	k0, k1         uint64  // two parts of key
+	x              [8]byte // buffer for unprocessed bytes
+	nx             int     // number of bytes in buffer x
+	size           int     // output size in bytes (8 or 16)
+	t              uint8   // message bytes counter (mod 256)
+}
+
+// newDigest returns a new digest with the given output size in bytes (must be 8 or 16).
+func newDigest(size int, key []byte) *digest {
+	if size != Size && size != Size128 {
+		panic("size must be 8 or 16")
+	}
+	d := new(digest)
+	d.k0 = uint64(key[0]) | uint64(key[1])<<8 | uint64(key[2])<<16 | uint64(key[3])<<24 |
+		uint64(key[4])<<32 | uint64(key[5])<<40 | uint64(key[6])<<48 | uint64(key[7])<<56
+	d.k1 = uint64(key[8]) | uint64(key[9])<<8 | uint64(key[10])<<16 | uint64(key[11])<<24 |
+		uint64(key[12])<<32 | uint64(key[13])<<40 | uint64(key[14])<<48 | uint64(key[15])<<56
+	d.size = size
+	d.Reset()
+	return d
+}
+
+// New returns a new hash.Hash64 computing SipHash-2-4 with 16-byte key and 8-byte output.
+func New(key []byte) hash.Hash64 {
+	return newDigest(Size, key)
+}
+
+// New128 returns a new hash.Hash computing SipHash-2-4 with 16-byte key and 16-byte output.
+//
+// Note that 16-byte output is considered experimental by SipHash authors at this time.
+func New128(key []byte) hash.Hash {
+	return newDigest(Size128, key)
+}
+
+func (d *digest) Reset() {
+	d.v0 = d.k0 ^ 0x736f6d6570736575
+	d.v1 = d.k1 ^ 0x646f72616e646f6d
+	d.v2 = d.k0 ^ 0x6c7967656e657261
+	d.v3 = d.k1 ^ 0x7465646279746573
+	d.t = 0
+	d.nx = 0
+	if d.size == Size128 {
+		d.v1 ^= 0xee
+	}
+}
+
+func (d *digest) Size() int { return d.size }
+
+func (d *digest) BlockSize() int { return BlockSize }
+
+func (d *digest) Write(p []byte) (nn int, err error) {
+	nn = len(p)
+	d.t += uint8(nn)
+	if d.nx > 0 {
+		n := len(p)
+		if n > BlockSize-d.nx {
+			n = BlockSize - d.nx
+		}
+		d.nx += copy(d.x[d.nx:], p)
+		if d.nx == BlockSize {
+			once(d)
+			d.nx = 0
+		}
+		p = p[n:]
+	}
+	if len(p) >= BlockSize {
+		n := len(p) &^ (BlockSize - 1)
+		blocks(d, p[:n])
+		p = p[n:]
+	}
+	if len(p) > 0 {
+		d.nx = copy(d.x[:], p)
+	}
+	return
+}
+
+func (d *digest) Sum64() uint64 {
+	for i := d.nx; i < BlockSize-1; i++ {
+		d.x[i] = 0
+	}
+	d.x[7] = d.t
+	return finalize(d)
+}
+
+func (d0 *digest) sum128() (r0, r1 uint64) {
+	// Make a copy of d0 so that caller can keep writing and summing.
+	d := *d0
+
+	for i := d.nx; i < BlockSize-1; i++ {
+		d.x[i] = 0
+	}
+	d.x[7] = d.t
+	blocks(&d, d.x[:])
+
+	v0, v1, v2, v3 := d.v0, d.v1, d.v2, d.v3
+	v2 ^= 0xee
+
+	// Round 1.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 2.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 3.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 4.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	r0 = v0 ^ v1 ^ v2 ^ v3
+
+	v1 ^= 0xdd
+
+	// Round 1.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 2.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 3.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	// Round 4.
+	v0 += v1
+	v1 = v1<<13 | v1>>(64-13)
+	v1 ^= v0
+	v0 = v0<<32 | v0>>(64-32)
+
+	v2 += v3
+	v3 = v3<<16 | v3>>(64-16)
+	v3 ^= v2
+
+	v0 += v3
+	v3 = v3<<21 | v3>>(64-21)
+	v3 ^= v0
+
+	v2 += v1
+	v1 = v1<<17 | v1>>(64-17)
+	v1 ^= v2
+	v2 = v2<<32 | v2>>(64-32)
+
+	r1 = v0 ^ v1 ^ v2 ^ v3
+
+	return r0, r1
+}
+
+func (d *digest) Sum(in []byte) []byte {
+	if d.size == Size {
+		r := d.Sum64()
+		in = append(in,
+			byte(r),
+			byte(r>>8),
+			byte(r>>16),
+			byte(r>>24),
+			byte(r>>32),
+			byte(r>>40),
+			byte(r>>48),
+			byte(r>>56))
+	} else {
+		r0, r1 := d.sum128()
+		in = append(in,
+			byte(r0),
+			byte(r0>>8),
+			byte(r0>>16),
+			byte(r0>>24),
+			byte(r0>>32),
+			byte(r0>>40),
+			byte(r0>>48),
+			byte(r0>>56),
+			byte(r1),
+			byte(r1>>8),
+			byte(r1>>16),
+			byte(r1>>24),
+			byte(r1>>32),
+			byte(r1>>40),
+			byte(r1>>48),
+			byte(r1>>56))
+	}
+	return in
+}

vendor/github.com/jinzhu/copier/Guardfile

@@ -0,0 +1,3 @@
+guard 'gotest' do
+  watch(%r{\.go$})
+end

vendor/github.com/jinzhu/copier/License

@@ -0,0 +1,20 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 Jinzhu
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

vendor/github.com/jinzhu/copier/README.md

@@ -0,0 +1,115 @@
+# Copier
+
+  I am a copier, I copy everything from one to another
+
+[![wercker status](https://app.wercker.com/status/9d44ad2d4e6253929c8fb71359effc0b/s/master "wercker status")](https://app.wercker.com/project/byKey/9d44ad2d4e6253929c8fb71359effc0b)
+
+## Features
+
+* Copy from field to field with same name
+* Copy from method to field with same name
+* Copy from field to method with same name
+* Copy from slice to slice
+* Copy from struct to slice
+* Enforce copying a field with a tag
+* Ignore a field with a tag
+
+## Usage
+
+```go
+package main
+
+import (
+	"fmt"
+	"github.com/jinzhu/copier"
+)
+
+type User struct {
+	Name string
+	Role string
+	Age  int32
+
+	// Explicitly ignored in the destination struct.
+	Salary   int
+}
+
+func (user *User) DoubleAge() int32 {
+	return 2 * user.Age
+}
+
+// Tags in the destination Struct provide instructions to copier.Copy to ignore
+// or enforce copying and to panic or return an error if a field was not copied.
+type Employee struct {
+	// Tell copier.Copy to panic if this field is not copied.
+	Name      string `copier:"must"`
+
+	// Tell copier.Copy to return an error if this field is not copied.
+	Age       int32  `copier:"must,nopanic"`
+
+	// Tell copier.Copy to explicitly ignore copying this field.
+	Salary    int    `copier:"-"`
+
+	DoubleAge int32
+	EmployeId int64
+	SuperRule string
+}
+
+func (employee *Employee) Role(role string) {
+	employee.SuperRule = "Super " + role
+}
+
+func main() {
+	var (
+		user      = User{Name: "Jinzhu", Age: 18, Role: "Admin", Salary: 200000}
+		users     = []User{{Name: "Jinzhu", Age: 18, Role: "Admin", Salary: 100000}, {Name: "jinzhu 2", Age: 30, Role: "Dev", Salary: 60000}}
+		employee  = Employee{Salary: 150000}
+		employees = []Employee{}
+	)
+
+	copier.Copy(&employee, &user)
+
+	fmt.Printf("%#v \n", employee)
+	// Employee{
+	//    Name: "Jinzhu",           // Copy from field
+	//    Age: 18,                  // Copy from field
+	//    Salary:150000,            // Copying explicitly ignored
+	//    DoubleAge: 36,            // Copy from method
+	//    EmployeeId: 0,            // Ignored
+	//    SuperRule: "Super Admin", // Copy to method
+	// }
+
+	// Copy struct to slice
+	copier.Copy(&employees, &user)
+
+	fmt.Printf("%#v \n", employees)
+	// []Employee{
+	//   {Name: "Jinzhu", Age: 18, Salary:0, DoubleAge: 36, EmployeId: 0, SuperRule: "Super Admin"}
+	// }
+
+	// Copy slice to slice
+	employees = []Employee{}
+	copier.Copy(&employees, &users)
+
+	fmt.Printf("%#v \n", employees)
+	// []Employee{
+	//   {Name: "Jinzhu", Age: 18, Salary:0, DoubleAge: 36, EmployeId: 0, SuperRule: "Super Admin"},
+	//   {Name: "jinzhu 2", Age: 30, Salary:0, DoubleAge: 60, EmployeId: 0, SuperRule: "Super Dev"},
+	// }
+}
+```
+
+## Contributing
+
+You can help to make the project better, check out [http://gorm.io/contribute.html](http://gorm.io/contribute.html) for things you can do.
+
+# Author
+
+**jinzhu**
+
+* <http://github.com/jinzhu>
+* <[email protected]>
+* <http://twitter.com/zhangjinzhu>
+
+## License
+
+Released under the [MIT License](https://github.com/jinzhu/copier/blob/master/License).

vendor/github.com/jinzhu/copier/copier.go

@@ -0,0 +1,275 @@
+package copier
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+// These flags define options for tag handling
+const (
+	// Denotes that a destination field must be copied to. If copying fails then a panic will ensue.
+	tagMust uint8 = 1 << iota
+
+	// Denotes that the program should not panic when the must flag is on and
+	// value is not copied. The program will return an error instead.
+	tagNoPanic
+
+	// Ignore a destation field from being copied to.
+	tagIgnore
+
+	// Denotes that the value as been copied
+	hasCopied
+)
+
+// Copy copy things
+func Copy(toValue interface{}, fromValue interface{}) (err error) {
+	var (
+		isSlice bool
+		amount  = 1
+		from    = indirect(reflect.ValueOf(fromValue))
+		to      = indirect(reflect.ValueOf(toValue))
+	)
+
+	if !to.CanAddr() {
+		return errors.New("copy to value is unaddressable")
+	}
+
+	// Return is from value is invalid
+	if !from.IsValid() {
+		return
+	}
+
+	fromType := indirectType(from.Type())
+	toType := indirectType(to.Type())
+
+	// Just set it if possible to assign
+	// And need to do copy anyway if the type is struct
+	if fromType.Kind() != reflect.Struct && from.Type().AssignableTo(to.Type()) {
+		to.Set(from)
+		return
+	}
+
+	if fromType.Kind() != reflect.Struct || toType.Kind() != reflect.Struct {
+		return
+	}
+
+	if to.Kind() == reflect.Slice {
+		isSlice = true
+		if from.Kind() == reflect.Slice {
+			amount = from.Len()
+		}
+	}
+
+	for i := 0; i < amount; i++ {
+		var dest, source reflect.Value
+
+		if isSlice {
+			// source
+			if from.Kind() == reflect.Slice {
+				source = indirect(from.Index(i))
+			} else {
+				source = indirect(from)
+			}
+			// dest
+			dest = indirect(reflect.New(toType).Elem())
+		} else {
+			source = indirect(from)
+			dest = indirect(to)
+		}
+
+		// Get tag options
+		tagBitFlags := map[string]uint8{}
+		if dest.IsValid() {
+			tagBitFlags = getBitFlags(toType)
+		}
+
+		// check source
+		if source.IsValid() {
+			fromTypeFields := deepFields(fromType)
+			//fmt.Printf("%#v", fromTypeFields)
+			// Copy from field to field or method
+			for _, field := range fromTypeFields {
+				name := field.Name
+
+				// Get bit flags for field
+				fieldFlags, _ := tagBitFlags[name]
+
+				// Check if we should ignore copying
+				if (fieldFlags & tagIgnore) != 0 {
+					continue
+				}
+
+				if fromField := source.FieldByName(name); fromField.IsValid() {
+					// has field
+					if toField := dest.FieldByName(name); toField.IsValid() {
+						if toField.CanSet() {
+							if !set(toField, fromField) {
+								if err := Copy(toField.Addr().Interface(), fromField.Interface()); err != nil {
+									return err
+								}
+							} else {
+								if fieldFlags != 0 {
+									// Note that a copy was made
+									tagBitFlags[name] = fieldFlags | hasCopied
+								}
+							}
+						}
+					} else {
+						// try to set to method
+						var toMethod reflect.Value
+						if dest.CanAddr() {
+							toMethod = dest.Addr().MethodByName(name)
+						} else {
+							toMethod = dest.MethodByName(name)
+						}
+
+						if toMethod.IsValid() && toMethod.Type().NumIn() == 1 && fromField.Type().AssignableTo(toMethod.Type().In(0)) {
+							toMethod.Call([]reflect.Value{fromField})
+						}
+					}
+				}
+			}
+
+			// Copy from method to field
+			for _, field := range deepFields(toType) {
+				name := field.Name
+
+				var fromMethod reflect.Value
+				if source.CanAddr() {
+					fromMethod = source.Addr().MethodByName(name)
+				} else {
+					fromMethod = source.MethodByName(name)
+				}
+
+				if fromMethod.IsValid() && fromMethod.Type().NumIn() == 0 && fromMethod.Type().NumOut() == 1 {
+					if toField := dest.FieldByName(name); toField.IsValid() && toField.CanSet() {
+						values := fromMethod.Call([]reflect.Value{})
+						if len(values) >= 1 {
+							set(toField, values[0])
+						}
+					}
+				}
+			}
+		}
+		if isSlice {
+			if dest.Addr().Type().AssignableTo(to.Type().Elem()) {
+				to.Set(reflect.Append(to, dest.Addr()))
+			} else if dest.Type().AssignableTo(to.Type().Elem()) {
+				to.Set(reflect.Append(to, dest))
+			}
+		}
+		err = checkBitFlags(tagBitFlags)
+	}
+	return
+}
+
+func deepFields(reflectType reflect.Type) []reflect.StructField {
+	var fields []reflect.StructField
+
+	if reflectType = indirectType(reflectType); reflectType.Kind() == reflect.Struct {
+		for i := 0; i < reflectType.NumField(); i++ {
+			v := reflectType.Field(i)
+			if v.Anonymous {
+				fields = append(fields, deepFields(v.Type)...)
+			} else {
+				fields = append(fields, v)
+			}
+		}
+	}
+
+	return fields
+}
+
+func indirect(reflectValue reflect.Value) reflect.Value {
+	for reflectValue.Kind() == reflect.Ptr {
+		reflectValue = reflectValue.Elem()
+	}
+	return reflectValue
+}
+
+func indirectType(reflectType reflect.Type) reflect.Type {
+	for reflectType.Kind() == reflect.Ptr || reflectType.Kind() == reflect.Slice {
+		reflectType = reflectType.Elem()
+	}
+	return reflectType
+}
+
+func set(to, from reflect.Value) bool {
+	if from.IsValid() {
+		if to.Kind() == reflect.Ptr {
+			//set `to` to nil if from is nil
+			if from.Kind() == reflect.Ptr && from.IsNil() {
+				to.Set(reflect.Zero(to.Type()))
+				return true
+			} else if to.IsNil() {
+				to.Set(reflect.New(to.Type().Elem()))
+			}
+			to = to.Elem()
+		}
+
+		if from.Type().ConvertibleTo(to.Type()) {
+			to.Set(from.Convert(to.Type()))
+		} else if scanner, ok := to.Addr().Interface().(sql.Scanner); ok {
+			err := scanner.Scan(from.Interface())
+			if err != nil {
+				return false
+			}
+		} else if from.Kind() == reflect.Ptr {
+			return set(to, from.Elem())
+		} else {
+			return false
+		}
+	}
+	return true
+}
+
+// parseTags Parses struct tags and returns uint8 bit flags.
+func parseTags(tag string) (flags uint8) {
+	for _, t := range strings.Split(tag, ",") {
+		switch t {
+		case "-":
+			flags = tagIgnore
+			return
+		case "must":
+			flags = flags | tagMust
+		case "nopanic":
+			flags = flags | tagNoPanic
+		}
+	}
+	return
+}
+
+// getBitFlags Parses struct tags for bit flags.
+func getBitFlags(toType reflect.Type) map[string]uint8 {
+	flags := map[string]uint8{}
+	toTypeFields := deepFields(toType)
+
+	// Get a list dest of tags
+	for _, field := range toTypeFields {
+		tags := field.Tag.Get("copier")
+		if tags != "" {
+			flags[field.Name] = parseTags(tags)
+		}
+	}
+	return flags
+}
+
+// checkBitFlags Checks flags for error or panic conditions.
+func checkBitFlags(flagsList map[string]uint8) (err error) {
+	// Check flag conditions were met
+	for name, flags := range flagsList {
+		if flags&hasCopied == 0 {
+			switch {
+			case flags&tagMust != 0 && flags&tagNoPanic != 0:
+				err = fmt.Errorf("Field %s has must tag but was not copied", name)
+				return
+			case flags&(tagMust) != 0:
+				panic(fmt.Sprintf("Field %s has must tag but was not copied", name))
+			}
+		}
+	}
+	return
+}

vendor/github.com/jinzhu/copier/go.mod

@@ -0,0 +1,3 @@
+module github.com/jinzhu/copier
+
+go 1.15

vendor/github.com/jinzhu/copier/wercker.yml

@@ -0,0 +1,23 @@
+box: golang
+
+build:
+  steps:
+    - setup-go-workspace
+
+    # Gets the dependencies
+    - script:
+        name: go get
+        code: |
+          go get
+
+    # Build the project
+    - script:
+        name: go build
+        code: |
+          go build ./...
+
+    # Test the project
+    - script:
+        name: go test
+        code: |
+          go test ./...

vendor/github.com/mroth/weightedrand/LICENSE.txt

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2018 Matthew Rothenberg
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/github.com/mroth/weightedrand/README.md

@@ -0,0 +1,85 @@
+# weightedrand :balance_scale:
+
+[![PkgGoDev](https://pkg.go.dev/badge/github.com/mroth/weightedrand)](https://pkg.go.dev/github.com/mroth/weightedrand)
+[![CodeFactor](https://www.codefactor.io/repository/github/mroth/weightedrand/badge)](https://www.codefactor.io/repository/github/mroth/weightedrand)
+[![Build Status](https://github.com/mroth/weightedrand/workflows/test/badge.svg)](https://github.com/mroth/weightedrand/actions)
+[![codecov](https://codecov.io/gh/mroth/weightedrand/branch/master/graph/badge.svg)](https://codecov.io/gh/mroth/weightedrand)
+
+> Fast weighted random selection for Go.
+
+Randomly selects an element from some kind of list, where the chances of each
+element to be selected are not equal, but rather defined by relative "weights"
+(or probabilities). This is called weighted random selection.
+
+## Usage
+
+```go
+import (
+    /* ...snip... */
+    wr "github.com/mroth/weightedrand"
+)
+
+func main() {
+    rand.Seed(time.Now().UTC().UnixNano()) // always seed random!
+
+    chooser, _ := wr.NewChooser(
+        wr.Choice{Item: "🍒", Weight: 0},
+        wr.Choice{Item: "🍋", Weight: 1},
+        wr.Choice{Item: "🍊", Weight: 1},
+        wr.Choice{Item: "🍉", Weight: 3},
+        wr.Choice{Item: "🥑", Weight: 5},
+    )
+    /* The following will print 🍋 and 🍊 with 0.1 probability, 🍉 with 0.3
+    probability, and 🥑 with 0.5 probability. 🍒 will never be printed. (Note
+    the weights don't have to add up to 10, that was just done here to make the
+    example easier to read.) */
+    result := chooser.Pick().(string)
+    fmt.Println(result)
+}
+```
+
+## Performance
+
+The existing Go library that has a comparable implementation of this is
+[`github.com/jmcvetta/randutil`][1], which optimizes for the single operation
+case. In contrast, this library creates a presorted cache optimized for binary
+search, allowing repeated selections from the same set to be significantly
+faster, especially for large data sets.
+
+[1]: https://github.com/jmcvetta/randutil
+
+Comparison of this library versus `randutil.ChooseWeighted` on my workstation.
+For repeated samplings from large collections, `weightedrand` will be much
+quicker:
+
+| Num choices |     `randutil` | `weightedrand` | `weightedrand -cpu=8`* |
+| ----------: | -------------: | -------------: | ---------------------: |
+|          10 |      201 ns/op |       38 ns/op |              2.9 ns/op |
+|         100 |      267 ns/op |       51 ns/op |              4.1 ns/op |
+|       1,000 |     1012 ns/op |       67 ns/op |              5.4 ns/op |
+|      10,000 |     8683 ns/op |       83 ns/op |              6.9 ns/op |
+|     100,000 |   123500 ns/op |      105 ns/op |             12.0 ns/op |
+|   1,000,000 |  2399614 ns/op |      218 ns/op |             17.2 ns/op |
+|  10,000,000 | 26804440 ns/op |      432 ns/op |             35.1 ns/op |
+
+**: Since `v0.3.0` weightedrand can efficiently utilize a single Chooser across
+multiple CPU cores in parallel, making it even faster in overall throughput. See
+[PR#2](https://github.com/mroth/weightedrand/pull/2) for details. Informal
+benchmarks conducted on an Intel Xeon W-2140B CPU (8 core @ 3.2GHz,
+hyperthreading enabled).*
+
+Don't be mislead by these numbers into thinking `weightedrand` is always the
+right choice! If you are only picking from the same distribution once,
+`randutil` will be faster. `weightedrand` optimizes for repeated calls at the
+expense of some initialization time and memory storage.
+
+## Caveats
+
+Note this library utilizes `math/rand` instead of `crypto/rand`, as it is
+optimized for performance, and is not intended to be used for cryptographically
+secure requirements.
+
+## Credits
+
+To better understand the algorithm used in this library (as well as the one used
+in randutil) check out this great blog post: [Weighted random generation in Python](https://eli.thegreenplace.net/2010/01/22/weighted-random-generation-in-python/).

vendor/github.com/mroth/weightedrand/go.mod

@@ -0,0 +1,3 @@
+module github.com/mroth/weightedrand
+
+go 1.10

vendor/github.com/mroth/weightedrand/weightedrand.go

@@ -0,0 +1,125 @@
+// Package weightedrand contains a performant data structure and algorithm used
+// to randomly select an element from some kind of list, where the chances of
+// each element to be selected not being equal, but defined by relative
+// "weights" (or probabilities). This is called weighted random selection.
+//
+// Compare this package with (github.com/jmcvetta/randutil).WeightedChoice,
+// which is optimized for the single operation case. In contrast, this package
+// creates a presorted cache optimized for binary search, allowing for repeated
+// selections from the same set to be significantly faster, especially for large
+// data sets.
+package weightedrand
+
+import (
+	"errors"
+	"math/rand"
+	"sort"
+)
+
+// Choice is a generic wrapper that can be used to add weights for any item.
+type Choice struct {
+	Item   interface{}
+	Weight uint
+}
+
+// NewChoice creates a new Choice with specified item and weight.
+func NewChoice(item interface{}, weight uint) Choice {
+	return Choice{Item: item, Weight: weight}
+}
+
+// A Chooser caches many possible Choices in a structure designed to improve
+// performance on repeated calls for weighted random selection.
+type Chooser struct {
+	data   []Choice
+	totals []int
+	max    int
+}
+
+// NewChooser initializes a new Chooser for picking from the provided choices.
+func NewChooser(choices ...Choice) (*Chooser, error) {
+	sort.Slice(choices, func(i, j int) bool {
+		return choices[i].Weight < choices[j].Weight
+	})
+
+	totals := make([]int, len(choices))
+	runningTotal := 0
+	for i, c := range choices {
+		weight := int(c.Weight)
+		if (maxInt - runningTotal) <= weight {
+			return nil, errWeightOverflow
+		}
+		runningTotal += weight
+		totals[i] = runningTotal
+	}
+
+	if runningTotal <= 1 {
+		return nil, errNoValidChoices
+	}
+
+	return &Chooser{data: choices, totals: totals, max: runningTotal}, nil
+}
+
+const (
+	intSize = 32 << (^uint(0) >> 63) // cf. strconv.IntSize
+	maxInt  = 1<<(intSize-1) - 1
+)
+
+// Possible errors returned by NewChooser, preventing the creation of a Chooser
+// with unsafe runtime states.
+var (
+	// If the sum of provided Choice weights exceed the maximum integer value
+	// for the current platform (e.g. math.MaxInt32 or math.MaxInt64), then
+	// the internal running total will overflow, resulting in an imbalanced
+	// distribution generating improper results.
+	errWeightOverflow = errors.New("sum of Choice Weights exceeds max int")
+	// If there are no Choices available to the Chooser with a weight >= 1,
+	// there are no valid choices and Pick would produce a runtime panic.
+	errNoValidChoices = errors.New("zero Choices with Weight >= 1")
+)
+
+// Pick returns a single weighted random Choice.Item from the Chooser.
+//
+// Utilizes global rand as the source of randomness.
+func (c Chooser) Pick() interface{} {
+	r := rand.Intn(c.max) + 1
+	i := searchInts(c.totals, r)
+	return c.data[i].Item
+}
+
+// PickSource returns a single weighted random Choice.Item from the Chooser,
+// utilizing the provided *rand.Rand source rs for randomness.
+//
+// The primary use-case for this is avoid lock contention from the global random
+// source if utilizing Chooser(s) from multiple goroutines in extremely
+// high-throughput situations.
+//
+// It is the responsibility of the caller to ensure the provided rand.Source is
+// free from thread safety issues.
+func (c Chooser) PickSource(rs *rand.Rand) interface{} {
+	r := rs.Intn(c.max) + 1
+	i := searchInts(c.totals, r)
+	return c.data[i].Item
+}
+
+// The standard library sort.SearchInts() just wraps the generic sort.Search()
+// function, which takes a function closure to determine truthfulness. However,
+// since this function is utilized within a for loop, it cannot currently be
+// properly inlined by the compiler, resulting in non-trivial performance
+// overhead.
+//
+// Thus, this is essentially manually inlined version.  In our use case here, it
+// results in a up to ~33% overall throughput increase for Pick().
+func searchInts(a []int, x int) int {
+	// Possible further future optimization for searchInts via SIMD if we want
+	// to write some Go assembly code: http://0x80.pl/articles/simd-search.html
+	i, j := 0, len(a)
+	for i < j {
+		h := int(uint(i+j) >> 1) // avoid overflow when computing h
+		if a[h] < x {
+			i = h + 1
+		} else {
+			j = h
+		}
+	}
+	return i
+}

vendor/github.com/refraction-networking/gotapdance/README.md

@@ -1,8 +1,8 @@
 <p align="center">
 <a href="https://refraction.network"><img src="https://user-images.githubusercontent.com/5443147/30133006-7c3019f4-930f-11e7-9f60-3df45ee13d9d.png" alt="refract"></a>
-<h1 class="header-title" align="center">TapDance Client</h1>
+<h1 class="header-title" align="center">Refraction Networking Client</h1>
 
-<p align="center">TapDance is a free-to-use anti-censorship technology, protected from enumeration attacks.</p>
+<p align="center">Refraction Networking is a free-to-use anti-censorship technology, that places proxies at Internet Service Providers, so they are harder to block. This client includes support for both the TapDance and Conjure protocols</p>
 <p align="center">
 <a href="https://travis-ci.org/refraction-networking/gotapdance"><img src="https://travis-ci.org/refraction-networking/gotapdance.svg?branch=master"></a>
 <a href="https://godoc.org/github.com/refraction-networking/gotapdance/tapdance"><img src="https://img.shields.io/badge/godoc-reference-blue.svg"></a>

vendor/github.com/refraction-networking/gotapdance/build-apk.sh

@@ -0,0 +1,69 @@
+#!/bin/bash
+
+
+REPO_DIR=$GOPATH/src/github.com/refraction-networking/gotapdance/
+
+#sed -i.bak "s/buildInfo = \"\"/buildInfo = \"$TRAVIS_BRANCH-$TRAVIS_COMMIT\"/" tapdance/logger.go
+git clone https://github.com/Psiphon-Labs/psiphon-tunnel-core.git $GOPATH/src/github.com/Psiphon-Labs/psiphon-tunnel-core
+cd $GOPATH/src/github.com/Psiphon-Labs/psiphon-tunnel-core && git checkout -b build-refraction-networking
+
+
+go get github.com/kardianos/govendor
+cd $GOPATH/src/github.com/Psiphon-Labs/psiphon-tunnel-core && $GOPATH/bin/govendor remove github.com/refraction-networking/gotapdance/...
+
+sed -i.bak 's/refraction_networking_tapdance.Logger().Out = ioutil.Discard//' $GOPATH/src/github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/tapdance/tapdance.go
+
+
+# Conjure APK
+echo "Conjure APK before_Script"
+
+cd $GOPATH/src/github.com/refraction-networking/gotapdance
+
+docker pull refraction/psiandroid:latest
+
+mkdir -p $GOPATH/src/bitbucket.org/psiphon
+hg clone https://bitbucket.org/psiphon/psiphon-circumvention-system $GOPATH/src/bitbucket.org/psiphon/psiphon-circumvention-system
+
+cd $GOPATH/src/bitbucket.org/psiphon/psiphon-circumvention-system #&& hg checkout
+
+# Use modified EmbeddedValues.java for TapDance
+cd $GOPATH/src/github.com/refraction-networking/gotapdance
+/usr/local/ssl/bin/openssl enc -nosalt -aes-256-cbc -md sha512 -pbkdf2 -iter 1000 -pass pass:$aes_cbc_passwd  -d -in build/EmbeddedValues.java.enc -out $GOPATH/src/bitbucket.org/psiphon/psiphon-circumvention-system/Android/app/src/main/java/com/psiphon3/psiphonlibrary/EmbeddedValues.java
+
+echo "patching..."
+# Patched tunneling protocol for TapDance
+patch $GOPATH/src/bitbucket.org/psiphon/psiphon-circumvention-system/Android/app/src/main/java/com/psiphon3/psiphonlibrary/TunnelManager.java build/TunnelManager.java.patch
+
+# Patch the Psiphon app's gradle build for java 1.8 compatibility [TODO]{priority:later} remove this when psiphon merges it themselves
+patch $GOPATH/src/bitbucket.org/psiphon/psiphon-circumvention-system/Android/app/build.gradle build/PsiphonCoreGradle.patch
+
+# Add dialer options to enable Conjure
+patch $GOPATH/src/github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/tapdance/tapdance.go build/conjure.golang.patch
+
+echo "digesting..."
+# Digest this branch's ClientConf into Psiphon's embedded_config
+./test_scripts/psiphon_digest_cc.sh ./assets/ClientConf $GOPATH/src/github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/tapdance/embedded_config.go
+
+echo "Conjure APK script"
+cd $REPO_DIR
+
+# Build Psiphon Android Library ca.psiphon.aar
+#docker run -v $DOCKER_DIR:$GOPATH/go/src/github.com/refraction-networking/gotapdance -v $GOPATH/src/github.com/Psiphon-Labs/psiphon-tunnel-core:$GOPATH/go/src/github.com/Psiphon-Labs/psiphon-tunnel-core refraction/psiandroid /bin/bash -c 'cd $GOPATH/src/github.com/Psiphon-Labs/psiphon-tunnel-core/MobileLibrary/Android && ./make.bash "TAPDANCE"'
+docker run -v $REPO_DIR:/go/src/github.com/refraction-networking/gotapdance -v $GOPATH/src/github.com/Psiphon-Labs/psiphon-tunnel-core:/go/src/github.com/Psiphon-Labs/psiphon-tunnel-core refraction/psiandroid /bin/bash -c 'cd /go/src/github.com/Psiphon-Labs/psiphon-tunnel-core/MobileLibrary/Android && ./make.bash "TAPDANCE"'
+
+echo "moving .aar"
+cd $GOPATH/src/github.com/refraction-networking/gotapdance
+mv $GOPATH/src/github.com/Psiphon-Labs/psiphon-tunnel-core/MobileLibrary/Android/ca.psiphon.aar build/
+
+# Build Psiphon Android App PsiphonAndroid-debug.apk
+cp -f build/ca.psiphon.aar $GOPATH/src/bitbucket.org/psiphon/psiphon-circumvention-system/Android/app/libs/
+
+cd $GOPATH/src/github.com/refraction-networking/gotapdance
+echo "docker run gradlew assembleDebug.."
+#docker run -v $DOCKER_DIR:/go/src/github.com/refraction-networking/gotapdance -v $GOPATH/src/bitbucket.org/psiphon/psiphon-circumvention-system/Android:/go/src/bitbucket.org/psiphon/psiphon-circumvention-system/Android refraction/psiandroid /bin/bash -c 'yes | /android-sdk-linux/tools/bin/sdkmanager --update && cd /go/src/bitbucket.org/psiphon/psiphon-circumvention-system/Android && ./gradlew assembleDebug'
+docker run -v $REPO_DIR:/go/src/github.com/refraction-networking/gotapdance -v $GOPATH/src/bitbucket.org/psiphon/psiphon-circumvention-system/Android:/go/src/bitbucket.org/psiphon/psiphon-circumvention-system/Android refraction/psiandroid /bin/bash -c 'yes | /android-sdk-linux/tools/bin/sdkmanager --update && cd /go/src/bitbucket.org/psiphon/psiphon-circumvention-system/Android && ./gradlew assembleDebug'
+
+cp $GOPATH/src/bitbucket.org/psiphon/psiphon-circumvention-system/Android/app/build/outputs/apk/debug/PsiphonAndroid-debug.apk build/PsiphonAndroid-CJ-debug.apk
+
+pwd
+echo "build/PsiphonAndroid-CJ-debug.apk"

vendor/github.com/refraction-networking/gotapdance/ed25519/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2012 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/github.com/refraction-networking/gotapdance/ed25519/edwards25519/const.go

@@ -0,0 +1,1411 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package edwards25519
+
+var d = FieldElement{
+	-10913610, 13857413, -15372611, 6949391, 114729, -8787816, -6275908, -3247719, -18696448, -12055116,
+}
+
+var d2 = FieldElement{
+	-21827239, -5839606, -30745221, 13898782, 229458, 15978800, -12551817, -6495438, 29715968, 9444199,
+}
+
+var SqrtM1 = FieldElement{
+	-32595792, -7943725, 9377950, 3500415, 12389472, -272473, -25146209, -2005654, 326686, 11406482,
+}
+
+var A = FieldElement{
+	486662, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+}
+
+var bi = [8]PreComputedGroupElement{
+	{
+		FieldElement{25967493, -14356035, 29566456, 3660896, -12694345, 4014787, 27544626, -11754271, -6079156, 2047605},
+		FieldElement{-12545711, 934262, -2722910, 3049990, -727428, 9406986, 12720692, 5043384, 19500929, -15469378},
+		FieldElement{-8738181, 4489570, 9688441, -14785194, 10184609, -12363380, 29287919, 11864899, -24514362, -4438546},
+	},
+	{
+		FieldElement{15636291, -9688557, 24204773, -7912398, 616977, -16685262, 27787600, -14772189, 28944400, -1550024},
+		FieldElement{16568933, 4717097, -11556148, -1102322, 15682896, -11807043, 16354577, -11775962, 7689662, 11199574},
+		FieldElement{30464156, -5976125, -11779434, -15670865, 23220365, 15915852, 7512774, 10017326, -17749093, -9920357},
+	},
+	{
+		FieldElement{10861363, 11473154, 27284546, 1981175, -30064349, 12577861, 32867885, 14515107, -15438304, 10819380},
+		FieldElement{4708026, 6336745, 20377586, 9066809, -11272109, 6594696, -25653668, 12483688, -12668491, 5581306},
+		FieldElement{19563160, 16186464, -29386857, 4097519, 10237984, -4348115, 28542350, 13850243, -23678021, -15815942},
+	},
+	{
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+		FieldElement{-30269007, -3463509, 7665486, 10083793, 28475525, 1649722, 20654025, 16520125, 30598449, 7715701},
+		FieldElement{28881845, 14381568, 9657904, 3680757, -20181635, 7843316, -31400660, 1370708, 29794553, -1409300},
+	},
+	{
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+	},
+	{
+		FieldElement{-33521811, 3180713, -2394130, 14003687, -16903474, -16270840, 17238398, 4729455, -18074513, 9256800},
+		FieldElement{-25182317, -4174131, 32336398, 5036987, -21236817, 11360617, 22616405, 9761698, -19827198, 630305},
+		FieldElement{-13720693, 2639453, -24237460, -7406481, 9494427, -5774029, -6554551, -15960994, -2449256, -14291300},
+	},
+	{
+		FieldElement{-3151181, -5046075, 9282714, 6866145, -31907062, -863023, -18940575, 15033784, 25105118, -7894876},
+		FieldElement{-24326370, 15950226, -31801215, -14592823, -11662737, -5090925, 1573892, -2625887, 2198790, -15804619},
+		FieldElement{-3099351, 10324967, -2241613, 7453183, -5446979, -2735503, -13812022, -16236442, -32461234, -12290683},
+	},
+}
+
+var base = [32][8]PreComputedGroupElement{
+	{
+		{
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+		},
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+		},
+		{
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+			FieldElement{30464156, -5976125, -11779434, -15670865, 23220365, 15915852, 7512774, 10017326, -17749093, -9920357},
+		},
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+		},
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+			FieldElement{-17751622, -2097826, 16544300, -13009300, -15914807, -14949081, 18345767, -13403753, 16291481, -5314038},
+			FieldElement{-33229194, 2553288, 32678213, 9875984, 8534129, 6889387, -9676774, 6957617, 4368891, 9788741},
+			FieldElement{16660756, 7281060, -10830758, 12911820, 20108584, -8101676, -21722536, -8613148, 16250552, -11111103},
+		},
+		{
+			FieldElement{-19765507, 2390526, -16551031, 14161980, 1905286, 6414907, 4689584, 10604807, -30190403, 4782747},
+			FieldElement{-1354539, 14736941, -7367442, -13292886, 7710542, -14155590, -9981571, 4383045, 22546403, 437323},
+			FieldElement{31665577, -12180464, -16186830, 1491339, -18368625, 3294682, 27343084, 2786261, -30633590, -14097016},
+		},
+		{
+			FieldElement{-14467279, -683715, -33374107, 7448552, 19294360, 14334329, -19690631, 2355319, -19284671, -6114373},
+			FieldElement{15121312, -15796162, 6377020, -6031361, -10798111, -12957845, 18952177, 15496498, -29380133, 11754228},
+			FieldElement{-2637277, -13483075, 8488727, -14303896, 12728761, -1622493, 7141596, 11724556, 22761615, -10134141},
+		},
+		{
+			FieldElement{16918416, 11729663, -18083579, 3022987, -31015732, -13339659, -28741185, -12227393, 32851222, 11717399},
+			FieldElement{11166634, 7338049, -6722523, 4531520, -29468672, -7302055, 31474879, 3483633, -1193175, -4030831},
+			FieldElement{-185635, 9921305, 31456609, -13536438, -12013818, 13348923, 33142652, 6546660, -19985279, -3948376},
+		},
+		{
+			FieldElement{-32460596, 11266712, -11197107, -7899103, 31703694, 3855903, -8537131, -12833048, -30772034, -15486313},
+			FieldElement{-18006477, 12709068, 3991746, -6479188, -21491523, -10550425, -31135347, -16049879, 10928917, 3011958},
+			FieldElement{-6957757, -15594337, 31696059, 334240, 29576716, 14796075, -30831056, -12805180, 18008031, 10258577},
+		},
+		{
+			FieldElement{-22448644, 15655569, 7018479, -4410003, -30314266, -1201591, -1853465, 1367120, 25127874, 6671743},
+			FieldElement{29701166, -14373934, -10878120, 9279288, -17568, 13127210, 21382910, 11042292, 25838796, 4642684},
+			FieldElement{-20430234, 14955537, -24126347, 8124619, -5369288, -5990470, 30468147, -13900640, 18423289, 4177476},
+		},
+	},
+}

vendor/github.com/refraction-networking/gotapdance/ed25519/edwards25519/edwards25519.go

@@ -0,0 +1,1773 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package edwards25519 implements operations in GF(2**255-19) and on an
+// Edwards curve that is isomorphic to curve25519. See
+// http://ed25519.cr.yp.to/.
+package edwards25519
+
+// This code is a port of the public domain, "ref10" implementation of ed25519
+// from SUPERCOP.
+
+// FieldElement represents an element of the field GF(2^255 - 19).  An element
+// t, entries t[0]...t[9], represents the integer t[0]+2^26 t[1]+2^51 t[2]+2^77
+// t[3]+2^102 t[4]+...+2^230 t[9].  Bounds on each t[i] vary depending on
+// context.
+type FieldElement [10]int32
+
+var zero FieldElement
+
+func FeZero(fe *FieldElement) {
+	copy(fe[:], zero[:])
+}
+
+func FeOne(fe *FieldElement) {
+	FeZero(fe)
+	fe[0] = 1
+}
+
+func FeAdd(dst, a, b *FieldElement) {
+	dst[0] = a[0] + b[0]
+	dst[1] = a[1] + b[1]
+	dst[2] = a[2] + b[2]
+	dst[3] = a[3] + b[3]
+	dst[4] = a[4] + b[4]
+	dst[5] = a[5] + b[5]
+	dst[6] = a[6] + b[6]
+	dst[7] = a[7] + b[7]
+	dst[8] = a[8] + b[8]
+	dst[9] = a[9] + b[9]
+}
+
+func FeSub(dst, a, b *FieldElement) {
+	dst[0] = a[0] - b[0]
+	dst[1] = a[1] - b[1]
+	dst[2] = a[2] - b[2]
+	dst[3] = a[3] - b[3]
+	dst[4] = a[4] - b[4]
+	dst[5] = a[5] - b[5]
+	dst[6] = a[6] - b[6]
+	dst[7] = a[7] - b[7]
+	dst[8] = a[8] - b[8]
+	dst[9] = a[9] - b[9]
+}
+
+func FeCopy(dst, src *FieldElement) {
+	copy(dst[:], src[:])
+}
+
+// Replace (f,g) with (g,g) if b == 1;
+// replace (f,g) with (f,g) if b == 0.
+//
+// Preconditions: b in {0,1}.
+func FeCMove(f, g *FieldElement, b int32) {
+	b = -b
+	f[0] ^= b & (f[0] ^ g[0])
+	f[1] ^= b & (f[1] ^ g[1])
+	f[2] ^= b & (f[2] ^ g[2])
+	f[3] ^= b & (f[3] ^ g[3])
+	f[4] ^= b & (f[4] ^ g[4])
+	f[5] ^= b & (f[5] ^ g[5])
+	f[6] ^= b & (f[6] ^ g[6])
+	f[7] ^= b & (f[7] ^ g[7])
+	f[8] ^= b & (f[8] ^ g[8])
+	f[9] ^= b & (f[9] ^ g[9])
+}
+
+func load3(in []byte) int64 {
+	var r int64
+	r = int64(in[0])
+	r |= int64(in[1]) << 8
+	r |= int64(in[2]) << 16
+	return r
+}
+
+func load4(in []byte) int64 {
+	var r int64
+	r = int64(in[0])
+	r |= int64(in[1]) << 8
+	r |= int64(in[2]) << 16
+	r |= int64(in[3]) << 24
+	return r
+}
+
+func FeFromBytes(dst *FieldElement, src *[32]byte) {
+	h0 := load4(src[:])
+	h1 := load3(src[4:]) << 6
+	h2 := load3(src[7:]) << 5
+	h3 := load3(src[10:]) << 3
+	h4 := load3(src[13:]) << 2
+	h5 := load4(src[16:])
+	h6 := load3(src[20:]) << 7
+	h7 := load3(src[23:]) << 5
+	h8 := load3(src[26:]) << 4
+	h9 := (load3(src[29:]) & 8388607) << 2
+
+	FeCombine(dst, h0, h1, h2, h3, h4, h5, h6, h7, h8, h9)
+}
+
+// FeToBytes marshals h to s.
+// Preconditions:
+//   |h| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc.
+//
+// Write p=2^255-19; q=floor(h/p).
+// Basic claim: q = floor(2^(-255)(h + 19 2^(-25)h9 + 2^(-1))).
+//
+// Proof:
+//   Have |h|<=p so |q|<=1 so |19^2 2^(-255) q|<1/4.
+//   Also have |h-2^230 h9|<2^230 so |19 2^(-255)(h-2^230 h9)|<1/4.
+//
+//   Write y=2^(-1)-19^2 2^(-255)q-19 2^(-255)(h-2^230 h9).
+//   Then 0<y<1.
+//
+//   Write r=h-pq.
+//   Have 0<=r<=p-1=2^255-20.
+//   Thus 0<=r+19(2^-255)r<r+19(2^-255)2^255<=2^255-1.
+//
+//   Write x=r+19(2^-255)r+y.
+//   Then 0<x<2^255 so floor(2^(-255)x) = 0 so floor(q+2^(-255)x) = q.
+//
+//   Have q+2^(-255)x = 2^(-255)(h + 19 2^(-25) h9 + 2^(-1))
+//   so floor(2^(-255)(h + 19 2^(-25) h9 + 2^(-1))) = q.
+func FeToBytes(s *[32]byte, h *FieldElement) {
+	var carry [10]int32
+
+	q := (19*h[9] + (1 << 24)) >> 25
+	q = (h[0] + q) >> 26
+	q = (h[1] + q) >> 25
+	q = (h[2] + q) >> 26
+	q = (h[3] + q) >> 25
+	q = (h[4] + q) >> 26
+	q = (h[5] + q) >> 25
+	q = (h[6] + q) >> 26
+	q = (h[7] + q) >> 25
+	q = (h[8] + q) >> 26
+	q = (h[9] + q) >> 25
+
+	// Goal: Output h-(2^255-19)q, which is between 0 and 2^255-20.
+	h[0] += 19 * q
+	// Goal: Output h-2^255 q, which is between 0 and 2^255-20.
+
+	carry[0] = h[0] >> 26
+	h[1] += carry[0]
+	h[0] -= carry[0] << 26
+	carry[1] = h[1] >> 25
+	h[2] += carry[1]
+	h[1] -= carry[1] << 25
+	carry[2] = h[2] >> 26
+	h[3] += carry[2]
+	h[2] -= carry[2] << 26
+	carry[3] = h[3] >> 25
+	h[4] += carry[3]
+	h[3] -= carry[3] << 25
+	carry[4] = h[4] >> 26
+	h[5] += carry[4]
+	h[4] -= carry[4] << 26
+	carry[5] = h[5] >> 25
+	h[6] += carry[5]
+	h[5] -= carry[5] << 25
+	carry[6] = h[6] >> 26
+	h[7] += carry[6]
+	h[6] -= carry[6] << 26
+	carry[7] = h[7] >> 25
+	h[8] += carry[7]
+	h[7] -= carry[7] << 25
+	carry[8] = h[8] >> 26
+	h[9] += carry[8]
+	h[8] -= carry[8] << 26
+	carry[9] = h[9] >> 25
+	h[9] -= carry[9] << 25
+	// h10 = carry9
+
+	// Goal: Output h[0]+...+2^255 h10-2^255 q, which is between 0 and 2^255-20.
+	// Have h[0]+...+2^230 h[9] between 0 and 2^255-1;
+	// evidently 2^255 h10-2^255 q = 0.
+	// Goal: Output h[0]+...+2^230 h[9].
+
+	s[0] = byte(h[0] >> 0)
+	s[1] = byte(h[0] >> 8)
+	s[2] = byte(h[0] >> 16)
+	s[3] = byte((h[0] >> 24) | (h[1] << 2))
+	s[4] = byte(h[1] >> 6)
+	s[5] = byte(h[1] >> 14)
+	s[6] = byte((h[1] >> 22) | (h[2] << 3))
+	s[7] = byte(h[2] >> 5)
+	s[8] = byte(h[2] >> 13)
+	s[9] = byte((h[2] >> 21) | (h[3] << 5))
+	s[10] = byte(h[3] >> 3)
+	s[11] = byte(h[3] >> 11)
+	s[12] = byte((h[3] >> 19) | (h[4] << 6))
+	s[13] = byte(h[4] >> 2)
+	s[14] = byte(h[4] >> 10)
+	s[15] = byte(h[4] >> 18)
+	s[16] = byte(h[5] >> 0)
+	s[17] = byte(h[5] >> 8)
+	s[18] = byte(h[5] >> 16)
+	s[19] = byte((h[5] >> 24) | (h[6] << 1))
+	s[20] = byte(h[6] >> 7)
+	s[21] = byte(h[6] >> 15)
+	s[22] = byte((h[6] >> 23) | (h[7] << 3))
+	s[23] = byte(h[7] >> 5)
+	s[24] = byte(h[7] >> 13)
+	s[25] = byte((h[7] >> 21) | (h[8] << 4))
+	s[26] = byte(h[8] >> 4)
+	s[27] = byte(h[8] >> 12)
+	s[28] = byte((h[8] >> 20) | (h[9] << 6))
+	s[29] = byte(h[9] >> 2)
+	s[30] = byte(h[9] >> 10)
+	s[31] = byte(h[9] >> 18)
+}
+
+func FeIsNegative(f *FieldElement) byte {
+	var s [32]byte
+	FeToBytes(&s, f)
+	return s[0] & 1
+}
+
+func FeIsNonZero(f *FieldElement) int32 {
+	var s [32]byte
+	FeToBytes(&s, f)
+	var x uint8
+	for _, b := range s {
+		x |= b
+	}
+	x |= x >> 4
+	x |= x >> 2
+	x |= x >> 1
+	return int32(x & 1)
+}
+
+// FeNeg sets h = -f
+//
+// Preconditions:
+//    |f| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc.
+//
+// Postconditions:
+//    |h| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc.
+func FeNeg(h, f *FieldElement) {
+	h[0] = -f[0]
+	h[1] = -f[1]
+	h[2] = -f[2]
+	h[3] = -f[3]
+	h[4] = -f[4]
+	h[5] = -f[5]
+	h[6] = -f[6]
+	h[7] = -f[7]
+	h[8] = -f[8]
+	h[9] = -f[9]
+}
+
+func FeCombine(h *FieldElement, h0, h1, h2, h3, h4, h5, h6, h7, h8, h9 int64) {
+	var c0, c1, c2, c3, c4, c5, c6, c7, c8, c9 int64
+
+	/*
+	  |h0| <= (1.1*1.1*2^52*(1+19+19+19+19)+1.1*1.1*2^50*(38+38+38+38+38))
+	    i.e. |h0| <= 1.2*2^59; narrower ranges for h2, h4, h6, h8
+	  |h1| <= (1.1*1.1*2^51*(1+1+19+19+19+19+19+19+19+19))
+	    i.e. |h1| <= 1.5*2^58; narrower ranges for h3, h5, h7, h9
+	*/
+
+	c0 = (h0 + (1 << 25)) >> 26
+	h1 += c0
+	h0 -= c0 << 26
+	c4 = (h4 + (1 << 25)) >> 26
+	h5 += c4
+	h4 -= c4 << 26
+	/* |h0| <= 2^25 */
+	/* |h4| <= 2^25 */
+	/* |h1| <= 1.51*2^58 */
+	/* |h5| <= 1.51*2^58 */
+
+	c1 = (h1 + (1 << 24)) >> 25
+	h2 += c1
+	h1 -= c1 << 25
+	c5 = (h5 + (1 << 24)) >> 25
+	h6 += c5
+	h5 -= c5 << 25
+	/* |h1| <= 2^24; from now on fits into int32 */
+	/* |h5| <= 2^24; from now on fits into int32 */
+	/* |h2| <= 1.21*2^59 */
+	/* |h6| <= 1.21*2^59 */
+
+	c2 = (h2 + (1 << 25)) >> 26
+	h3 += c2
+	h2 -= c2 << 26
+	c6 = (h6 + (1 << 25)) >> 26
+	h7 += c6
+	h6 -= c6 << 26
+	/* |h2| <= 2^25; from now on fits into int32 unchanged */
+	/* |h6| <= 2^25; from now on fits into int32 unchanged */
+	/* |h3| <= 1.51*2^58 */
+	/* |h7| <= 1.51*2^58 */
+
+	c3 = (h3 + (1 << 24)) >> 25
+	h4 += c3
+	h3 -= c3 << 25
+	c7 = (h7 + (1 << 24)) >> 25
+	h8 += c7
+	h7 -= c7 << 25
+	/* |h3| <= 2^24; from now on fits into int32 unchanged */
+	/* |h7| <= 2^24; from now on fits into int32 unchanged */
+	/* |h4| <= 1.52*2^33 */
+	/* |h8| <= 1.52*2^33 */
+
+	c4 = (h4 + (1 << 25)) >> 26
+	h5 += c4
+	h4 -= c4 << 26
+	c8 = (h8 + (1 << 25)) >> 26
+	h9 += c8
+	h8 -= c8 << 26
+	/* |h4| <= 2^25; from now on fits into int32 unchanged */
+	/* |h8| <= 2^25; from now on fits into int32 unchanged */
+	/* |h5| <= 1.01*2^24 */
+	/* |h9| <= 1.51*2^58 */
+
+	c9 = (h9 + (1 << 24)) >> 25
+	h0 += c9 * 19
+	h9 -= c9 << 25
+	/* |h9| <= 2^24; from now on fits into int32 unchanged */
+	/* |h0| <= 1.8*2^37 */
+
+	c0 = (h0 + (1 << 25)) >> 26
+	h1 += c0
+	h0 -= c0 << 26
+	/* |h0| <= 2^25; from now on fits into int32 unchanged */
+	/* |h1| <= 1.01*2^24 */
+
+	h[0] = int32(h0)
+	h[1] = int32(h1)
+	h[2] = int32(h2)
+	h[3] = int32(h3)
+	h[4] = int32(h4)
+	h[5] = int32(h5)
+	h[6] = int32(h6)
+	h[7] = int32(h7)
+	h[8] = int32(h8)
+	h[9] = int32(h9)
+}
+
+// FeMul calculates h = f * g
+// Can overlap h with f or g.
+//
+// Preconditions:
+//    |f| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc.
+//    |g| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc.
+//
+// Postconditions:
+//    |h| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc.
+//
+// Notes on implementation strategy:
+//
+// Using schoolbook multiplication.
+// Karatsuba would save a little in some cost models.
+//
+// Most multiplications by 2 and 19 are 32-bit precomputations;
+// cheaper than 64-bit postcomputations.
+//
+// There is one remaining multiplication by 19 in the carry chain;
+// one *19 precomputation can be merged into this,
+// but the resulting data flow is considerably less clean.
+//
+// There are 12 carries below.
+// 10 of them are 2-way parallelizable and vectorizable.
+// Can get away with 11 carries, but then data flow is much deeper.
+//
+// With tighter constraints on inputs can squeeze carries into int32.
+func FeMul(h, f, g *FieldElement) {
+	f0 := int64(f[0])
+	f1 := int64(f[1])
+	f2 := int64(f[2])
+	f3 := int64(f[3])
+	f4 := int64(f[4])
+	f5 := int64(f[5])
+	f6 := int64(f[6])
+	f7 := int64(f[7])
+	f8 := int64(f[8])
+	f9 := int64(f[9])
+
+	f1_2 := int64(2 * f[1])
+	f3_2 := int64(2 * f[3])
+	f5_2 := int64(2 * f[5])
+	f7_2 := int64(2 * f[7])
+	f9_2 := int64(2 * f[9])
+
+	g0 := int64(g[0])
+	g1 := int64(g[1])
+	g2 := int64(g[2])
+	g3 := int64(g[3])
+	g4 := int64(g[4])
+	g5 := int64(g[5])
+	g6 := int64(g[6])
+	g7 := int64(g[7])
+	g8 := int64(g[8])
+	g9 := int64(g[9])
+
+	g1_19 := int64(19 * g[1]) /* 1.4*2^29 */
+	g2_19 := int64(19 * g[2]) /* 1.4*2^30; still ok */
+	g3_19 := int64(19 * g[3])
+	g4_19 := int64(19 * g[4])
+	g5_19 := int64(19 * g[5])
+	g6_19 := int64(19 * g[6])
+	g7_19 := int64(19 * g[7])
+	g8_19 := int64(19 * g[8])
+	g9_19 := int64(19 * g[9])
+
+	h0 := f0*g0 + f1_2*g9_19 + f2*g8_19 + f3_2*g7_19 + f4*g6_19 + f5_2*g5_19 + f6*g4_19 + f7_2*g3_19 + f8*g2_19 + f9_2*g1_19
+	h1 := f0*g1 + f1*g0 + f2*g9_19 + f3*g8_19 + f4*g7_19 + f5*g6_19 + f6*g5_19 + f7*g4_19 + f8*g3_19 + f9*g2_19
+	h2 := f0*g2 + f1_2*g1 + f2*g0 + f3_2*g9_19 + f4*g8_19 + f5_2*g7_19 + f6*g6_19 + f7_2*g5_19 + f8*g4_19 + f9_2*g3_19
+	h3 := f0*g3 + f1*g2 + f2*g1 + f3*g0 + f4*g9_19 + f5*g8_19 + f6*g7_19 + f7*g6_19 + f8*g5_19 + f9*g4_19
+	h4 := f0*g4 + f1_2*g3 + f2*g2 + f3_2*g1 + f4*g0 + f5_2*g9_19 + f6*g8_19 + f7_2*g7_19 + f8*g6_19 + f9_2*g5_19
+	h5 := f0*g5 + f1*g4 + f2*g3 + f3*g2 + f4*g1 + f5*g0 + f6*g9_19 + f7*g8_19 + f8*g7_19 + f9*g6_19
+	h6 := f0*g6 + f1_2*g5 + f2*g4 + f3_2*g3 + f4*g2 + f5_2*g1 + f6*g0 + f7_2*g9_19 + f8*g8_19 + f9_2*g7_19
+	h7 := f0*g7 + f1*g6 + f2*g5 + f3*g4 + f4*g3 + f5*g2 + f6*g1 + f7*g0 + f8*g9_19 + f9*g8_19
+	h8 := f0*g8 + f1_2*g7 + f2*g6 + f3_2*g5 + f4*g4 + f5_2*g3 + f6*g2 + f7_2*g1 + f8*g0 + f9_2*g9_19
+	h9 := f0*g9 + f1*g8 + f2*g7 + f3*g6 + f4*g5 + f5*g4 + f6*g3 + f7*g2 + f8*g1 + f9*g0
+
+	FeCombine(h, h0, h1, h2, h3, h4, h5, h6, h7, h8, h9)
+}
+
+func feSquare(f *FieldElement) (h0, h1, h2, h3, h4, h5, h6, h7, h8, h9 int64) {
+	f0 := int64(f[0])
+	f1 := int64(f[1])
+	f2 := int64(f[2])
+	f3 := int64(f[3])
+	f4 := int64(f[4])
+	f5 := int64(f[5])
+	f6 := int64(f[6])
+	f7 := int64(f[7])
+	f8 := int64(f[8])
+	f9 := int64(f[9])
+	f0_2 := int64(2 * f[0])
+	f1_2 := int64(2 * f[1])
+	f2_2 := int64(2 * f[2])
+	f3_2 := int64(2 * f[3])
+	f4_2 := int64(2 * f[4])
+	f5_2 := int64(2 * f[5])
+	f6_2 := int64(2 * f[6])
+	f7_2 := int64(2 * f[7])
+	f5_38 := 38 * f5 // 1.31*2^30
+	f6_19 := 19 * f6 // 1.31*2^30
+	f7_38 := 38 * f7 // 1.31*2^30
+	f8_19 := 19 * f8 // 1.31*2^30
+	f9_38 := 38 * f9 // 1.31*2^30
+
+	h0 = f0*f0 + f1_2*f9_38 + f2_2*f8_19 + f3_2*f7_38 + f4_2*f6_19 + f5*f5_38
+	h1 = f0_2*f1 + f2*f9_38 + f3_2*f8_19 + f4*f7_38 + f5_2*f6_19
+	h2 = f0_2*f2 + f1_2*f1 + f3_2*f9_38 + f4_2*f8_19 + f5_2*f7_38 + f6*f6_19
+	h3 = f0_2*f3 + f1_2*f2 + f4*f9_38 + f5_2*f8_19 + f6*f7_38
+	h4 = f0_2*f4 + f1_2*f3_2 + f2*f2 + f5_2*f9_38 + f6_2*f8_19 + f7*f7_38
+	h5 = f0_2*f5 + f1_2*f4 + f2_2*f3 + f6*f9_38 + f7_2*f8_19
+	h6 = f0_2*f6 + f1_2*f5_2 + f2_2*f4 + f3_2*f3 + f7_2*f9_38 + f8*f8_19
+	h7 = f0_2*f7 + f1_2*f6 + f2_2*f5 + f3_2*f4 + f8*f9_38
+	h8 = f0_2*f8 + f1_2*f7_2 + f2_2*f6 + f3_2*f5_2 + f4*f4 + f9*f9_38
+	h9 = f0_2*f9 + f1_2*f8 + f2_2*f7 + f3_2*f6 + f4_2*f5
+
+	return
+}
+
+// FeSquare calculates h = f*f. Can overlap h with f.
+//
+// Preconditions:
+//    |f| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc.
+//
+// Postconditions:
+//    |h| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc.
+func FeSquare(h, f *FieldElement) {
+	h0, h1, h2, h3, h4, h5, h6, h7, h8, h9 := feSquare(f)
+	FeCombine(h, h0, h1, h2, h3, h4, h5, h6, h7, h8, h9)
+}
+
+// FeSquare2 sets h = 2 * f * f
+//
+// Can overlap h with f.
+//
+// Preconditions:
+//    |f| bounded by 1.65*2^26,1.65*2^25,1.65*2^26,1.65*2^25,etc.
+//
+// Postconditions:
+//    |h| bounded by 1.01*2^25,1.01*2^24,1.01*2^25,1.01*2^24,etc.
+// See fe_mul.c for discussion of implementation strategy.
+func FeSquare2(h, f *FieldElement) {
+	h0, h1, h2, h3, h4, h5, h6, h7, h8, h9 := feSquare(f)
+
+	h0 += h0
+	h1 += h1
+	h2 += h2
+	h3 += h3
+	h4 += h4
+	h5 += h5
+	h6 += h6
+	h7 += h7
+	h8 += h8
+	h9 += h9
+
+	FeCombine(h, h0, h1, h2, h3, h4, h5, h6, h7, h8, h9)
+}
+
+func FeInvert(out, z *FieldElement) {
+	var t0, t1, t2, t3 FieldElement
+	var i int
+
+	FeSquare(&t0, z)        // 2^1
+	FeSquare(&t1, &t0)      // 2^2
+	for i = 1; i < 2; i++ { // 2^3
+		FeSquare(&t1, &t1)
+	}
+	FeMul(&t1, z, &t1)      // 2^3 + 2^0
+	FeMul(&t0, &t0, &t1)    // 2^3 + 2^1 + 2^0
+	FeSquare(&t2, &t0)      // 2^4 + 2^2 + 2^1
+	FeMul(&t1, &t1, &t2)    // 2^4 + 2^3 + 2^2 + 2^1 + 2^0
+	FeSquare(&t2, &t1)      // 5,4,3,2,1
+	for i = 1; i < 5; i++ { // 9,8,7,6,5
+		FeSquare(&t2, &t2)
+	}
+	FeMul(&t1, &t2, &t1)     // 9,8,7,6,5,4,3,2,1,0
+	FeSquare(&t2, &t1)       // 10..1
+	for i = 1; i < 10; i++ { // 19..10
+		FeSquare(&t2, &t2)
+	}
+	FeMul(&t2, &t2, &t1)     // 19..0
+	FeSquare(&t3, &t2)       // 20..1
+	for i = 1; i < 20; i++ { // 39..20
+		FeSquare(&t3, &t3)
+	}
+	FeMul(&t2, &t3, &t2)     // 39..0
+	FeSquare(&t2, &t2)       // 40..1
+	for i = 1; i < 10; i++ { // 49..10
+		FeSquare(&t2, &t2)
+	}
+	FeMul(&t1, &t2, &t1)     // 49..0
+	FeSquare(&t2, &t1)       // 50..1
+	for i = 1; i < 50; i++ { // 99..50
+		FeSquare(&t2, &t2)
+	}
+	FeMul(&t2, &t2, &t1)      // 99..0
+	FeSquare(&t3, &t2)        // 100..1
+	for i = 1; i < 100; i++ { // 199..100
+		FeSquare(&t3, &t3)
+	}
+	FeMul(&t2, &t3, &t2)     // 199..0
+	FeSquare(&t2, &t2)       // 200..1
+	for i = 1; i < 50; i++ { // 249..50
+		FeSquare(&t2, &t2)
+	}
+	FeMul(&t1, &t2, &t1)    // 249..0
+	FeSquare(&t1, &t1)      // 250..1
+	for i = 1; i < 5; i++ { // 254..5
+		FeSquare(&t1, &t1)
+	}
+	FeMul(out, &t1, &t0) // 254..5,3,1,0
+}
+
+func fePow22523(out, z *FieldElement) {
+	var t0, t1, t2 FieldElement
+	var i int
+
+	FeSquare(&t0, z)
+	for i = 1; i < 1; i++ {
+		FeSquare(&t0, &t0)
+	}
+	FeSquare(&t1, &t0)
+	for i = 1; i < 2; i++ {
+		FeSquare(&t1, &t1)
+	}
+	FeMul(&t1, z, &t1)
+	FeMul(&t0, &t0, &t1)
+	FeSquare(&t0, &t0)
+	for i = 1; i < 1; i++ {
+		FeSquare(&t0, &t0)
+	}
+	FeMul(&t0, &t1, &t0)
+	FeSquare(&t1, &t0)
+	for i = 1; i < 5; i++ {
+		FeSquare(&t1, &t1)
+	}
+	FeMul(&t0, &t1, &t0)
+	FeSquare(&t1, &t0)
+	for i = 1; i < 10; i++ {
+		FeSquare(&t1, &t1)
+	}
+	FeMul(&t1, &t1, &t0)
+	FeSquare(&t2, &t1)
+	for i = 1; i < 20; i++ {
+		FeSquare(&t2, &t2)
+	}
+	FeMul(&t1, &t2, &t1)
+	FeSquare(&t1, &t1)
+	for i = 1; i < 10; i++ {
+		FeSquare(&t1, &t1)
+	}
+	FeMul(&t0, &t1, &t0)
+	FeSquare(&t1, &t0)
+	for i = 1; i < 50; i++ {
+		FeSquare(&t1, &t1)
+	}
+	FeMul(&t1, &t1, &t0)
+	FeSquare(&t2, &t1)
+	for i = 1; i < 100; i++ {
+		FeSquare(&t2, &t2)
+	}
+	FeMul(&t1, &t2, &t1)
+	FeSquare(&t1, &t1)
+	for i = 1; i < 50; i++ {
+		FeSquare(&t1, &t1)
+	}
+	FeMul(&t0, &t1, &t0)
+	FeSquare(&t0, &t0)
+	for i = 1; i < 2; i++ {
+		FeSquare(&t0, &t0)
+	}
+	FeMul(out, &t0, z)
+}
+
+// Group elements are members of the elliptic curve -x^2 + y^2 = 1 + d * x^2 *
+// y^2 where d = -121665/121666.
+//
+// Several representations are used:
+//   ProjectiveGroupElement: (X:Y:Z) satisfying x=X/Z, y=Y/Z
+//   ExtendedGroupElement: (X:Y:Z:T) satisfying x=X/Z, y=Y/Z, XY=ZT
+//   CompletedGroupElement: ((X:Z),(Y:T)) satisfying x=X/Z, y=Y/T
+//   PreComputedGroupElement: (y+x,y-x,2dxy)
+
+type ProjectiveGroupElement struct {
+	X, Y, Z FieldElement
+}
+
+type ExtendedGroupElement struct {
+	X, Y, Z, T FieldElement
+}
+
+type CompletedGroupElement struct {
+	X, Y, Z, T FieldElement
+}
+
+type PreComputedGroupElement struct {
+	yPlusX, yMinusX, xy2d FieldElement
+}
+
+type CachedGroupElement struct {
+	yPlusX, yMinusX, Z, T2d FieldElement
+}
+
+func (p *ProjectiveGroupElement) Zero() {
+	FeZero(&p.X)
+	FeOne(&p.Y)
+	FeOne(&p.Z)
+}
+
+func (p *ProjectiveGroupElement) Double(r *CompletedGroupElement) {
+	var t0 FieldElement
+
+	FeSquare(&r.X, &p.X)
+	FeSquare(&r.Z, &p.Y)
+	FeSquare2(&r.T, &p.Z)
+	FeAdd(&r.Y, &p.X, &p.Y)
+	FeSquare(&t0, &r.Y)
+	FeAdd(&r.Y, &r.Z, &r.X)
+	FeSub(&r.Z, &r.Z, &r.X)
+	FeSub(&r.X, &t0, &r.Y)
+	FeSub(&r.T, &r.T, &r.Z)
+}
+
+func (p *ProjectiveGroupElement) ToBytes(s *[32]byte) {
+	var recip, x, y FieldElement
+
+	FeInvert(&recip, &p.Z)
+	FeMul(&x, &p.X, &recip)
+	FeMul(&y, &p.Y, &recip)
+	FeToBytes(s, &y)
+	s[31] ^= FeIsNegative(&x) << 7
+}
+
+func (p *ExtendedGroupElement) Zero() {
+	FeZero(&p.X)
+	FeOne(&p.Y)
+	FeOne(&p.Z)
+	FeZero(&p.T)
+}
+
+func (p *ExtendedGroupElement) Double(r *CompletedGroupElement) {
+	var q ProjectiveGroupElement
+	p.ToProjective(&q)
+	q.Double(r)
+}
+
+func (p *ExtendedGroupElement) ToCached(r *CachedGroupElement) {
+	FeAdd(&r.yPlusX, &p.Y, &p.X)
+	FeSub(&r.yMinusX, &p.Y, &p.X)
+	FeCopy(&r.Z, &p.Z)
+	FeMul(&r.T2d, &p.T, &d2)
+}
+
+func (p *ExtendedGroupElement) ToProjective(r *ProjectiveGroupElement) {
+	FeCopy(&r.X, &p.X)
+	FeCopy(&r.Y, &p.Y)
+	FeCopy(&r.Z, &p.Z)
+}
+
+func (p *ExtendedGroupElement) ToBytes(s *[32]byte) {
+	var recip, x, y FieldElement
+
+	FeInvert(&recip, &p.Z)
+	FeMul(&x, &p.X, &recip)
+	FeMul(&y, &p.Y, &recip)
+	FeToBytes(s, &y)
+	s[31] ^= FeIsNegative(&x) << 7
+}
+
+func (p *ExtendedGroupElement) FromBytes(s *[32]byte) bool {
+	var u, v, v3, vxx, check FieldElement
+
+	FeFromBytes(&p.Y, s)
+	FeOne(&p.Z)
+	FeSquare(&u, &p.Y)
+	FeMul(&v, &u, &d)
+	FeSub(&u, &u, &p.Z) // y = y^2-1
+	FeAdd(&v, &v, &p.Z) // v = dy^2+1
+
+	FeSquare(&v3, &v)
+	FeMul(&v3, &v3, &v) // v3 = v^3
+	FeSquare(&p.X, &v3)
+	FeMul(&p.X, &p.X, &v)
+	FeMul(&p.X, &p.X, &u) // x = uv^7
+
+	fePow22523(&p.X, &p.X) // x = (uv^7)^((q-5)/8)
+	FeMul(&p.X, &p.X, &v3)
+	FeMul(&p.X, &p.X, &u) // x = uv^3(uv^7)^((q-5)/8)
+
+	var tmpX, tmp2 [32]byte
+
+	FeSquare(&vxx, &p.X)
+	FeMul(&vxx, &vxx, &v)
+	FeSub(&check, &vxx, &u) // vx^2-u
+	if FeIsNonZero(&check) == 1 {
+		FeAdd(&check, &vxx, &u) // vx^2+u
+		if FeIsNonZero(&check) == 1 {
+			return false
+		}
+		FeMul(&p.X, &p.X, &SqrtM1)
+
+		FeToBytes(&tmpX, &p.X)
+		for i, v := range tmpX {
+			tmp2[31-i] = v
+		}
+	}
+
+	if FeIsNegative(&p.X) != (s[31] >> 7) {
+		FeNeg(&p.X, &p.X)
+	}
+
+	FeMul(&p.T, &p.X, &p.Y)
+	return true
+}
+
+func (p *CompletedGroupElement) ToProjective(r *ProjectiveGroupElement) {
+	FeMul(&r.X, &p.X, &p.T)
+	FeMul(&r.Y, &p.Y, &p.Z)
+	FeMul(&r.Z, &p.Z, &p.T)
+}
+
+func (p *CompletedGroupElement) ToExtended(r *ExtendedGroupElement) {
+	FeMul(&r.X, &p.X, &p.T)
+	FeMul(&r.Y, &p.Y, &p.Z)
+	FeMul(&r.Z, &p.Z, &p.T)
+	FeMul(&r.T, &p.X, &p.Y)
+}
+
+func (p *PreComputedGroupElement) Zero() {
+	FeOne(&p.yPlusX)
+	FeOne(&p.yMinusX)
+	FeZero(&p.xy2d)
+}
+
+func geAdd(r *CompletedGroupElement, p *ExtendedGroupElement, q *CachedGroupElement) {
+	var t0 FieldElement
+
+	FeAdd(&r.X, &p.Y, &p.X)
+	FeSub(&r.Y, &p.Y, &p.X)
+	FeMul(&r.Z, &r.X, &q.yPlusX)
+	FeMul(&r.Y, &r.Y, &q.yMinusX)
+	FeMul(&r.T, &q.T2d, &p.T)
+	FeMul(&r.X, &p.Z, &q.Z)
+	FeAdd(&t0, &r.X, &r.X)
+	FeSub(&r.X, &r.Z, &r.Y)
+	FeAdd(&r.Y, &r.Z, &r.Y)
+	FeAdd(&r.Z, &t0, &r.T)
+	FeSub(&r.T, &t0, &r.T)
+}
+
+func geSub(r *CompletedGroupElement, p *ExtendedGroupElement, q *CachedGroupElement) {
+	var t0 FieldElement
+
+	FeAdd(&r.X, &p.Y, &p.X)
+	FeSub(&r.Y, &p.Y, &p.X)
+	FeMul(&r.Z, &r.X, &q.yMinusX)
+	FeMul(&r.Y, &r.Y, &q.yPlusX)
+	FeMul(&r.T, &q.T2d, &p.T)
+	FeMul(&r.X, &p.Z, &q.Z)
+	FeAdd(&t0, &r.X, &r.X)
+	FeSub(&r.X, &r.Z, &r.Y)
+	FeAdd(&r.Y, &r.Z, &r.Y)
+	FeSub(&r.Z, &t0, &r.T)
+	FeAdd(&r.T, &t0, &r.T)
+}
+
+func geMixedAdd(r *CompletedGroupElement, p *ExtendedGroupElement, q *PreComputedGroupElement) {
+	var t0 FieldElement
+
+	FeAdd(&r.X, &p.Y, &p.X)
+	FeSub(&r.Y, &p.Y, &p.X)
+	FeMul(&r.Z, &r.X, &q.yPlusX)
+	FeMul(&r.Y, &r.Y, &q.yMinusX)
+	FeMul(&r.T, &q.xy2d, &p.T)
+	FeAdd(&t0, &p.Z, &p.Z)
+	FeSub(&r.X, &r.Z, &r.Y)
+	FeAdd(&r.Y, &r.Z, &r.Y)
+	FeAdd(&r.Z, &t0, &r.T)
+	FeSub(&r.T, &t0, &r.T)
+}
+
+func geMixedSub(r *CompletedGroupElement, p *ExtendedGroupElement, q *PreComputedGroupElement) {
+	var t0 FieldElement
+
+	FeAdd(&r.X, &p.Y, &p.X)
+	FeSub(&r.Y, &p.Y, &p.X)
+	FeMul(&r.Z, &r.X, &q.yMinusX)
+	FeMul(&r.Y, &r.Y, &q.yPlusX)
+	FeMul(&r.T, &q.xy2d, &p.T)
+	FeAdd(&t0, &p.Z, &p.Z)
+	FeSub(&r.X, &r.Z, &r.Y)
+	FeAdd(&r.Y, &r.Z, &r.Y)
+	FeSub(&r.Z, &t0, &r.T)
+	FeAdd(&r.T, &t0, &r.T)
+}
+
+func slide(r *[256]int8, a *[32]byte) {
+	for i := range r {
+		r[i] = int8(1 & (a[i>>3] >> uint(i&7)))
+	}
+
+	for i := range r {
+		if r[i] != 0 {
+			for b := 1; b <= 6 && i+b < 256; b++ {
+				if r[i+b] != 0 {
+					if r[i]+(r[i+b]<<uint(b)) <= 15 {
+						r[i] += r[i+b] << uint(b)
+						r[i+b] = 0
+					} else if r[i]-(r[i+b]<<uint(b)) >= -15 {
+						r[i] -= r[i+b] << uint(b)
+						for k := i + b; k < 256; k++ {
+							if r[k] == 0 {
+								r[k] = 1
+								break
+							}
+							r[k] = 0
+						}
+					} else {
+						break
+					}
+				}
+			}
+		}
+	}
+}
+
+// GeDoubleScalarMultVartime sets r = a*A + b*B
+// where a = a[0]+256*a[1]+...+256^31 a[31].
+// and b = b[0]+256*b[1]+...+256^31 b[31].
+// B is the Ed25519 base point (x,4/5) with x positive.
+func GeDoubleScalarMultVartime(r *ProjectiveGroupElement, a *[32]byte, A *ExtendedGroupElement, b *[32]byte) {
+	var aSlide, bSlide [256]int8
+	var Ai [8]CachedGroupElement // A,3A,5A,7A,9A,11A,13A,15A
+	var t CompletedGroupElement
+	var u, A2 ExtendedGroupElement
+	var i int
+
+	slide(&aSlide, a)
+	slide(&bSlide, b)
+
+	A.ToCached(&Ai[0])
+	A.Double(&t)
+	t.ToExtended(&A2)
+
+	for i := 0; i < 7; i++ {
+		geAdd(&t, &A2, &Ai[i])
+		t.ToExtended(&u)
+		u.ToCached(&Ai[i+1])
+	}
+
+	r.Zero()
+
+	for i = 255; i >= 0; i-- {
+		if aSlide[i] != 0 || bSlide[i] != 0 {
+			break
+		}
+	}
+
+	for ; i >= 0; i-- {
+		r.Double(&t)
+
+		if aSlide[i] > 0 {
+			t.ToExtended(&u)
+			geAdd(&t, &u, &Ai[aSlide[i]/2])
+		} else if aSlide[i] < 0 {
+			t.ToExtended(&u)
+			geSub(&t, &u, &Ai[(-aSlide[i])/2])
+		}
+
+		if bSlide[i] > 0 {
+			t.ToExtended(&u)
+			geMixedAdd(&t, &u, &bi[bSlide[i]/2])
+		} else if bSlide[i] < 0 {
+			t.ToExtended(&u)
+			geMixedSub(&t, &u, &bi[(-bSlide[i])/2])
+		}
+
+		t.ToProjective(r)
+	}
+}
+
+// equal returns 1 if b == c and 0 otherwise.
+func equal(b, c int32) int32 {
+	x := uint32(b ^ c)
+	x--
+	return int32(x >> 31)
+}
+
+// negative returns 1 if b < 0 and 0 otherwise.
+func negative(b int32) int32 {
+	return (b >> 31) & 1
+}
+
+func PreComputedGroupElementCMove(t, u *PreComputedGroupElement, b int32) {
+	FeCMove(&t.yPlusX, &u.yPlusX, b)
+	FeCMove(&t.yMinusX, &u.yMinusX, b)
+	FeCMove(&t.xy2d, &u.xy2d, b)
+}
+
+func selectPoint(t *PreComputedGroupElement, pos int32, b int32) {
+	var minusT PreComputedGroupElement
+	bNegative := negative(b)
+	bAbs := b - (((-bNegative) & b) << 1)
+
+	t.Zero()
+	for i := int32(0); i < 8; i++ {
+		PreComputedGroupElementCMove(t, &base[pos][i], equal(bAbs, i+1))
+	}
+	FeCopy(&minusT.yPlusX, &t.yMinusX)
+	FeCopy(&minusT.yMinusX, &t.yPlusX)
+	FeNeg(&minusT.xy2d, &t.xy2d)
+	PreComputedGroupElementCMove(t, &minusT, bNegative)
+}
+
+// GeScalarMultBase computes h = a*B, where
+//   a = a[0]+256*a[1]+...+256^31 a[31]
+//   B is the Ed25519 base point (x,4/5) with x positive.
+//
+// Preconditions:
+//   a[31] <= 127
+func GeScalarMultBase(h *ExtendedGroupElement, a *[32]byte) {
+	var e [64]int8
+
+	for i, v := range a {
+		e[2*i] = int8(v & 15)
+		e[2*i+1] = int8((v >> 4) & 15)
+	}
+
+	// each e[i] is between 0 and 15 and e[63] is between 0 and 7.
+
+	carry := int8(0)
+	for i := 0; i < 63; i++ {
+		e[i] += carry
+		carry = (e[i] + 8) >> 4
+		e[i] -= carry << 4
+	}
+	e[63] += carry
+	// each e[i] is between -8 and 8.
+
+	h.Zero()
+	var t PreComputedGroupElement
+	var r CompletedGroupElement
+	for i := int32(1); i < 64; i += 2 {
+		selectPoint(&t, i/2, int32(e[i]))
+		geMixedAdd(&r, h, &t)
+		r.ToExtended(h)
+	}
+
+	var s ProjectiveGroupElement
+
+	h.Double(&r)
+	r.ToProjective(&s)
+	s.Double(&r)
+	r.ToProjective(&s)
+	s.Double(&r)
+	r.ToProjective(&s)
+	s.Double(&r)
+	r.ToExtended(h)
+
+	for i := int32(0); i < 64; i += 2 {
+		selectPoint(&t, i/2, int32(e[i]))
+		geMixedAdd(&r, h, &t)
+		r.ToExtended(h)
+	}
+}
+
+// The scalars are GF(2^252 + 27742317777372353535851937790883648493).
+
+// Input:
+//   a[0]+256*a[1]+...+256^31*a[31] = a
+//   b[0]+256*b[1]+...+256^31*b[31] = b
+//   c[0]+256*c[1]+...+256^31*c[31] = c
+//
+// Output:
+//   s[0]+256*s[1]+...+256^31*s[31] = (ab+c) mod l
+//   where l = 2^252 + 27742317777372353535851937790883648493.
+func ScMulAdd(s, a, b, c *[32]byte) {
+	a0 := 2097151 & load3(a[:])
+	a1 := 2097151 & (load4(a[2:]) >> 5)
+	a2 := 2097151 & (load3(a[5:]) >> 2)
+	a3 := 2097151 & (load4(a[7:]) >> 7)
+	a4 := 2097151 & (load4(a[10:]) >> 4)
+	a5 := 2097151 & (load3(a[13:]) >> 1)
+	a6 := 2097151 & (load4(a[15:]) >> 6)
+	a7 := 2097151 & (load3(a[18:]) >> 3)
+	a8 := 2097151 & load3(a[21:])
+	a9 := 2097151 & (load4(a[23:]) >> 5)
+	a10 := 2097151 & (load3(a[26:]) >> 2)
+	a11 := (load4(a[28:]) >> 7)
+	b0 := 2097151 & load3(b[:])
+	b1 := 2097151 & (load4(b[2:]) >> 5)
+	b2 := 2097151 & (load3(b[5:]) >> 2)
+	b3 := 2097151 & (load4(b[7:]) >> 7)
+	b4 := 2097151 & (load4(b[10:]) >> 4)
+	b5 := 2097151 & (load3(b[13:]) >> 1)
+	b6 := 2097151 & (load4(b[15:]) >> 6)
+	b7 := 2097151 & (load3(b[18:]) >> 3)
+	b8 := 2097151 & load3(b[21:])
+	b9 := 2097151 & (load4(b[23:]) >> 5)
+	b10 := 2097151 & (load3(b[26:]) >> 2)
+	b11 := (load4(b[28:]) >> 7)
+	c0 := 2097151 & load3(c[:])
+	c1 := 2097151 & (load4(c[2:]) >> 5)
+	c2 := 2097151 & (load3(c[5:]) >> 2)
+	c3 := 2097151 & (load4(c[7:]) >> 7)
+	c4 := 2097151 & (load4(c[10:]) >> 4)
+	c5 := 2097151 & (load3(c[13:]) >> 1)
+	c6 := 2097151 & (load4(c[15:]) >> 6)
+	c7 := 2097151 & (load3(c[18:]) >> 3)
+	c8 := 2097151 & load3(c[21:])
+	c9 := 2097151 & (load4(c[23:]) >> 5)
+	c10 := 2097151 & (load3(c[26:]) >> 2)
+	c11 := (load4(c[28:]) >> 7)
+	var carry [23]int64
+
+	s0 := c0 + a0*b0
+	s1 := c1 + a0*b1 + a1*b0
+	s2 := c2 + a0*b2 + a1*b1 + a2*b0
+	s3 := c3 + a0*b3 + a1*b2 + a2*b1 + a3*b0
+	s4 := c4 + a0*b4 + a1*b3 + a2*b2 + a3*b1 + a4*b0
+	s5 := c5 + a0*b5 + a1*b4 + a2*b3 + a3*b2 + a4*b1 + a5*b0
+	s6 := c6 + a0*b6 + a1*b5 + a2*b4 + a3*b3 + a4*b2 + a5*b1 + a6*b0
+	s7 := c7 + a0*b7 + a1*b6 + a2*b5 + a3*b4 + a4*b3 + a5*b2 + a6*b1 + a7*b0
+	s8 := c8 + a0*b8 + a1*b7 + a2*b6 + a3*b5 + a4*b4 + a5*b3 + a6*b2 + a7*b1 + a8*b0
+	s9 := c9 + a0*b9 + a1*b8 + a2*b7 + a3*b6 + a4*b5 + a5*b4 + a6*b3 + a7*b2 + a8*b1 + a9*b0
+	s10 := c10 + a0*b10 + a1*b9 + a2*b8 + a3*b7 + a4*b6 + a5*b5 + a6*b4 + a7*b3 + a8*b2 + a9*b1 + a10*b0
+	s11 := c11 + a0*b11 + a1*b10 + a2*b9 + a3*b8 + a4*b7 + a5*b6 + a6*b5 + a7*b4 + a8*b3 + a9*b2 + a10*b1 + a11*b0
+	s12 := a1*b11 + a2*b10 + a3*b9 + a4*b8 + a5*b7 + a6*b6 + a7*b5 + a8*b4 + a9*b3 + a10*b2 + a11*b1
+	s13 := a2*b11 + a3*b10 + a4*b9 + a5*b8 + a6*b7 + a7*b6 + a8*b5 + a9*b4 + a10*b3 + a11*b2
+	s14 := a3*b11 + a4*b10 + a5*b9 + a6*b8 + a7*b7 + a8*b6 + a9*b5 + a10*b4 + a11*b3
+	s15 := a4*b11 + a5*b10 + a6*b9 + a7*b8 + a8*b7 + a9*b6 + a10*b5 + a11*b4
+	s16 := a5*b11 + a6*b10 + a7*b9 + a8*b8 + a9*b7 + a10*b6 + a11*b5
+	s17 := a6*b11 + a7*b10 + a8*b9 + a9*b8 + a10*b7 + a11*b6
+	s18 := a7*b11 + a8*b10 + a9*b9 + a10*b8 + a11*b7
+	s19 := a8*b11 + a9*b10 + a10*b9 + a11*b8
+	s20 := a9*b11 + a10*b10 + a11*b9
+	s21 := a10*b11 + a11*b10
+	s22 := a11 * b11
+	s23 := int64(0)
+
+	carry[0] = (s0 + (1 << 20)) >> 21
+	s1 += carry[0]
+	s0 -= carry[0] << 21
+	carry[2] = (s2 + (1 << 20)) >> 21
+	s3 += carry[2]
+	s2 -= carry[2] << 21
+	carry[4] = (s4 + (1 << 20)) >> 21
+	s5 += carry[4]
+	s4 -= carry[4] << 21
+	carry[6] = (s6 + (1 << 20)) >> 21
+	s7 += carry[6]
+	s6 -= carry[6] << 21
+	carry[8] = (s8 + (1 << 20)) >> 21
+	s9 += carry[8]
+	s8 -= carry[8] << 21
+	carry[10] = (s10 + (1 << 20)) >> 21
+	s11 += carry[10]
+	s10 -= carry[10] << 21
+	carry[12] = (s12 + (1 << 20)) >> 21
+	s13 += carry[12]
+	s12 -= carry[12] << 21
+	carry[14] = (s14 + (1 << 20)) >> 21
+	s15 += carry[14]
+	s14 -= carry[14] << 21
+	carry[16] = (s16 + (1 << 20)) >> 21
+	s17 += carry[16]
+	s16 -= carry[16] << 21
+	carry[18] = (s18 + (1 << 20)) >> 21
+	s19 += carry[18]
+	s18 -= carry[18] << 21
+	carry[20] = (s20 + (1 << 20)) >> 21
+	s21 += carry[20]
+	s20 -= carry[20] << 21
+	carry[22] = (s22 + (1 << 20)) >> 21
+	s23 += carry[22]
+	s22 -= carry[22] << 21
+
+	carry[1] = (s1 + (1 << 20)) >> 21
+	s2 += carry[1]
+	s1 -= carry[1] << 21
+	carry[3] = (s3 + (1 << 20)) >> 21
+	s4 += carry[3]
+	s3 -= carry[3] << 21
+	carry[5] = (s5 + (1 << 20)) >> 21
+	s6 += carry[5]
+	s5 -= carry[5] << 21
+	carry[7] = (s7 + (1 << 20)) >> 21
+	s8 += carry[7]
+	s7 -= carry[7] << 21
+	carry[9] = (s9 + (1 << 20)) >> 21
+	s10 += carry[9]
+	s9 -= carry[9] << 21
+	carry[11] = (s11 + (1 << 20)) >> 21
+	s12 += carry[11]
+	s11 -= carry[11] << 21
+	carry[13] = (s13 + (1 << 20)) >> 21
+	s14 += carry[13]
+	s13 -= carry[13] << 21
+	carry[15] = (s15 + (1 << 20)) >> 21
+	s16 += carry[15]
+	s15 -= carry[15] << 21
+	carry[17] = (s17 + (1 << 20)) >> 21
+	s18 += carry[17]
+	s17 -= carry[17] << 21
+	carry[19] = (s19 + (1 << 20)) >> 21
+	s20 += carry[19]
+	s19 -= carry[19] << 21
+	carry[21] = (s21 + (1 << 20)) >> 21
+	s22 += carry[21]
+	s21 -= carry[21] << 21
+
+	s11 += s23 * 666643
+	s12 += s23 * 470296
+	s13 += s23 * 654183
+	s14 -= s23 * 997805
+	s15 += s23 * 136657
+	s16 -= s23 * 683901
+	s23 = 0
+
+	s10 += s22 * 666643
+	s11 += s22 * 470296
+	s12 += s22 * 654183
+	s13 -= s22 * 997805
+	s14 += s22 * 136657
+	s15 -= s22 * 683901
+	s22 = 0
+
+	s9 += s21 * 666643
+	s10 += s21 * 470296
+	s11 += s21 * 654183
+	s12 -= s21 * 997805
+	s13 += s21 * 136657
+	s14 -= s21 * 683901
+	s21 = 0
+
+	s8 += s20 * 666643
+	s9 += s20 * 470296
+	s10 += s20 * 654183
+	s11 -= s20 * 997805
+	s12 += s20 * 136657
+	s13 -= s20 * 683901
+	s20 = 0
+
+	s7 += s19 * 666643
+	s8 += s19 * 470296
+	s9 += s19 * 654183
+	s10 -= s19 * 997805
+	s11 += s19 * 136657
+	s12 -= s19 * 683901
+	s19 = 0
+
+	s6 += s18 * 666643
+	s7 += s18 * 470296
+	s8 += s18 * 654183
+	s9 -= s18 * 997805
+	s10 += s18 * 136657
+	s11 -= s18 * 683901
+	s18 = 0
+
+	carry[6] = (s6 + (1 << 20)) >> 21
+	s7 += carry[6]
+	s6 -= carry[6] << 21
+	carry[8] = (s8 + (1 << 20)) >> 21
+	s9 += carry[8]
+	s8 -= carry[8] << 21
+	carry[10] = (s10 + (1 << 20)) >> 21
+	s11 += carry[10]
+	s10 -= carry[10] << 21
+	carry[12] = (s12 + (1 << 20)) >> 21
+	s13 += carry[12]
+	s12 -= carry[12] << 21
+	carry[14] = (s14 + (1 << 20)) >> 21
+	s15 += carry[14]
+	s14 -= carry[14] << 21
+	carry[16] = (s16 + (1 << 20)) >> 21
+	s17 += carry[16]
+	s16 -= carry[16] << 21
+
+	carry[7] = (s7 + (1 << 20)) >> 21
+	s8 += carry[7]
+	s7 -= carry[7] << 21
+	carry[9] = (s9 + (1 << 20)) >> 21
+	s10 += carry[9]
+	s9 -= carry[9] << 21
+	carry[11] = (s11 + (1 << 20)) >> 21
+	s12 += carry[11]
+	s11 -= carry[11] << 21
+	carry[13] = (s13 + (1 << 20)) >> 21
+	s14 += carry[13]
+	s13 -= carry[13] << 21
+	carry[15] = (s15 + (1 << 20)) >> 21
+	s16 += carry[15]
+	s15 -= carry[15] << 21
+
+	s5 += s17 * 666643
+	s6 += s17 * 470296
+	s7 += s17 * 654183
+	s8 -= s17 * 997805
+	s9 += s17 * 136657
+	s10 -= s17 * 683901
+	s17 = 0
+
+	s4 += s16 * 666643
+	s5 += s16 * 470296
+	s6 += s16 * 654183
+	s7 -= s16 * 997805
+	s8 += s16 * 136657
+	s9 -= s16 * 683901
+	s16 = 0
+
+	s3 += s15 * 666643
+	s4 += s15 * 470296
+	s5 += s15 * 654183
+	s6 -= s15 * 997805
+	s7 += s15 * 136657
+	s8 -= s15 * 683901
+	s15 = 0
+
+	s2 += s14 * 666643
+	s3 += s14 * 470296
+	s4 += s14 * 654183
+	s5 -= s14 * 997805
+	s6 += s14 * 136657
+	s7 -= s14 * 683901
+	s14 = 0
+
+	s1 += s13 * 666643
+	s2 += s13 * 470296
+	s3 += s13 * 654183
+	s4 -= s13 * 997805
+	s5 += s13 * 136657
+	s6 -= s13 * 683901
+	s13 = 0
+
+	s0 += s12 * 666643
+	s1 += s12 * 470296
+	s2 += s12 * 654183
+	s3 -= s12 * 997805
+	s4 += s12 * 136657
+	s5 -= s12 * 683901
+	s12 = 0
+
+	carry[0] = (s0 + (1 << 20)) >> 21
+	s1 += carry[0]
+	s0 -= carry[0] << 21
+	carry[2] = (s2 + (1 << 20)) >> 21
+	s3 += carry[2]
+	s2 -= carry[2] << 21
+	carry[4] = (s4 + (1 << 20)) >> 21
+	s5 += carry[4]
+	s4 -= carry[4] << 21
+	carry[6] = (s6 + (1 << 20)) >> 21
+	s7 += carry[6]
+	s6 -= carry[6] << 21
+	carry[8] = (s8 + (1 << 20)) >> 21
+	s9 += carry[8]
+	s8 -= carry[8] << 21
+	carry[10] = (s10 + (1 << 20)) >> 21
+	s11 += carry[10]
+	s10 -= carry[10] << 21
+
+	carry[1] = (s1 + (1 << 20)) >> 21
+	s2 += carry[1]
+	s1 -= carry[1] << 21
+	carry[3] = (s3 + (1 << 20)) >> 21
+	s4 += carry[3]
+	s3 -= carry[3] << 21
+	carry[5] = (s5 + (1 << 20)) >> 21
+	s6 += carry[5]
+	s5 -= carry[5] << 21
+	carry[7] = (s7 + (1 << 20)) >> 21
+	s8 += carry[7]
+	s7 -= carry[7] << 21
+	carry[9] = (s9 + (1 << 20)) >> 21
+	s10 += carry[9]
+	s9 -= carry[9] << 21
+	carry[11] = (s11 + (1 << 20)) >> 21
+	s12 += carry[11]
+	s11 -= carry[11] << 21
+
+	s0 += s12 * 666643
+	s1 += s12 * 470296
+	s2 += s12 * 654183
+	s3 -= s12 * 997805
+	s4 += s12 * 136657
+	s5 -= s12 * 683901
+	s12 = 0
+
+	carry[0] = s0 >> 21
+	s1 += carry[0]
+	s0 -= carry[0] << 21
+	carry[1] = s1 >> 21
+	s2 += carry[1]
+	s1 -= carry[1] << 21
+	carry[2] = s2 >> 21
+	s3 += carry[2]
+	s2 -= carry[2] << 21
+	carry[3] = s3 >> 21
+	s4 += carry[3]
+	s3 -= carry[3] << 21
+	carry[4] = s4 >> 21
+	s5 += carry[4]
+	s4 -= carry[4] << 21
+	carry[5] = s5 >> 21
+	s6 += carry[5]
+	s5 -= carry[5] << 21
+	carry[6] = s6 >> 21
+	s7 += carry[6]
+	s6 -= carry[6] << 21
+	carry[7] = s7 >> 21
+	s8 += carry[7]
+	s7 -= carry[7] << 21
+	carry[8] = s8 >> 21
+	s9 += carry[8]
+	s8 -= carry[8] << 21
+	carry[9] = s9 >> 21
+	s10 += carry[9]
+	s9 -= carry[9] << 21
+	carry[10] = s10 >> 21
+	s11 += carry[10]
+	s10 -= carry[10] << 21
+	carry[11] = s11 >> 21
+	s12 += carry[11]
+	s11 -= carry[11] << 21
+
+	s0 += s12 * 666643
+	s1 += s12 * 470296
+	s2 += s12 * 654183
+	s3 -= s12 * 997805
+	s4 += s12 * 136657
+	s5 -= s12 * 683901
+	s12 = 0
+
+	carry[0] = s0 >> 21
+	s1 += carry[0]
+	s0 -= carry[0] << 21
+	carry[1] = s1 >> 21
+	s2 += carry[1]
+	s1 -= carry[1] << 21
+	carry[2] = s2 >> 21
+	s3 += carry[2]
+	s2 -= carry[2] << 21
+	carry[3] = s3 >> 21
+	s4 += carry[3]
+	s3 -= carry[3] << 21
+	carry[4] = s4 >> 21
+	s5 += carry[4]
+	s4 -= carry[4] << 21
+	carry[5] = s5 >> 21
+	s6 += carry[5]
+	s5 -= carry[5] << 21
+	carry[6] = s6 >> 21
+	s7 += carry[6]
+	s6 -= carry[6] << 21
+	carry[7] = s7 >> 21
+	s8 += carry[7]
+	s7 -= carry[7] << 21
+	carry[8] = s8 >> 21
+	s9 += carry[8]
+	s8 -= carry[8] << 21
+	carry[9] = s9 >> 21
+	s10 += carry[9]
+	s9 -= carry[9] << 21
+	carry[10] = s10 >> 21
+	s11 += carry[10]
+	s10 -= carry[10] << 21
+
+	s[0] = byte(s0 >> 0)
+	s[1] = byte(s0 >> 8)
+	s[2] = byte((s0 >> 16) | (s1 << 5))
+	s[3] = byte(s1 >> 3)
+	s[4] = byte(s1 >> 11)
+	s[5] = byte((s1 >> 19) | (s2 << 2))
+	s[6] = byte(s2 >> 6)
+	s[7] = byte((s2 >> 14) | (s3 << 7))
+	s[8] = byte(s3 >> 1)
+	s[9] = byte(s3 >> 9)
+	s[10] = byte((s3 >> 17) | (s4 << 4))
+	s[11] = byte(s4 >> 4)
+	s[12] = byte(s4 >> 12)
+	s[13] = byte((s4 >> 20) | (s5 << 1))
+	s[14] = byte(s5 >> 7)
+	s[15] = byte((s5 >> 15) | (s6 << 6))
+	s[16] = byte(s6 >> 2)
+	s[17] = byte(s6 >> 10)
+	s[18] = byte((s6 >> 18) | (s7 << 3))
+	s[19] = byte(s7 >> 5)
+	s[20] = byte(s7 >> 13)
+	s[21] = byte(s8 >> 0)
+	s[22] = byte(s8 >> 8)
+	s[23] = byte((s8 >> 16) | (s9 << 5))
+	s[24] = byte(s9 >> 3)
+	s[25] = byte(s9 >> 11)
+	s[26] = byte((s9 >> 19) | (s10 << 2))
+	s[27] = byte(s10 >> 6)
+	s[28] = byte((s10 >> 14) | (s11 << 7))
+	s[29] = byte(s11 >> 1)
+	s[30] = byte(s11 >> 9)
+	s[31] = byte(s11 >> 17)
+}
+
+// Input:
+//   s[0]+256*s[1]+...+256^63*s[63] = s
+//
+// Output:
+//   s[0]+256*s[1]+...+256^31*s[31] = s mod l
+//   where l = 2^252 + 27742317777372353535851937790883648493.
+func ScReduce(out *[32]byte, s *[64]byte) {
+	s0 := 2097151 & load3(s[:])
+	s1 := 2097151 & (load4(s[2:]) >> 5)
+	s2 := 2097151 & (load3(s[5:]) >> 2)
+	s3 := 2097151 & (load4(s[7:]) >> 7)
+	s4 := 2097151 & (load4(s[10:]) >> 4)
+	s5 := 2097151 & (load3(s[13:]) >> 1)
+	s6 := 2097151 & (load4(s[15:]) >> 6)
+	s7 := 2097151 & (load3(s[18:]) >> 3)
+	s8 := 2097151 & load3(s[21:])
+	s9 := 2097151 & (load4(s[23:]) >> 5)
+	s10 := 2097151 & (load3(s[26:]) >> 2)
+	s11 := 2097151 & (load4(s[28:]) >> 7)
+	s12 := 2097151 & (load4(s[31:]) >> 4)
+	s13 := 2097151 & (load3(s[34:]) >> 1)
+	s14 := 2097151 & (load4(s[36:]) >> 6)
+	s15 := 2097151 & (load3(s[39:]) >> 3)
+	s16 := 2097151 & load3(s[42:])
+	s17 := 2097151 & (load4(s[44:]) >> 5)
+	s18 := 2097151 & (load3(s[47:]) >> 2)
+	s19 := 2097151 & (load4(s[49:]) >> 7)
+	s20 := 2097151 & (load4(s[52:]) >> 4)
+	s21 := 2097151 & (load3(s[55:]) >> 1)
+	s22 := 2097151 & (load4(s[57:]) >> 6)
+	s23 := (load4(s[60:]) >> 3)
+
+	s11 += s23 * 666643
+	s12 += s23 * 470296
+	s13 += s23 * 654183
+	s14 -= s23 * 997805
+	s15 += s23 * 136657
+	s16 -= s23 * 683901
+	s23 = 0
+
+	s10 += s22 * 666643
+	s11 += s22 * 470296
+	s12 += s22 * 654183
+	s13 -= s22 * 997805
+	s14 += s22 * 136657
+	s15 -= s22 * 683901
+	s22 = 0
+
+	s9 += s21 * 666643
+	s10 += s21 * 470296
+	s11 += s21 * 654183
+	s12 -= s21 * 997805
+	s13 += s21 * 136657
+	s14 -= s21 * 683901
+	s21 = 0
+
+	s8 += s20 * 666643
+	s9 += s20 * 470296
+	s10 += s20 * 654183
+	s11 -= s20 * 997805
+	s12 += s20 * 136657
+	s13 -= s20 * 683901
+	s20 = 0
+
+	s7 += s19 * 666643
+	s8 += s19 * 470296
+	s9 += s19 * 654183
+	s10 -= s19 * 997805
+	s11 += s19 * 136657
+	s12 -= s19 * 683901
+	s19 = 0
+
+	s6 += s18 * 666643
+	s7 += s18 * 470296
+	s8 += s18 * 654183
+	s9 -= s18 * 997805
+	s10 += s18 * 136657
+	s11 -= s18 * 683901
+	s18 = 0
+
+	var carry [17]int64
+
+	carry[6] = (s6 + (1 << 20)) >> 21
+	s7 += carry[6]
+	s6 -= carry[6] << 21
+	carry[8] = (s8 + (1 << 20)) >> 21
+	s9 += carry[8]
+	s8 -= carry[8] << 21
+	carry[10] = (s10 + (1 << 20)) >> 21
+	s11 += carry[10]
+	s10 -= carry[10] << 21
+	carry[12] = (s12 + (1 << 20)) >> 21
+	s13 += carry[12]
+	s12 -= carry[12] << 21
+	carry[14] = (s14 + (1 << 20)) >> 21
+	s15 += carry[14]
+	s14 -= carry[14] << 21
+	carry[16] = (s16 + (1 << 20)) >> 21
+	s17 += carry[16]
+	s16 -= carry[16] << 21
+
+	carry[7] = (s7 + (1 << 20)) >> 21
+	s8 += carry[7]
+	s7 -= carry[7] << 21
+	carry[9] = (s9 + (1 << 20)) >> 21
+	s10 += carry[9]
+	s9 -= carry[9] << 21
+	carry[11] = (s11 + (1 << 20)) >> 21
+	s12 += carry[11]
+	s11 -= carry[11] << 21
+	carry[13] = (s13 + (1 << 20)) >> 21
+	s14 += carry[13]
+	s13 -= carry[13] << 21
+	carry[15] = (s15 + (1 << 20)) >> 21
+	s16 += carry[15]
+	s15 -= carry[15] << 21
+
+	s5 += s17 * 666643
+	s6 += s17 * 470296
+	s7 += s17 * 654183
+	s8 -= s17 * 997805
+	s9 += s17 * 136657
+	s10 -= s17 * 683901
+	s17 = 0
+
+	s4 += s16 * 666643
+	s5 += s16 * 470296
+	s6 += s16 * 654183
+	s7 -= s16 * 997805
+	s8 += s16 * 136657
+	s9 -= s16 * 683901
+	s16 = 0
+
+	s3 += s15 * 666643
+	s4 += s15 * 470296
+	s5 += s15 * 654183
+	s6 -= s15 * 997805
+	s7 += s15 * 136657
+	s8 -= s15 * 683901
+	s15 = 0
+
+	s2 += s14 * 666643
+	s3 += s14 * 470296
+	s4 += s14 * 654183
+	s5 -= s14 * 997805
+	s6 += s14 * 136657
+	s7 -= s14 * 683901
+	s14 = 0
+
+	s1 += s13 * 666643
+	s2 += s13 * 470296
+	s3 += s13 * 654183
+	s4 -= s13 * 997805
+	s5 += s13 * 136657
+	s6 -= s13 * 683901
+	s13 = 0
+
+	s0 += s12 * 666643
+	s1 += s12 * 470296
+	s2 += s12 * 654183
+	s3 -= s12 * 997805
+	s4 += s12 * 136657
+	s5 -= s12 * 683901
+	s12 = 0
+
+	carry[0] = (s0 + (1 << 20)) >> 21
+	s1 += carry[0]
+	s0 -= carry[0] << 21
+	carry[2] = (s2 + (1 << 20)) >> 21
+	s3 += carry[2]
+	s2 -= carry[2] << 21
+	carry[4] = (s4 + (1 << 20)) >> 21
+	s5 += carry[4]
+	s4 -= carry[4] << 21
+	carry[6] = (s6 + (1 << 20)) >> 21
+	s7 += carry[6]
+	s6 -= carry[6] << 21
+	carry[8] = (s8 + (1 << 20)) >> 21
+	s9 += carry[8]
+	s8 -= carry[8] << 21
+	carry[10] = (s10 + (1 << 20)) >> 21
+	s11 += carry[10]
+	s10 -= carry[10] << 21
+
+	carry[1] = (s1 + (1 << 20)) >> 21
+	s2 += carry[1]
+	s1 -= carry[1] << 21
+	carry[3] = (s3 + (1 << 20)) >> 21
+	s4 += carry[3]
+	s3 -= carry[3] << 21
+	carry[5] = (s5 + (1 << 20)) >> 21
+	s6 += carry[5]
+	s5 -= carry[5] << 21
+	carry[7] = (s7 + (1 << 20)) >> 21
+	s8 += carry[7]
+	s7 -= carry[7] << 21
+	carry[9] = (s9 + (1 << 20)) >> 21
+	s10 += carry[9]
+	s9 -= carry[9] << 21
+	carry[11] = (s11 + (1 << 20)) >> 21
+	s12 += carry[11]
+	s11 -= carry[11] << 21
+
+	s0 += s12 * 666643
+	s1 += s12 * 470296
+	s2 += s12 * 654183
+	s3 -= s12 * 997805
+	s4 += s12 * 136657
+	s5 -= s12 * 683901
+	s12 = 0
+
+	carry[0] = s0 >> 21
+	s1 += carry[0]
+	s0 -= carry[0] << 21
+	carry[1] = s1 >> 21
+	s2 += carry[1]
+	s1 -= carry[1] << 21
+	carry[2] = s2 >> 21
+	s3 += carry[2]
+	s2 -= carry[2] << 21
+	carry[3] = s3 >> 21
+	s4 += carry[3]
+	s3 -= carry[3] << 21
+	carry[4] = s4 >> 21
+	s5 += carry[4]
+	s4 -= carry[4] << 21
+	carry[5] = s5 >> 21
+	s6 += carry[5]
+	s5 -= carry[5] << 21
+	carry[6] = s6 >> 21
+	s7 += carry[6]
+	s6 -= carry[6] << 21
+	carry[7] = s7 >> 21
+	s8 += carry[7]
+	s7 -= carry[7] << 21
+	carry[8] = s8 >> 21
+	s9 += carry[8]
+	s8 -= carry[8] << 21
+	carry[9] = s9 >> 21
+	s10 += carry[9]
+	s9 -= carry[9] << 21
+	carry[10] = s10 >> 21
+	s11 += carry[10]
+	s10 -= carry[10] << 21
+	carry[11] = s11 >> 21
+	s12 += carry[11]
+	s11 -= carry[11] << 21
+
+	s0 += s12 * 666643
+	s1 += s12 * 470296
+	s2 += s12 * 654183
+	s3 -= s12 * 997805
+	s4 += s12 * 136657
+	s5 -= s12 * 683901
+	s12 = 0
+
+	carry[0] = s0 >> 21
+	s1 += carry[0]
+	s0 -= carry[0] << 21
+	carry[1] = s1 >> 21
+	s2 += carry[1]
+	s1 -= carry[1] << 21
+	carry[2] = s2 >> 21
+	s3 += carry[2]
+	s2 -= carry[2] << 21
+	carry[3] = s3 >> 21
+	s4 += carry[3]
+	s3 -= carry[3] << 21
+	carry[4] = s4 >> 21
+	s5 += carry[4]
+	s4 -= carry[4] << 21
+	carry[5] = s5 >> 21
+	s6 += carry[5]
+	s5 -= carry[5] << 21
+	carry[6] = s6 >> 21
+	s7 += carry[6]
+	s6 -= carry[6] << 21
+	carry[7] = s7 >> 21
+	s8 += carry[7]
+	s7 -= carry[7] << 21
+	carry[8] = s8 >> 21
+	s9 += carry[8]
+	s8 -= carry[8] << 21
+	carry[9] = s9 >> 21
+	s10 += carry[9]
+	s9 -= carry[9] << 21
+	carry[10] = s10 >> 21
+	s11 += carry[10]
+	s10 -= carry[10] << 21
+
+	out[0] = byte(s0 >> 0)
+	out[1] = byte(s0 >> 8)
+	out[2] = byte((s0 >> 16) | (s1 << 5))
+	out[3] = byte(s1 >> 3)
+	out[4] = byte(s1 >> 11)
+	out[5] = byte((s1 >> 19) | (s2 << 2))
+	out[6] = byte(s2 >> 6)
+	out[7] = byte((s2 >> 14) | (s3 << 7))
+	out[8] = byte(s3 >> 1)
+	out[9] = byte(s3 >> 9)
+	out[10] = byte((s3 >> 17) | (s4 << 4))
+	out[11] = byte(s4 >> 4)
+	out[12] = byte(s4 >> 12)
+	out[13] = byte((s4 >> 20) | (s5 << 1))
+	out[14] = byte(s5 >> 7)
+	out[15] = byte((s5 >> 15) | (s6 << 6))
+	out[16] = byte(s6 >> 2)
+	out[17] = byte(s6 >> 10)
+	out[18] = byte((s6 >> 18) | (s7 << 3))
+	out[19] = byte(s7 >> 5)
+	out[20] = byte(s7 >> 13)
+	out[21] = byte(s8 >> 0)
+	out[22] = byte(s8 >> 8)
+	out[23] = byte((s8 >> 16) | (s9 << 5))
+	out[24] = byte(s9 >> 3)
+	out[25] = byte(s9 >> 11)
+	out[26] = byte((s9 >> 19) | (s10 << 2))
+	out[27] = byte(s10 >> 6)
+	out[28] = byte((s10 >> 14) | (s11 << 7))
+	out[29] = byte(s11 >> 1)
+	out[30] = byte(s11 >> 9)
+	out[31] = byte(s11 >> 17)
+}

vendor/github.com/refraction-networking/gotapdance/ed25519/extra25519/extra25519.go

@@ -0,0 +1,347 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package extra25519
+
+import (
+	"crypto/sha512"
+
+	"github.com/refraction-networking/gotapdance/ed25519/edwards25519"
+)
+
+// PrivateKeyToCurve25519 converts an ed25519 private key into a corresponding
+// curve25519 private key such that the resulting curve25519 public key will
+// equal the result from PublicKeyToCurve25519.
+func PrivateKeyToCurve25519(curve25519Private *[32]byte, privateKey *[64]byte) {
+	h := sha512.New()
+	h.Write(privateKey[:32])
+	digest := h.Sum(nil)
+
+	digest[0] &= 248
+	digest[31] &= 127
+	digest[31] |= 64
+
+	copy(curve25519Private[:], digest)
+}
+
+func edwardsToMontgomeryX(outX, y *edwards25519.FieldElement) {
+	// We only need the x-coordinate of the curve25519 point, which I'll
+	// call u. The isomorphism is u=(y+1)/(1-y), since y=Y/Z, this gives
+	// u=(Y+Z)/(Z-Y). We know that Z=1, thus u=(Y+1)/(1-Y).
+	var oneMinusY edwards25519.FieldElement
+	edwards25519.FeOne(&oneMinusY)
+	edwards25519.FeSub(&oneMinusY, &oneMinusY, y)
+	edwards25519.FeInvert(&oneMinusY, &oneMinusY)
+
+	edwards25519.FeOne(outX)
+	edwards25519.FeAdd(outX, outX, y)
+
+	edwards25519.FeMul(outX, outX, &oneMinusY)
+}
+
+// PublicKeyToCurve25519 converts an Ed25519 public key into the curve25519
+// public key that would be generated from the same private key.
+func PublicKeyToCurve25519(curve25519Public *[32]byte, publicKey *[32]byte) bool {
+	var A edwards25519.ExtendedGroupElement
+	if !A.FromBytes(publicKey) {
+		return false
+	}
+
+	// A.Z = 1 as a postcondition of FromBytes.
+	var x edwards25519.FieldElement
+	edwardsToMontgomeryX(&x, &A.Y)
+	edwards25519.FeToBytes(curve25519Public, &x)
+	return true
+}
+
+// sqrtMinusAPlus2 is sqrt(-(486662+2))
+var sqrtMinusAPlus2 = edwards25519.FieldElement{
+	-12222970, -8312128, -11511410, 9067497, -15300785, -241793, 25456130, 14121551, -12187136, 3972024,
+}
+
+// sqrtMinusHalf is sqrt(-1/2)
+var sqrtMinusHalf = edwards25519.FieldElement{
+	-17256545, 3971863, 28865457, -1750208, 27359696, -16640980, 12573105, 1002827, -163343, 11073975,
+}
+
+// halfQMinus1Bytes is (2^255-20)/2 expressed in little endian form.
+var halfQMinus1Bytes = [32]byte{
+	0xf6, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3f,
+}
+
+// feBytesLess returns one if a <= b and zero otherwise.
+func feBytesLE(a, b *[32]byte) int32 {
+	equalSoFar := int32(-1)
+	greater := int32(0)
+
+	for i := uint(31); i < 32; i-- {
+		x := int32(a[i])
+		y := int32(b[i])
+
+		greater = (^equalSoFar & greater) | (equalSoFar & ((x - y) >> 31))
+		equalSoFar = equalSoFar & (((x ^ y) - 1) >> 31)
+	}
+
+	return int32(^equalSoFar & 1 & greater)
+}
+
+// ScalarBaseMult computes a curve25519 public key from a private key and also
+// a uniform representative for that public key. Note that this function will
+// fail and return false for about half of private keys.
+// See http://elligator.cr.yp.to/elligator-20130828.pdf.
+func ScalarBaseMult(publicKey, representative, privateKey *[32]byte) bool {
+	var maskedPrivateKey [32]byte
+	copy(maskedPrivateKey[:], privateKey[:])
+
+	maskedPrivateKey[0] &= 248
+	maskedPrivateKey[31] &= 127
+	maskedPrivateKey[31] |= 64
+
+	var A edwards25519.ExtendedGroupElement
+	edwards25519.GeScalarMultBase(&A, &maskedPrivateKey)
+
+	var inv1 edwards25519.FieldElement
+	edwards25519.FeSub(&inv1, &A.Z, &A.Y)
+	edwards25519.FeMul(&inv1, &inv1, &A.X)
+	edwards25519.FeInvert(&inv1, &inv1)
+
+	var t0, u edwards25519.FieldElement
+	edwards25519.FeMul(&u, &inv1, &A.X)
+	edwards25519.FeAdd(&t0, &A.Y, &A.Z)
+	edwards25519.FeMul(&u, &u, &t0)
+
+	var v edwards25519.FieldElement
+	edwards25519.FeMul(&v, &t0, &inv1)
+	edwards25519.FeMul(&v, &v, &A.Z)
+	edwards25519.FeMul(&v, &v, &sqrtMinusAPlus2)
+
+	var b edwards25519.FieldElement
+	edwards25519.FeAdd(&b, &u, &edwards25519.A)
+
+	var c, b3, b7, b8 edwards25519.FieldElement
+	edwards25519.FeSquare(&b3, &b)   // 2
+	edwards25519.FeMul(&b3, &b3, &b) // 3
+	edwards25519.FeSquare(&c, &b3)   // 6
+	edwards25519.FeMul(&b7, &c, &b)  // 7
+	edwards25519.FeMul(&b8, &b7, &b) // 8
+	edwards25519.FeMul(&c, &b7, &u)
+	q58(&c, &c)
+
+	var chi edwards25519.FieldElement
+	edwards25519.FeSquare(&chi, &c)
+	edwards25519.FeSquare(&chi, &chi)
+
+	edwards25519.FeSquare(&t0, &u)
+	edwards25519.FeMul(&chi, &chi, &t0)
+
+	edwards25519.FeSquare(&t0, &b7) // 14
+	edwards25519.FeMul(&chi, &chi, &t0)
+	edwards25519.FeNeg(&chi, &chi)
+
+	var chiBytes [32]byte
+	edwards25519.FeToBytes(&chiBytes, &chi)
+	// chi[1] is either 0 or 0xff
+	if chiBytes[1] == 0xff {
+		return false
+	}
+
+	// Calculate r1 = sqrt(-u/(2*(u+A)))
+	var r1 edwards25519.FieldElement
+	edwards25519.FeMul(&r1, &c, &u)
+	edwards25519.FeMul(&r1, &r1, &b3)
+	edwards25519.FeMul(&r1, &r1, &sqrtMinusHalf)
+
+	var maybeSqrtM1 edwards25519.FieldElement
+	edwards25519.FeSquare(&t0, &r1)
+	edwards25519.FeMul(&t0, &t0, &b)
+	edwards25519.FeAdd(&t0, &t0, &t0)
+	edwards25519.FeAdd(&t0, &t0, &u)
+
+	edwards25519.FeOne(&maybeSqrtM1)
+	edwards25519.FeCMove(&maybeSqrtM1, &edwards25519.SqrtM1, edwards25519.FeIsNonZero(&t0))
+	edwards25519.FeMul(&r1, &r1, &maybeSqrtM1)
+
+	// Calculate r = sqrt(-(u+A)/(2u))
+	var r edwards25519.FieldElement
+	edwards25519.FeSquare(&t0, &c)   // 2
+	edwards25519.FeMul(&t0, &t0, &c) // 3
+	edwards25519.FeSquare(&t0, &t0)  // 6
+	edwards25519.FeMul(&r, &t0, &c)  // 7
+
+	edwards25519.FeSquare(&t0, &u)   // 2
+	edwards25519.FeMul(&t0, &t0, &u) // 3
+	edwards25519.FeMul(&r, &r, &t0)
+
+	edwards25519.FeSquare(&t0, &b8)   // 16
+	edwards25519.FeMul(&t0, &t0, &b8) // 24
+	edwards25519.FeMul(&t0, &t0, &b)  // 25
+	edwards25519.FeMul(&r, &r, &t0)
+	edwards25519.FeMul(&r, &r, &sqrtMinusHalf)
+
+	edwards25519.FeSquare(&t0, &r)
+	edwards25519.FeMul(&t0, &t0, &u)
+	edwards25519.FeAdd(&t0, &t0, &t0)
+	edwards25519.FeAdd(&t0, &t0, &b)
+	edwards25519.FeOne(&maybeSqrtM1)
+	edwards25519.FeCMove(&maybeSqrtM1, &edwards25519.SqrtM1, edwards25519.FeIsNonZero(&t0))
+	edwards25519.FeMul(&r, &r, &maybeSqrtM1)
+
+	var vBytes [32]byte
+	edwards25519.FeToBytes(&vBytes, &v)
+	vInSquareRootImage := feBytesLE(&vBytes, &halfQMinus1Bytes)
+	edwards25519.FeCMove(&r, &r1, vInSquareRootImage)
+
+	// // 5.5: Here |b| means b if b in {0, 1, ..., (q - 1)/2}, otherwise -b.
+	var rBytes [32]byte
+	edwards25519.FeToBytes(&rBytes, &r)
+	negateB := 1 & (^feBytesLE(&rBytes, &halfQMinus1Bytes))
+	edwards25519.FeNeg(&r1, &r)
+	edwards25519.FeCMove(&r, &r1, negateB)
+
+	edwards25519.FeToBytes(publicKey, &u)
+	edwards25519.FeToBytes(representative, &r)
+	return true
+}
+
+// q58 calculates out = z^((p-5)/8).
+func q58(out, z *edwards25519.FieldElement) {
+	var t1, t2, t3 edwards25519.FieldElement
+	var i int
+
+	edwards25519.FeSquare(&t1, z)     // 2^1
+	edwards25519.FeMul(&t1, &t1, z)   // 2^1 + 2^0
+	edwards25519.FeSquare(&t1, &t1)   // 2^2 + 2^1
+	edwards25519.FeSquare(&t2, &t1)   // 2^3 + 2^2
+	edwards25519.FeSquare(&t2, &t2)   // 2^4 + 2^3
+	edwards25519.FeMul(&t2, &t2, &t1) // 4,3,2,1
+	edwards25519.FeMul(&t1, &t2, z)   // 4..0
+	edwards25519.FeSquare(&t2, &t1)   // 5..1
+	for i = 1; i < 5; i++ {           // 9,8,7,6,5
+		edwards25519.FeSquare(&t2, &t2)
+	}
+	edwards25519.FeMul(&t1, &t2, &t1) // 9,8,7,6,5,4,3,2,1,0
+	edwards25519.FeSquare(&t2, &t1)   // 10..1
+	for i = 1; i < 10; i++ {          // 19..10
+		edwards25519.FeSquare(&t2, &t2)
+	}
+	edwards25519.FeMul(&t2, &t2, &t1) // 19..0
+	edwards25519.FeSquare(&t3, &t2)   // 20..1
+	for i = 1; i < 20; i++ {          // 39..20
+		edwards25519.FeSquare(&t3, &t3)
+	}
+	edwards25519.FeMul(&t2, &t3, &t2) // 39..0
+	edwards25519.FeSquare(&t2, &t2)   // 40..1
+	for i = 1; i < 10; i++ {          // 49..10
+		edwards25519.FeSquare(&t2, &t2)
+	}
+	edwards25519.FeMul(&t1, &t2, &t1) // 49..0
+	edwards25519.FeSquare(&t2, &t1)   // 50..1
+	for i = 1; i < 50; i++ {          // 99..50
+		edwards25519.FeSquare(&t2, &t2)
+	}
+	edwards25519.FeMul(&t2, &t2, &t1) // 99..0
+	edwards25519.FeSquare(&t3, &t2)   // 100..1
+	for i = 1; i < 100; i++ {         // 199..100
+		edwards25519.FeSquare(&t3, &t3)
+	}
+	edwards25519.FeMul(&t2, &t3, &t2) // 199..0
+	edwards25519.FeSquare(&t2, &t2)   // 200..1
+	for i = 1; i < 50; i++ {          // 249..50
+		edwards25519.FeSquare(&t2, &t2)
+	}
+	edwards25519.FeMul(&t1, &t2, &t1) // 249..0
+	edwards25519.FeSquare(&t1, &t1)   // 250..1
+	edwards25519.FeSquare(&t1, &t1)   // 251..2
+	edwards25519.FeMul(out, &t1, z)   // 251..2,0
+}
+
+// chi calculates out = z^((p-1)/2). The result is either 1, 0, or -1 depending
+// on whether z is a non-zero square, zero, or a non-square.
+func chi(out, z *edwards25519.FieldElement) {
+	var t0, t1, t2, t3 edwards25519.FieldElement
+	var i int
+
+	edwards25519.FeSquare(&t0, z)     // 2^1
+	edwards25519.FeMul(&t1, &t0, z)   // 2^1 + 2^0
+	edwards25519.FeSquare(&t0, &t1)   // 2^2 + 2^1
+	edwards25519.FeSquare(&t2, &t0)   // 2^3 + 2^2
+	edwards25519.FeSquare(&t2, &t2)   // 4,3
+	edwards25519.FeMul(&t2, &t2, &t0) // 4,3,2,1
+	edwards25519.FeMul(&t1, &t2, z)   // 4..0
+	edwards25519.FeSquare(&t2, &t1)   // 5..1
+	for i = 1; i < 5; i++ {           // 9,8,7,6,5
+		edwards25519.FeSquare(&t2, &t2)
+	}
+	edwards25519.FeMul(&t1, &t2, &t1) // 9,8,7,6,5,4,3,2,1,0
+	edwards25519.FeSquare(&t2, &t1)   // 10..1
+	for i = 1; i < 10; i++ {          // 19..10
+		edwards25519.FeSquare(&t2, &t2)
+	}
+	edwards25519.FeMul(&t2, &t2, &t1) // 19..0
+	edwards25519.FeSquare(&t3, &t2)   // 20..1
+	for i = 1; i < 20; i++ {          // 39..20
+		edwards25519.FeSquare(&t3, &t3)
+	}
+	edwards25519.FeMul(&t2, &t3, &t2) // 39..0
+	edwards25519.FeSquare(&t2, &t2)   // 40..1
+	for i = 1; i < 10; i++ {          // 49..10
+		edwards25519.FeSquare(&t2, &t2)
+	}
+	edwards25519.FeMul(&t1, &t2, &t1) // 49..0
+	edwards25519.FeSquare(&t2, &t1)   // 50..1
+	for i = 1; i < 50; i++ {          // 99..50
+		edwards25519.FeSquare(&t2, &t2)
+	}
+	edwards25519.FeMul(&t2, &t2, &t1) // 99..0
+	edwards25519.FeSquare(&t3, &t2)   // 100..1
+	for i = 1; i < 100; i++ {         // 199..100
+		edwards25519.FeSquare(&t3, &t3)
+	}
+	edwards25519.FeMul(&t2, &t3, &t2) // 199..0
+	edwards25519.FeSquare(&t2, &t2)   // 200..1
+	for i = 1; i < 50; i++ {          // 249..50
+		edwards25519.FeSquare(&t2, &t2)
+	}
+	edwards25519.FeMul(&t1, &t2, &t1) // 249..0
+	edwards25519.FeSquare(&t1, &t1)   // 250..1
+	for i = 1; i < 4; i++ {           // 253..4
+		edwards25519.FeSquare(&t1, &t1)
+	}
+	edwards25519.FeMul(out, &t1, &t0) // 253..4,2,1
+}
+
+// RepresentativeToPublicKey converts a uniform representative value for a
+// curve25519 public key, as produced by ScalarBaseMult, to a curve25519 public
+// key.
+func RepresentativeToPublicKey(publicKey, representative *[32]byte) {
+	var rr2, v, e edwards25519.FieldElement
+	edwards25519.FeFromBytes(&rr2, representative)
+
+	edwards25519.FeSquare2(&rr2, &rr2)
+	rr2[0]++
+	edwards25519.FeInvert(&rr2, &rr2)
+	edwards25519.FeMul(&v, &edwards25519.A, &rr2)
+	edwards25519.FeNeg(&v, &v)
+
+	var v2, v3 edwards25519.FieldElement
+	edwards25519.FeSquare(&v2, &v)
+	edwards25519.FeMul(&v3, &v, &v2)
+	edwards25519.FeAdd(&e, &v3, &v)
+	edwards25519.FeMul(&v2, &v2, &edwards25519.A)
+	edwards25519.FeAdd(&e, &v2, &e)
+	chi(&e, &e)
+	var eBytes [32]byte
+	edwards25519.FeToBytes(&eBytes, &e)
+	// eBytes[1] is either 0 (for e = 1) or 0xff (for e = -1)
+	eIsMinus1 := int32(eBytes[1]) & 1
+	var negV edwards25519.FieldElement
+	edwards25519.FeNeg(&negV, &v)
+	edwards25519.FeCMove(&v, &negV, eIsMinus1)
+
+	edwards25519.FeZero(&v2)
+	edwards25519.FeCMove(&v2, &edwards25519.A, eIsMinus1)
+	edwards25519.FeSub(&v, &v, &v2)
+
+	edwards25519.FeToBytes(publicKey, &v)
+}

vendor/github.com/refraction-networking/gotapdance/protobuf/extensions.go

@@ -5,6 +5,8 @@ package tdproto
 import (
 	"encoding/binary"
 	"net"
+
+	"github.com/jinzhu/copier"
 )
 
 // InitTLSDecoySpec creates TLSDecoySpec from ip address and server name.
@@ -19,7 +21,7 @@ func InitTLSDecoySpec(ip string, sni string) *TLSDecoySpec {
 	if _ip.To4() != nil {
 		ipUint32 = new(uint32)
 		*ipUint32 = binary.BigEndian.Uint32(net.ParseIP(ip).To4())
-	} else if _ip.To16() != nil  {
+	} else if _ip.To16() != nil {
 		ipv6Bytes = _ip
 	}
 	tlsDecoy := TLSDecoySpec{Hostname: &sni, Ipv4Addr: ipUint32, Ipv6Addr: ipv6Bytes}
@@ -28,6 +30,9 @@ func InitTLSDecoySpec(ip string, sni string) *TLSDecoySpec {
 
 // GetIpAddrStr returns IP address of TLSDecoySpec as a string.
 func (ds *TLSDecoySpec) GetIpAddrStr() string {
+	if ds == nil {
+		return ""
+	}
 	if ds.Ipv4Addr != nil {
 		_ip := make(net.IP, 4)
 		binary.BigEndian.PutUint32(_ip, ds.GetIpv4Addr())
@@ -38,3 +43,10 @@ func (ds *TLSDecoySpec) GetIpAddrStr() string {
 	}
 	return ""
 }
+
+// DeepCopy - Create a Deep Copy of a given TLSDecoySpec Object
+func (ds *TLSDecoySpec) DeepCopy() *TLSDecoySpec {
+	newDs := TLSDecoySpec{}
+	copier.Copy(&newDs, ds)
+	return &newDs
+}

vendor/github.com/refraction-networking/gotapdance/protobuf/signalling.pb.go

@@ -235,6 +235,92 @@ func (ErrorReasonS2C) EnumDescriptor() ([]byte, []int) {
 	return fileDescriptor_39f66308029891ad, []int{3}
 }
 
+type TransportType int32
+
+const (
+	TransportType_Null  TransportType = 0
+	TransportType_Min   TransportType = 1
+	TransportType_Obfs4 TransportType = 2
+)
+
+var TransportType_name = map[int32]string{
+	0: "Null",
+	1: "Min",
+	2: "Obfs4",
+}
+
+var TransportType_value = map[string]int32{
+	"Null":  0,
+	"Min":   1,
+	"Obfs4": 2,
+}
+
+func (x TransportType) Enum() *TransportType {
+	p := new(TransportType)
+	*p = x
+	return p
+}
+
+func (x TransportType) String() string {
+	return proto.EnumName(TransportType_name, int32(x))
+}
+
+func (x *TransportType) UnmarshalJSON(data []byte) error {
+	value, err := proto.UnmarshalJSONEnum(TransportType_value, data, "TransportType")
+	if err != nil {
+		return err
+	}
+	*x = TransportType(value)
+	return nil
+}
+
+func (TransportType) EnumDescriptor() ([]byte, []int) {
+	return fileDescriptor_39f66308029891ad, []int{4}
+}
+
+type RegistrationSource int32
+
+const (
+	RegistrationSource_Detector        RegistrationSource = 0
+	RegistrationSource_API             RegistrationSource = 1
+	RegistrationSource_DetectorPrescan RegistrationSource = 2
+)
+
+var RegistrationSource_name = map[int32]string{
+	0: "Detector",
+	1: "API",
+	2: "DetectorPrescan",
+}
+
+var RegistrationSource_value = map[string]int32{
+	"Detector":        0,
+	"API":             1,
+	"DetectorPrescan": 2,
+}
+
+func (x RegistrationSource) Enum() *RegistrationSource {
+	p := new(RegistrationSource)
+	*p = x
+	return p
+}
+
+func (x RegistrationSource) String() string {
+	return proto.EnumName(RegistrationSource_name, int32(x))
+}
+
+func (x *RegistrationSource) UnmarshalJSON(data []byte) error {
+	value, err := proto.UnmarshalJSONEnum(RegistrationSource_value, data, "RegistrationSource")
+	if err != nil {
+		return err
+	}
+	*x = RegistrationSource(value)
+	return nil
+}
+
+func (RegistrationSource) EnumDescriptor() ([]byte, []int) {
+	return fileDescriptor_39f66308029891ad, []int{5}
+}
+
 type PubKey struct {
 	// A public key, as used by the station.
 	Key                  []byte   `protobuf:"bytes,1,opt,name=key" json:"key,omitempty"`
@@ -389,12 +475,14 @@ func (m *TLSDecoySpec) GetTcpwin() uint32 {
 }
 
 type ClientConf struct {
-	DecoyList            *DecoyList `protobuf:"bytes,1,opt,name=decoy_list,json=decoyList" json:"decoy_list,omitempty"`
-	Generation           *uint32    `protobuf:"varint,2,opt,name=generation" json:"generation,omitempty"`
-	DefaultPubkey        *PubKey    `protobuf:"bytes,3,opt,name=default_pubkey,json=defaultPubkey" json:"default_pubkey,omitempty"`
-	XXX_NoUnkeyedLiteral struct{}   `json:"-"`
-	XXX_unrecognized     []byte     `json:"-"`
-	XXX_sizecache        int32      `json:"-"`
+	DecoyList            *DecoyList       `protobuf:"bytes,1,opt,name=decoy_list,json=decoyList" json:"decoy_list,omitempty"`
+	Generation           *uint32          `protobuf:"varint,2,opt,name=generation" json:"generation,omitempty"`
+	DefaultPubkey        *PubKey          `protobuf:"bytes,3,opt,name=default_pubkey,json=defaultPubkey" json:"default_pubkey,omitempty"`
+	DarkDecoyBlocks      *DarkDecoyBlocks `protobuf:"bytes,4,opt,name=dark_decoy_blocks,json=darkDecoyBlocks" json:"dark_decoy_blocks,omitempty"`
+	ConjurePubkey        *PubKey          `protobuf:"bytes,5,opt,name=conjure_pubkey,json=conjurePubkey" json:"conjure_pubkey,omitempty"`
+	XXX_NoUnkeyedLiteral struct{}         `json:"-"`
+	XXX_unrecognized     []byte           `json:"-"`
+	XXX_sizecache        int32            `json:"-"`
 }
 
 func (m *ClientConf) Reset()         { *m = ClientConf{} }
@@ -443,6 +531,20 @@ func (m *ClientConf) GetDefaultPubkey() *PubKey {
 	return nil
 }
 
+func (m *ClientConf) GetDarkDecoyBlocks() *DarkDecoyBlocks {
+	if m != nil {
+		return m.DarkDecoyBlocks
+	}
+	return nil
+}
+
+func (m *ClientConf) GetConjurePubkey() *PubKey {
+	if m != nil {
+		return m.ConjurePubkey
+	}
+	return nil
+}
+
 type DecoyList struct {
 	TlsDecoys            []*TLSDecoySpec `protobuf:"bytes,1,rep,name=tls_decoys,json=tlsDecoys" json:"tls_decoys,omitempty"`
 	XXX_NoUnkeyedLiteral struct{}        `json:"-"`
@@ -482,6 +584,45 @@ func (m *DecoyList) GetTlsDecoys() []*TLSDecoySpec {
 	return nil
 }
 
+type DarkDecoyBlocks struct {
+	Blocks               []string `protobuf:"bytes,1,rep,name=blocks" json:"blocks,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *DarkDecoyBlocks) Reset()         { *m = DarkDecoyBlocks{} }
+func (m *DarkDecoyBlocks) String() string { return proto.CompactTextString(m) }
+func (*DarkDecoyBlocks) ProtoMessage()    {}
+func (*DarkDecoyBlocks) Descriptor() ([]byte, []int) {
+	return fileDescriptor_39f66308029891ad, []int{4}
+}
+
+func (m *DarkDecoyBlocks) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_DarkDecoyBlocks.Unmarshal(m, b)
+}
+func (m *DarkDecoyBlocks) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_DarkDecoyBlocks.Marshal(b, m, deterministic)
+}
+func (m *DarkDecoyBlocks) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_DarkDecoyBlocks.Merge(m, src)
+}
+func (m *DarkDecoyBlocks) XXX_Size() int {
+	return xxx_messageInfo_DarkDecoyBlocks.Size(m)
+}
+func (m *DarkDecoyBlocks) XXX_DiscardUnknown() {
+	xxx_messageInfo_DarkDecoyBlocks.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_DarkDecoyBlocks proto.InternalMessageInfo
+
+func (m *DarkDecoyBlocks) GetBlocks() []string {
+	if m != nil {
+		return m.Blocks
+	}
+	return nil
+}
+
 type StationToClient struct {
 	// Should accompany (at least) SESSION_INIT and CONFIRM_RECONNECT.
 	ProtocolVersion *uint32 `protobuf:"varint,1,opt,name=protocol_version,json=protocolVersion" json:"protocol_version,omitempty"`
@@ -508,7 +649,7 @@ func (m *StationToClient) Reset()         { *m = StationToClient{} }
 func (m *StationToClient) String() string { return proto.CompactTextString(m) }
 func (*StationToClient) ProtoMessage()    {}
 func (*StationToClient) Descriptor() ([]byte, []int) {
-	return fileDescriptor_39f66308029891ad, []int{4}
+	return fileDescriptor_39f66308029891ad, []int{5}
 }
 
 func (m *StationToClient) XXX_Unmarshal(b []byte) error {
@@ -578,6 +719,77 @@ func (m *StationToClient) GetPadding() []byte {
 	return nil
 }
 
+type RegistrationFlags struct {
+	UploadOnly           *bool    `protobuf:"varint,1,opt,name=upload_only,json=uploadOnly" json:"upload_only,omitempty"`
+	DarkDecoy            *bool    `protobuf:"varint,2,opt,name=dark_decoy,json=darkDecoy" json:"dark_decoy,omitempty"`
+	ProxyHeader          *bool    `protobuf:"varint,3,opt,name=proxy_header,json=proxyHeader" json:"proxy_header,omitempty"`
+	Use_TIL              *bool    `protobuf:"varint,4,opt,name=use_TIL,json=useTIL" json:"use_TIL,omitempty"`
+	Prescanned           *bool    `protobuf:"varint,5,opt,name=prescanned" json:"prescanned,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *RegistrationFlags) Reset()         { *m = RegistrationFlags{} }
+func (m *RegistrationFlags) String() string { return proto.CompactTextString(m) }
+func (*RegistrationFlags) ProtoMessage()    {}
+func (*RegistrationFlags) Descriptor() ([]byte, []int) {
+	return fileDescriptor_39f66308029891ad, []int{6}
+}
+
+func (m *RegistrationFlags) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_RegistrationFlags.Unmarshal(m, b)
+}
+func (m *RegistrationFlags) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_RegistrationFlags.Marshal(b, m, deterministic)
+}
+func (m *RegistrationFlags) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_RegistrationFlags.Merge(m, src)
+}
+func (m *RegistrationFlags) XXX_Size() int {
+	return xxx_messageInfo_RegistrationFlags.Size(m)
+}
+func (m *RegistrationFlags) XXX_DiscardUnknown() {
+	xxx_messageInfo_RegistrationFlags.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_RegistrationFlags proto.InternalMessageInfo
+
+func (m *RegistrationFlags) GetUploadOnly() bool {
+	if m != nil && m.UploadOnly != nil {
+		return *m.UploadOnly
+	}
+	return false
+}
+
+func (m *RegistrationFlags) GetDarkDecoy() bool {
+	if m != nil && m.DarkDecoy != nil {
+		return *m.DarkDecoy
+	}
+	return false
+}
+
+func (m *RegistrationFlags) GetProxyHeader() bool {
+	if m != nil && m.ProxyHeader != nil {
+		return *m.ProxyHeader
+	}
+	return false
+}
+
+func (m *RegistrationFlags) GetUse_TIL() bool {
+	if m != nil && m.Use_TIL != nil {
+		return *m.Use_TIL
+	}
+	return false
+}
+
+func (m *RegistrationFlags) GetPrescanned() bool {
+	if m != nil && m.Prescanned != nil {
+		return *m.Prescanned
+	}
+	return false
+}
+
 type ClientToStation struct {
 	ProtocolVersion *uint32 `protobuf:"varint,1,opt,name=protocol_version,json=protocolVersion" json:"protocol_version,omitempty"`
 	// The client reports its decoy list's version number here, which the
@@ -592,6 +804,8 @@ type ClientToStation struct {
 	// Could be sent in chunks
 	FailedDecoys []string      `protobuf:"bytes,10,rep,name=failed_decoys,json=failedDecoys" json:"failed_decoys,omitempty"`
 	Stats        *SessionStats `protobuf:"bytes,11,opt,name=stats" json:"stats,omitempty"`
+	// NullTransport, MinTransport, Obfs4Transport, etc. Transport type we want from phantom proxy
+	Transport *TransportType `protobuf:"varint,12,opt,name=transport,enum=tapdance.TransportType" json:"transport,omitempty"`
 	// Station is only required to check this variable during session initialization.
 	// If set, station must facilitate connection to said target by itself, i.e. write into squid
 	// socket an HTTP/SOCKS/any other connection request.
@@ -599,6 +813,13 @@ type ClientToStation struct {
 	// resolvable hostname) and port
 	// TODO: make it required for initialization, and stop connecting any client straight to squid?
 	CovertAddress *string `protobuf:"bytes,20,opt,name=covert_address,json=covertAddress" json:"covert_address,omitempty"`
+	// Used in dark decoys to signal which dark decoy it will connect to.
+	MaskedDecoyServerName *string `protobuf:"bytes,21,opt,name=masked_decoy_server_name,json=maskedDecoyServerName" json:"masked_decoy_server_name,omitempty"`
+	// Used to indicate to server if client is registering v4, v6 or both
+	V6Support *bool `protobuf:"varint,22,opt,name=v6_support,json=v6Support" json:"v6_support,omitempty"`
+	V4Support *bool `protobuf:"varint,23,opt,name=v4_support,json=v4Support" json:"v4_support,omitempty"`
+	// A collection of optional flags for the registration.
+	Flags *RegistrationFlags `protobuf:"bytes,24,opt,name=flags" json:"flags,omitempty"`
 	// Random-sized junk to defeat packet size fingerprinting.
 	Padding              []byte   `protobuf:"bytes,100,opt,name=padding" json:"padding,omitempty"`
 	XXX_NoUnkeyedLiteral struct{} `json:"-"`
@@ -610,7 +831,7 @@ func (m *ClientToStation) Reset()         { *m = ClientToStation{} }
 func (m *ClientToStation) String() string { return proto.CompactTextString(m) }
 func (*ClientToStation) ProtoMessage()    {}
 func (*ClientToStation) Descriptor() ([]byte, []int) {
-	return fileDescriptor_39f66308029891ad, []int{5}
+	return fileDescriptor_39f66308029891ad, []int{7}
 }
 
 func (m *ClientToStation) XXX_Unmarshal(b []byte) error {
@@ -673,6 +894,13 @@ func (m *ClientToStation) GetStats() *SessionStats {
 	return nil
 }
 
+func (m *ClientToStation) GetTransport() TransportType {
+	if m != nil && m.Transport != nil {
+		return *m.Transport
+	}
+	return TransportType_Null
+}
+
 func (m *ClientToStation) GetCovertAddress() string {
 	if m != nil && m.CovertAddress != nil {
 		return *m.CovertAddress
@@ -680,6 +908,34 @@ func (m *ClientToStation) GetCovertAddress() string {
 	return ""
 }
 
+func (m *ClientToStation) GetMaskedDecoyServerName() string {
+	if m != nil && m.MaskedDecoyServerName != nil {
+		return *m.MaskedDecoyServerName
+	}
+	return ""
+}
+
+func (m *ClientToStation) GetV6Support() bool {
+	if m != nil && m.V6Support != nil {
+		return *m.V6Support
+	}
+	return false
+}
+
+func (m *ClientToStation) GetV4Support() bool {
+	if m != nil && m.V4Support != nil {
+		return *m.V4Support
+	}
+	return false
+}
+
+func (m *ClientToStation) GetFlags() *RegistrationFlags {
+	if m != nil {
+		return m.Flags
+	}
+	return nil
+}
+
 func (m *ClientToStation) GetPadding() []byte {
 	if m != nil {
 		return m.Padding
@@ -687,6 +943,79 @@ func (m *ClientToStation) GetPadding() []byte {
 	return nil
 }
 
+type C2SWrapper struct {
+	SharedSecret        []byte              `protobuf:"bytes,1,opt,name=shared_secret,json=sharedSecret" json:"shared_secret,omitempty"`
+	RegistrationPayload *ClientToStation    `protobuf:"bytes,3,opt,name=registration_payload,json=registrationPayload" json:"registration_payload,omitempty"`
+	RegistrationSource  *RegistrationSource `protobuf:"varint,4,opt,name=registration_source,json=registrationSource,enum=tapdance.RegistrationSource" json:"registration_source,omitempty"`
+	// client source address when receiving a registration
+	RegistrationAddress []byte `protobuf:"bytes,6,opt,name=registration_address,json=registrationAddress" json:"registration_address,omitempty"`
+	// Decoy address used when registering over Decoy registrar
+	DecoyAddress         []byte   `protobuf:"bytes,7,opt,name=decoy_address,json=decoyAddress" json:"decoy_address,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *C2SWrapper) Reset()         { *m = C2SWrapper{} }
+func (m *C2SWrapper) String() string { return proto.CompactTextString(m) }
+func (*C2SWrapper) ProtoMessage()    {}
+func (*C2SWrapper) Descriptor() ([]byte, []int) {
+	return fileDescriptor_39f66308029891ad, []int{8}
+}
+
+func (m *C2SWrapper) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_C2SWrapper.Unmarshal(m, b)
+}
+func (m *C2SWrapper) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_C2SWrapper.Marshal(b, m, deterministic)
+}
+func (m *C2SWrapper) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_C2SWrapper.Merge(m, src)
+}
+func (m *C2SWrapper) XXX_Size() int {
+	return xxx_messageInfo_C2SWrapper.Size(m)
+}
+func (m *C2SWrapper) XXX_DiscardUnknown() {
+	xxx_messageInfo_C2SWrapper.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_C2SWrapper proto.InternalMessageInfo
+
+func (m *C2SWrapper) GetSharedSecret() []byte {
+	if m != nil {
+		return m.SharedSecret
+	}
+	return nil
+}
+
+func (m *C2SWrapper) GetRegistrationPayload() *ClientToStation {
+	if m != nil {
+		return m.RegistrationPayload
+	}
+	return nil
+}
+
+func (m *C2SWrapper) GetRegistrationSource() RegistrationSource {
+	if m != nil && m.RegistrationSource != nil {
+		return *m.RegistrationSource
+	}
+	return RegistrationSource_Detector
+}
+
+func (m *C2SWrapper) GetRegistrationAddress() []byte {
+	if m != nil {
+		return m.RegistrationAddress
+	}
+	return nil
+}
+
+func (m *C2SWrapper) GetDecoyAddress() []byte {
+	if m != nil {
+		return m.DecoyAddress
+	}
+	return nil
+}
+
 type SessionStats struct {
 	FailedDecoysAmount *uint32 `protobuf:"varint,20,opt,name=failed_decoys_amount,json=failedDecoysAmount" json:"failed_decoys_amount,omitempty"`
 	// Applicable to whole session:
@@ -704,7 +1033,7 @@ func (m *SessionStats) Reset()         { *m = SessionStats{} }
 func (m *SessionStats) String() string { return proto.CompactTextString(m) }
 func (*SessionStats) ProtoMessage()    {}
 func (*SessionStats) Descriptor() ([]byte, []int) {
-	return fileDescriptor_39f66308029891ad, []int{6}
+	return fileDescriptor_39f66308029891ad, []int{9}
 }
 
 func (m *SessionStats) XXX_Unmarshal(b []byte) error {
@@ -765,81 +1094,112 @@ func init() {
 	proto.RegisterEnum("tapdance.C2S_Transition", C2S_Transition_name, C2S_Transition_value)
 	proto.RegisterEnum("tapdance.S2C_Transition", S2C_Transition_name, S2C_Transition_value)
 	proto.RegisterEnum("tapdance.ErrorReasonS2C", ErrorReasonS2C_name, ErrorReasonS2C_value)
+	proto.RegisterEnum("tapdance.TransportType", TransportType_name, TransportType_value)
+	proto.RegisterEnum("tapdance.RegistrationSource", RegistrationSource_name, RegistrationSource_value)
 	proto.RegisterType((*PubKey)(nil), "tapdance.PubKey")
 	proto.RegisterType((*TLSDecoySpec)(nil), "tapdance.TLSDecoySpec")
 	proto.RegisterType((*ClientConf)(nil), "tapdance.ClientConf")
 	proto.RegisterType((*DecoyList)(nil), "tapdance.DecoyList")
+	proto.RegisterType((*DarkDecoyBlocks)(nil), "tapdance.DarkDecoyBlocks")
 	proto.RegisterType((*StationToClient)(nil), "tapdance.StationToClient")
+	proto.RegisterType((*RegistrationFlags)(nil), "tapdance.RegistrationFlags")
 	proto.RegisterType((*ClientToStation)(nil), "tapdance.ClientToStation")
+	proto.RegisterType((*C2SWrapper)(nil), "tapdance.C2SWrapper")
 	proto.RegisterType((*SessionStats)(nil), "tapdance.SessionStats")
 }
 
 func init() { proto.RegisterFile("signalling.proto", fileDescriptor_39f66308029891ad) }
 
 var fileDescriptor_39f66308029891ad = []byte{
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+	0xd1, 0x25, 0xf7, 0x26, 0x72, 0x7b, 0x3e, 0xb0, 0xef, 0x16, 0xa3, 0xf9, 0x2d, 0xcd, 0xac, 0xde,
+	0xed, 0x9e, 0xdd, 0xf3, 0xbe, 0xab, 0x99, 0x45, 0x4d, 0xf9, 0x2c, 0x0d, 0x15, 0xe9, 0xb5, 0xb2,
+	0xa6, 0xde, 0x2c, 0x0d, 0xd1, 0x73, 0x68, 0x4d, 0x82, 0x38, 0xa1, 0x51, 0x39, 0x3d, 0xa0, 0x74,
+	0xdf, 0xd4, 0xa0, 0x1e, 0x14, 0xf4, 0x33, 0x58, 0x97, 0x1f, 0xe6, 0x56, 0x43, 0x69, 0xae, 0x32,
+	0x5a, 0x1e, 0xe5, 0x92, 0xa0, 0x2c, 0x09, 0xc7, 0xda, 0x09, 0x9d, 0x42, 0x5d, 0xa5, 0x9c, 0x67,
+	0x4c, 0x58, 0x4d, 0x95, 0xf1, 0x7e, 0x65, 0x18, 0x4b, 0x93, 0xda, 0xd4, 0x0b, 0x4f, 0xf4, 0x42,
+	0xae, 0x82, 0x5b, 0xca, 0x04, 0x91, 0x8b, 0x95, 0x72, 0x6e, 0xed, 0x28, 0x45, 0xb5, 0x34, 0xda,
+	0xd7, 0x20, 0x7a, 0x0d, 0xd6, 0x4d, 0xc0, 0xaf, 0xcb, 0x84, 0x09, 0xa7, 0xec, 0x96, 0x32, 0xa2,
+	0x96, 0xfa, 0xae, 0xba, 0xb0, 0xab, 0xed, 0x7a, 0xe4, 0x95, 0x75, 0x24, 0x37, 0xfc, 0x13, 0x80,
+	0xdb, 0x33, 0xc2, 0xa7, 0xb9, 0xca, 0x6b, 0x4f, 0xab, 0xe7, 0xf6, 0xcc, 0xd3, 0x80, 0x32, 0x9f,
+	0xcc, 0xcd, 0xfb, 0x85, 0xf9, 0xa4, 0x34, 0x1f, 0xc3, 0xfa, 0x44, 0xaa, 0xd4, 0xb2, 0x54, 0x09,
+	0x1e, 0x2d, 0x08, 0xdd, 0x13, 0x32, 0xd6, 0x9e, 0xdf, 0xd1, 0xff, 0x5f, 0xe5, 0x62, 0xef, 0x79,
+	0xbf, 0x61, 0x41, 0x9e, 0x53, 0x26, 0x7b, 0xc0, 0xbf, 0x04, 0x8c, 0x46, 0x84, 0xd3, 0x90, 0x51,
+	0x51, 0xbc, 0x75, 0x4d, 0x0d, 0x7a, 0x0a, 0x43, 0x43, 0xd8, 0x61, 0x95, 0x48, 0x24, 0x0f, 0x66,
+	0xb2, 0x89, 0xc5, 0x1a, 0x78, 0x78, 0x77, 0x0d, 0xcc, 0x65, 0x8a, 0xb7, 0xab, 0xd7, 0xc6, 0xfa,
+	0x16, 0xba, 0x80, 0x25, 0x98, 0xf0, 0x6c, 0xca, 0x42, 0x5a, 0x6c, 0x87, 0xc7, 0xdf, 0x26, 0xe7,
+	0x29, 0x1f, 0x8c, 0xd8, 0x3d, 0x0c, 0x1d, 0xdf, 0x49, 0xae, 0xec, 0xa0, 0x7e, 0x2d, 0x97, 0x42,
+	0x95, 0x7d, 0x7c, 0x0e, 0x2d, 0xdd, 0xc0, 0xd2, 0x77, 0x53, 0x93, 0x56, 0x60, 0xe1, 0xd4, 0xfd,
+	0xa7, 0x01, 0xcd, 0xaa, 0xc4, 0xd0, 0x2f, 0x60, 0x67, 0x49, 0xae, 0x24, 0xb8, 0xc9, 0xa6, 0xa9,
+	0x50, 0x52, 0x69, 0x61, 0x54, 0x55, 0x6d, 0x5f, 0x59, 0xd0, 0x31, 0xec, 0x8a, 0x4c, 0x04, 0x09,
+	0x91, 0xaf, 0x2d, 0x11, 0x19, 0x09, 0xb3, 0x34, 0xa5, 0xa1, 0xb0, 0x9e, 0xea, 0x2b, 0xca, 0xe8,
+	0xc7, 0x37, 0xd4, 0xcf, 0x6c, 0x6d, 0x41, 0x3f, 0x82, 0x36, 0x13, 0x42, 0xfa, 0x16, 0xcb, 0xcc,
+	0x7a, 0xa6, 0x7c, 0x9b, 0x4c, 0x54, 0xc6, 0xff, 0x00, 0x9a, 0xf2, 0xd1, 0x11, 0x59, 0xb1, 0x8f,
+	0x7e, 0x5c, 0xec, 0xc7, 0x84, 0xfb, 0x99, 0x5e, 0x48, 0xd2, 0x23, 0xcc, 0x17, 0x1e, 0x3f, 0x29,
+	0x3c, 0xc2, 0xbc, 0xf0, 0x38, 0xfa, 0x29, 0x6c, 0x16, 0xff, 0x59, 0x50, 0x07, 0x1a, 0x7d, 0xc7,
+	0x23, 0xef, 0xec, 0x0b, 0x72, 0xdc, 0xfb, 0xa5, 0xf9, 0xbb, 0x2a, 0xd0, 0x3b, 0x3d, 0x33, 0x7f,
+	0x7f, 0xf4, 0x2f, 0x03, 0xda, 0xcb, 0xf3, 0x8e, 0xb6, 0xa0, 0x25, 0x91, 0x91, 0x4b, 0xec, 0xf7,
+	0xfd, 0xd1, 0x3b, 0xc7, 0x7c, 0x80, 0x76, 0xc0, 0x94, 0x90, 0xe7, 0x78, 0xde, 0xc0, 0x1d, 0x91,
+	0xc1, 0x68, 0xe0, 0x9b, 0x06, 0x7a, 0x04, 0xfb, 0x55, 0xd4, 0x76, 0x3f, 0x39, 0xd8, 0xd7, 0xc6,
+	0x06, 0xb2, 0x60, 0x47, 0x1a, 0x9d, 0xdf, 0x8e, 0x1d, 0xdb, 0x27, 0xd8, 0xb1, 0xdd, 0xd1, 0xc8,
+	0xb1, 0x7d, 0x73, 0x05, 0xed, 0xc2, 0xd6, 0xd2, 0xb5, 0xa1, 0xeb, 0x39, 0xe6, 0x6a, 0x19, 0xe3,
+	0xf3, 0xc0, 0x19, 0x9e, 0x93, 0x8f, 0xe3, 0xa1, 0xdb, 0x3f, 0x37, 0xd7, 0xd0, 0x1e, 0x20, 0x89,
+	0xf6, 0xed, 0x5f, 0x7f, 0x1c, 0x60, 0xa7, 0xc4, 0xd7, 0xd1, 0x01, 0x3c, 0xae, 0x7c, 0x5e, 0xc3,
+	0xee, 0x68, 0xf8, 0xb9, 0x88, 0x64, 0x6e, 0xa0, 0x36, 0xd4, 0x95, 0x07, 0xc6, 0x2e, 0x36, 0xff,
+	0x6d, 0x1c, 0xfd, 0xd9, 0x80, 0xf6, 0xf2, 0x6b, 0x28, 0x99, 0x4a, 0xe4, 0x0e, 0x53, 0x09, 0xdd,
+	0x67, 0x5a, 0x45, 0x97, 0x99, 0x3e, 0x84, 0x5d, 0x69, 0xb4, 0xdd, 0xd1, 0xdb, 0x01, 0xbe, 0xb8,
+	0x4b, 0x75, 0xe9, 0x5e, 0x41, 0xb5, 0x0d, 0x75, 0x09, 0xcf, 0x53, 0xfb, 0x9b, 0x01, 0xed, 0xe5,
+	0x27, 0x13, 0x35, 0xa1, 0x36, 0x72, 0x0b, 0x8f, 0x07, 0xaa, 0x25, 0x3a, 0xa6, 0xe7, 0x63, 0xa7,
+	0x7f, 0x61, 0x1a, 0x68, 0x1b, 0x3a, 0xf6, 0x70, 0xe0, 0x8c, 0x64, 0x6d, 0xc7, 0x2e, 0xf6, 0x9d,
+	0x73, 0x73, 0xa5, 0x02, 0x8e, 0xb1, 0xeb, 0xbb, 0xb6, 0x3b, 0xd4, 0x85, 0xf5, 0xfc, 0xbe, 0xaf,
+	0xe9, 0xf8, 0x0e, 0x1e, 0xf5, 0x87, 0xe6, 0x1a, 0x42, 0xd0, 0x3e, 0x77, 0x6c, 0xf7, 0x33, 0x91,
+	0xdf, 0x2d, 0x8a, 0x2a, 0xc3, 0xe8, 0xeb, 0x45, 0x98, 0x48, 0xba, 0x15, 0x90, 0x3f, 0xb8, 0x70,
+	0xdc, 0x8f, 0xbe, 0x49, 0x8f, 0x7e, 0x0e, 0xad, 0xa5, 0x85, 0x8b, 0x6a, 0xb0, 0x36, 0x9a, 0x26,
+	0x89, 0xf9, 0x00, 0x6d, 0xc2, 0xea, 0x45, 0x9c, 0x9a, 0x06, 0xaa, 0xc3, 0xba, 0x7b, 0x39, 0xe1,
+	0x27, 0xe6, 0xca, 0xd1, 0xaf, 0x00, 0xdd, 0x9f, 0x78, 0x49, 0xf0, 0x9c, 0x0a, 0x1a, 0x8a, 0x8c,
+	0xe9, 0x7b, 0xfd, 0xf1, 0x40, 0xd3, 0x2a, 0xe1, 0xb1, 0x7e, 0x29, 0xcd, 0x95, 0xff, 0x04, 0x00,
+	0x00, 0xff, 0xff, 0xe3, 0x30, 0x4c, 0x88, 0xd4, 0x0b, 0x00, 0x00,
 }

vendor/github.com/refraction-networking/gotapdance/protobuf/signalling.proto

@@ -83,12 +83,18 @@ message ClientConf {
     optional DecoyList decoy_list = 1;
     optional uint32 generation = 2;
     optional PubKey default_pubkey = 3;
+    optional DarkDecoyBlocks dark_decoy_blocks = 4;
+    optional PubKey conjure_pubkey = 5;
 }
 
 message DecoyList {
     repeated TLSDecoySpec tls_decoys = 1;
 }
 
+message DarkDecoyBlocks{
+    repeated string blocks = 1;
+}
+
 // State transitions of the client
 enum C2S_Transition {
     C2S_NO_CHANGE = 0;
@@ -126,6 +132,12 @@ enum ErrorReasonS2C {
     CLIENT_TIMEOUT = 101; // You never came back. (This is impossible to send)
 }
 
+enum TransportType {
+    Null = 0;
+    Min = 1;   // Send a 32-byte HMAC id to let the station distinguish registrations to same host
+    Obfs4 = 2; // Not implemented yet?
+}
+
 message StationToClient {
     // Should accompany (at least) SESSION_INIT and CONFIRM_RECONNECT.
     optional uint32 protocol_version = 1;
@@ -151,6 +163,14 @@ message StationToClient {
     optional bytes padding = 100;
 }
 
+message RegistrationFlags {
+	optional bool upload_only = 1;
+	optional bool dark_decoy = 2;
+	optional bool proxy_header = 3;
+    optional bool use_TIL = 4;
+    optional bool prescanned = 5;
+}
+
 message ClientToStation {
     optional uint32 protocol_version = 1;
 
@@ -172,6 +192,9 @@ message ClientToStation {
 
     optional SessionStats stats = 11;
 
+    // NullTransport, MinTransport, Obfs4Transport, etc. Transport type we want from phantom proxy
+    optional TransportType transport = 12;
+
     // Station is only required to check this variable during session initialization.
     // If set, station must facilitate connection to said target by itself, i.e. write into squid
     // socket an HTTP/SOCKS/any other connection request.
@@ -180,10 +203,39 @@ message ClientToStation {
     // TODO: make it required for initialization, and stop connecting any client straight to squid?
     optional string covert_address = 20;
 
+    // Used in dark decoys to signal which dark decoy it will connect to.
+    optional string masked_decoy_server_name = 21;
+
+    // Used to indicate to server if client is registering v4, v6 or both
+    optional bool v6_support = 22;
+    optional bool v4_support = 23;
+
+	// A collection of optional flags for the registration.
+	optional RegistrationFlags flags = 24;
+
     // Random-sized junk to defeat packet size fingerprinting.
     optional bytes padding = 100;
 }
 
+
+enum RegistrationSource {
+	Detector = 0;
+	API = 1;
+    DetectorPrescan = 2;
+}
+
+message C2SWrapper {
+	optional bytes shared_secret = 1;
+	optional ClientToStation registration_payload = 3;
+    optional RegistrationSource registration_source = 4;
+    
+    // client source address when receiving a registration
+    optional bytes registration_address = 6;
+
+    // Decoy address used when registering over Decoy registrar
+    optional bytes decoy_address = 7;
+}
+
 message SessionStats {
     optional uint32 failed_decoys_amount = 20; // how many decoys were tried before success
 

vendor/github.com/refraction-networking/gotapdance/tapdance/assets.go

@@ -3,12 +3,12 @@ package tapdance
 import (
 	"crypto/x509"
 	"encoding/binary"
+	"encoding/hex"
 	"errors"
 	"io/ioutil"
 	"net"
 	"os"
 	"path"
-	"strconv"
 	"strings"
 	"sync"
 
@@ -20,13 +20,14 @@ type assets struct {
 	sync.RWMutex
 	path string
 
-	config pb.ClientConf
+	config *pb.ClientConf
 
 	roots *x509.CertPool
 
-	filenameStationPubkey string
-	filenameRoots         string
-	filenameClientConf    string
+	filenameRoots      string
+	filenameClientConf string
+
+	socksAddr string
 }
 
 // could reset this internally to refresh assets and avoid woes of singleton testing
@@ -48,12 +49,12 @@ func AssetsSetDir(dir string) *assets {
 	_initAssets := func() { initAssets(dir) }
 	if assetsInstance != nil {
 		assetsInstance.Lock()
+		defer assetsInstance.Unlock()
 		if dir != assetsInstance.path {
 			Logger().Warnf("Assets path changed %s->%s. (Re)initializing.\n",
 				assetsInstance.path, dir)
 			assetsInstance.path = dir
 			assetsInstance.readConfigs()
-			assetsInstance.Unlock()
 			return assetsInstance
 		}
 	}
@@ -61,6 +62,14 @@ func AssetsSetDir(dir string) *assets {
 	return assetsInstance
 }
 
+func getDefaultKey() []byte {
+	// keyStr := "515868be7f45ab6f310afed4b229b7a479fc9fde553dea4ccdb369ab1899e70c"
+	keyStr := "a1cb97be697c5ed5aefd78ffa4db7e68101024603511e40a89951bc158807177"
+	key := make([]byte, hex.DecodedLen(len(keyStr)))
+	hex.Decode(key, []byte(keyStr))
+	return key
+}
+
 func initAssets(path string) {
 	var defaultDecoys = []*pb.TLSDecoySpec{
 		pb.InitTLSDecoySpec("192.122.190.104", "tapdance1.freeaeskey.xyz"),
@@ -68,9 +77,7 @@ func initAssets(path string) {
 		pb.InitTLSDecoySpec("192.122.190.106", "tapdance3.freeaeskey.xyz"),
 	}
 
-	defaultKey := []byte{81, 88, 104, 190, 127, 69, 171, 111, 49, 10, 254, 212, 178, 41, 183,
-		164, 121, 252, 159, 222, 85, 61, 234, 76, 205, 179, 105, 171, 24, 153, 231, 12}
-
+	defaultKey := getDefaultKey()
 	defualtKeyType := pb.KeyType_AES_GCM_128
 	defaultPubKey := pb.PubKey{Key: defaultKey, Type: &defualtKeyType}
 	defaultGeneration := uint32(0)
@@ -80,11 +87,11 @@ func initAssets(path string) {
 		Generation:    &defaultGeneration}
 
 	assetsInstance = &assets{
-		path:                  path,
-		config:                defaultClientConf,
-		filenameRoots:         "roots",
-		filenameClientConf:    "ClientConf",
-		filenameStationPubkey: "station_pubkey",
+		path:               path,
+		config:             &defaultClientConf,
+		filenameRoots:      "roots",
+		filenameClientConf: "ClientConf",
+		socksAddr:          "",
 	}
 	assetsInstance.readConfigs()
 }
@@ -115,8 +122,8 @@ func (a *assets) readConfigs() {
 		if err != nil {
 			return err
 		}
-		clientConf := pb.ClientConf{}
-		err = proto.Unmarshal(buf, &clientConf)
+		clientConf := &pb.ClientConf{}
+		err = proto.Unmarshal(buf, clientConf)
 		if err != nil {
 			return err
 		}
@@ -124,19 +131,6 @@ func (a *assets) readConfigs() {
 		return nil
 	}
 
-	readPubkey := func(filename string) error {
-		staionPubkey, err := ioutil.ReadFile(filename)
-		if err != nil {
-			return err
-		}
-		if len(staionPubkey) != 32 {
-			return errors.New("Unexpected keyfile length! Expected: 32. Got: " +
-				strconv.Itoa(len(staionPubkey)))
-		}
-		copy(a.config.DefaultPubkey.Key[:], staionPubkey[0:32])
-		return nil
-	}
-
 	var err error
 	Logger().Infoln("Assets: reading from folder " + a.path)
 
@@ -155,14 +149,6 @@ func (a *assets) readConfigs() {
 	} else {
 		Logger().Infoln("Client config successfully read from " + clientConfFilename)
 	}
-
-	pubkeyFilename := path.Join(a.path, a.filenameStationPubkey)
-	err = readPubkey(pubkeyFilename)
-	if err != nil {
-		Logger().Debugln("Assets: failed to read pubkey file: " + err.Error())
-	} else {
-		Logger().Infoln("Pubkey successfully read from " + pubkeyFilename)
-	}
 }
 
 // Picks random decoy, returns Server Name Indication and addr in format ipv4:port
@@ -177,27 +163,61 @@ func (a *assets) GetDecoyAddress() (sni string, addr string) {
 	decoyIndex := getRandInt(0, len(decoys)-1)
 	ip := make(net.IP, 4)
 	binary.BigEndian.PutUint32(ip, decoys[decoyIndex].GetIpv4Addr())
-	// TODO: what checks need to be done, and what's guaranteed?
+	//[TODO]{priority:winter-break}: what checks need to be done, and what's guaranteed?
 	addr = ip.To4().String() + ":443"
 	sni = decoys[decoyIndex].GetHostname()
 	return
 }
 
-// Gets random DecoySpec.
-func (a *assets) GetDecoy() pb.TLSDecoySpec {
+// Get all Decoys from ClientConf
+func (a *assets) GetAllDecoys() []*pb.TLSDecoySpec {
+	return a.config.GetDecoyList().GetTlsDecoys()
+}
+
+// Get all Decoys from ClientConf that have an IPv6 address
+func (a *assets) GetV6Decoys() []*pb.TLSDecoySpec {
+	v6Decoys := make([]*pb.TLSDecoySpec, 0)
+	allDecoys := a.config.GetDecoyList().GetTlsDecoys()
+
+	for _, decoy := range allDecoys {
+		if decoy.GetIpv6Addr() != nil {
+			v6Decoys = append(v6Decoys, decoy)
+		}
+	}
+
+	return v6Decoys
+}
+
+// Get all Decoys from ClientConf that have an IPv6 address
+func (a *assets) GetV4Decoys() []*pb.TLSDecoySpec {
+	v6Decoys := make([]*pb.TLSDecoySpec, 0)
+	allDecoys := a.config.GetDecoyList().GetTlsDecoys()
+
+	for _, decoy := range allDecoys {
+		if decoy.GetIpv4Addr() != 0 {
+			v6Decoys = append(v6Decoys, decoy)
+		}
+	}
+
+	return v6Decoys
+}
+
+// GetDecoy - Gets random DecoySpec
+func (a *assets) GetDecoy() *pb.TLSDecoySpec {
 	a.RLock()
 	defer a.RUnlock()
 
 	decoys := a.config.GetDecoyList().GetTlsDecoys()
-	chosenDecoy := pb.TLSDecoySpec{}
+	chosenDecoy := &pb.TLSDecoySpec{}
 	if len(decoys) == 0 {
 		return chosenDecoy
 	}
 	decoyIndex := getRandInt(0, len(decoys)-1)
-	chosenDecoy = *decoys[decoyIndex]
+	chosenDecoy = decoys[decoyIndex]
 
-	// TODO: stop enforcing values >= defaults.
+	//[TODO]{priority:soon} stop enforcing values >= defaults.
 	// Fix ackhole instead
+	// No value checks when using
 	if chosenDecoy.GetTimeout() < timeoutMin {
 		timeout := uint32(timeoutMax)
 		chosenDecoy.Timeout = &timeout
@@ -209,6 +229,23 @@ func (a *assets) GetDecoy() pb.TLSDecoySpec {
 	return chosenDecoy
 }
 
+// GetDecoy - Gets random IPv6 DecoySpec
+func (a *assets) GetV6Decoy() *pb.TLSDecoySpec {
+	a.RLock()
+	defer a.RUnlock()
+
+	decoys := a.GetV6Decoys()
+	chosenDecoy := &pb.TLSDecoySpec{}
+	if len(decoys) == 0 {
+		return chosenDecoy
+	}
+	decoyIndex := getRandInt(0, len(decoys)-1)
+	chosenDecoy = decoys[decoyIndex]
+
+	// No enforcing TCPWIN etc. values because this is conjure only
+	return chosenDecoy
+}
+
 func (a *assets) GetRoots() *x509.CertPool {
 	a.RLock()
 	defer a.RUnlock()
@@ -225,6 +262,15 @@ func (a *assets) GetPubkey() *[32]byte {
 	return &pKey
 }
 
+func (a *assets) GetConjurePubkey() *[32]byte {
+	a.RLock()
+	defer a.RUnlock()
+
+	var pKey [32]byte
+	copy(pKey[:], a.config.GetConjurePubkey().GetKey()[:])
+	return &pKey
+}
+
 func (a *assets) GetGeneration() uint32 {
 	a.RLock()
 	defer a.RUnlock()
@@ -244,12 +290,11 @@ func (a *assets) SetGeneration(gen uint32) (err error) {
 }
 
 // Set Public key and store config to disk
-func (a *assets) SetPubkey(pubkey pb.PubKey) (err error) {
+func (a *assets) SetPubkey(pubkey *pb.PubKey) (err error) {
 	a.Lock()
 	defer a.Unlock()
 
-	copyPubkey := pubkey
-	a.config.DefaultPubkey = &copyPubkey
+	a.config.DefaultPubkey = pubkey
 	err = a.saveClientConf()
 	return
 }
@@ -259,14 +304,14 @@ func (a *assets) SetClientConf(conf *pb.ClientConf) (err error) {
 	a.Lock()
 	defer a.Unlock()
 
-	a.config = *conf
+	a.config = conf
 	err = a.saveClientConf()
 	return
 }
 
 // Not goroutine-safe, use at your own risk
 func (a *assets) GetClientConfPtr() *pb.ClientConf {
-	return &a.config
+	return a.config
 }
 
 // Overwrite currently used decoys and store config to disk
@@ -283,7 +328,7 @@ func (a *assets) SetDecoys(decoys []*pb.TLSDecoySpec) (err error) {
 }
 
 // Checks if decoy is in currently used ClientConf decoys list
-func (a *assets) IsDecoyInList(decoy pb.TLSDecoySpec) bool {
+func (a *assets) IsDecoyInList(decoy *pb.TLSDecoySpec) bool {
 	ipv4str := decoy.GetIpAddrStr()
 	hostname := decoy.GetHostname()
 	a.RLock()
@@ -298,7 +343,7 @@ func (a *assets) IsDecoyInList(decoy pb.TLSDecoySpec) bool {
 }
 
 func (a *assets) saveClientConf() error {
-	buf, err := proto.Marshal(&a.config)
+	buf, err := proto.Marshal(a.config)
 	if err != nil {
 		return err
 	}
@@ -311,3 +356,8 @@ func (a *assets) saveClientConf() error {
 
 	return os.Rename(tmpFilename, filename)
 }
+
+// SetStatsSocksAddr - Provide a socks address for reporting stats from the client in the form "addr:port"
+func (a *assets) SetStatsSocksAddr(addr string) {
+	a.socksAddr = addr
+}

vendor/github.com/refraction-networking/gotapdance/tapdance/common.go

@@ -1,15 +1,20 @@
 package tapdance
 
 import (
+	"crypto/rand"
 	"encoding/hex"
 	"errors"
 	"fmt"
-	"github.com/refraction-networking/utls"
 	"os"
 	"strconv"
 	"time"
+
+	"github.com/refraction-networking/gotapdance/ed25519/extra25519"
+	"golang.org/x/crypto/curve25519"
 )
 
+const AES_GCM_TAG_SIZE = 16
+
 const timeoutMax = 30000
 const timeoutMin = 20000
 
@@ -33,10 +38,20 @@ const maxInt16 = int16(^uint16(0) >> 1) // max msg size -> might have to chunk
 
 type flowType int8
 
+/*______________________TapdanceFlowConn Mode Chart _________________________________\
+|FlowType     |Default Tag|Diff from old-school bidirectional       | Engines spawned|
+|-------------|-----------|-----------------------------------------|----------------|
+|Bidirectional| HTTP GET  |                                         | Writer, Reader |
+|Upload       | HTTP POST | acquires upload                         | Writer, Reader |
+|ReadOnly     | HTTP GET  | yields upload, writer sync ignored      | Reader         |
+|Rendezvous   | HTTP GET  | passes data in handshake and shuts down |                |
+\_____________|___________|_________________________________________|_______________*/
+
 const (
 	flowUpload        flowType = 0x1
 	flowReadOnly      flowType = 0x2
 	flowBidirectional flowType = 0x4
+	flowRendezvous    flowType = 0x0 // rendezvous flows shutdown after handshake
 )
 
 func (m *flowType) Str() string {
@@ -94,28 +109,33 @@ func (m *tdTagType) Str() string {
 	}
 }
 
-// First byte of tag is for FLAGS
+// Fixed-Size-Payload has a 1 byte flags field.
 // bit 0 (1 << 7) determines if flow is bidirectional(0) or upload-only(1)
-// bits 1-5 are unassigned
+// bit 1 (1 << 6) enables dark-decoys
+// bits 2-5 are unassigned
 // bit 6 determines whether PROXY-protocol-formatted string will be sent
 // bit 7 (1 << 0) signals to use TypeLen outer proto
 var (
-	tdFlagUploadOnly  = uint8(1 << 7)
+	tdFlagUploadOnly = uint8(1 << 7)
+	// tdFlagDarkDecoy   = uint8(1 << 6)
 	tdFlagProxyHeader = uint8(1 << 1)
 	tdFlagUseTIL      = uint8(1 << 0)
 )
 
 var default_flags = tdFlagUseTIL
 
-// Requests station to proxy client IP to upstream in following form:
-// CONNECT 1.2.3.4:443 HTTP/1.1\r\n
-// Host: 1.2.3.4\r\n
-// \r\n
+// Global EnableProxyProtocol() is deprecated,
+// use tapdance.Dialer with UseProxyHeader flag instead
+//
+// Requests station to send client's IP to covert in following form:
 // PROXY TCP4 x.x.x.x 127.0.0.1 1111 1234\r\n
 //       ^__^ ^_____^ ^_________________^
 //      proto clientIP      garbage
 func EnableProxyProtocol() {
+	Logger().Println("tapdance.EnableProxyProtocol() is deprecated, " +
+		"use tapdance.Dialer with UseProxyHeader flag instead.")
 	default_flags |= tdFlagProxyHeader
+	return
 }
 
 var tlsSecretLog string
@@ -149,17 +169,6 @@ func WriteTlsLog(clientRandom, masterSecret []byte) error {
 	return nil
 }
 
-// List of actually supported ciphers(not a list of offered ciphers!)
-// Essentially all working AES_GCM_128 ciphers
-var tapDanceSupportedCiphers = []uint16{
-	tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
-	tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
-	tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
-	tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
-	tls.TLS_RSA_WITH_AES_128_GCM_SHA256,
-	tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
-}
-
 // How much time to sleep on trying to connect to decoys to prevent overwhelming them
 func sleepBeforeConnect(attempt int) (waitTime <-chan time.Time) {
 	if attempt >= 6 { // return nil for first 6 attempts
@@ -167,3 +176,36 @@ func sleepBeforeConnect(attempt int) (waitTime <-chan time.Time) {
 	}
 	return
 }
+
+// takes Station's Public Key
+// returns Shared Secret, and Eligator Representative
+func generateEligatorTransformedKey(stationPubkey []byte) ([]byte, []byte, error) {
+	if len(stationPubkey) != 32 {
+		return nil, nil, errors.New("Unexpected station pubkey length. Expected: 32." +
+			" Received: " + strconv.Itoa(len(stationPubkey)) + ".")
+	}
+	var sharedSecret, clientPrivate, clientPublic, representative [32]byte
+	for ok := false; ok != true; {
+		var sliceKeyPrivate []byte = clientPrivate[:]
+		_, err := rand.Read(sliceKeyPrivate)
+		if err != nil {
+			return nil, nil, err
+		}
+
+		ok = extra25519.ScalarBaseMult(&clientPublic, &representative, &clientPrivate)
+	}
+	var stationPubkeyByte32 [32]byte
+	copy(stationPubkeyByte32[:], stationPubkey)
+	curve25519.ScalarMult(&sharedSecret, &clientPrivate, &stationPubkeyByte32)
+
+	// extra25519.ScalarBaseMult does not randomize most significant bit(sign of y_coord?)
+	// Other implementations of elligator may have up to 2 non-random bits.
+	// Here we randomize the bit, expecting it to be flipped back to 0 on station
+	randByte := make([]byte, 1)
+	_, err := rand.Read(randByte)
+	if err != nil {
+		return nil, nil, err
+	}
+	representative[31] |= (0xC0 & randByte[0])
+	return sharedSecret[:], representative[:], nil
+}

vendor/github.com/refraction-networking/gotapdance/tapdance/conjure.go

@@ -0,0 +1,1105 @@
+package tapdance
+
+import (
+	"bytes"
+	"context"
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/binary"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"math/big"
+	"net"
+	"net/http"
+	"strconv"
+	"sync"
+	"time"
+
+	pt "git.torproject.org/pluggable-transports/goptlib.git"
+	"github.com/golang/protobuf/proto"
+	pb "github.com/refraction-networking/gotapdance/protobuf"
+	ps "github.com/refraction-networking/gotapdance/tapdance/phantoms"
+	tls "github.com/refraction-networking/utls"
+	"gitlab.com/yawning/obfs4.git/common/ntor"
+	"gitlab.com/yawning/obfs4.git/transports/obfs4"
+	"golang.org/x/crypto/curve25519"
+	"golang.org/x/crypto/hkdf"
+)
+
+// V6 - Struct to track V6 support and cache result across sessions
+type V6 struct {
+	support bool
+	include uint
+}
+
+// Registrar defines the interface for a service executing
+// decoy registrations.
+type Registrar interface {
+	Register(*ConjureSession, context.Context) (*ConjureReg, error)
+}
+
+type DecoyRegistrar struct {
+
+	// TcpDialer is a custom TCP dailer to use when establishing TCP connections
+	// to decoys. When nil, Dialer.TcpDialer will be used.
+	TcpDialer func(context.Context, string, string) (net.Conn, error)
+}
+
+func (r DecoyRegistrar) Register(cjSession *ConjureSession, ctx context.Context) (*ConjureReg, error) {
+	Logger().Debugf("%v Registering V4 and V6 via DecoyRegistrar", cjSession.IDString())
+
+	// Choose N (width) decoys from decoylist
+	cjSession.RegDecoys = SelectDecoys(cjSession.Keys.SharedSecret, cjSession.V6Support.include, cjSession.Width)
+	phantom4, phantom6, err := SelectPhantom(cjSession.Keys.ConjureSeed, cjSession.V6Support.include)
+	if err != nil {
+		Logger().Warnf("%v failed to select Phantom: %v", cjSession.IDString(), err)
+		return nil, err
+	}
+
+	//[reference] Prepare registration
+	reg := &ConjureReg{
+		sessionIDStr:   cjSession.IDString(),
+		keys:           cjSession.Keys,
+		stats:          &pb.SessionStats{},
+		phantom4:       phantom4,
+		phantom6:       phantom6,
+		v6Support:      cjSession.V6Support.include,
+		covertAddress:  cjSession.CovertAddress,
+		transport:      cjSession.Transport,
+		TcpDialer:      cjSession.TcpDialer,
+		useProxyHeader: cjSession.UseProxyHeader,
+	}
+
+	if r.TcpDialer != nil {
+		reg.TcpDialer = r.TcpDialer
+	}
+
+	// //[TODO]{priority:later} How to pass context to multiple registration goroutines?
+	if ctx == nil {
+		ctx = context.Background()
+	}
+
+	width := uint(len(cjSession.RegDecoys))
+	if width < cjSession.Width {
+		Logger().Warnf("%v Using width %v (default %v)", cjSession.IDString(), width, cjSession.Width)
+	}
+
+	Logger().Debugf("%v Registration - v6:%v, covert:%v, phantoms:%v,[%v], width:%v, transport:%v",
+		reg.sessionIDStr,
+		reg.v6SupportStr(),
+		reg.covertAddress,
+		reg.phantom4.String(),
+		reg.phantom6.String(),
+		cjSession.Width,
+		cjSession.Transport,
+	)
+
+	//[reference] Send registrations to each decoy
+	dialErrors := make(chan error, width)
+	for _, decoy := range cjSession.RegDecoys {
+		Logger().Debugf("%v Sending Reg: %v, %v", cjSession.IDString(), decoy.GetHostname(), decoy.GetIpAddrStr())
+		//decoyAddr := decoy.GetIpAddrStr()
+		go reg.send(ctx, decoy, dialErrors, cjSession.registrationCallback)
+	}
+
+	//[reference] Dial errors happen immediately so block until all N dials complete
+	var unreachableCount uint = 0
+	for err := range dialErrors {
+		if err != nil {
+			Logger().Debugf("%v %v", cjSession.IDString(), err)
+			if dialErr, ok := err.(RegError); ok && dialErr.code == Unreachable {
+				// If we failed because ipv6 network was unreachable try v4 only.
+				unreachableCount++
+				if unreachableCount < width {
+					continue
+				} else {
+					break
+				}
+			}
+		}
+		//[reference] if we succeed or fail for any other reason then the network is reachable and we can continue
+		break
+	}
+
+	//[reference] if ALL fail to dial return error (retry in parent if ipv6 unreachable)
+	if unreachableCount == width {
+		Logger().Debugf("%v NETWORK UNREACHABLE", cjSession.IDString())
+		return nil, &RegError{code: Unreachable, msg: "All decoys failed to register -- Dial Unreachable"}
+	}
+
+	// randomized sleeping here to break the intraflow signal
+	toSleep := reg.getRandomDuration(3000, 212, 3449)
+	Logger().Debugf("%v Successfully sent registrations, sleeping for: %v", cjSession.IDString(), toSleep)
+	time.Sleep(toSleep)
+
+	return reg, nil
+}
+
+// Registration strategy using a centralized REST API to
+// create registrations. Only the Endpoint need be specified;
+// the remaining fields are valid with their zero values and
+// provide the opportunity for additional control over the process.
+type APIRegistrar struct {
+	// Endpoint to use in registration request
+	Endpoint string
+
+	// HTTP client to use in request
+	Client *http.Client
+
+	// Length of time to delay after confirming successful
+	// registration before attempting a connection,
+	// allowing for propagation throughout the stations.
+	ConnectionDelay time.Duration
+
+	// Maximum number of retries before giving up
+	MaxRetries int
+
+	// A secondary registration method to use on failure.
+	// Because the API registration can give us definite
+	// indication of a failure to register, this can be
+	// used as a "backup" in the case of the API being
+	// down or being blocked.
+	//
+	// If this field is nil, no secondary registration will
+	// be attempted. If it is non-nil, after failing to register
+	// (retrying MaxRetries times) we will fall back to
+	// the Register method on this field.
+	SecondaryRegistrar Registrar
+}
+
+func (r APIRegistrar) Register(cjSession *ConjureSession, ctx context.Context) (*ConjureReg, error) {
+	Logger().Debugf("%v registering via APIRegistrar", cjSession.IDString())
+	// TODO: this section is duplicated from DecoyRegistrar; consider consolidating
+	phantom4, phantom6, err := SelectPhantom(cjSession.Keys.ConjureSeed, cjSession.V6Support.include)
+	if err != nil {
+		Logger().Warnf("%v failed to select Phantom: %v", cjSession.IDString(), err)
+		return nil, err
+	}
+
+	// [reference] Prepare registration
+	reg := &ConjureReg{
+		sessionIDStr:   cjSession.IDString(),
+		keys:           cjSession.Keys,
+		stats:          &pb.SessionStats{},
+		phantom4:       phantom4,
+		phantom6:       phantom6,
+		v6Support:      cjSession.V6Support.include,
+		covertAddress:  cjSession.CovertAddress,
+		transport:      cjSession.Transport,
+		TcpDialer:      cjSession.TcpDialer,
+		useProxyHeader: cjSession.UseProxyHeader,
+	}
+
+	c2s := reg.generateClientToStation()
+
+	protoPayload := pb.C2SWrapper{
+		SharedSecret:        cjSession.Keys.SharedSecret,
+		RegistrationPayload: c2s,
+	}
+
+	payload, err := proto.Marshal(&protoPayload)
+	if err != nil {
+		Logger().Warnf("%v failed to marshal ClientToStation payload: %v", cjSession.IDString(), err)
+		return nil, err
+	}
+
+	if r.Client == nil {
+		// Transports should ideally be re-used for TCP connection pooling,
+		// but each registration is most likely making precisely one request,
+		// or if it's making more than one, is most likely due to an underlying
+		// connection issue rather than an application-level error anyways.
+		t := http.DefaultTransport.(*http.Transport).Clone()
+		t.DialContext = reg.TcpDialer
+		r.Client = &http.Client{Transport: t}
+	}
+
+	tries := 0
+	for tries < r.MaxRetries+1 {
+		tries++
+		err = r.executeHTTPRequest(cjSession, payload)
+		if err == nil {
+			Logger().Debugf("%v API registration succeeded", cjSession.IDString())
+			if r.ConnectionDelay != 0 {
+				Logger().Debugf("%v sleeping for %v", cjSession.IDString(), r.ConnectionDelay)
+				time.Sleep(r.ConnectionDelay)
+			}
+			return reg, nil
+		}
+		Logger().Warnf("%v failed API registration, attempt %d/%d", cjSession.IDString(), tries, r.MaxRetries+1)
+	}
+
+	// If we make it here, we failed API registration
+	Logger().Warnf("%v giving up on API registration", cjSession.IDString())
+
+	if r.SecondaryRegistrar != nil {
+		Logger().Debugf("%v trying secondary registration method", cjSession.IDString())
+		return r.SecondaryRegistrar.Register(cjSession, ctx)
+	}
+
+	return nil, err
+}
+
+func (r APIRegistrar) executeHTTPRequest(cjSession *ConjureSession, payload []byte) error {
+	req, err := http.NewRequest("POST", r.Endpoint, bytes.NewReader(payload))
+	if err != nil {
+		Logger().Warnf("%v failed to create HTTP request to registration endpoint %s: %v", cjSession.IDString(), r.Endpoint, err)
+		return err
+	}
+
+	resp, err := r.Client.Do(req)
+	if err != nil {
+		Logger().Warnf("%v failed to do HTTP request to registration endpoint %s: %v", cjSession.IDString(), r.Endpoint, err)
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		Logger().Warnf("%v got non-success response code %d from registration endpoint %v", cjSession.IDString(), resp.StatusCode, r.Endpoint)
+		return fmt.Errorf("non-success response code %d on %s", resp.StatusCode, r.Endpoint)
+	}
+
+	return nil
+}
+
+const (
+	v4 uint = iota
+	v6
+	both
+)
+
+//[TODO]{priority:winter-break} make this not constant
+const defaultRegWidth = 5
+
+// DialConjureAddr - Perform Registration and Dial after creating  a Conjure session from scratch
+func DialConjureAddr(ctx context.Context, address string, registrationMethod Registrar) (net.Conn, error) {
+	cjSession := makeConjureSession(address, pb.TransportType_Min)
+	return DialConjure(ctx, cjSession, registrationMethod)
+}
+
+// DialConjure - Perform Registration and Dial on an existing Conjure session
+func DialConjure(ctx context.Context, cjSession *ConjureSession, registrationMethod Registrar) (net.Conn, error) {
+
+	if cjSession == nil {
+		return nil, fmt.Errorf("No Session Provided")
+	}
+
+	cjSession.setV6Support(both)
+
+	// Choose Phantom Address in Register depending on v6 support.
+	registration, err := registrationMethod.Register(cjSession, ctx)
+	if err != nil {
+		Logger().Debugf("%v Failed to register: %v", cjSession.IDString(), err)
+		return nil, err
+	}
+
+	Logger().Debugf("%v Attempting to Connect ...", cjSession.IDString())
+
+	return registration.Connect(ctx)
+	// return Connect(cjSession)
+}
+
+// // testV6 -- This is over simple and incomplete (currently unused)
+// // checking for unreachable alone does not account for local ipv6 addresses
+// // [TODO]{priority:winter-break} use getifaddr reverse bindings
+// func testV6() bool {
+// 	dialError := make(chan error, 1)
+// 	d := Assets().GetV6Decoy()
+// 	go func() {
+// 		conn, err := net.Dial("tcp", d.GetIpAddrStr())
+// 		if err != nil {
+// 			dialError <- err
+// 			return
+// 		}
+// 		conn.Close()
+// 		dialError <- nil
+// 	}()
+
+// 	time.Sleep(500 * time.Microsecond)
+// 	// The only error that would return before this is a network unreachable error
+// 	select {
+// 	case err := <-dialError:
+// 		Logger().Debugf("v6 unreachable received: %v", err)
+// 		return false
+// 	default:
+// 		return true
+// 	}
+// }
+
+// Connect - Dial the Phantom IP address after registration
+func Connect(ctx context.Context, reg *ConjureReg) (net.Conn, error) {
+	return reg.Connect(ctx)
+}
+
+// ConjureSession - Create a session with details for registration and connection
+type ConjureSession struct {
+	Keys           *sharedKeys
+	Width          uint
+	V6Support      *V6
+	UseProxyHeader bool
+	SessionID      uint64
+	RegDecoys      []*pb.TLSDecoySpec // pb.DecoyList
+	Phantom        *net.IP
+	Transport      pb.TransportType
+	CovertAddress  string
+	// rtt			   uint // tracked in stats
+
+	// THIS IS REQUIRED TO INTERFACE WITH PSIPHON ANDROID
+	//		we use their dialer to prevent connection loopback into our own proxy
+	//		connection when tunneling the whole device.
+	TcpDialer func(context.Context, string, string) (net.Conn, error)
+
+	// performance tracking
+	stats *pb.SessionStats
+}
+
+func makeConjureSession(covert string, transport pb.TransportType) *ConjureSession {
+
+	keys, err := generateSharedKeys(getStationKey())
+	if err != nil {
+		return nil
+	}
+	//[TODO]{priority:NOW} move v6support initialization to assets so it can be tracked across dials
+	cjSession := &ConjureSession{
+		Keys:           keys,
+		Width:          defaultRegWidth,
+		V6Support:      &V6{support: true, include: both},
+		UseProxyHeader: false,
+		Transport:      transport,
+		CovertAddress:  covert,
+		SessionID:      sessionsTotal.GetAndInc(),
+	}
+
+	sharedSecretStr := make([]byte, hex.EncodedLen(len(keys.SharedSecret)))
+	hex.Encode(sharedSecretStr, keys.SharedSecret)
+	Logger().Debugf("%v Shared Secret  - %s", cjSession.IDString(), sharedSecretStr)
+
+	Logger().Debugf("%v covert %s", cjSession.IDString(), covert)
+
+	reprStr := make([]byte, hex.EncodedLen(len(keys.Representative)))
+	hex.Encode(reprStr, keys.Representative)
+	Logger().Debugf("%v Representative - %s", cjSession.IDString(), reprStr)
+
+	return cjSession
+}
+
+// IDString - Get the ID string for the session
+func (cjSession *ConjureSession) IDString() string {
+	if cjSession.Keys == nil || cjSession.Keys.SharedSecret == nil {
+		return fmt.Sprintf("[%v-000000]", strconv.FormatUint(cjSession.SessionID, 10))
+	}
+
+	secret := make([]byte, hex.EncodedLen(len(cjSession.Keys.SharedSecret)))
+	n := hex.Encode(secret, cjSession.Keys.SharedSecret)
+	if n < 6 {
+		return fmt.Sprintf("[%v-000000]", strconv.FormatUint(cjSession.SessionID, 10))
+	}
+	return fmt.Sprintf("[%v-%s]", strconv.FormatUint(cjSession.SessionID, 10), secret[:6])
+}
+
+// String - Print the string for debug and/or logging
+func (cjSession *ConjureSession) String() string {
+	return cjSession.IDString()
+	// expand for debug??
+}
+
+type resultTuple struct {
+	conn net.Conn
+	err  error
+}
+
+// Simple type alias for brevity
+type dialFunc = func(ctx context.Context, network, addr string) (net.Conn, error)
+
+func (reg *ConjureReg) connect(ctx context.Context, addr string, dialer dialFunc) (net.Conn, error) {
+	//[reference] Create Context with deadline
+	deadline, deadlineAlreadySet := ctx.Deadline()
+	if !deadlineAlreadySet {
+		//[reference] randomized timeout to Dial dark decoy address
+		deadline = time.Now().Add(reg.getRandomDuration(0, 1061*2, 1953*3))
+		//[TODO]{priority:@sfrolov} explain these numbers and why they were chosen for the boundaries.
+	}
+	childCtx, childCancelFunc := context.WithDeadline(ctx, deadline)
+	defer childCancelFunc()
+
+	//[reference] Connect to Phantom Host
+	phantomAddr := net.JoinHostPort(addr, "443")
+
+	// conn, err := reg.TcpDialer(childCtx, "tcp", phantomAddr)
+	return dialer(childCtx, "tcp", phantomAddr)
+}
+
+func (reg *ConjureReg) getFirstConnection(ctx context.Context, dialer dialFunc, phantoms []net.IP) (net.Conn, error) {
+	connChannel := make(chan resultTuple, len(phantoms))
+	for _, p := range phantoms {
+		go func(phantom net.IP) {
+			conn, err := reg.connect(ctx, phantom.String(), dialer)
+			if err != nil {
+				Logger().Infof("%v failed to dial phantom %v: %v", reg.sessionIDStr, phantom.String(), err)
+				connChannel <- resultTuple{nil, err}
+				return
+			}
+			Logger().Infof("%v Connected to phantom %v using transport %d", reg.sessionIDStr, phantom.String(), reg.transport)
+			connChannel <- resultTuple{conn, nil}
+		}(p)
+	}
+
+	open := len(phantoms)
+	for open > 0 {
+		rt := <-connChannel
+		if rt.err != nil {
+			open--
+			continue
+		}
+
+		// If we made it here we're returning the connection, so
+		// set up a goroutine to close the others
+		go func() {
+			// Close all but one connection (the good one)
+			for open > 1 {
+				t := <-connChannel
+				if t.err == nil {
+					t.conn.Close()
+				}
+				open--
+			}
+		}()
+
+		return rt.conn, nil
+	}
+
+	return nil, fmt.Errorf("no open connections")
+}
+
+// Connect - Use a registration (result of calling Register) to connect to a phantom
+// Note: This is hacky but should work for v4, v6, or both as any nil phantom addr will
+// return a dial error and be ignored.
+func (reg *ConjureReg) Connect(ctx context.Context) (net.Conn, error) {
+	phantoms := []net.IP{*reg.phantom4, *reg.phantom6}
+	//[reference] Provide chosen transport to sent bytes (or connect) if necessary
+	switch reg.transport {
+	case pb.TransportType_Min:
+		conn, err := reg.getFirstConnection(ctx, reg.TcpDialer, phantoms)
+		if err != nil {
+			Logger().Infof("%v failed to form phantom connection: %v", reg.sessionIDStr, err)
+			return nil, err
+		}
+
+		// Send hmac(seed, str) bytes to indicate to station (min transport)
+		connectTag := conjureHMAC(reg.keys.SharedSecret, "MinTrasportHMACString")
+		conn.Write(connectTag)
+		return conn, nil
+
+	case pb.TransportType_Obfs4:
+		args := pt.Args{}
+		args.Add("node-id", reg.keys.Obfs4Keys.NodeID.Hex())
+		args.Add("public-key", reg.keys.Obfs4Keys.PublicKey.Hex())
+		args.Add("iat-mode", "1")
+
+		Logger().Infof("%v node_id = %s; public key = %s", reg.sessionIDStr, reg.keys.Obfs4Keys.NodeID.Hex(), reg.keys.Obfs4Keys.PublicKey.Hex())
+
+		t := obfs4.Transport{}
+		c, err := t.ClientFactory("")
+		if err != nil {
+			Logger().Infof("%v failed to create client factory: %v", reg.sessionIDStr, err)
+			return nil, err
+		}
+
+		parsedArgs, err := c.ParseArgs(&args)
+		if err != nil {
+			Logger().Infof("%v failed to parse obfs4 args: %v", reg.sessionIDStr, err)
+			return nil, err
+		}
+
+		dialer := func(dialContext context.Context, network string, address string) (net.Conn, error) {
+			d := func(network, address string) (net.Conn, error) { return reg.TcpDialer(dialContext, network, address) }
+			return c.Dial("tcp", address, d, parsedArgs)
+		}
+
+		conn, err := reg.getFirstConnection(ctx, dialer, phantoms)
+		if err != nil {
+			Logger().Infof("%v failed to form obfs4 connection: %v", reg.sessionIDStr, err)
+			return nil, err
+		}
+
+		return conn, err
+	case pb.TransportType_Null:
+		// Dial and do nothing to the connection before returning it to the user.
+		return reg.getFirstConnection(ctx, reg.TcpDialer, phantoms)
+	default:
+		// If transport is unrecognized use min transport.
+		return nil, fmt.Errorf("Unknown Transport")
+	}
+}
+
+// ConjureReg - Registration structure created for each individual registration within a session.
+type ConjureReg struct {
+	seed           []byte
+	sessionIDStr   string
+	phantom4       *net.IP
+	phantom6       *net.IP
+	useProxyHeader bool
+	covertAddress  string
+	phantomSNI     string
+	v6Support      uint
+	transport      pb.TransportType
+
+	// THIS IS REQUIRED TO INTERFACE WITH PSIPHON ANDROID
+	//		we use their dialer to prevent connection loopback into our own proxy
+	//		connection when tunneling the whole device.
+	TcpDialer func(context.Context, string, string) (net.Conn, error)
+
+	stats *pb.SessionStats
+	keys  *sharedKeys
+	m     sync.Mutex
+}
+
+func (reg *ConjureReg) createRequest(tlsConn *tls.UConn, decoy *pb.TLSDecoySpec) ([]byte, error) {
+	//[reference] generate and encrypt variable size payload
+	vsp, err := reg.generateVSP()
+	if err != nil {
+		return nil, err
+	}
+	if len(vsp) > int(^uint16(0)) {
+		return nil, fmt.Errorf("Variable-Size Payload exceeds %v", ^uint16(0))
+	}
+	encryptedVsp, err := aesGcmEncrypt(vsp, reg.keys.VspKey, reg.keys.VspIv)
+	if err != nil {
+		return nil, err
+	}
+
+	//[reference] generate and encrypt fixed size payload
+	fsp := reg.generateFSP(uint16(len(encryptedVsp)))
+	encryptedFsp, err := aesGcmEncrypt(fsp, reg.keys.FspKey, reg.keys.FspIv)
+	if err != nil {
+		return nil, err
+	}
+
+	var tag []byte // tag will be base-64 style encoded
+	tag = append(encryptedVsp, reg.keys.Representative...)
+	tag = append(tag, encryptedFsp...)
+
+	httpRequest := generateHTTPRequestBeginning(decoy.GetHostname())
+	keystreamOffset := len(httpRequest)
+	keystreamSize := (len(tag)/3+1)*4 + keystreamOffset // we can't use first 2 bits of every byte
+	wholeKeystream, err := tlsConn.GetOutKeystream(keystreamSize)
+	if err != nil {
+		return nil, err
+	}
+	keystreamAtTag := wholeKeystream[keystreamOffset:]
+	httpRequest = append(httpRequest, reverseEncrypt(tag, keystreamAtTag)...)
+	httpRequest = append(httpRequest, []byte("\r\n\r\n")...)
+	return httpRequest, nil
+}
+
+// Being called in parallel -> no changes to ConjureReg allowed in this function
+func (reg *ConjureReg) send(ctx context.Context, decoy *pb.TLSDecoySpec, dialError chan error, callback func(*ConjureReg)) {
+
+	deadline, deadlineAlreadySet := ctx.Deadline()
+	if !deadlineAlreadySet {
+		deadline = time.Now().Add(getRandomDuration(deadlineTCPtoDecoyMin, deadlineTCPtoDecoyMax))
+	}
+	childCtx, childCancelFunc := context.WithDeadline(ctx, deadline)
+	defer childCancelFunc()
+
+	//[reference] TCP to decoy
+	tcpToDecoyStartTs := time.Now()
+
+	//[Note] decoy.GetIpAddrStr() will get only v4 addr if a decoy has both
+	dialConn, err := reg.TcpDialer(childCtx, "tcp", decoy.GetIpAddrStr())
+
+	reg.setTCPToDecoy(durationToU32ptrMs(time.Since(tcpToDecoyStartTs)))
+	if err != nil {
+		if opErr, ok := err.(*net.OpError); ok && opErr.Err.Error() == "connect: network is unreachable" {
+			dialError <- RegError{msg: err.Error(), code: Unreachable}
+			return
+		}
+		dialError <- err
+		return
+	}
+
+	//[reference] connection stats tracking
+	rtt := rttInt(uint32(time.Since(tcpToDecoyStartTs).Milliseconds()))
+	delay := getRandomDuration(1061*rtt*2, 1953*rtt*3) //[TODO]{priority:@sfrolov} why these values??
+	TLSDeadline := time.Now().Add(delay)
+
+	tlsToDecoyStartTs := time.Now()
+	tlsConn, err := reg.createTLSConn(dialConn, decoy.GetIpAddrStr(), decoy.GetHostname(), TLSDeadline)
+	if err != nil {
+		dialConn.Close()
+		msg := fmt.Sprintf("%v - %v createConn: %v", decoy.GetHostname(), decoy.GetIpAddrStr(), err.Error())
+		dialError <- RegError{msg: msg, code: TLSError}
+		return
+	}
+	reg.setTLSToDecoy(durationToU32ptrMs(time.Since(tlsToDecoyStartTs)))
+
+	//[reference] Create the HTTP request for the registration
+	httpRequest, err := reg.createRequest(tlsConn, decoy)
+	if err != nil {
+		msg := fmt.Sprintf("%v - %v createReq: %v", decoy.GetHostname(), decoy.GetIpAddrStr(), err.Error())
+		dialError <- RegError{msg: msg, code: TLSError}
+		return
+	}
+
+	//[reference] Write reg into conn
+	_, err = tlsConn.Write(httpRequest)
+	if err != nil {
+		// // This will not get printed because it is executed in a goroutine.
+		// Logger().Errorf("%v - %v Could not send Conjure registration request, error: %v", decoy.GetHostname(), decoy.GetIpAddrStr(), err.Error())
+		tlsConn.Close()
+		msg := fmt.Sprintf("%v - %v Write: %v", decoy.GetHostname(), decoy.GetIpAddrStr(), err.Error())
+		dialError <- RegError{msg: msg, code: TLSError}
+		return
+	}
+
+	dialError <- nil
+	readAndClose(dialConn, time.Second*15)
+	callback(reg)
+}
+
+func (reg *ConjureReg) createTLSConn(dialConn net.Conn, address string, hostname string, deadline time.Time) (*tls.UConn, error) {
+	var err error
+	//[reference] TLS to Decoy
+	config := tls.Config{ServerName: hostname}
+	if config.ServerName == "" {
+		// if SNI is unset -- try IP
+		config.ServerName, _, err = net.SplitHostPort(address)
+		if err != nil {
+			return nil, err
+		}
+		Logger().Debugf("%v SNI was nil. Setting it to %v ", reg.sessionIDStr, config.ServerName)
+	}
+	//[TODO]{priority:medium} parroting Chrome 62 ClientHello -- parrot newer.
+	tlsConn := tls.UClient(dialConn, &config, tls.HelloChrome_62)
+
+	err = tlsConn.BuildHandshakeState()
+	if err != nil {
+		return nil, err
+	}
+	err = tlsConn.MarshalClientHello()
+	if err != nil {
+		return nil, err
+	}
+
+	tlsConn.SetDeadline(deadline)
+	err = tlsConn.Handshake()
+	if err != nil {
+		return nil, err
+	}
+
+	return tlsConn, nil
+}
+
+func (reg *ConjureReg) setTCPToDecoy(tcprtt *uint32) {
+	reg.m.Lock()
+	defer reg.m.Unlock()
+
+	if reg.stats == nil {
+		reg.stats = &pb.SessionStats{}
+	}
+	reg.stats.TcpToDecoy = tcprtt
+}
+
+func (reg *ConjureReg) setTLSToDecoy(tlsrtt *uint32) {
+	reg.m.Lock()
+	defer reg.m.Unlock()
+
+	if reg.stats == nil {
+		reg.stats = &pb.SessionStats{}
+	}
+	reg.stats.TlsToDecoy = tlsrtt
+}
+
+func (reg *ConjureReg) getPbTransport() pb.TransportType {
+	return pb.TransportType(reg.transport)
+}
+
+func (reg *ConjureReg) generateFlags() *pb.RegistrationFlags {
+	flags := &pb.RegistrationFlags{}
+	mask := default_flags
+	if reg.useProxyHeader {
+		mask |= tdFlagProxyHeader
+	}
+
+	uploadOnly := mask&tdFlagUploadOnly == tdFlagUploadOnly
+	proxy := mask&tdFlagProxyHeader == tdFlagProxyHeader
+	til := mask&tdFlagUseTIL == tdFlagUseTIL
+
+	flags.UploadOnly = &uploadOnly
+	flags.ProxyHeader = &proxy
+	flags.Use_TIL = &til
+
+	return flags
+}
+
+func (reg *ConjureReg) generateClientToStation() *pb.ClientToStation {
+	var covert *string
+	if len(reg.covertAddress) > 0 {
+		//[TODO]{priority:medium} this isn't the correct place to deal with signaling to the station
+		//transition = pb.C2S_Transition_C2S_SESSION_COVERT_INIT
+		covert = &reg.covertAddress
+	}
+
+	//[reference] Generate ClientToStation protobuf
+	// transition := pb.C2S_Transition_C2S_SESSION_INIT
+	currentGen := Assets().GetGeneration()
+	transport := reg.getPbTransport()
+	initProto := &pb.ClientToStation{
+		CovertAddress:       covert,
+		DecoyListGeneration: &currentGen,
+		V6Support:           reg.getV6Support(),
+		V4Support:           reg.getV4Support(),
+		Transport:           &transport,
+		Flags:               reg.generateFlags(),
+		// StateTransition:     &transition,
+
+		//[TODO]{priority:medium} specify width in C2S because different width might
+		// 		be useful in different regions (constant for now.)
+	}
+
+	if len(reg.phantomSNI) > 0 {
+		initProto.MaskedDecoyServerName = &reg.phantomSNI
+	}
+
+	for (proto.Size(initProto)+AES_GCM_TAG_SIZE)%3 != 0 {
+		initProto.Padding = append(initProto.Padding, byte(0))
+	}
+
+	return initProto
+}
+
+func (reg *ConjureReg) generateVSP() ([]byte, error) {
+	//[reference] Marshal ClientToStation protobuf
+	return proto.Marshal(reg.generateClientToStation())
+}
+
+func (reg *ConjureReg) generateFSP(espSize uint16) []byte {
+	buf := make([]byte, 6)
+	binary.BigEndian.PutUint16(buf[0:2], espSize)
+
+	return buf
+}
+
+func (reg *ConjureReg) getV4Support() *bool {
+	// for now return true and register both
+	support := true
+	if reg.v6Support == v6 {
+		support = false
+	}
+	return &support
+}
+
+func (reg *ConjureReg) getV6Support() *bool {
+	support := true
+	if reg.v6Support == v4 {
+		support = false
+	}
+	return &support
+}
+
+func (reg *ConjureReg) v6SupportStr() string {
+	switch reg.v6Support {
+	case both:
+		return "Both"
+	case v4:
+		return "V4"
+	case v6:
+		return "V6"
+	default:
+		return "unknown"
+	}
+}
+
+func (reg *ConjureReg) digestStats() string {
+	//[TODO]{priority:eventually} add decoy details to digest
+	if reg == nil || reg.stats == nil {
+		return fmt.Sprint("{result:\"no stats tracked\"}")
+	}
+
+	reg.m.Lock()
+	defer reg.m.Unlock()
+	return fmt.Sprintf("{result:\"success\", tcp_to_decoy:%v, tls_to_decoy:%v, total_time_to_connect:%v}",
+		reg.stats.GetTcpToDecoy(),
+		reg.stats.GetTlsToDecoy(),
+		reg.stats.GetTotalTimeToConnect())
+}
+
+func (reg *ConjureReg) getRandomDuration(base, min, max int) time.Duration {
+	addon := getRandInt(min, max) / 1000 // why this min and max???
+	rtt := rttInt(reg.getTcpToDecoy())
+	return time.Millisecond * time.Duration(base+rtt*addon)
+}
+
+func (reg *ConjureReg) getTcpToDecoy() uint32 {
+	reg.m.Lock()
+	defer reg.m.Unlock()
+	if reg != nil {
+		if reg.stats != nil {
+			return reg.stats.GetTcpToDecoy()
+		}
+	}
+	return 0
+}
+
+func (cjSession *ConjureSession) setV6Support(support uint) {
+	switch support {
+	case v4:
+		cjSession.V6Support.support = false
+		cjSession.V6Support.include = v4
+	case v6:
+		cjSession.V6Support.support = true
+		cjSession.V6Support.include = v6
+	case both:
+		cjSession.V6Support.support = true
+		cjSession.V6Support.include = both
+	default:
+		cjSession.V6Support.support = true
+		cjSession.V6Support.include = v6
+	}
+}
+
+// When a registration send goroutine finishes it will call this and log
+//	 	session stats and/or errors.
+func (cjSession *ConjureSession) registrationCallback(reg *ConjureReg) {
+	//[TODO]{priority:NOW}
+	Logger().Infof("%v %v", cjSession.IDString(), reg.digestStats())
+}
+
+func (cjSession *ConjureSession) getRandomDuration(base, min, max int) time.Duration {
+	addon := getRandInt(min, max) / 1000 // why this min and max???
+	rtt := rttInt(cjSession.getTcpToDecoy())
+	return time.Millisecond * time.Duration(base+rtt*addon)
+}
+
+func (cjSession *ConjureSession) getTcpToDecoy() uint32 {
+	if cjSession != nil {
+		if cjSession.stats != nil {
+			return cjSession.stats.GetTcpToDecoy()
+		}
+	}
+	return 0
+}
+
+func (cjSession *ConjureSession) randomSleep() {
+	toSleep := cjSession.getRandomDuration(300, 212, 3449)
+	Logger().Debugf("%v Sleeping %v ms", cjSession.IDString(), toSleep)
+	time.Sleep(toSleep)
+}
+
+func rttInt(millis uint32) int {
+	defaultValue := 300
+	if millis == 0 {
+		return defaultValue
+	}
+	return int(millis)
+}
+
+// SelectDecoys - Get an array of `width` decoys to be used for registration
+func SelectDecoys(sharedSecret []byte, version uint, width uint) []*pb.TLSDecoySpec {
+
+	//[reference] prune to v6 only decoys if useV6 is true
+	var allDecoys []*pb.TLSDecoySpec
+	switch version {
+	case v6:
+		allDecoys = Assets().GetV6Decoys()
+	case v4:
+		allDecoys = Assets().GetV4Decoys()
+	case both:
+		allDecoys = Assets().GetAllDecoys()
+	default:
+		allDecoys = Assets().GetAllDecoys()
+	}
+
+	decoys := make([]*pb.TLSDecoySpec, width)
+	numDecoys := big.NewInt(int64(len(allDecoys)))
+	hmacInt := new(big.Int)
+	idx := new(big.Int)
+
+	//[reference] select decoys
+	for i := uint(0); i < width; i++ {
+		macString := fmt.Sprintf("registrationdecoy%d", i)
+		hmac := conjureHMAC(sharedSecret, macString)
+		hmacInt = hmacInt.SetBytes(hmac[:8])
+		hmacInt.SetBytes(hmac)
+		hmacInt.Abs(hmacInt)
+		idx.Mod(hmacInt, numDecoys)
+		decoys[i] = allDecoys[int(idx.Int64())]
+	}
+	return decoys
+}
+
+// var phantomSubnets = []conjurePhantomSubnet{
+// 	{subnet: "192.122.190.0/24", weight: 90.0},
+// 	{subnet: "2001:48a8:687f:1::/64", weight: 90.0},
+// 	{subnet: "141.219.0.0/16", weight: 10.0},
+// 	{subnet: "35.8.0.0/16", weight: 10.0},
+// }
+
+var phantomSubnets = ps.SubnetConfig{
+	WeightedSubnets: []ps.ConjurePhantomSubnet{
+		{Weight: 9, Subnets: []string{"192.122.190.0/24", "2001:48a8:687f:1::/64"}},
+		{Weight: 1, Subnets: []string{"141.219.0.0/16", "35.8.0.0/16"}},
+	},
+}
+
+// SelectPhantom - select one phantom IP address based on shared secret
+func SelectPhantom(seed []byte, support uint) (*net.IP, *net.IP, error) {
+	switch support {
+	case v4:
+		phantomIPv4, err := ps.SelectPhantom(seed, phantomSubnets, ps.V4Only, true)
+		if err != nil {
+			return nil, nil, err
+		}
+		return phantomIPv4, nil, nil
+	case v6:
+		phantomIPv6, err := ps.SelectPhantom(seed, phantomSubnets, ps.V6Only, true)
+		if err != nil {
+			return nil, nil, err
+		}
+		return nil, phantomIPv6, nil
+	case both:
+		phantomIPv4, err := ps.SelectPhantom(seed, phantomSubnets, ps.V4Only, true)
+		if err != nil {
+			return nil, nil, err
+		}
+		phantomIPv6, err := ps.SelectPhantom(seed, phantomSubnets, ps.V6Only, true)
+		if err != nil {
+			return nil, nil, err
+		}
+		return phantomIPv4, phantomIPv6, nil
+	default:
+		return nil, nil, fmt.Errorf("unknown v4/v6 support")
+	}
+}
+
+func getStationKey() [32]byte {
+	return *Assets().GetConjurePubkey()
+}
+
+type Obfs4Keys struct {
+	PrivateKey *ntor.PrivateKey
+	PublicKey  *ntor.PublicKey
+	NodeID     *ntor.NodeID
+}
+
+func generateObfs4Keys(rand io.Reader) (Obfs4Keys, error) {
+	keys := Obfs4Keys{
+		PrivateKey: new(ntor.PrivateKey),
+		PublicKey:  new(ntor.PublicKey),
+		NodeID:     new(ntor.NodeID),
+	}
+
+	_, err := rand.Read(keys.PrivateKey[:])
+	if err != nil {
+		return keys, err
+	}
+
+	keys.PrivateKey[0] &= 248
+	keys.PrivateKey[31] &= 127
+	keys.PrivateKey[31] |= 64
+
+	pub, err := curve25519.X25519(keys.PrivateKey[:], curve25519.Basepoint)
+	if err != nil {
+		return keys, err
+	}
+	copy(keys.PublicKey[:], pub)
+
+	_, err = rand.Read(keys.NodeID[:])
+	return keys, err
+}
+
+type sharedKeys struct {
+	SharedSecret, Representative                               []byte
+	FspKey, FspIv, VspKey, VspIv, NewMasterSecret, ConjureSeed []byte
+	Obfs4Keys                                                  Obfs4Keys
+}
+
+func generateSharedKeys(pubkey [32]byte) (*sharedKeys, error) {
+	sharedSecret, representative, err := generateEligatorTransformedKey(pubkey[:])
+	if err != nil {
+		return nil, err
+	}
+
+	tdHkdf := hkdf.New(sha256.New, sharedSecret, []byte("conjureconjureconjureconjure"), nil)
+	keys := &sharedKeys{
+		SharedSecret:    sharedSecret,
+		Representative:  representative,
+		FspKey:          make([]byte, 16),
+		FspIv:           make([]byte, 12),
+		VspKey:          make([]byte, 16),
+		VspIv:           make([]byte, 12),
+		NewMasterSecret: make([]byte, 48),
+		ConjureSeed:     make([]byte, 16),
+	}
+
+	if _, err := tdHkdf.Read(keys.FspKey); err != nil {
+		return keys, err
+	}
+	if _, err := tdHkdf.Read(keys.FspIv); err != nil {
+		return keys, err
+	}
+	if _, err := tdHkdf.Read(keys.VspKey); err != nil {
+		return keys, err
+	}
+	if _, err := tdHkdf.Read(keys.VspIv); err != nil {
+		return keys, err
+	}
+	if _, err := tdHkdf.Read(keys.NewMasterSecret); err != nil {
+		return keys, err
+	}
+	if _, err := tdHkdf.Read(keys.ConjureSeed); err != nil {
+		return keys, err
+	}
+	keys.Obfs4Keys, err = generateObfs4Keys(tdHkdf)
+	return keys, err
+}
+
+//
+func conjureHMAC(key []byte, str string) []byte {
+	hash := hmac.New(sha256.New, key)
+	hash.Write([]byte(str))
+	return hash.Sum(nil)
+}
+
+// RegError - Registration Error passed during registration to indicate failure mode
+type RegError struct {
+	code uint
+	msg  string
+}
+
+func (err RegError) Error() string {
+	return fmt.Sprintf("Registration Error [%v]: %v", err.CodeStr(), err.msg)
+}
+
+// CodeStr - Get desctriptor associated with error code
+func (err RegError) CodeStr() string {
+	switch err.code {
+	case Unreachable:
+		return "UNREACHABLE"
+	case DialFailure:
+		return "DIAL_FAILURE"
+	case NotImplemented:
+		return "NOT_IMPLEMENTED"
+	case TLSError:
+		return "TLS_ERROR"
+	default:
+		return "UNKNOWN"
+	}
+}
+
+const (
+	// Unreachable -Dial Error Unreachable -- likely network unavailable (i.e. ipv6 error)
+	Unreachable = iota
+
+	// DialFailure - Dial Error Other than unreachable
+	DialFailure
+
+	// NotImplemented - Related Function Not Implemented
+	NotImplemented
+
+	// TLS Error (Expired, Wrong-Host, Untrusted-Root, ...)
+	TLSError
+
+	// Unknown - Error occurred without obvious explanation
+	Unknown
+)

vendor/github.com/refraction-networking/gotapdance/tapdance/conn_dual.go

@@ -1,118 +0,0 @@
-package tapdance
-
-import (
-	"context"
-	"errors"
-	"net"
-	"strconv"
-)
-
-// DualConn is composed of 2 separate TapdanceFlowConn.
-// Allows to achieve substantially higher upload speed
-// and slightly higher download speed.
-type DualConn struct {
-	net.Conn
-	writerConn *TapdanceFlowConn
-	readerConn *TapdanceFlowConn
-
-	sessionId uint64 // constant for logging
-}
-
-// returns TapDance connection that utilizes 2 flows underneath: reader and writer
-func dialSplitFlow(ctx context.Context, customDialer func(context.Context, string, string) (net.Conn, error),
-	covert string) (net.Conn, error) {
-	dualConn := DualConn{sessionId: sessionsTotal.GetAndInc()}
-	stationPubkey := Assets().GetPubkey()
-
-	rawRConn := makeTdRaw(tagHttpGetIncomplete, stationPubkey[:])
-	if customDialer != nil {
-		rawRConn.TcpDialer = customDialer
-	}
-	rawRConn.sessionId = dualConn.sessionId
-	rawRConn.strIdSuffix = "R"
-
-	var err error
-	dualConn.readerConn, err = makeTdFlow(flowReadOnly, rawRConn, covert)
-	if err != nil {
-		return nil, err
-	}
-	err = dualConn.readerConn.DialContext(ctx)
-	if err != nil {
-		return nil, err
-	}
-
-	// net.Conn functions that are not explicitly declared will be performed by readerConn
-	dualConn.Conn = dualConn.readerConn
-
-	// TODO: traffic fingerprinting issue
-	// TODO: fundamental issue of observable dependency between 2 flows
-	err = dualConn.readerConn.yieldUpload()
-	if err != nil {
-		dualConn.readerConn.closeWithErrorOnce(err)
-		return nil, err
-	}
-
-	rawWConn := makeTdRaw(tagHttpPostIncomplete,
-		stationPubkey[:])
-	if customDialer != nil {
-		rawRConn.TcpDialer = customDialer
-	}
-	rawWConn.sessionId = dualConn.sessionId
-	rawWConn.strIdSuffix = "W"
-	rawWConn.decoySpec = rawRConn.decoySpec
-	rawWConn.pinDecoySpec = true
-
-	dualConn.writerConn, err = makeTdFlow(flowUpload, rawWConn, covert)
-	if err != nil {
-		dualConn.readerConn.closeWithErrorOnce(err)
-		return nil, err
-	}
-	err = dualConn.writerConn.DialContext(ctx)
-	if err != nil {
-		dualConn.readerConn.closeWithErrorOnce(err)
-		return nil, err
-	}
-
-	err = dualConn.writerConn.acquireUpload()
-	if err != nil {
-		dualConn.readerConn.closeWithErrorOnce(err)
-		dualConn.writerConn.closeWithErrorOnce(err)
-		return nil, err
-	}
-	/* // TODO: yield confirmation
-	writerConn.yieldConfirmed = make(chan struct{})
-	go func() {
-		time.Sleep(time.Duration(getRandInt(1234, 5432)) * time.Millisecond)
-		Logger().Infoln(dualConn.idStr() + " faking yield confirmation!")
-		writerConn.yieldConfirmed <- struct{}{}
-	}()
-	err = writerConn.WaitForYieldConfirmation()
-	if err != nil {
-		dualConn.readerConn.Close()
-		writerConn.Close()
-		return nil, err
-	}
-	*/
-	go func() {
-		select {
-		case <-dualConn.readerConn.closed:
-			dualConn.writerConn.closeWithErrorOnce(errors.New("in paired readerConn: " +
-				dualConn.readerConn.closeErr.Error()))
-		case <-dualConn.writerConn.closed:
-			dualConn.readerConn.closeWithErrorOnce(errors.New("in paired writerConn: " +
-				dualConn.writerConn.closeErr.Error()))
-		}
-	}()
-	return &dualConn, nil
-}
-
-// Write writes data to the connection.
-// Write can be made to time out and return an Error with Timeout() == true
-// after a fixed time limit; see SetDeadline and SetWriteDeadline.
-func (tdConn *DualConn) Write(b []byte) (int, error) {
-	return tdConn.writerConn.Write(b)
-}
-
-func (tdConn *DualConn) idStr() string {
-	return "[Session " + strconv.FormatUint(tdConn.sessionId, 10) + "]"
-}

vendor/github.com/refraction-networking/gotapdance/tapdance/conn_flow.go

@@ -18,8 +18,8 @@ import (
 	"time"
 
 	"github.com/golang/protobuf/proto"
-	"github.com/sergeyfrolov/bsbuffer"
 	pb "github.com/refraction-networking/gotapdance/protobuf"
+	"github.com/sergeyfrolov/bsbuffer"
 )
 
 // TapdanceFlowConn represents single TapDance flow.
@@ -49,14 +49,6 @@ type TapdanceFlowConn struct {
 	flowType flowType
 }
 
-/*______________________TapdanceFlowConn Mode Chart _____________________________
-|FlowType     |Default Tag|Diff from old-school bidirectional  | Engines spawned|
-|-------------|-----------|------------------------------------|----------------|
-|Bidirectional| HTTP GET  |                                    | Writer, Reader |
-|Upload       | HTTP POST |acquires upload                     | Writer, Reader |
-|ReadOnly     | HTTP GET  |yields upload, writer sync ignored  | Reader         |
-\_____________|___________|____________________________________|_______________*/
-
 // NewTapDanceConn returns TapDance connection, that is ready to be Dial'd
 func NewTapDanceConn() (net.Conn, error) {
 	return makeTdFlow(flowBidirectional, nil, "")
@@ -92,6 +84,7 @@ func (flowConn *TapdanceFlowConn) DialContext(ctx context.Context) error {
 			return err
 		}
 	}
+
 	// don't lose initial msg from station
 	// strip off state transition and push protobuf up for processing
 	flowConn.tdRaw.initialMsg.StateTransition = nil
@@ -111,13 +104,13 @@ func (flowConn *TapdanceFlowConn) DialContext(ctx context.Context) error {
 		flowConn.writeResultChan = make(chan ioOpResult)
 		go flowConn.spawnReaderEngine()
 		go flowConn.spawnWriterEngine()
-		return nil
 	case flowReadOnly:
 		go flowConn.spawnReaderEngine()
-		return nil
+	case flowRendezvous:
 	default:
 		panic("Not implemented")
 	}
+	return nil
 }
 
 type ioOpResult struct {
@@ -301,7 +294,7 @@ func (flowConn *TapdanceFlowConn) readRawData(msgLen int) ([]byte, error) {
 	return flowConn.recvbuf[:readBytesTotal], err
 }
 
-func (flowConn *TapdanceFlowConn) readProtobuf(msgLen int) (msg pb.StationToClient, err error) {
+func (flowConn *TapdanceFlowConn) readProtobuf(msgLen int) (msg *pb.StationToClient, err error) {
 	rbuf := make([]byte, msgLen)
 	var readBytes int
 	var readBytesTotal int // both header and body
@@ -316,7 +309,8 @@ func (flowConn *TapdanceFlowConn) readProtobuf(msgLen int) (msg pb.StationToClie
 			}
 		}
 	}
-	err = proto.Unmarshal(rbuf[:], &msg)
+	msg = &pb.StationToClient{}
+	err = proto.Unmarshal(rbuf[:], msg)
 	return
 }
 
@@ -544,8 +538,10 @@ func (flowConn *TapdanceFlowConn) idStr() string {
 	return flowConn.tdRaw.idStr()
 }
 
-func (flowConn *TapdanceFlowConn) processProto(msg pb.StationToClient) error {
-	handleConfigInfo := func(conf *pb.ClientConf) {
+func (flowConn *TapdanceFlowConn) processProto(msg *pb.StationToClient) error {
+	// //[TODO]{priority:after-placement-updates} uncomment to re-enable automatic clientconf downloads
+	//handleConfigInfo := func(conf *pb.ClientConf) {
+	_ = func(conf *pb.ClientConf) {
 		currGen := Assets().GetGeneration()
 		if conf.GetGeneration() < currGen {
 			Logger().Infoln(flowConn.idStr()+" not appliying new config due"+
@@ -567,7 +563,8 @@ func (flowConn *TapdanceFlowConn) processProto(msg pb.StationToClient) error {
 	Logger().Debugln(flowConn.idStr() + " processing incoming protobuf: " + msg.String())
 	// handle ConfigInfo
 	if confInfo := msg.ConfigInfo; confInfo != nil {
-		handleConfigInfo(confInfo)
+		// //[TODO]{priority:after-placement-updates} uncomment to re-enable automatic clientconf downloads
+		// handleConfigInfo(confInfo)
 		// TODO: if we ever get a ``safe'' decoy rotation - code below has to be rewritten
 		if !Assets().IsDecoyInList(flowConn.tdRaw.decoySpec) {
 			Logger().Warningln(flowConn.idStr() + " current decoy is no " +

vendor/github.com/refraction-networking/gotapdance/tapdance/conn_raw.go

@@ -18,7 +18,7 @@ import (
 
 	"github.com/golang/protobuf/proto"
 	pb "github.com/refraction-networking/gotapdance/protobuf"
-	"github.com/refraction-networking/utls"
+	tls "github.com/refraction-networking/utls"
 )
 
 // Simply establishes TLS and TapDance connection.
@@ -32,11 +32,11 @@ type tdRawConn struct {
 
 	TcpDialer func(context.Context, string, string) (net.Conn, error)
 
-	decoySpec            pb.TLSDecoySpec
-	pinDecoySpec         bool // don't ever change decoy (still changeable from outside)
-	initialMsg           pb.StationToClient
-	defaultStationPubkey []byte // this pubkey is used if the per-decoy key (tdRaw.decoySpec.Pubkey.Key) is not set
-	tagType              tdTagType
+	decoySpec     *pb.TLSDecoySpec
+	pinDecoySpec  bool // don't ever change decoy (still changeable from outside)
+	initialMsg    *pb.StationToClient
+	stationPubkey []byte
+	tagType       tdTagType
 
 	remoteConnId []byte // 32 byte ID of the connection to station, used for reconnection
 
@@ -46,19 +46,28 @@ type tdRawConn struct {
 	closed    chan struct{}
 	closeOnce sync.Once
 
+	useProxyHeader bool // request the station to prepend the connection with PROXY header
+
+	// dark decoy variables
+	darkDecoyUsed      bool
+	darkDecoySNI       string
+	darkDecoyV6Support bool // *bool so that it is a nullable type. that can be overridden by the dialer
+
 	// stats to report
 	sessionStats pb.SessionStats
 	failedDecoys []string
 
 	// purely for logging and stats reporting purposes:
-	flowId      CounterUint64 // id of the flow within the session (=how many times reconnected)
-	sessionId   uint64        // id of the local session
-	strIdSuffix string        // suffix for every log string (e.g. to mark upload-only flows)
+	flowId      uint64 // id of the flow within the session (=how many times reconnected)
+	sessionId   uint64 // id of the local session
+	strIdSuffix string // suffix for every log string (e.g. to mark upload-only flows)
+
+	tdKeys tapdanceSharedKeys
 }
 
 func makeTdRaw(handshakeType tdTagType, stationPubkey []byte) *tdRawConn {
 	tdRaw := &tdRawConn{tagType: handshakeType,
-		defaultStationPubkey: stationPubkey,
+		stationPubkey: stationPubkey,
 	}
 	tdRaw.closed = make(chan struct{})
 	return tdRaw
@@ -69,7 +78,7 @@ func (tdRaw *tdRawConn) DialContext(ctx context.Context) error {
 }
 
 func (tdRaw *tdRawConn) RedialContext(ctx context.Context) error {
-	tdRaw.flowId.Inc()
+	tdRaw.flowId++
 	return tdRaw.dial(ctx, true)
 }
 
@@ -153,6 +162,13 @@ func (tdRaw *tdRawConn) tryDialOnce(ctx context.Context, expectedTransition pb.S
 			") failed with " + err.Error())
 		return err
 	}
+
+	err = WriteTlsLog(tdRaw.tlsConn.HandshakeState.Hello.Random,
+		tdRaw.tlsConn.HandshakeState.MasterSecret)
+	if err != nil {
+		Logger().Warningf("Failed to write TLS secret log: %s", err)
+	}
+
 	tdRaw.sessionStats.TlsToDecoy = durationToU32ptrMs(tlsToDecoyTotalTs)
 	Logger().Infof("%s Connected to decoy %s(%s) in %s", tdRaw.idStr(), tdRaw.decoySpec.GetHostname(),
 		tdRaw.decoySpec.GetIpAddrStr(), tlsToDecoyTotalTs.String())
@@ -163,27 +179,7 @@ func (tdRaw *tdRawConn) tryDialOnce(ctx context.Context, expectedTransition pb.S
 		return errors.New("Closed")
 	}
 
-	// Check if cipher is supported
-	cipherIsSupported := func(id uint16) bool {
-		for _, c := range tapDanceSupportedCiphers {
-			if c == id {
-				return true
-			}
-		}
-		return false
-	}
-	if !cipherIsSupported(tdRaw.tlsConn.ConnectionState().CipherSuite) {
-		Logger().Errorf("%s decoy %s offered unsupported cipher %d\n Client ciphers: %#v\n",
-			tdRaw.idStr(), tdRaw.decoySpec.GetHostname(),
-			tdRaw.tlsConn.ConnectionState().CipherSuite,
-			tdRaw.tlsConn.HandshakeState.Hello.CipherSuites)
-		err = errors.New("Unsupported cipher.")
-		tdRaw.tlsConn.Close()
-		return err
-	}
-
-	var tdRequest string
-	tdRequest, err = tdRaw.prepareTDRequest(tdRaw.tagType)
+	tdRequest, err := tdRaw.prepareTDRequest(tdRaw.tagType)
 	if err != nil {
 		Logger().Errorf(tdRaw.idStr() +
 			" Preparation of initial TD request failed with " + err.Error())
@@ -195,6 +191,7 @@ func (tdRaw *tdRawConn) tryDialOnce(ctx context.Context, expectedTransition pb.S
 	Logger().Infoln(tdRaw.idStr() + " Attempting to connect to TapDance Station" +
 		" with connection ID: " + hex.EncodeToString(tdRaw.remoteConnId[:]) + ", method: " +
 		tdRaw.tagType.Str())
+
 	rttToStationStartTs := time.Now()
 	_, err = tdRaw.tlsConn.Write([]byte(tdRequest))
 	if err != nil {
@@ -246,7 +243,7 @@ func (tdRaw *tdRawConn) tryDialOnce(ctx context.Context, expectedTransition pb.S
 			return err
 		}
 		Logger().Infoln(tdRaw.idStr() + " Successfully connected to TapDance Station [" + tdRaw.initialMsg.GetStationId() + "]")
-	case tagHttpPostIncomplete:
+	case tagHttpPostIncomplete, tagHttpGetComplete:
 		// don't wait for response
 	default:
 		panic("Unsupported td handshake type:" + tdRaw.tagType.Str())
@@ -337,6 +334,44 @@ func (tdRaw *tdRawConn) closeWrite() error {
 	return tdRaw.tcpConn.CloseWrite()
 }
 
+// func (tdRaw *tdRawConn) generateFSP(espSize uint16) []byte {
+// 	buf := make([]byte, 6)
+// 	binary.BigEndian.PutUint16(buf[0:2], espSize)
+// 	flags := default_flags
+// 	if tdRaw.tagType == tagHttpPostIncomplete {
+// 		flags |= tdFlagUploadOnly
+// 	}
+// 	if tdRaw.useProxyHeader {
+// 		flags |= tdFlagProxyHeader
+// 	}
+// 	buf[2] = flags
+
+// 	return buf
+// }
+
+func (tdRaw *tdRawConn) generateVSP() ([]byte, error) {
+	// Generate and marshal protobuf
+	transition := pb.C2S_Transition_C2S_SESSION_INIT
+	var covert *string
+	if len(tdRaw.covert) > 0 {
+		transition = pb.C2S_Transition_C2S_SESSION_COVERT_INIT
+		covert = &tdRaw.covert
+	}
+	currGen := Assets().GetGeneration()
+	initProto := &pb.ClientToStation{
+		CovertAddress:       covert,
+		StateTransition:     &transition,
+		DecoyListGeneration: &currGen,
+	}
+
+	Logger().Debugln(tdRaw.idStr()+" Initial protobuf", initProto)
+	const AES_GCM_TAG_SIZE = 16
+	for (proto.Size(initProto)+AES_GCM_TAG_SIZE)%3 != 0 {
+		initProto.Padding = append(initProto.Padding, byte(0))
+	}
+	return proto.Marshal(initProto)
+}
+
 func (tdRaw *tdRawConn) prepareTDRequest(handshakeType tdTagType) (string, error) {
 	// Generate tag for the initial TapDance request
 	buf := new(bytes.Buffer) // What we have to encrypt with the shared secret using AES
@@ -348,6 +383,9 @@ func (tdRaw *tdRawConn) prepareTDRequest(handshakeType tdTagType) (string, error
 	if tdRaw.tagType == tagHttpPostIncomplete {
 		flags |= tdFlagUploadOnly
 	}
+	if tdRaw.useProxyHeader {
+		flags |= tdFlagProxyHeader
+	}
 	if err := binary.Write(buf, binary.BigEndian, flags); err != nil {
 		return "", err
 	}
@@ -389,7 +427,7 @@ func (tdRaw *tdRawConn) prepareTDRequest(handshakeType tdTagType) (string, error
 	Logger().Debugln(tdRaw.idStr()+" Initial protobuf", initProto)
 
 	// Choose the station pubkey
-	pubkey := tdRaw.defaultStationPubkey
+	pubkey := tdRaw.stationPubkey
 	if perDecoyKey := tdRaw.decoySpec.GetPubkey().GetKey(); perDecoyKey != nil {
 		pubkey = perDecoyKey // per-decoy key takes preference over default global pubkey
 	}
@@ -402,64 +440,15 @@ func (tdRaw *tdRawConn) prepareTDRequest(handshakeType tdTagType) (string, error
 	return tdRaw.genHTTP1Tag(tag, encryptedProtoMsg)
 }
 
-// mutates tdRaw: sets tdRaw.UploadLimit
-func (tdRaw *tdRawConn) genHTTP1Tag(tag, encryptedProtoMsg []byte) (string, error) {
-	sharedHeaders := `Host: ` + tdRaw.decoySpec.GetHostname() +
-		"\nUser-Agent: TapDance/1.2 (+https://refraction.network/info)"
-	if len(encryptedProtoMsg) > 0 {
-		sharedHeaders += "\nX-Proto: " + base64.StdEncoding.EncodeToString(encryptedProtoMsg)
-	}
-	var httpTag string
-	switch tdRaw.tagType {
-	// for complete copy http generator of golang
-	case tagHttpGetComplete:
-		fallthrough
-	case tagHttpGetIncomplete:
-		tdRaw.UploadLimit = int(tdRaw.decoySpec.GetTcpwin()) - getRandInt(1, 1045)
-		httpTag = fmt.Sprintf(`GET / HTTP/1.1
-%s
-X-Ignore: %s`, sharedHeaders, getRandPadding(7, maxInt(612-len(sharedHeaders), 7), 10))
-		httpTag = strings.Replace(httpTag, "\n", "\r\n", -1)
-	case tagHttpPostIncomplete:
-		ContentLength := getRandInt(900000, 1045000)
-		tdRaw.UploadLimit = ContentLength - 1
-		httpTag = fmt.Sprintf(`POST / HTTP/1.1
-%s
-Accept-Encoding: None
-X-Padding: %s
-Content-Type: application/zip; boundary=----WebKitFormBoundaryaym16ehT29q60rUx
-Content-Length: %s
-----WebKitFormBoundaryaym16ehT29q60rUx
-Content-Disposition: form-data; name=\"td.zip\"
-`, sharedHeaders, getRandPadding(1, maxInt(461-len(sharedHeaders), 1), 10), strconv.Itoa(ContentLength))
-		httpTag = strings.Replace(httpTag, "\n", "\r\n", -1)
-	}
-
-	keystreamOffset := len(httpTag)
-	keystreamSize := (len(tag)/3+1)*4 + keystreamOffset // we can't use first 2 bits of every byte
-	wholeKeystream, err := tdRaw.tlsConn.GetOutKeystream(keystreamSize)
-	if err != nil {
-		return httpTag, err
-	}
-	keystreamAtTag := wholeKeystream[keystreamOffset:]
-
-	httpTag += reverseEncrypt(tag, keystreamAtTag)
-	if tdRaw.tagType == tagHttpGetComplete {
-		httpTag += "\r\n\r\n"
-	}
-	Logger().Debugf("Generated HTTP TAG:\n%s\n", httpTag)
-	return httpTag, nil
-}
-
 func (tdRaw *tdRawConn) idStr() string {
 	return "[Session " + strconv.FormatUint(tdRaw.sessionId, 10) + ", " +
-		"Flow " + strconv.FormatUint(tdRaw.flowId.Get(), 10) + tdRaw.strIdSuffix + "]"
+		"Flow " + strconv.FormatUint(tdRaw.flowId, 10) + tdRaw.strIdSuffix + "]"
 }
 
 // Simply reads and returns protobuf
 // Returns error if it's not a protobuf
 // TODO: redesign it pb, data, err
-func (tdRaw *tdRawConn) readProto() (msg pb.StationToClient, err error) {
+func (tdRaw *tdRawConn) readProto() (msg *pb.StationToClient, err error) {
 	var readBuffer bytes.Buffer
 
 	var outerProtoMsgType msgType
@@ -499,7 +488,8 @@ func (tdRaw *tdRawConn) readProto() (msg pb.StationToClient, err error) {
 		return
 	}
 
-	err = proto.Unmarshal(readBuffer.Bytes(), &msg)
+	msg = &pb.StationToClient{}
+	err = proto.Unmarshal(readBuffer.Bytes(), msg)
 	if err != nil {
 		return
 	}
@@ -521,7 +511,7 @@ func (tdRaw *tdRawConn) writeTransition(transition pb.C2S_Transition) (n int, er
 		DecoyListGeneration: &currGen,
 		StateTransition:     &transition,
 		UploadSync:          new(uint64)} // TODO: remove
-	if tdRaw.flowId.Get() == 0 {
+	if tdRaw.flowId == 0 {
 		// we have stats for each reconnect, but only send stats for the initial connection
 		msg.Stats = &tdRaw.sessionStats
 	}
@@ -557,6 +547,55 @@ func (tdRaw *tdRawConn) writeTransition(transition pb.C2S_Transition) (n int, er
 	return
 }
 
+// mutates tdRaw: sets tdRaw.UploadLimit
+func (tdRaw *tdRawConn) genHTTP1Tag(tag, encryptedProtoMsg []byte) (string, error) {
+	sharedHeaders := `Host: ` + tdRaw.decoySpec.GetHostname() +
+		"\nUser-Agent: TapDance/1.2 (+https://refraction.network/info)"
+	if len(encryptedProtoMsg) > 0 {
+		sharedHeaders += "\nX-Proto: " + base64.StdEncoding.EncodeToString(encryptedProtoMsg)
+	}
+	var httpTag string
+	switch tdRaw.tagType {
+	// for complete copy http generator of golang
+	case tagHttpGetComplete:
+		fallthrough
+	case tagHttpGetIncomplete:
+		tdRaw.UploadLimit = int(tdRaw.decoySpec.GetTcpwin()) - getRandInt(1, 1045)
+		httpTag = fmt.Sprintf(`GET / HTTP/1.1
+%s
+X-Ignore: %s`, sharedHeaders, getRandPadding(7, maxInt(612-len(sharedHeaders), 7), 10))
+		httpTag = strings.Replace(httpTag, "\n", "\r\n", -1)
+	case tagHttpPostIncomplete:
+		ContentLength := getRandInt(900000, 1045000)
+		tdRaw.UploadLimit = ContentLength - 1
+		httpTag = fmt.Sprintf(`POST / HTTP/1.1
+%s
+Accept-Encoding: None
+X-Padding: %s
+Content-Type: application/zip; boundary=----WebKitFormBoundaryaym16ehT29q60rUx
+Content-Length: %s
+----WebKitFormBoundaryaym16ehT29q60rUx
+Content-Disposition: form-data; name=\"td.zip\"
+`, sharedHeaders, getRandPadding(1, maxInt(461-len(sharedHeaders), 1), 10), strconv.Itoa(ContentLength))
+		httpTag = strings.Replace(httpTag, "\n", "\r\n", -1)
+	}
+
+	keystreamOffset := len(httpTag)
+	keystreamSize := (len(tag)/3+1)*4 + keystreamOffset // we can't use first 2 bits of every byte
+	wholeKeystream, err := tdRaw.tlsConn.GetOutKeystream(keystreamSize)
+	if err != nil {
+		return httpTag, err
+	}
+	keystreamAtTag := wholeKeystream[keystreamOffset:]
+
+	httpTag += string(reverseEncrypt(tag, keystreamAtTag))
+	if tdRaw.tagType == tagHttpGetComplete {
+		httpTag += "\r\n\r\n"
+	}
+	Logger().Debugf("Generated HTTP TAG:\n%s\n", httpTag)
+	return httpTag, nil
+}
+
 func (tdRaw *tdRawConn) IsClosed() bool {
 	select {
 	case <-tdRaw.closed:

vendor/github.com/refraction-networking/gotapdance/tapdance/dialer.go

@@ -2,7 +2,10 @@ package tapdance
 
 import (
 	"context"
+	"errors"
 	"net"
+
+	pb "github.com/refraction-networking/gotapdance/protobuf"
 )
 
 var sessionsTotal CounterUint64
@@ -10,7 +13,23 @@ var sessionsTotal CounterUint64
 // Dialer contains options and implements advanced functions for establishing TapDance connection.
 type Dialer struct {
 	SplitFlows bool
-	TcpDialer  func(context.Context, string, string) (net.Conn, error)
+
+	// THIS IS REQUIRED TO INTERFACE WITH PSIPHON ANDROID
+	//		we use their dialer to prevent connection loopback into our own proxy
+	//		connection when tunneling the whole device.
+	TcpDialer func(context.Context, string, string) (net.Conn, error)
+
+	DarkDecoy bool
+
+	// The type of registrar to use when performing Conjure registrations.
+	DarkDecoyRegistrar Registrar
+
+	// The type of transport to use for Conjure connections.
+	Transport pb.TransportType
+
+	UseProxyHeader bool
+	V6Support      bool // *bool so that it is a nullable type. that can be overridden
+	Width          int
 }
 
 // Dial connects to the address on the named network.
@@ -53,15 +72,43 @@ func (d *Dialer) DialContext(ctx context.Context, network, address string) (net.
 		}
 	}
 
+	if d.TcpDialer == nil {
+		// custom dialer is not set, use default
+		defaultDialer := net.Dialer{}
+		d.TcpDialer = defaultDialer.DialContext
+	}
+
 	if !d.SplitFlows {
-		flow, err := makeTdFlow(flowBidirectional, nil, address)
-		if err != nil {
-			return nil, err
+		if !d.DarkDecoy {
+			flow, err := makeTdFlow(flowBidirectional, nil, address)
+			if err != nil {
+				return nil, err
+			}
+			flow.tdRaw.TcpDialer = d.TcpDialer
+			flow.tdRaw.useProxyHeader = d.UseProxyHeader
+			return flow, flow.DialContext(ctx)
+		} else {
+			// _, err := makeTdFlow(flowBidirectional, nil, address)
+			// if err != nil {
+			// 	return nil, err
+			// }
+			cjSession := makeConjureSession(address, d.Transport)
+			cjSession.TcpDialer = d.TcpDialer
+			cjSession.UseProxyHeader = d.UseProxyHeader
+			cjSession.Width = uint(d.Width)
+
+			if d.V6Support {
+				cjSession.V6Support = &V6{include: both, support: true}
+			} else {
+				cjSession.V6Support = &V6{include: v4, support: false}
+			}
+			if len(address) == 0 {
+				return nil, errors.New("Dark Decoys require target address to be set")
+			}
+			return DialConjure(ctx, cjSession, d.DarkDecoyRegistrar)
 		}
-		flow.tdRaw.TcpDialer = d.TcpDialer
-		return flow, flow.DialContext(ctx)
 	}
-	return dialSplitFlow(ctx, d.TcpDialer, address)
+	return nil, errors.New("SplitFlows are not supported")
 }
 
 // DialProxy establishes direct connection to TapDance station proxy.
@@ -70,7 +117,7 @@ func (d *Dialer) DialProxy() (net.Conn, error) {
 	return d.DialProxyContext(context.Background())
 }
 
-// DialProxy establishes direct connection to TapDance station proxy using the provided context.
+// DialProxyContext establishes direct connection to TapDance station proxy using the provided context.
 // Users are expected to send HTTP CONNECT request next.
 func (d *Dialer) DialProxyContext(ctx context.Context) (net.Conn, error) {
 	return d.DialContext(ctx, "tcp", "")

vendor/github.com/refraction-networking/gotapdance/tapdance/logger.go

@@ -2,8 +2,9 @@ package tapdance
 
 import (
 	"fmt"
-	"github.com/sirupsen/logrus"
 	"sync"
+
+	"github.com/sirupsen/logrus"
 )
 
 // implements interface logrus.Formatter
@@ -22,8 +23,8 @@ func Logger() *logrus.Logger {
 	initLoggerOnce.Do(func() {
 		logrusLogger = logrus.New()
 		logrusLogger.Formatter = new(formatter)
-		logrusLogger.Level = logrus.InfoLevel
-		// logrusLogger.Level = logrus.DebugLevel
+		// logrusLogger.Level = logrus.InfoLevel
+		logrusLogger.Level = logrus.DebugLevel
 
 		// buildInfo const will be overwritten by CI with `sed` for test builds
 		// if not overwritten -- this is a NO-OP

vendor/github.com/refraction-networking/gotapdance/tapdance/phantoms/phantoms.go

@@ -0,0 +1,235 @@
+package phantoms
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"math/big"
+	"math/rand"
+	"net"
+
+	wr "github.com/mroth/weightedrand"
+)
+
+type ConjurePhantomSubnet struct {
+	Weight  float32
+	Subnets []string
+}
+
+type SubnetConfig struct {
+	WeightedSubnets []ConjurePhantomSubnet
+}
+
+// getSubnets - return EITHER all subnet strings as one composite array if we are
+//		selecting unweighted, or return the array associated with the (seed) selected
+//		array of subnet strings based on the associated weights
+func (sc *SubnetConfig) getSubnets(seed []byte, weighted bool) []string {
+
+	var out []string = []string{}
+
+	if weighted {
+		// seed random with hkdf derived seed provided by client
+		seedInt, err := binary.ReadVarint(bytes.NewBuffer(seed))
+		if err != nil {
+			return nil
+		}
+		rand.Seed(seedInt)
+
+		choices := make([]wr.Choice, 0, len(sc.WeightedSubnets))
+		for _, cjSubnet := range sc.WeightedSubnets {
+			choices = append(choices, wr.Choice{Item: cjSubnet.Subnets, Weight: uint(cjSubnet.Weight)})
+		}
+		c, _ := wr.NewChooser(choices...)
+		out = c.Pick().([]string)
+	} else {
+
+		// Use unweighted config for subnets, concat all into one array and return.
+		for _, cjSubnet := range sc.WeightedSubnets {
+			for _, subnet := range cjSubnet.Subnets {
+				out = append(out, subnet)
+			}
+		}
+	}
+
+	return out
+}
+
+// SubnetFilter - Filter IP subnets based on whatever to prevent specific subnets from
+//		inclusion in choice. See v4Only and v6Only for reference.
+type SubnetFilter func([]*net.IPNet) ([]*net.IPNet, error)
+
+func V4Only(obj []*net.IPNet) ([]*net.IPNet, error) {
+	var out []*net.IPNet = []*net.IPNet{}
+
+	for _, _net := range obj {
+		if ipv4net := _net.IP.To4(); ipv4net != nil {
+			out = append(out, _net)
+		}
+	}
+	return out, nil
+}
+
+func V6Only(obj []*net.IPNet) ([]*net.IPNet, error) {
+	var out []*net.IPNet = []*net.IPNet{}
+
+	for _, _net := range obj {
+		if ipv6net := _net.IP.To16(); ipv6net != nil {
+			out = append(out, _net)
+		}
+	}
+	return out, nil
+}
+
+func parseSubnets(phantomSubnets []string) ([]*net.IPNet, error) {
+	var subnets []*net.IPNet = []*net.IPNet{}
+
+	if len(phantomSubnets) == 0 {
+		return nil, fmt.Errorf("parseSubnets - no subnets provided")
+	}
+
+	for _, strNet := range phantomSubnets {
+		_, parsedNet, err := net.ParseCIDR(strNet)
+		if err != nil {
+			return nil, err
+		}
+		if parsedNet == nil {
+			return nil, fmt.Errorf("failed to parse %v as subnet", parsedNet)
+		}
+
+		subnets = append(subnets, parsedNet)
+	}
+
+	return subnets, nil
+	// return nil, fmt.Errorf("parseSubnets not implemented yet")
+}
+
+// SelectAddrFromSubnet - given a seed and a CIDR block choose an address.
+// 		This is done by generating a seeded random bytes up to teh length of the
+//		full address then using the net mask to zero out any bytes that are
+//		already specified by the CIDR block. Tde masked random value is then
+//		added to the cidr block base giving the final randomly selected address.
+func SelectAddrFromSubnet(seed []byte, net1 *net.IPNet) (net.IP, error) {
+	bits, addrLen := net1.Mask.Size()
+
+	ipBigInt := &big.Int{}
+	if v4net := net1.IP.To4(); v4net != nil {
+		ipBigInt.SetBytes(net1.IP.To4())
+	} else if v6net := net1.IP.To16(); v6net != nil {
+		ipBigInt.SetBytes(net1.IP.To16())
+	}
+
+	seedInt, err := binary.ReadVarint(bytes.NewBuffer(seed))
+	if err != nil {
+		return nil, err
+	}
+
+	rand.Seed(seedInt)
+	randBytes := make([]byte, addrLen/8)
+	_, err = rand.Read(randBytes)
+	if err != nil {
+		return nil, err
+	}
+	randBigInt := &big.Int{}
+	randBigInt.SetBytes(randBytes)
+
+	mask := make([]byte, addrLen/8)
+	for i := 0; i < addrLen/8; i++ {
+		mask[i] = 0xff
+	}
+	maskBigInt := &big.Int{}
+	maskBigInt.SetBytes(mask)
+	maskBigInt.Rsh(maskBigInt, uint(bits))
+
+	randBigInt.And(randBigInt, maskBigInt)
+	ipBigInt.Add(ipBigInt, randBigInt)
+
+	return net.IP(ipBigInt.Bytes()), nil
+}
+
+func selectIPAddr(seed []byte, subnets []*net.IPNet) (*net.IP, error) {
+
+	addresses_total := big.NewInt(0)
+
+	type idNet struct {
+		min, max big.Int
+		net      *net.IPNet
+	}
+	var idNets []idNet
+
+	for _, _net := range subnets {
+		netMaskOnes, _ := _net.Mask.Size()
+		if ipv4net := _net.IP.To4(); ipv4net != nil {
+			_idNet := idNet{}
+			_idNet.min.Set(addresses_total)
+			addresses_total.Add(addresses_total, big.NewInt(2).Exp(big.NewInt(2), big.NewInt(int64(32-netMaskOnes)), nil))
+			addresses_total.Sub(addresses_total, big.NewInt(1))
+			_idNet.max.Set(addresses_total)
+			_idNet.net = _net
+			idNets = append(idNets, _idNet)
+		} else if ipv6net := _net.IP.To16(); ipv6net != nil {
+			_idNet := idNet{}
+			_idNet.min.Set(addresses_total)
+			addresses_total.Add(addresses_total, big.NewInt(2).Exp(big.NewInt(2), big.NewInt(int64(128-netMaskOnes)), nil))
+			addresses_total.Sub(addresses_total, big.NewInt(1))
+			_idNet.max.Set(addresses_total)
+			_idNet.net = _net
+			idNets = append(idNets, _idNet)
+		} else {
+			return nil, fmt.Errorf("failed to parse %v", _net)
+		}
+	}
+
+	if addresses_total.Cmp(big.NewInt(0)) <= 0 {
+		return nil, fmt.Errorf("No valid addresses specified")
+	}
+
+	id := &big.Int{}
+	id.SetBytes(seed)
+	if id.Cmp(addresses_total) > 0 {
+		id.Mod(id, addresses_total)
+	}
+
+	var result net.IP
+	var err error
+	for _, _idNet := range idNets {
+		if _idNet.max.Cmp(id) >= 0 && _idNet.min.Cmp(id) == -1 {
+			result, err = SelectAddrFromSubnet(seed, _idNet.net)
+			if err != nil {
+				return nil, fmt.Errorf("Failed to chose IP address: %v", err)
+			}
+		}
+	}
+	if result == nil {
+		return nil, errors.New("let's rewrite the phantom address selector")
+	}
+	return &result, nil
+}
+
+// SelectPhantom - select one phantom IP address based on shared secret
+func SelectPhantom(seed []byte, subnets SubnetConfig, transform SubnetFilter, weighted bool) (*net.IP, error) {
+
+	s, err := parseSubnets(subnets.getSubnets(seed, weighted))
+	if err != nil {
+		return nil, fmt.Errorf("Failed to parse subnets: %v", err)
+	}
+
+	if transform != nil {
+		s, err = transform(s)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return selectIPAddr(seed, s)
+}
+
+// SelectPhantomUnweighted - select one phantom IP address based on shared secret
+func SelectPhantomUnweighted(seed []byte, subnets SubnetConfig, transform SubnetFilter) (*net.IP, error) {
+	return SelectPhantom(seed, subnets, transform, false)
+}
+
+// SelectPhantomWeighted - select one phantom IP address based on shared secret
+func SelectPhantomWeighted(seed []byte, subnets SubnetConfig, transform SubnetFilter) (*net.IP, error) {
+	return SelectPhantom(seed, subnets, transform, true)
+}

vendor/github.com/refraction-networking/gotapdance/tapdance/utils.go

@@ -8,13 +8,14 @@ import (
 	"crypto/sha256"
 	"encoding/binary"
 	"errors"
+	"fmt"
 	mrand "math/rand"
 	"net"
 	"strconv"
 	"strings"
 	"time"
 
-	"github.com/agl/ed25519/extra25519"
+	"github.com/refraction-networking/gotapdance/ed25519/extra25519"
 	"golang.org/x/crypto/curve25519"
 )
 
@@ -85,75 +86,8 @@ func getRandString(length int) string {
 	return string(randString)
 }
 
-// obfuscateTagAndProtobuf() generates key-pair and combines it /w stationPubkey to generate
-// sharedSecret. Client will use Eligator to find and send uniformly random representative for its
-// public key (and avoid sending it directly over the wire, as points on ellyptic curve are
-// distinguishable)
-// Then the sharedSecret will be used to encrypt stegoPayload and protobuf slices:
-//  - stegoPayload is encrypted with AES-GCM KEY=sharedSecret[0:16], IV=sharedSecret[16:28]
-//  - protobuf is encrypted with AES-GCM KEY=sharedSecret[0:16], IV={new random IV}, that will be
-//    prepended to encryptedProtobuf and eventually sent out together
-// Returns
-//  - tag(concatenated representative and encrypted stegoPayload),
-//  - encryptedProtobuf(concatenated 12 byte IV + encrypted protobuf)
-//  - error
-func obfuscateTagAndProtobuf(stegoPayload []byte, protobuf []byte, stationPubkey []byte) ([]byte, []byte, error) {
-	if len(stationPubkey) != 32 {
-		return nil, nil, errors.New("Unexpected station pubkey length. Expected: 32." +
-			" Received: " + strconv.Itoa(len(stationPubkey)) + ".")
-	}
-	var sharedSecret, clientPrivate, clientPublic, representative [32]byte
-	for ok := false; ok != true; {
-		var sliceKeyPrivate []byte = clientPrivate[:]
-		_, err := rand.Read(sliceKeyPrivate)
-		if err != nil {
-			return nil, nil, err
-		}
-
-		ok = extra25519.ScalarBaseMult(&clientPublic, &representative, &clientPrivate)
-	}
-	var stationPubkeyByte32 [32]byte
-	copy(stationPubkeyByte32[:], stationPubkey)
-	curve25519.ScalarMult(&sharedSecret, &clientPrivate, &stationPubkeyByte32)
-
-	// extra25519.ScalarBaseMult does not randomize most significant bit(sign of y_coord?)
-	// Other implementations of elligator may have up to 2 non-random bits.
-	// Here we randomize the bit, expecting it to be flipped back to 0 on station
-	randByte := make([]byte, 1)
-	_, err := rand.Read(randByte)
-	if err != nil {
-		return nil, nil, err
-	}
-	representative[31] |= (0x80 & randByte[0])
-
-	tagBuf := new(bytes.Buffer) // What we have to encrypt with the shared secret using AES
-	tagBuf.Write(representative[:])
-
-	stationPubkeyHash := sha256.Sum256(sharedSecret[:])
-	aesKey := stationPubkeyHash[:16]
-	aesIvTag := stationPubkeyHash[16:28] // 12 bytes for stegoPayload nonce
-
-	encryptedStegoPayload, err := aesGcmEncrypt(stegoPayload, aesKey, aesIvTag)
-	if err != nil {
-		return nil, nil, err
-	}
-
-	tagBuf.Write(encryptedStegoPayload)
-	tag := tagBuf.Bytes()
-
-	if len(protobuf) == 0 {
-		return tag, nil, err
-	}
-
-	// probably could have used all zeros as IV here, but better to err on safe side
-	aesIvProtobuf := make([]byte, 12)
-	_, err = rand.Read(aesIvProtobuf)
-	if err != nil {
-		return nil, nil, err
-	}
-
-	encryptedProtobuf, err := aesGcmEncrypt(protobuf, aesKey, aesIvProtobuf)
-	return tag, append(aesIvProtobuf, encryptedProtobuf...), err
+type tapdanceSharedKeys struct {
+	FspKey, FspIv, VspKey, VspIv, NewMasterSecret, ConjureSeed []byte
 }
 
 func getMsgWithHeader(msgType msgType, msgBytes []byte) []byte {
@@ -197,7 +131,18 @@ func uint16toInt16(i uint16) int16 {
 	return pos + neg
 }
 
-func reverseEncrypt(ciphertext []byte, keyStream []byte) (plaintext string) {
+// generates HTTP request, that is ready to have tag prepended to it
+func generateHTTPRequestBeginning(decoyHostname string) []byte {
+	sharedHeaders := `Host: ` + decoyHostname +
+		"\nUser-Agent: TapDance/1.2 (+https://refraction.network/info)"
+	httpTag := fmt.Sprintf(`GET / HTTP/1.1
+%s
+X-Ignore: %s`, sharedHeaders, getRandPadding(7, maxInt(612-len(sharedHeaders), 7), 10))
+	return []byte(strings.Replace(httpTag, "\n", "\r\n", -1))
+}
+
+func reverseEncrypt(ciphertext []byte, keyStream []byte) []byte {
+	var plaintext string
 	// our plaintext can be antyhing where x & 0xc0 == 0x40
 	// i.e. 64-127 in ascii (@, A-Z, [\]^_`, a-z, {|}~ DEL)
 	// This means that we are allowed to choose the last 6 bits
@@ -241,7 +186,7 @@ func reverseEncrypt(ciphertext []byte, keyStream []byte) (plaintext string) {
 		plaintext += string(pc)
 		plaintext += string(pd)
 	}
-	return
+	return []byte(plaintext)
 }
 
 func minInt(a, b int) int {
@@ -282,3 +227,74 @@ func errIsTimeout(err error) bool {
 	}
 	return false
 }
+
+// obfuscateTagAndProtobuf() generates key-pair and combines it /w stationPubkey to generate
+// sharedSecret. Client will use Eligator to find and send uniformly random representative for its
+// public key (and avoid sending it directly over the wire, as points on ellyptic curve are
+// distinguishable)
+// Then the sharedSecret will be used to encrypt stegoPayload and protobuf slices:
+//  - stegoPayload is encrypted with AES-GCM KEY=sharedSecret[0:16], IV=sharedSecret[16:28]
+//  - protobuf is encrypted with AES-GCM KEY=sharedSecret[0:16], IV={new random IV}, that will be
+//    prepended to encryptedProtobuf and eventually sent out together
+// Returns
+//  - tag(concatenated representative and encrypted stegoPayload),
+//  - encryptedProtobuf(concatenated 12 byte IV + encrypted protobuf)
+//  - error
+func obfuscateTagAndProtobuf(stegoPayload []byte, protobuf []byte, stationPubkey []byte) ([]byte, []byte, error) {
+	if len(stationPubkey) != 32 {
+		return nil, nil, errors.New("Unexpected station pubkey length. Expected: 32." +
+			" Received: " + strconv.Itoa(len(stationPubkey)) + ".")
+	}
+	var sharedSecret, clientPrivate, clientPublic, representative [32]byte
+	for ok := false; ok != true; {
+		var sliceKeyPrivate []byte = clientPrivate[:]
+		_, err := rand.Read(sliceKeyPrivate)
+		if err != nil {
+			return nil, nil, err
+		}
+
+		ok = extra25519.ScalarBaseMult(&clientPublic, &representative, &clientPrivate)
+	}
+	var stationPubkeyByte32 [32]byte
+	copy(stationPubkeyByte32[:], stationPubkey)
+	curve25519.ScalarMult(&sharedSecret, &clientPrivate, &stationPubkeyByte32)
+
+	// extra25519.ScalarBaseMult does not randomize most significant bit(sign of y_coord?)
+	// Other implementations of elligator may have up to 2 non-random bits.
+	// Here we randomize the bit, expecting it to be flipped back to 0 on station
+	randByte := make([]byte, 1)
+	_, err := rand.Read(randByte)
+	if err != nil {
+		return nil, nil, err
+	}
+	representative[31] |= (0x80 & randByte[0])
+
+	tagBuf := new(bytes.Buffer) // What we have to encrypt with the shared secret using AES
+	tagBuf.Write(representative[:])
+
+	stationPubkeyHash := sha256.Sum256(sharedSecret[:])
+	aesKey := stationPubkeyHash[:16]
+	aesIvTag := stationPubkeyHash[16:28] // 12 bytes for stegoPayload nonce
+
+	encryptedStegoPayload, err := aesGcmEncrypt(stegoPayload, aesKey, aesIvTag)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	tagBuf.Write(encryptedStegoPayload)
+	tag := tagBuf.Bytes()
+
+	if len(protobuf) == 0 {
+		return tag, nil, err
+	}
+
+	// probably could have used all zeros as IV here, but better to err on safe side
+	aesIvProtobuf := make([]byte, 12)
+	_, err = rand.Read(aesIvProtobuf)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	encryptedProtobuf, err := aesGcmEncrypt(protobuf, aesKey, aesIvProtobuf)
+	return tag, append(aesIvProtobuf, encryptedProtobuf...), err
+}

vendor/gitlab.com/yawning/obfs4.git/LICENSE

@@ -0,0 +1,55 @@
+Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice,
+   this list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+
+==============================================================================
+
+Copyright (c) 2012 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+

vendor/gitlab.com/yawning/obfs4.git/common/csrand/csrand.go

@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+// Package csrand implements the math/rand interface over crypto/rand, along
+// with some utility functions for common random number/byte related tasks.
+//
+// Not all of the convinience routines are replicated, only those that are
+// immediately useful.  The Rand variable provides access to the full math/rand
+// API.
+package csrand // import "gitlab.com/yawning/obfs4.git/common/csrand"
+
+import (
+	cryptRand "crypto/rand"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"math/rand"
+)
+
+var (
+	csRandSourceInstance csRandSource
+
+	// Rand is a math/rand instance backed by crypto/rand CSPRNG.
+	Rand = rand.New(csRandSourceInstance)
+)
+
+type csRandSource struct {
+	// This does not keep any state as it is backed by crypto/rand.
+}
+
+func (r csRandSource) Int63() int64 {
+	var src [8]byte
+	if err := Bytes(src[:]); err != nil {
+		panic(err)
+	}
+	val := binary.BigEndian.Uint64(src[:])
+	val &= (1<<63 - 1)
+
+	return int64(val)
+}
+
+func (r csRandSource) Seed(seed int64) {
+	// No-op.
+}
+
+// Intn returns, as a int, a pseudo random number in [0, n).
+func Intn(n int) int {
+	return Rand.Intn(n)
+}
+
+// Float64 returns, as a float64, a pesudo random number in [0.0,1.0).
+func Float64() float64 {
+	return Rand.Float64()
+}
+
+// IntRange returns a uniformly distributed int [min, max].
+func IntRange(min, max int) int {
+	if max < min {
+		panic(fmt.Sprintf("IntRange: min > max (%d, %d)", min, max))
+	}
+
+	r := (max + 1) - min
+	ret := Rand.Intn(r)
+	return ret + min
+}
+
+// Bytes fills the slice with random data.
+func Bytes(buf []byte) error {
+	if _, err := io.ReadFull(cryptRand.Reader, buf); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Reader is a alias of rand.Reader.
+var Reader = cryptRand.Reader

vendor/gitlab.com/yawning/obfs4.git/common/drbg/hash_drbg.go

@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+// Package drbg implements a minimalistic DRBG based off SipHash-2-4 in OFB
+// mode.
+package drbg // import "gitlab.com/yawning/obfs4.git/common/drbg"
+
+import (
+	"encoding/binary"
+	"encoding/hex"
+	"fmt"
+	"hash"
+
+	"github.com/dchest/siphash"
+	"gitlab.com/yawning/obfs4.git/common/csrand"
+)
+
+// Size is the length of the HashDrbg output.
+const Size = siphash.Size
+
+// SeedLength is the length of the HashDrbg seed.
+const SeedLength = 16 + Size
+
+// Seed is the initial state for a HashDrbg.  It consists of a SipHash-2-4
+// key, and 8 bytes of initial data.
+type Seed [SeedLength]byte
+
+// Bytes returns a pointer to the raw HashDrbg seed.
+func (seed *Seed) Bytes() *[SeedLength]byte {
+	return (*[SeedLength]byte)(seed)
+}
+
+// Hex returns the hexdecimal representation of the seed.
+func (seed *Seed) Hex() string {
+	return hex.EncodeToString(seed.Bytes()[:])
+}
+
+// NewSeed returns a Seed initialized with the runtime CSPRNG.
+func NewSeed() (seed *Seed, err error) {
+	seed = new(Seed)
+	if err = csrand.Bytes(seed.Bytes()[:]); err != nil {
+		return nil, err
+	}
+
+	return
+}
+
+// SeedFromBytes creates a Seed from the raw bytes, truncating to SeedLength as
+// appropriate.
+func SeedFromBytes(src []byte) (seed *Seed, err error) {
+	if len(src) < SeedLength {
+		return nil, InvalidSeedLengthError(len(src))
+	}
+
+	seed = new(Seed)
+	copy(seed.Bytes()[:], src)
+
+	return
+}
+
+// SeedFromHex creates a Seed from the hexdecimal representation, truncating to
+// SeedLength as appropriate.
+func SeedFromHex(encoded string) (seed *Seed, err error) {
+	var raw []byte
+	if raw, err = hex.DecodeString(encoded); err != nil {
+		return nil, err
+	}
+
+	return SeedFromBytes(raw)
+}
+
+// InvalidSeedLengthError is the error returned when the seed provided to the
+// DRBG is an invalid length.
+type InvalidSeedLengthError int
+
+func (e InvalidSeedLengthError) Error() string {
+	return fmt.Sprintf("invalid seed length: %d", int(e))
+}
+
+// HashDrbg is a CSDRBG based off of SipHash-2-4 in OFB mode.
+type HashDrbg struct {
+	sip hash.Hash64
+	ofb [Size]byte
+}
+
+// NewHashDrbg makes a HashDrbg instance based off an optional seed.  The seed
+// is truncated to SeedLength.
+func NewHashDrbg(seed *Seed) (*HashDrbg, error) {
+	drbg := new(HashDrbg)
+	if seed == nil {
+		var err error
+		if seed, err = NewSeed(); err != nil {
+			return nil, err
+		}
+	}
+	drbg.sip = siphash.New(seed.Bytes()[:16])
+	copy(drbg.ofb[:], seed.Bytes()[16:])
+
+	return drbg, nil
+}
+
+// Int63 returns a uniformly distributed random integer [0, 1 << 63).
+func (drbg *HashDrbg) Int63() int64 {
+	block := drbg.NextBlock()
+	ret := binary.BigEndian.Uint64(block)
+	ret &= (1<<63 - 1)
+
+	return int64(ret)
+}
+
+// Seed does nothing, call NewHashDrbg if you want to reseed.
+func (drbg *HashDrbg) Seed(seed int64) {
+	// No-op.
+}
+
+// NextBlock returns the next 8 byte DRBG block.
+func (drbg *HashDrbg) NextBlock() []byte {
+	_, _ = drbg.sip.Write(drbg.ofb[:])
+	copy(drbg.ofb[:], drbg.sip.Sum(nil))
+
+	ret := make([]byte, Size)
+	copy(ret, drbg.ofb[:])
+	return ret
+}

vendor/gitlab.com/yawning/obfs4.git/common/ntor/ntor.go

@@ -0,0 +1,431 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+// Package ntor implements the Tor Project's ntor handshake as defined in
+// proposal 216 "Improved circuit-creation key exchange".  It also supports
+// using Elligator to transform the Curve25519 public keys sent over the wire
+// to a form that is indistinguishable from random strings.
+//
+// Before using this package, it is strongly recommended that the specification
+// is read and understood.
+package ntor // import "gitlab.com/yawning/obfs4.git/common/ntor"
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/sha256"
+	"crypto/subtle"
+	"encoding/hex"
+	"fmt"
+	"io"
+
+	"github.com/agl/ed25519/extra25519"
+	"gitlab.com/yawning/obfs4.git/common/csrand"
+	"golang.org/x/crypto/curve25519"
+	"golang.org/x/crypto/hkdf"
+)
+
+const (
+	// PublicKeyLength is the length of a Curve25519 public key.
+	PublicKeyLength = 32
+
+	// RepresentativeLength is the length of an Elligator representative.
+	RepresentativeLength = 32
+
+	// PrivateKeyLength is the length of a Curve25519 private key.
+	PrivateKeyLength = 32
+
+	// SharedSecretLength is the length of a Curve25519 shared secret.
+	SharedSecretLength = 32
+
+	// NodeIDLength is the length of a ntor node identifier.
+	NodeIDLength = 20
+
+	// KeySeedLength is the length of the derived KEY_SEED.
+	KeySeedLength = sha256.Size
+
+	// AuthLength is the lenght of the derived AUTH.
+	AuthLength = sha256.Size
+)
+
+var protoID = []byte("ntor-curve25519-sha256-1")
+var tMac = append(protoID, []byte(":mac")...)
+var tKey = append(protoID, []byte(":key_extract")...)
+var tVerify = append(protoID, []byte(":key_verify")...)
+var mExpand = append(protoID, []byte(":key_expand")...)
+
+// PublicKeyLengthError is the error returned when the public key being
+// imported is an invalid length.
+type PublicKeyLengthError int
+
+func (e PublicKeyLengthError) Error() string {
+	return fmt.Sprintf("ntor: Invalid Curve25519 public key length: %d",
+		int(e))
+}
+
+// PrivateKeyLengthError is the error returned when the private key being
+// imported is an invalid length.
+type PrivateKeyLengthError int
+
+func (e PrivateKeyLengthError) Error() string {
+	return fmt.Sprintf("ntor: Invalid Curve25519 private key length: %d",
+		int(e))
+}
+
+// NodeIDLengthError is the error returned when the node ID being imported is
+// an invalid length.
+type NodeIDLengthError int
+
+func (e NodeIDLengthError) Error() string {
+	return fmt.Sprintf("ntor: Invalid NodeID length: %d", int(e))
+}
+
+// KeySeed is the key material that results from a handshake (KEY_SEED).
+type KeySeed [KeySeedLength]byte
+
+// Bytes returns a pointer to the raw key material.
+func (key_seed *KeySeed) Bytes() *[KeySeedLength]byte {
+	return (*[KeySeedLength]byte)(key_seed)
+}
+
+// Auth is the verifier that results from a handshake (AUTH).
+type Auth [AuthLength]byte
+
+// Bytes returns a pointer to the raw auth.
+func (auth *Auth) Bytes() *[AuthLength]byte {
+	return (*[AuthLength]byte)(auth)
+}
+
+// NodeID is a ntor node identifier.
+type NodeID [NodeIDLength]byte
+
+// NewNodeID creates a NodeID from the raw bytes.
+func NewNodeID(raw []byte) (*NodeID, error) {
+	if len(raw) != NodeIDLength {
+		return nil, NodeIDLengthError(len(raw))
+	}
+
+	nodeID := new(NodeID)
+	copy(nodeID[:], raw)
+
+	return nodeID, nil
+}
+
+// NodeIDFromHex creates a new NodeID from the hexdecimal representation.
+func NodeIDFromHex(encoded string) (*NodeID, error) {
+	raw, err := hex.DecodeString(encoded)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewNodeID(raw)
+}
+
+// Bytes returns a pointer to the raw NodeID.
+func (id *NodeID) Bytes() *[NodeIDLength]byte {
+	return (*[NodeIDLength]byte)(id)
+}
+
+// Hex returns the hexdecimal representation of the NodeID.
+func (id *NodeID) Hex() string {
+	return hex.EncodeToString(id[:])
+}
+
+// PublicKey is a Curve25519 public key in little-endian byte order.
+type PublicKey [PublicKeyLength]byte
+
+// Bytes returns a pointer to the raw Curve25519 public key.
+func (public *PublicKey) Bytes() *[PublicKeyLength]byte {
+	return (*[PublicKeyLength]byte)(public)
+}
+
+// Hex returns the hexdecimal representation of the Curve25519 public key.
+func (public *PublicKey) Hex() string {
+	return hex.EncodeToString(public.Bytes()[:])
+}
+
+// NewPublicKey creates a PublicKey from the raw bytes.
+func NewPublicKey(raw []byte) (*PublicKey, error) {
+	if len(raw) != PublicKeyLength {
+		return nil, PublicKeyLengthError(len(raw))
+	}
+
+	pubKey := new(PublicKey)
+	copy(pubKey[:], raw)
+
+	return pubKey, nil
+}
+
+// PublicKeyFromHex returns a PublicKey from the hexdecimal representation.
+func PublicKeyFromHex(encoded string) (*PublicKey, error) {
+	raw, err := hex.DecodeString(encoded)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewPublicKey(raw)
+}
+
+// Representative is an Elligator representative of a Curve25519 public key
+// in little-endian byte order.
+type Representative [RepresentativeLength]byte
+
+// Bytes returns a pointer to the raw Elligator representative.
+func (repr *Representative) Bytes() *[RepresentativeLength]byte {
+	return (*[RepresentativeLength]byte)(repr)
+}
+
+// ToPublic converts a Elligator representative to a Curve25519 public key.
+func (repr *Representative) ToPublic() *PublicKey {
+	pub := new(PublicKey)
+
+	extra25519.RepresentativeToPublicKey(pub.Bytes(), repr.Bytes())
+	return pub
+}
+
+// PrivateKey is a Curve25519 private key in little-endian byte order.
+type PrivateKey [PrivateKeyLength]byte
+
+// Bytes returns a pointer to the raw Curve25519 private key.
+func (private *PrivateKey) Bytes() *[PrivateKeyLength]byte {
+	return (*[PrivateKeyLength]byte)(private)
+}
+
+// Hex returns the hexdecimal representation of the Curve25519 private key.
+func (private *PrivateKey) Hex() string {
+	return hex.EncodeToString(private.Bytes()[:])
+}
+
+// Keypair is a Curve25519 keypair with an optional Elligator representative.
+// As only certain Curve25519 keys can be obfuscated with Elligator, the
+// representative must be generated along with the keypair.
+type Keypair struct {
+	public         *PublicKey
+	private        *PrivateKey
+	representative *Representative
+}
+
+// Public returns the Curve25519 public key belonging to the Keypair.
+func (keypair *Keypair) Public() *PublicKey {
+	return keypair.public
+}
+
+// Private returns the Curve25519 private key belonging to the Keypair.
+func (keypair *Keypair) Private() *PrivateKey {
+	return keypair.private
+}
+
+// Representative returns the Elligator representative of the public key
+// belonging to the Keypair.
+func (keypair *Keypair) Representative() *Representative {
+	return keypair.representative
+}
+
+// HasElligator returns true if the Keypair has an Elligator representative.
+func (keypair *Keypair) HasElligator() bool {
+	return nil != keypair.representative
+}
+
+// NewKeypair generates a new Curve25519 keypair, and optionally also generates
+// an Elligator representative of the public key.
+func NewKeypair(elligator bool) (*Keypair, error) {
+	keypair := new(Keypair)
+	keypair.private = new(PrivateKey)
+	keypair.public = new(PublicKey)
+	if elligator {
+		keypair.representative = new(Representative)
+	}
+
+	for {
+		// Generate a Curve25519 private key.  Like everyone who does this,
+		// run the CSPRNG output through SHA256 for extra tinfoil hattery.
+		priv := keypair.private.Bytes()[:]
+		if err := csrand.Bytes(priv); err != nil {
+			return nil, err
+		}
+		digest := sha256.Sum256(priv)
+		digest[0] &= 248
+		digest[31] &= 127
+		digest[31] |= 64
+		copy(priv, digest[:])
+
+		if elligator {
+			// Apply the Elligator transform.  This fails ~50% of the time.
+			if !extra25519.ScalarBaseMult(keypair.public.Bytes(),
+				keypair.representative.Bytes(),
+				keypair.private.Bytes()) {
+				continue
+			}
+		} else {
+			// Generate the corresponding Curve25519 public key.
+			curve25519.ScalarBaseMult(keypair.public.Bytes(),
+				keypair.private.Bytes())
+		}
+
+		return keypair, nil
+	}
+}
+
+// KeypairFromHex returns a Keypair from the hexdecimal representation of the
+// private key.
+func KeypairFromHex(encoded string) (*Keypair, error) {
+	raw, err := hex.DecodeString(encoded)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(raw) != PrivateKeyLength {
+		return nil, PrivateKeyLengthError(len(raw))
+	}
+
+	keypair := new(Keypair)
+	keypair.private = new(PrivateKey)
+	keypair.public = new(PublicKey)
+
+	copy(keypair.private[:], raw)
+	curve25519.ScalarBaseMult(keypair.public.Bytes(),
+		keypair.private.Bytes())
+
+	return keypair, nil
+}
+
+// ServerHandshake does the server side of a ntor handshake and returns status,
+// KEY_SEED, and AUTH.  If status is not true, the handshake MUST be aborted.
+func ServerHandshake(clientPublic *PublicKey, serverKeypair *Keypair, idKeypair *Keypair, id *NodeID) (ok bool, keySeed *KeySeed, auth *Auth) {
+	var notOk int
+	var secretInput bytes.Buffer
+
+	// Server side uses EXP(X,y) | EXP(X,b)
+	var exp [SharedSecretLength]byte
+	curve25519.ScalarMult(&exp, serverKeypair.private.Bytes(),
+		clientPublic.Bytes())
+	notOk |= constantTimeIsZero(exp[:])
+	secretInput.Write(exp[:])
+
+	curve25519.ScalarMult(&exp, idKeypair.private.Bytes(),
+		clientPublic.Bytes())
+	notOk |= constantTimeIsZero(exp[:])
+	secretInput.Write(exp[:])
+
+	keySeed, auth = ntorCommon(secretInput, id, idKeypair.public,
+		clientPublic, serverKeypair.public)
+	return notOk == 0, keySeed, auth
+}
+
+// ClientHandshake does the client side of a ntor handshake and returnes
+// status, KEY_SEED, and AUTH.  If status is not true or AUTH does not match
+// the value recieved from the server, the handshake MUST be aborted.
+func ClientHandshake(clientKeypair *Keypair, serverPublic *PublicKey, idPublic *PublicKey, id *NodeID) (ok bool, keySeed *KeySeed, auth *Auth) {
+	var notOk int
+	var secretInput bytes.Buffer
+
+	// Client side uses EXP(Y,x) | EXP(B,x)
+	var exp [SharedSecretLength]byte
+	curve25519.ScalarMult(&exp, clientKeypair.private.Bytes(),
+		serverPublic.Bytes())
+	notOk |= constantTimeIsZero(exp[:])
+	secretInput.Write(exp[:])
+
+	curve25519.ScalarMult(&exp, clientKeypair.private.Bytes(),
+		idPublic.Bytes())
+	notOk |= constantTimeIsZero(exp[:])
+	secretInput.Write(exp[:])
+
+	keySeed, auth = ntorCommon(secretInput, id, idPublic,
+		clientKeypair.public, serverPublic)
+	return notOk == 0, keySeed, auth
+}
+
+// CompareAuth does a constant time compare of a Auth and a byte slice
+// (presumably received over a network).
+func CompareAuth(auth1 *Auth, auth2 []byte) bool {
+	auth1Bytes := auth1.Bytes()
+	return hmac.Equal(auth1Bytes[:], auth2)
+}
+
+func ntorCommon(secretInput bytes.Buffer, id *NodeID, b *PublicKey, x *PublicKey, y *PublicKey) (*KeySeed, *Auth) {
+	keySeed := new(KeySeed)
+	auth := new(Auth)
+
+	// secret_input/auth_input use this common bit, build it once.
+	suffix := bytes.NewBuffer(b.Bytes()[:])
+	suffix.Write(b.Bytes()[:])
+	suffix.Write(x.Bytes()[:])
+	suffix.Write(y.Bytes()[:])
+	suffix.Write(protoID)
+	suffix.Write(id[:])
+
+	// At this point secret_input has the 2 exponents, concatenated, append the
+	// client/server common suffix.
+	secretInput.Write(suffix.Bytes())
+
+	// KEY_SEED = H(secret_input, t_key)
+	h := hmac.New(sha256.New, tKey)
+	_, _ = h.Write(secretInput.Bytes())
+	tmp := h.Sum(nil)
+	copy(keySeed[:], tmp)
+
+	// verify = H(secret_input, t_verify)
+	h = hmac.New(sha256.New, tVerify)
+	_, _ = h.Write(secretInput.Bytes())
+	verify := h.Sum(nil)
+
+	// auth_input = verify | ID | B | Y | X | PROTOID | "Server"
+	authInput := bytes.NewBuffer(verify)
+	_, _ = authInput.Write(suffix.Bytes())
+	_, _ = authInput.Write([]byte("Server"))
+	h = hmac.New(sha256.New, tMac)
+	_, _ = h.Write(authInput.Bytes())
+	tmp = h.Sum(nil)
+	copy(auth[:], tmp)
+
+	return keySeed, auth
+}
+
+func constantTimeIsZero(x []byte) int {
+	var ret byte
+	for _, v := range x {
+		ret |= v
+	}
+
+	return subtle.ConstantTimeByteEq(ret, 0)
+}
+
+// Kdf extracts and expands KEY_SEED via HKDF-SHA256 and returns `okm_len` bytes
+// of key material.
+func Kdf(keySeed []byte, okmLen int) []byte {
+	kdf := hkdf.New(sha256.New, keySeed, tKey, mExpand)
+	okm := make([]byte, okmLen)
+	n, err := io.ReadFull(kdf, okm)
+	if err != nil {
+		panic(fmt.Sprintf("BUG: Failed HKDF: %s", err.Error()))
+	} else if n != len(okm) {
+		panic(fmt.Sprintf("BUG: Got truncated HKDF output: %d", n))
+	}
+
+	return okm
+}

vendor/gitlab.com/yawning/obfs4.git/common/probdist/weighted_dist.go

@@ -0,0 +1,245 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+// Package probdist implements a weighted probability distribution suitable for
+// protocol parameterization.  To allow for easy reproduction of a given
+// distribution, the drbg package is used as the random number source.
+package probdist // import "gitlab.com/yawning/obfs4.git/common/probdist"
+
+import (
+	"bytes"
+	"container/list"
+	"fmt"
+	"math/rand"
+	"sync"
+
+	"gitlab.com/yawning/obfs4.git/common/csrand"
+	"gitlab.com/yawning/obfs4.git/common/drbg"
+)
+
+const (
+	minValues = 1
+	maxValues = 100
+)
+
+// WeightedDist is a weighted distribution.
+type WeightedDist struct {
+	sync.Mutex
+
+	minValue int
+	maxValue int
+	biased   bool
+	values   []int
+	weights  []float64
+
+	alias []int
+	prob  []float64
+}
+
+// New creates a weighted distribution of values ranging from min to max
+// based on a HashDrbg initialized with seed.  Optionally, bias the weight
+// generation to match the ScrambleSuit non-uniform distribution from
+// obfsproxy.
+func New(seed *drbg.Seed, min, max int, biased bool) (w *WeightedDist) {
+	w = &WeightedDist{minValue: min, maxValue: max, biased: biased}
+
+	if max <= min {
+		panic(fmt.Sprintf("wDist.Reset(): min >= max (%d, %d)", min, max))
+	}
+
+	w.Reset(seed)
+
+	return
+}
+
+// genValues creates a slice containing a random number of random values
+// that when scaled by adding minValue will fall into [min, max].
+func (w *WeightedDist) genValues(rng *rand.Rand) {
+	nValues := (w.maxValue + 1) - w.minValue
+	values := rng.Perm(nValues)
+	if nValues < minValues {
+		nValues = minValues
+	}
+	if nValues > maxValues {
+		nValues = maxValues
+	}
+	nValues = rng.Intn(nValues) + 1
+	w.values = values[:nValues]
+}
+
+// genBiasedWeights generates a non-uniform weight list, similar to the
+// ScrambleSuit prob_dist module.
+func (w *WeightedDist) genBiasedWeights(rng *rand.Rand) {
+	w.weights = make([]float64, len(w.values))
+
+	culmProb := 0.0
+	for i := range w.weights {
+		p := (1.0 - culmProb) * rng.Float64()
+		w.weights[i] = p
+		culmProb += p
+	}
+}
+
+// genUniformWeights generates a uniform weight list.
+func (w *WeightedDist) genUniformWeights(rng *rand.Rand) {
+	w.weights = make([]float64, len(w.values))
+	for i := range w.weights {
+		w.weights[i] = rng.Float64()
+	}
+}
+
+// genTables calculates the alias and prob tables used for Vose's Alias method.
+// Algorithm taken from http://www.keithschwarz.com/darts-dice-coins/
+func (w *WeightedDist) genTables() {
+	n := len(w.weights)
+	var sum float64
+	for _, weight := range w.weights {
+		sum += weight
+	}
+
+	// Create arrays $Alias$ and $Prob$, each of size $n$.
+	alias := make([]int, n)
+	prob := make([]float64, n)
+
+	// Create two worklists, $Small$ and $Large$.
+	small := list.New()
+	large := list.New()
+
+	scaled := make([]float64, n)
+	for i, weight := range w.weights {
+		// Multiply each probability by $n$.
+		p_i := weight * float64(n) / sum
+		scaled[i] = p_i
+
+		// For each scaled probability $p_i$:
+		if scaled[i] < 1.0 {
+			// If $p_i < 1$, add $i$ to $Small$.
+			small.PushBack(i)
+		} else {
+			// Otherwise ($p_i \ge 1$), add $i$ to $Large$.
+			large.PushBack(i)
+		}
+	}
+
+	// While $Small$ and $Large$ are not empty: ($Large$ might be emptied first)
+	for small.Len() > 0 && large.Len() > 0 {
+		// Remove the first element from $Small$; call it $l$.
+		l := small.Remove(small.Front()).(int)
+		// Remove the first element from $Large$; call it $g$.
+		g := large.Remove(large.Front()).(int)
+
+		// Set $Prob[l] = p_l$.
+		prob[l] = scaled[l]
+		// Set $Alias[l] = g$.
+		alias[l] = g
+
+		// Set $p_g := (p_g + p_l) - 1$. (This is a more numerically stable option.)
+		scaled[g] = (scaled[g] + scaled[l]) - 1.0
+
+		if scaled[g] < 1.0 {
+			// If $p_g < 1$, add $g$ to $Small$.
+			small.PushBack(g)
+		} else {
+			// Otherwise ($p_g \ge 1$), add $g$ to $Large$.
+			large.PushBack(g)
+		}
+	}
+
+	// While $Large$ is not empty:
+	for large.Len() > 0 {
+		// Remove the first element from $Large$; call it $g$.
+		g := large.Remove(large.Front()).(int)
+		// Set $Prob[g] = 1$.
+		prob[g] = 1.0
+	}
+
+	// While $Small$ is not empty: This is only possible due to numerical instability.
+	for small.Len() > 0 {
+		// Remove the first element from $Small$; call it $l$.
+		l := small.Remove(small.Front()).(int)
+		// Set $Prob[l] = 1$.
+		prob[l] = 1.0
+	}
+
+	w.prob = prob
+	w.alias = alias
+}
+
+// Reset generates a new distribution with the same min/max based on a new
+// seed.
+func (w *WeightedDist) Reset(seed *drbg.Seed) {
+	// Initialize the deterministic random number generator.
+	drbg, _ := drbg.NewHashDrbg(seed)
+	rng := rand.New(drbg)
+
+	w.Lock()
+	defer w.Unlock()
+
+	w.genValues(rng)
+	if w.biased {
+		w.genBiasedWeights(rng)
+	} else {
+		w.genUniformWeights(rng)
+	}
+	w.genTables()
+}
+
+// Sample generates a random value according to the distribution.
+func (w *WeightedDist) Sample() int {
+	var idx int
+
+	w.Lock()
+	defer w.Unlock()
+
+	// Generate a fair die roll from an $n$-sided die; call the side $i$.
+	i := csrand.Intn(len(w.values))
+	// Flip a biased coin that comes up heads with probability $Prob[i]$.
+	if csrand.Float64() <= w.prob[i] {
+		// If the coin comes up "heads," return $i$.
+		idx = i
+	} else {
+		// Otherwise, return $Alias[i]$.
+		idx = w.alias[i]
+	}
+
+	return w.minValue + w.values[idx]
+}
+
+// String returns a dump of the distribution table.
+func (w *WeightedDist) String() string {
+	var buf bytes.Buffer
+
+	buf.WriteString("[ ")
+	for i, v := range w.values {
+		p := w.weights[i]
+		if p > 0.01 { // Squelch tiny probabilities.
+			buf.WriteString(fmt.Sprintf("%d: %f ", v, p))
+		}
+	}
+	buf.WriteString("]")
+	return buf.String()
+}

vendor/gitlab.com/yawning/obfs4.git/common/replayfilter/replay_filter.go

@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+// Package replayfilter implements a generic replay detection filter with a
+// caller specifiable time-to-live.  It only detects if a given byte sequence
+// has been seen before based on the SipHash-2-4 digest of the sequence.
+// Collisions are treated as positive matches, though the probability of this
+// happening is negligible.
+package replayfilter // import "gitlab.com/yawning/obfs4.git/common/replayfilter"
+
+import (
+	"container/list"
+	"encoding/binary"
+	"sync"
+	"time"
+
+	"github.com/dchest/siphash"
+	"gitlab.com/yawning/obfs4.git/common/csrand"
+)
+
+// maxFilterSize is the maximum capacity of a replay filter.  This value is
+// more as a safeguard to prevent runaway filter growth, and is sized to be
+// serveral orders of magnitude greater than the number of connections a busy
+// bridge sees in one day, so in practice should never be reached.
+const maxFilterSize = 100 * 1024
+
+type entry struct {
+	digest    uint64
+	firstSeen time.Time
+	element   *list.Element
+}
+
+// ReplayFilter is a simple filter designed only to detect if a given byte
+// sequence has been seen before.
+type ReplayFilter struct {
+	sync.Mutex
+
+	filter map[uint64]*entry
+	fifo   *list.List
+
+	key [2]uint64
+	ttl time.Duration
+}
+
+// New creates a new ReplayFilter instance.
+func New(ttl time.Duration) (filter *ReplayFilter, err error) {
+	// Initialize the SipHash-2-4 instance with a random key.
+	var key [16]byte
+	if err = csrand.Bytes(key[:]); err != nil {
+		return
+	}
+
+	filter = new(ReplayFilter)
+	filter.filter = make(map[uint64]*entry)
+	filter.fifo = list.New()
+	filter.key[0] = binary.BigEndian.Uint64(key[0:8])
+	filter.key[1] = binary.BigEndian.Uint64(key[8:16])
+	filter.ttl = ttl
+
+	return
+}
+
+// TestAndSet queries the filter for a given byte sequence, inserts the
+// sequence, and returns if it was present before the insertion operation.
+func (f *ReplayFilter) TestAndSet(now time.Time, buf []byte) bool {
+	digest := siphash.Hash(f.key[0], f.key[1], buf)
+
+	f.Lock()
+	defer f.Unlock()
+
+	f.compactFilter(now)
+
+	if e := f.filter[digest]; e != nil {
+		// Hit.  Just return.
+		return true
+	}
+
+	// Miss.  Add a new entry.
+	e := new(entry)
+	e.digest = digest
+	e.firstSeen = now
+	e.element = f.fifo.PushBack(e)
+	f.filter[digest] = e
+
+	return false
+}
+
+func (f *ReplayFilter) compactFilter(now time.Time) {
+	e := f.fifo.Front()
+	for e != nil {
+		ent, _ := e.Value.(*entry)
+
+		// If the filter is not full, only purge entries that exceed the TTL,
+		// otherwise purge at least one entry, then revert to TTL based
+		// compaction.
+		if f.fifo.Len() < maxFilterSize && f.ttl > 0 {
+			deltaT := now.Sub(ent.firstSeen)
+			if deltaT < 0 {
+				// Aeeeeeee, the system time jumped backwards, potentially by
+				// a lot.  This will eventually self-correct, but "eventually"
+				// could be a long time.  As much as this sucks, jettison the
+				// entire filter.
+				f.reset()
+				return
+			} else if deltaT < f.ttl {
+				return
+			}
+		}
+
+		// Remove the eldest entry.
+		eNext := e.Next()
+		delete(f.filter, ent.digest)
+		f.fifo.Remove(ent.element)
+		ent.element = nil
+		e = eNext
+	}
+}
+
+func (f *ReplayFilter) reset() {
+	f.filter = make(map[uint64]*entry)
+	f.fifo = list.New()
+}

vendor/gitlab.com/yawning/obfs4.git/transports/base/base.go

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+// Package base provides the common interface that each supported transport
+// protocol must implement.
+package base // import "gitlab.com/yawning/obfs4.git/transports/base"
+
+import (
+	"net"
+
+	"git.torproject.org/pluggable-transports/goptlib.git"
+)
+
+type DialFunc func(string, string) (net.Conn, error)
+
+// ClientFactory is the interface that defines the factory for creating
+// pluggable transport protocol client instances.
+type ClientFactory interface {
+	// Transport returns the Transport instance that this ClientFactory belongs
+	// to.
+	Transport() Transport
+
+	// ParseArgs parses the supplied arguments into an internal representation
+	// for use with WrapConn.  This routine is called before the outgoing
+	// TCP/IP connection is created to allow doing things (like keypair
+	// generation) to be hidden from third parties.
+	ParseArgs(args *pt.Args) (interface{}, error)
+
+	// Dial creates an outbound net.Conn, and does whatever is required
+	// (eg: handshaking) to get the connection to the point where it is
+	// ready to relay data.
+	Dial(network, address string, dialFn DialFunc, args interface{}) (net.Conn, error)
+}
+
+// ServerFactory is the interface that defines the factory for creating
+// plugable transport protocol server instances.  As the arguments are the
+// property of the factory, validation is done at factory creation time.
+type ServerFactory interface {
+	// Transport returns the Transport instance that this ServerFactory belongs
+	// to.
+	Transport() Transport
+
+	// Args returns the Args required on the client side to handshake with
+	// server connections created by this factory.
+	Args() *pt.Args
+
+	// WrapConn wraps the provided net.Conn with a transport protocol
+	// implementation, and does whatever is required (eg: handshaking) to get
+	// the connection to a point where it is ready to relay data.
+	WrapConn(conn net.Conn) (net.Conn, error)
+}
+
+// Transport is an interface that defines a pluggable transport protocol.
+type Transport interface {
+	// Name returns the name of the transport protocol.  It MUST be a valid C
+	// identifier.
+	Name() string
+
+	// ClientFactory returns a ClientFactory instance for this transport
+	// protocol.
+	ClientFactory(stateDir string) (ClientFactory, error)
+
+	// ServerFactory returns a ServerFactory instance for this transport
+	// protocol.  This can fail if the provided arguments are invalid.
+	ServerFactory(stateDir string, args *pt.Args) (ServerFactory, error)
+}

vendor/gitlab.com/yawning/obfs4.git/transports/obfs4/framing/framing.go

@@ -0,0 +1,305 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+//
+// Package framing implements the obfs4 link framing and cryptography.
+//
+// The Encoder/Decoder shared secret format is:
+//    uint8_t[32] NaCl secretbox key
+//    uint8_t[16] NaCl Nonce prefix
+//    uint8_t[16] SipHash-2-4 key (used to obfsucate length)
+//    uint8_t[8]  SipHash-2-4 IV
+//
+// The frame format is:
+//   uint16_t length (obfsucated, big endian)
+//   NaCl secretbox (Poly1305/XSalsa20) containing:
+//     uint8_t[16] tag (Part of the secretbox construct)
+//     uint8_t[]   payload
+//
+// The length field is length of the NaCl secretbox XORed with the truncated
+// SipHash-2-4 digest ran in OFB mode.
+//
+//     Initialize K, IV[0] with values from the shared secret.
+//     On each packet, IV[n] = H(K, IV[n - 1])
+//     mask[n] = IV[n][0:2]
+//     obfsLen = length ^ mask[n]
+//
+// The NaCl secretbox (Poly1305/XSalsa20) nonce format is:
+//     uint8_t[24] prefix (Fixed)
+//     uint64_t    counter (Big endian)
+//
+// The counter is initialized to 1, and is incremented on each frame.  Since
+// the protocol is designed to be used over a reliable medium, the nonce is not
+// transmitted over the wire as both sides of the conversation know the prefix
+// and the initial counter value.  It is imperative that the counter does not
+// wrap, and sessions MUST terminate before 2^64 frames are sent.
+//
+package framing // import "gitlab.com/yawning/obfs4.git/transports/obfs4/framing"
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+
+	"gitlab.com/yawning/obfs4.git/common/csrand"
+	"gitlab.com/yawning/obfs4.git/common/drbg"
+	"golang.org/x/crypto/nacl/secretbox"
+)
+
+const (
+	// MaximumSegmentLength is the length of the largest possible segment
+	// including overhead.
+	MaximumSegmentLength = 1500 - (40 + 12)
+
+	// FrameOverhead is the length of the framing overhead.
+	FrameOverhead = lengthLength + secretbox.Overhead
+
+	// MaximumFramePayloadLength is the length of the maximum allowed payload
+	// per frame.
+	MaximumFramePayloadLength = MaximumSegmentLength - FrameOverhead
+
+	// KeyLength is the length of the Encoder/Decoder secret key.
+	KeyLength = keyLength + noncePrefixLength + drbg.SeedLength
+
+	maxFrameLength = MaximumSegmentLength - lengthLength
+	minFrameLength = FrameOverhead - lengthLength
+
+	keyLength = 32
+
+	noncePrefixLength  = 16
+	nonceCounterLength = 8
+	nonceLength        = noncePrefixLength + nonceCounterLength
+
+	lengthLength = 2
+)
+
+// Error returned when Decoder.Decode() requires more data to continue.
+var ErrAgain = errors.New("framing: More data needed to decode")
+
+// Error returned when Decoder.Decode() failes to authenticate a frame.
+var ErrTagMismatch = errors.New("framing: Poly1305 tag mismatch")
+
+// Error returned when the NaCl secretbox nonce's counter wraps (FATAL).
+var ErrNonceCounterWrapped = errors.New("framing: Nonce counter wrapped")
+
+// InvalidPayloadLengthError is the error returned when Encoder.Encode()
+// rejects the payload length.
+type InvalidPayloadLengthError int
+
+func (e InvalidPayloadLengthError) Error() string {
+	return fmt.Sprintf("framing: Invalid payload length: %d", int(e))
+}
+
+type boxNonce struct {
+	prefix  [noncePrefixLength]byte
+	counter uint64
+}
+
+func (nonce *boxNonce) init(prefix []byte) {
+	if noncePrefixLength != len(prefix) {
+		panic(fmt.Sprintf("BUG: Nonce prefix length invalid: %d", len(prefix)))
+	}
+
+	copy(nonce.prefix[:], prefix)
+	nonce.counter = 1
+}
+
+func (nonce boxNonce) bytes(out *[nonceLength]byte) error {
+	// The security guarantee of Poly1305 is broken if a nonce is ever reused
+	// for a given key.  Detect this by checking for counter wraparound since
+	// we start each counter at 1.  If it ever happens that more than 2^64 - 1
+	// frames are transmitted over a given connection, support for rekeying
+	// will be neccecary, but that's unlikely to happen.
+	if nonce.counter == 0 {
+		return ErrNonceCounterWrapped
+	}
+
+	copy(out[:], nonce.prefix[:])
+	binary.BigEndian.PutUint64(out[noncePrefixLength:], nonce.counter)
+
+	return nil
+}
+
+// Encoder is a frame encoder instance.
+type Encoder struct {
+	key   [keyLength]byte
+	nonce boxNonce
+	drbg  *drbg.HashDrbg
+}
+
+// NewEncoder creates a new Encoder instance.  It must be supplied a slice
+// containing exactly KeyLength bytes of keying material.
+func NewEncoder(key []byte) *Encoder {
+	if len(key) != KeyLength {
+		panic(fmt.Sprintf("BUG: Invalid encoder key length: %d", len(key)))
+	}
+
+	encoder := new(Encoder)
+	copy(encoder.key[:], key[0:keyLength])
+	encoder.nonce.init(key[keyLength : keyLength+noncePrefixLength])
+	seed, err := drbg.SeedFromBytes(key[keyLength+noncePrefixLength:])
+	if err != nil {
+		panic(fmt.Sprintf("BUG: Failed to initialize DRBG: %s", err))
+	}
+	encoder.drbg, _ = drbg.NewHashDrbg(seed)
+
+	return encoder
+}
+
+// Encode encodes a single frame worth of payload and returns the encoded
+// length.  InvalidPayloadLengthError is recoverable, all other errors MUST be
+// treated as fatal and the session aborted.
+func (encoder *Encoder) Encode(frame, payload []byte) (n int, err error) {
+	payloadLen := len(payload)
+	if MaximumFramePayloadLength < payloadLen {
+		return 0, InvalidPayloadLengthError(payloadLen)
+	}
+	if len(frame) < payloadLen+FrameOverhead {
+		return 0, io.ErrShortBuffer
+	}
+
+	// Generate a new nonce.
+	var nonce [nonceLength]byte
+	if err = encoder.nonce.bytes(&nonce); err != nil {
+		return 0, err
+	}
+	encoder.nonce.counter++
+
+	// Encrypt and MAC payload.
+	box := secretbox.Seal(frame[:lengthLength], payload, &nonce, &encoder.key)
+
+	// Obfuscate the length.
+	length := uint16(len(box) - lengthLength)
+	lengthMask := encoder.drbg.NextBlock()
+	length ^= binary.BigEndian.Uint16(lengthMask)
+	binary.BigEndian.PutUint16(frame[:2], length)
+
+	// Return the frame.
+	return len(box), nil
+}
+
+// Decoder is a frame decoder instance.
+type Decoder struct {
+	key   [keyLength]byte
+	nonce boxNonce
+	drbg  *drbg.HashDrbg
+
+	nextNonce         [nonceLength]byte
+	nextLength        uint16
+	nextLengthInvalid bool
+}
+
+// NewDecoder creates a new Decoder instance.  It must be supplied a slice
+// containing exactly KeyLength bytes of keying material.
+func NewDecoder(key []byte) *Decoder {
+	if len(key) != KeyLength {
+		panic(fmt.Sprintf("BUG: Invalid decoder key length: %d", len(key)))
+	}
+
+	decoder := new(Decoder)
+	copy(decoder.key[:], key[0:keyLength])
+	decoder.nonce.init(key[keyLength : keyLength+noncePrefixLength])
+	seed, err := drbg.SeedFromBytes(key[keyLength+noncePrefixLength:])
+	if err != nil {
+		panic(fmt.Sprintf("BUG: Failed to initialize DRBG: %s", err))
+	}
+	decoder.drbg, _ = drbg.NewHashDrbg(seed)
+
+	return decoder
+}
+
+// Decode decodes a stream of data and returns the length if any.  ErrAgain is
+// a temporary failure, all other errors MUST be treated as fatal and the
+// session aborted.
+func (decoder *Decoder) Decode(data []byte, frames *bytes.Buffer) (int, error) {
+	// A length of 0 indicates that we do not know how big the next frame is
+	// going to be.
+	if decoder.nextLength == 0 {
+		// Attempt to pull out the next frame length.
+		if lengthLength > frames.Len() {
+			return 0, ErrAgain
+		}
+
+		// Remove the length field from the buffer.
+		var obfsLen [lengthLength]byte
+		_, err := io.ReadFull(frames, obfsLen[:])
+		if err != nil {
+			return 0, err
+		}
+
+		// Derive the nonce the peer used.
+		if err = decoder.nonce.bytes(&decoder.nextNonce); err != nil {
+			return 0, err
+		}
+
+		// Deobfuscate the length field.
+		length := binary.BigEndian.Uint16(obfsLen[:])
+		lengthMask := decoder.drbg.NextBlock()
+		length ^= binary.BigEndian.Uint16(lengthMask)
+		if maxFrameLength < length || minFrameLength > length {
+			// Per "Plaintext Recovery Attacks Against SSH" by
+			// Martin R. Albrecht, Kenneth G. Paterson and Gaven J. Watson,
+			// there are a class of attacks againt protocols that use similar
+			// sorts of framing schemes.
+			//
+			// While obfs4 should not allow plaintext recovery (CBC mode is
+			// not used), attempt to mitigate out of bound frame length errors
+			// by pretending that the length was a random valid range as per
+			// the countermeasure suggested by Denis Bider in section 6 of the
+			// paper.
+
+			decoder.nextLengthInvalid = true
+			length = uint16(csrand.IntRange(minFrameLength, maxFrameLength))
+		}
+		decoder.nextLength = length
+	}
+
+	if int(decoder.nextLength) > frames.Len() {
+		return 0, ErrAgain
+	}
+
+	// Unseal the frame.
+	var box [maxFrameLength]byte
+	n, err := io.ReadFull(frames, box[:decoder.nextLength])
+	if err != nil {
+		return 0, err
+	}
+	out, ok := secretbox.Open(data[:0], box[:n], &decoder.nextNonce, &decoder.key)
+	if !ok || decoder.nextLengthInvalid {
+		// When a random length is used (on length error) the tag should always
+		// mismatch, but be paranoid.
+		return 0, ErrTagMismatch
+	}
+
+	// Clean up and prepare for the next frame.
+	decoder.nextLength = 0
+	decoder.nonce.counter++
+
+	return len(out), nil
+}

vendor/gitlab.com/yawning/obfs4.git/transports/obfs4/handshake_ntor.go

@@ -0,0 +1,424 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package obfs4
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"hash"
+	"strconv"
+	"time"
+
+	"gitlab.com/yawning/obfs4.git/common/csrand"
+	"gitlab.com/yawning/obfs4.git/common/ntor"
+	"gitlab.com/yawning/obfs4.git/common/replayfilter"
+	"gitlab.com/yawning/obfs4.git/transports/obfs4/framing"
+)
+
+const (
+	maxHandshakeLength = 8192
+
+	clientMinPadLength = (serverMinHandshakeLength + inlineSeedFrameLength) -
+		clientMinHandshakeLength
+	clientMaxPadLength       = maxHandshakeLength - clientMinHandshakeLength
+	clientMinHandshakeLength = ntor.RepresentativeLength + markLength + macLength
+
+	serverMinPadLength = 0
+	serverMaxPadLength = maxHandshakeLength - (serverMinHandshakeLength +
+		inlineSeedFrameLength)
+	serverMinHandshakeLength = ntor.RepresentativeLength + ntor.AuthLength +
+		markLength + macLength
+
+	markLength = sha256.Size / 2
+	macLength  = sha256.Size / 2
+
+	inlineSeedFrameLength = framing.FrameOverhead + packetOverhead + seedPacketPayloadLength
+)
+
+// ErrMarkNotFoundYet is the error returned when the obfs4 handshake is
+// incomplete and requires more data to continue.  This error is non-fatal and
+// is the equivalent to EAGAIN/EWOULDBLOCK.
+var ErrMarkNotFoundYet = errors.New("handshake: M_[C,S] not found yet")
+
+// ErrInvalidHandshake is the error returned when the obfs4 handshake fails due
+// to the peer not sending the correct mark.  This error is fatal and the
+// connection MUST be dropped.
+var ErrInvalidHandshake = errors.New("handshake: Failed to find M_[C,S]")
+
+// ErrReplayedHandshake is the error returned when the obfs4 handshake fails
+// due it being replayed.  This error is fatal and the connection MUST be
+// dropped.
+var ErrReplayedHandshake = errors.New("handshake: Replay detected")
+
+// ErrNtorFailed is the error returned when the ntor handshake fails.  This
+// error is fatal and the connection MUST be dropped.
+var ErrNtorFailed = errors.New("handshake: ntor handshake failure")
+
+// InvalidMacError is the error returned when the handshake MACs do not match.
+// This error is fatal and the connection MUST be dropped.
+type InvalidMacError struct {
+	Derived  []byte
+	Received []byte
+}
+
+func (e *InvalidMacError) Error() string {
+	return fmt.Sprintf("handshake: MAC mismatch: Dervied: %s Received: %s.",
+		hex.EncodeToString(e.Derived), hex.EncodeToString(e.Received))
+}
+
+// InvalidAuthError is the error returned when the ntor AUTH tags do not match.
+// This error is fatal and the connection MUST be dropped.
+type InvalidAuthError struct {
+	Derived  *ntor.Auth
+	Received *ntor.Auth
+}
+
+func (e *InvalidAuthError) Error() string {
+	return fmt.Sprintf("handshake: ntor AUTH mismatch: Derived: %s Received:%s.",
+		hex.EncodeToString(e.Derived.Bytes()[:]),
+		hex.EncodeToString(e.Received.Bytes()[:]))
+}
+
+type clientHandshake struct {
+	keypair        *ntor.Keypair
+	nodeID         *ntor.NodeID
+	serverIdentity *ntor.PublicKey
+	epochHour      []byte
+
+	padLen int
+	mac    hash.Hash
+
+	serverRepresentative *ntor.Representative
+	serverAuth           *ntor.Auth
+	serverMark           []byte
+}
+
+func newClientHandshake(nodeID *ntor.NodeID, serverIdentity *ntor.PublicKey, sessionKey *ntor.Keypair) *clientHandshake {
+	hs := new(clientHandshake)
+	hs.keypair = sessionKey
+	hs.nodeID = nodeID
+	hs.serverIdentity = serverIdentity
+	hs.padLen = csrand.IntRange(clientMinPadLength, clientMaxPadLength)
+	hs.mac = hmac.New(sha256.New, append(hs.serverIdentity.Bytes()[:], hs.nodeID.Bytes()[:]...))
+
+	return hs
+}
+
+func (hs *clientHandshake) generateHandshake() ([]byte, error) {
+	var buf bytes.Buffer
+
+	hs.mac.Reset()
+	_, _ = hs.mac.Write(hs.keypair.Representative().Bytes()[:])
+	mark := hs.mac.Sum(nil)[:markLength]
+
+	// The client handshake is X | P_C | M_C | MAC(X | P_C | M_C | E) where:
+	//  * X is the client's ephemeral Curve25519 public key representative.
+	//  * P_C is [clientMinPadLength,clientMaxPadLength] bytes of random padding.
+	//  * M_C is HMAC-SHA256-128(serverIdentity | NodeID, X)
+	//  * MAC is HMAC-SHA256-128(serverIdentity | NodeID, X .... E)
+	//  * E is the string representation of the number of hours since the UNIX
+	//    epoch.
+
+	// Generate the padding
+	pad, err := makePad(hs.padLen)
+	if err != nil {
+		return nil, err
+	}
+
+	// Write X, P_C, M_C.
+	buf.Write(hs.keypair.Representative().Bytes()[:])
+	buf.Write(pad)
+	buf.Write(mark)
+
+	// Calculate and write the MAC.
+	hs.mac.Reset()
+	_, _ = hs.mac.Write(buf.Bytes())
+	hs.epochHour = []byte(strconv.FormatInt(getEpochHour(), 10))
+	_, _ = hs.mac.Write(hs.epochHour)
+	buf.Write(hs.mac.Sum(nil)[:macLength])
+
+	return buf.Bytes(), nil
+}
+
+func (hs *clientHandshake) parseServerHandshake(resp []byte) (int, []byte, error) {
+	// No point in examining the data unless the miminum plausible response has
+	// been received.
+	if serverMinHandshakeLength > len(resp) {
+		return 0, nil, ErrMarkNotFoundYet
+	}
+
+	if hs.serverRepresentative == nil || hs.serverAuth == nil {
+		// Pull out the representative/AUTH. (XXX: Add ctors to ntor)
+		hs.serverRepresentative = new(ntor.Representative)
+		copy(hs.serverRepresentative.Bytes()[:], resp[0:ntor.RepresentativeLength])
+		hs.serverAuth = new(ntor.Auth)
+		copy(hs.serverAuth.Bytes()[:], resp[ntor.RepresentativeLength:])
+
+		// Derive the mark.
+		hs.mac.Reset()
+		_, _ = hs.mac.Write(hs.serverRepresentative.Bytes()[:])
+		hs.serverMark = hs.mac.Sum(nil)[:markLength]
+	}
+
+	// Attempt to find the mark + MAC.
+	pos := findMarkMac(hs.serverMark, resp, ntor.RepresentativeLength+ntor.AuthLength+serverMinPadLength,
+		maxHandshakeLength, false)
+	if pos == -1 {
+		if len(resp) >= maxHandshakeLength {
+			return 0, nil, ErrInvalidHandshake
+		}
+		return 0, nil, ErrMarkNotFoundYet
+	}
+
+	// Validate the MAC.
+	hs.mac.Reset()
+	_, _ = hs.mac.Write(resp[:pos+markLength])
+	_, _ = hs.mac.Write(hs.epochHour)
+	macCmp := hs.mac.Sum(nil)[:macLength]
+	macRx := resp[pos+markLength : pos+markLength+macLength]
+	if !hmac.Equal(macCmp, macRx) {
+		return 0, nil, &InvalidMacError{macCmp, macRx}
+	}
+
+	// Complete the handshake.
+	serverPublic := hs.serverRepresentative.ToPublic()
+	ok, seed, auth := ntor.ClientHandshake(hs.keypair, serverPublic,
+		hs.serverIdentity, hs.nodeID)
+	if !ok {
+		return 0, nil, ErrNtorFailed
+	}
+	if !ntor.CompareAuth(auth, hs.serverAuth.Bytes()[:]) {
+		return 0, nil, &InvalidAuthError{auth, hs.serverAuth}
+	}
+
+	return pos + markLength + macLength, seed.Bytes()[:], nil
+}
+
+type serverHandshake struct {
+	keypair        *ntor.Keypair
+	nodeID         *ntor.NodeID
+	serverIdentity *ntor.Keypair
+	epochHour      []byte
+	serverAuth     *ntor.Auth
+
+	padLen int
+	mac    hash.Hash
+
+	clientRepresentative *ntor.Representative
+	clientMark           []byte
+}
+
+func newServerHandshake(nodeID *ntor.NodeID, serverIdentity *ntor.Keypair, sessionKey *ntor.Keypair) *serverHandshake {
+	hs := new(serverHandshake)
+	hs.keypair = sessionKey
+	hs.nodeID = nodeID
+	hs.serverIdentity = serverIdentity
+	hs.padLen = csrand.IntRange(serverMinPadLength, serverMaxPadLength)
+	hs.mac = hmac.New(sha256.New, append(hs.serverIdentity.Public().Bytes()[:], hs.nodeID.Bytes()[:]...))
+
+	return hs
+}
+
+func (hs *serverHandshake) parseClientHandshake(filter *replayfilter.ReplayFilter, resp []byte) ([]byte, error) {
+	// No point in examining the data unless the miminum plausible response has
+	// been received.
+	if clientMinHandshakeLength > len(resp) {
+		return nil, ErrMarkNotFoundYet
+	}
+
+	if hs.clientRepresentative == nil {
+		// Pull out the representative/AUTH. (XXX: Add ctors to ntor)
+		hs.clientRepresentative = new(ntor.Representative)
+		copy(hs.clientRepresentative.Bytes()[:], resp[0:ntor.RepresentativeLength])
+
+		// Derive the mark.
+		hs.mac.Reset()
+		_, _ = hs.mac.Write(hs.clientRepresentative.Bytes()[:])
+		hs.clientMark = hs.mac.Sum(nil)[:markLength]
+	}
+
+	// Attempt to find the mark + MAC.
+	pos := findMarkMac(hs.clientMark, resp, ntor.RepresentativeLength+clientMinPadLength,
+		maxHandshakeLength, true)
+	if pos == -1 {
+		if len(resp) >= maxHandshakeLength {
+			return nil, ErrInvalidHandshake
+		}
+		return nil, ErrMarkNotFoundYet
+	}
+
+	// Validate the MAC.
+	macFound := false
+	for _, off := range []int64{0, -1, 1} {
+		// Allow epoch to be off by up to a hour in either direction.
+		epochHour := []byte(strconv.FormatInt(getEpochHour()+int64(off), 10))
+		hs.mac.Reset()
+		_, _ = hs.mac.Write(resp[:pos+markLength])
+		_, _ = hs.mac.Write(epochHour)
+		macCmp := hs.mac.Sum(nil)[:macLength]
+		macRx := resp[pos+markLength : pos+markLength+macLength]
+		if hmac.Equal(macCmp, macRx) {
+			// Ensure that this handshake has not been seen previously.
+			if filter.TestAndSet(time.Now(), macRx) {
+				// The client either happened to generate exactly the same
+				// session key and padding, or someone is replaying a previous
+				// handshake.  In either case, fuck them.
+				return nil, ErrReplayedHandshake
+			}
+
+			macFound = true
+			hs.epochHour = epochHour
+
+			// We could break out here, but in the name of reducing timing
+			// variation, evaluate all 3 MACs.
+		}
+	}
+	if !macFound {
+		// This probably should be an InvalidMacError, but conveying the 3 MACS
+		// that would be accepted is annoying so just return a generic fatal
+		// failure.
+		return nil, ErrInvalidHandshake
+	}
+
+	// Client should never sent trailing garbage.
+	if len(resp) != pos+markLength+macLength {
+		return nil, ErrInvalidHandshake
+	}
+
+	clientPublic := hs.clientRepresentative.ToPublic()
+	ok, seed, auth := ntor.ServerHandshake(clientPublic, hs.keypair,
+		hs.serverIdentity, hs.nodeID)
+	if !ok {
+		return nil, ErrNtorFailed
+	}
+	hs.serverAuth = auth
+
+	return seed.Bytes()[:], nil
+}
+
+func (hs *serverHandshake) generateHandshake() ([]byte, error) {
+	var buf bytes.Buffer
+
+	hs.mac.Reset()
+	_, _ = hs.mac.Write(hs.keypair.Representative().Bytes()[:])
+	mark := hs.mac.Sum(nil)[:markLength]
+
+	// The server handshake is Y | AUTH | P_S | M_S | MAC(Y | AUTH | P_S | M_S | E) where:
+	//  * Y is the server's ephemeral Curve25519 public key representative.
+	//  * AUTH is the ntor handshake AUTH value.
+	//  * P_S is [serverMinPadLength,serverMaxPadLength] bytes of random padding.
+	//  * M_S is HMAC-SHA256-128(serverIdentity | NodeID, Y)
+	//  * MAC is HMAC-SHA256-128(serverIdentity | NodeID, Y .... E)
+	//  * E is the string representation of the number of hours since the UNIX
+	//    epoch.
+
+	// Generate the padding
+	pad, err := makePad(hs.padLen)
+	if err != nil {
+		return nil, err
+	}
+
+	// Write Y, AUTH, P_S, M_S.
+	buf.Write(hs.keypair.Representative().Bytes()[:])
+	buf.Write(hs.serverAuth.Bytes()[:])
+	buf.Write(pad)
+	buf.Write(mark)
+
+	// Calculate and write the MAC.
+	hs.mac.Reset()
+	_, _ = hs.mac.Write(buf.Bytes())
+	_, _ = hs.mac.Write(hs.epochHour) // Set in hs.parseClientHandshake()
+	buf.Write(hs.mac.Sum(nil)[:macLength])
+
+	return buf.Bytes(), nil
+}
+
+// getEpochHour returns the number of hours since the UNIX epoch.
+func getEpochHour() int64 {
+	return time.Now().Unix() / 3600
+}
+
+func findMarkMac(mark, buf []byte, startPos, maxPos int, fromTail bool) (pos int) {
+	if len(mark) != markLength {
+		panic(fmt.Sprintf("BUG: Invalid mark length: %d", len(mark)))
+	}
+
+	endPos := len(buf)
+	if startPos > len(buf) {
+		return -1
+	}
+	if endPos > maxPos {
+		endPos = maxPos
+	}
+	if endPos-startPos < markLength+macLength {
+		return -1
+	}
+
+	if fromTail {
+		// The server can optimize the search process by only examining the
+		// tail of the buffer.  The client can't send valid data past M_C |
+		// MAC_C as it does not have the server's public key yet.
+		pos = endPos - (markLength + macLength)
+		if !hmac.Equal(buf[pos:pos+markLength], mark) {
+			return -1
+		}
+
+		return
+	}
+
+	// The client has to actually do a substring search since the server can
+	// and will send payload trailing the response.
+	//
+	// XXX: bytes.Index() uses a naive search, which kind of sucks.
+	pos = bytes.Index(buf[startPos:endPos], mark)
+	if pos == -1 {
+		return -1
+	}
+
+	// Ensure that there is enough trailing data for the MAC.
+	if startPos+pos+markLength+macLength > endPos {
+		return -1
+	}
+
+	// Return the index relative to the start of the slice.
+	pos += startPos
+	return
+}
+
+func makePad(padLen int) ([]byte, error) {
+	pad := make([]byte, padLen)
+	if err := csrand.Bytes(pad); err != nil {
+		return nil, err
+	}
+
+	return pad, nil
+}

vendor/gitlab.com/yawning/obfs4.git/transports/obfs4/obfs4.go

@@ -0,0 +1,647 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+// Package obfs4 provides an implementation of the Tor Project's obfs4
+// obfuscation protocol.
+package obfs4 // import "gitlab.com/yawning/obfs4.git/transports/obfs4"
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"flag"
+	"fmt"
+	"math/rand"
+	"net"
+	"strconv"
+	"syscall"
+	"time"
+
+	"git.torproject.org/pluggable-transports/goptlib.git"
+	"gitlab.com/yawning/obfs4.git/common/drbg"
+	"gitlab.com/yawning/obfs4.git/common/ntor"
+	"gitlab.com/yawning/obfs4.git/common/probdist"
+	"gitlab.com/yawning/obfs4.git/common/replayfilter"
+	"gitlab.com/yawning/obfs4.git/transports/base"
+	"gitlab.com/yawning/obfs4.git/transports/obfs4/framing"
+)
+
+const (
+	transportName = "obfs4"
+
+	nodeIDArg     = "node-id"
+	publicKeyArg  = "public-key"
+	privateKeyArg = "private-key"
+	seedArg       = "drbg-seed"
+	iatArg        = "iat-mode"
+	certArg       = "cert"
+
+	biasCmdArg = "obfs4-distBias"
+
+	seedLength             = drbg.SeedLength
+	headerLength           = framing.FrameOverhead + packetOverhead
+	clientHandshakeTimeout = time.Duration(60) * time.Second
+	serverHandshakeTimeout = time.Duration(30) * time.Second
+	replayTTL              = time.Duration(3) * time.Hour
+
+	maxIATDelay        = 100
+	maxCloseDelayBytes = maxHandshakeLength
+	maxCloseDelay      = 60
+)
+
+const (
+	iatNone = iota
+	iatEnabled
+	iatParanoid
+)
+
+// biasedDist controls if the probability table will be ScrambleSuit style or
+// uniformly distributed.
+var biasedDist bool
+
+type obfs4ClientArgs struct {
+	nodeID     *ntor.NodeID
+	publicKey  *ntor.PublicKey
+	sessionKey *ntor.Keypair
+	iatMode    int
+}
+
+// Transport is the obfs4 implementation of the base.Transport interface.
+type Transport struct{}
+
+// Name returns the name of the obfs4 transport protocol.
+func (t *Transport) Name() string {
+	return transportName
+}
+
+// ClientFactory returns a new obfs4ClientFactory instance.
+func (t *Transport) ClientFactory(stateDir string) (base.ClientFactory, error) {
+	cf := &obfs4ClientFactory{transport: t}
+	return cf, nil
+}
+
+// ServerFactory returns a new obfs4ServerFactory instance.
+func (t *Transport) ServerFactory(stateDir string, args *pt.Args) (base.ServerFactory, error) {
+	st, err := serverStateFromArgs(stateDir, args)
+	if err != nil {
+		return nil, err
+	}
+
+	var iatSeed *drbg.Seed
+	if st.iatMode != iatNone {
+		iatSeedSrc := sha256.Sum256(st.drbgSeed.Bytes()[:])
+		var err error
+		iatSeed, err = drbg.SeedFromBytes(iatSeedSrc[:])
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// Store the arguments that should appear in our descriptor for the clients.
+	ptArgs := pt.Args{}
+	ptArgs.Add(certArg, st.cert.String())
+	ptArgs.Add(iatArg, strconv.Itoa(st.iatMode))
+
+	// Initialize the replay filter.
+	filter, err := replayfilter.New(replayTTL)
+	if err != nil {
+		return nil, err
+	}
+
+	// Initialize the close thresholds for failed connections.
+	drbg, err := drbg.NewHashDrbg(st.drbgSeed)
+	if err != nil {
+		return nil, err
+	}
+	rng := rand.New(drbg)
+
+	sf := &obfs4ServerFactory{t, &ptArgs, st.nodeID, st.identityKey, st.drbgSeed, iatSeed, st.iatMode, filter, rng.Intn(maxCloseDelayBytes), rng.Intn(maxCloseDelay)}
+	return sf, nil
+}
+
+type obfs4ClientFactory struct {
+	transport base.Transport
+}
+
+func (cf *obfs4ClientFactory) Transport() base.Transport {
+	return cf.transport
+}
+
+func (cf *obfs4ClientFactory) ParseArgs(args *pt.Args) (interface{}, error) {
+	var nodeID *ntor.NodeID
+	var publicKey *ntor.PublicKey
+
+	// The "new" (version >= 0.0.3) bridge lines use a unified "cert" argument
+	// for the Node ID and Public Key.
+	certStr, ok := args.Get(certArg)
+	if ok {
+		cert, err := serverCertFromString(certStr)
+		if err != nil {
+			return nil, err
+		}
+		nodeID, publicKey = cert.unpack()
+	} else {
+		// The "old" style (version <= 0.0.2) bridge lines use separate Node ID
+		// and Public Key arguments in Base16 encoding and are a UX disaster.
+		nodeIDStr, ok := args.Get(nodeIDArg)
+		if !ok {
+			return nil, fmt.Errorf("missing argument '%s'", nodeIDArg)
+		}
+		var err error
+		if nodeID, err = ntor.NodeIDFromHex(nodeIDStr); err != nil {
+			return nil, err
+		}
+
+		publicKeyStr, ok := args.Get(publicKeyArg)
+		if !ok {
+			return nil, fmt.Errorf("missing argument '%s'", publicKeyArg)
+		}
+		if publicKey, err = ntor.PublicKeyFromHex(publicKeyStr); err != nil {
+			return nil, err
+		}
+	}
+
+	// IAT config is common across the two bridge line formats.
+	iatStr, ok := args.Get(iatArg)
+	if !ok {
+		return nil, fmt.Errorf("missing argument '%s'", iatArg)
+	}
+	iatMode, err := strconv.Atoi(iatStr)
+	if err != nil || iatMode < iatNone || iatMode > iatParanoid {
+		return nil, fmt.Errorf("invalid iat-mode '%d'", iatMode)
+	}
+
+	// Generate the session key pair before connectiong to hide the Elligator2
+	// rejection sampling from network observers.
+	sessionKey, err := ntor.NewKeypair(true)
+	if err != nil {
+		return nil, err
+	}
+
+	return &obfs4ClientArgs{nodeID, publicKey, sessionKey, iatMode}, nil
+}
+
+func (cf *obfs4ClientFactory) Dial(network, addr string, dialFn base.DialFunc, args interface{}) (net.Conn, error) {
+	// Validate args before bothering to open connection.
+	ca, ok := args.(*obfs4ClientArgs)
+	if !ok {
+		return nil, fmt.Errorf("invalid argument type for args")
+	}
+	conn, err := dialFn(network, addr)
+	if err != nil {
+		return nil, err
+	}
+	dialConn := conn
+	if conn, err = newObfs4ClientConn(conn, ca); err != nil {
+		dialConn.Close()
+		return nil, err
+	}
+	return conn, nil
+}
+
+type obfs4ServerFactory struct {
+	transport base.Transport
+	args      *pt.Args
+
+	nodeID       *ntor.NodeID
+	identityKey  *ntor.Keypair
+	lenSeed      *drbg.Seed
+	iatSeed      *drbg.Seed
+	iatMode      int
+	replayFilter *replayfilter.ReplayFilter
+
+	closeDelayBytes int
+	closeDelay      int
+}
+
+func (sf *obfs4ServerFactory) Transport() base.Transport {
+	return sf.transport
+}
+
+func (sf *obfs4ServerFactory) Args() *pt.Args {
+	return sf.args
+}
+
+func (sf *obfs4ServerFactory) WrapConn(conn net.Conn) (net.Conn, error) {
+	// Not much point in having a separate newObfs4ServerConn routine when
+	// wrapping requires using values from the factory instance.
+
+	// Generate the session keypair *before* consuming data from the peer, to
+	// attempt to mask the rejection sampling due to use of Elligator2.  This
+	// might be futile, but the timing differential isn't very large on modern
+	// hardware, and there are far easier statistical attacks that can be
+	// mounted as a distinguisher.
+	sessionKey, err := ntor.NewKeypair(true)
+	if err != nil {
+		return nil, err
+	}
+
+	lenDist := probdist.New(sf.lenSeed, 0, framing.MaximumSegmentLength, biasedDist)
+	var iatDist *probdist.WeightedDist
+	if sf.iatSeed != nil {
+		iatDist = probdist.New(sf.iatSeed, 0, maxIATDelay, biasedDist)
+	}
+
+	c := &obfs4Conn{conn, true, lenDist, iatDist, sf.iatMode, bytes.NewBuffer(nil), bytes.NewBuffer(nil), make([]byte, consumeReadSize), nil, nil}
+
+	startTime := time.Now()
+
+	if err = c.serverHandshake(sf, sessionKey); err != nil {
+		c.closeAfterDelay(sf, startTime)
+		return nil, err
+	}
+
+	return c, nil
+}
+
+type obfs4Conn struct {
+	net.Conn
+
+	isServer bool
+
+	lenDist *probdist.WeightedDist
+	iatDist *probdist.WeightedDist
+	iatMode int
+
+	receiveBuffer        *bytes.Buffer
+	receiveDecodedBuffer *bytes.Buffer
+	readBuffer           []byte
+
+	encoder *framing.Encoder
+	decoder *framing.Decoder
+}
+
+func newObfs4ClientConn(conn net.Conn, args *obfs4ClientArgs) (c *obfs4Conn, err error) {
+	// Generate the initial protocol polymorphism distribution(s).
+	var seed *drbg.Seed
+	if seed, err = drbg.NewSeed(); err != nil {
+		return
+	}
+	lenDist := probdist.New(seed, 0, framing.MaximumSegmentLength, biasedDist)
+	var iatDist *probdist.WeightedDist
+	if args.iatMode != iatNone {
+		var iatSeed *drbg.Seed
+		iatSeedSrc := sha256.Sum256(seed.Bytes()[:])
+		if iatSeed, err = drbg.SeedFromBytes(iatSeedSrc[:]); err != nil {
+			return
+		}
+		iatDist = probdist.New(iatSeed, 0, maxIATDelay, biasedDist)
+	}
+
+	// Allocate the client structure.
+	c = &obfs4Conn{conn, false, lenDist, iatDist, args.iatMode, bytes.NewBuffer(nil), bytes.NewBuffer(nil), make([]byte, consumeReadSize), nil, nil}
+
+	// Start the handshake timeout.
+	deadline := time.Now().Add(clientHandshakeTimeout)
+	if err = conn.SetDeadline(deadline); err != nil {
+		return nil, err
+	}
+
+	if err = c.clientHandshake(args.nodeID, args.publicKey, args.sessionKey); err != nil {
+		return nil, err
+	}
+
+	// Stop the handshake timeout.
+	if err = conn.SetDeadline(time.Time{}); err != nil {
+		return nil, err
+	}
+
+	return
+}
+
+func (conn *obfs4Conn) clientHandshake(nodeID *ntor.NodeID, peerIdentityKey *ntor.PublicKey, sessionKey *ntor.Keypair) error {
+	if conn.isServer {
+		return fmt.Errorf("clientHandshake called on server connection")
+	}
+
+	// Generate and send the client handshake.
+	hs := newClientHandshake(nodeID, peerIdentityKey, sessionKey)
+	blob, err := hs.generateHandshake()
+	if err != nil {
+		return err
+	}
+	if _, err = conn.Conn.Write(blob); err != nil {
+		return err
+	}
+
+	// Consume the server handshake.
+	var hsBuf [maxHandshakeLength]byte
+	for {
+		n, err := conn.Conn.Read(hsBuf[:])
+		if err != nil {
+			// The Read() could have returned data and an error, but there is
+			// no point in continuing on an EOF or whatever.
+			return err
+		}
+		conn.receiveBuffer.Write(hsBuf[:n])
+
+		n, seed, err := hs.parseServerHandshake(conn.receiveBuffer.Bytes())
+		if err == ErrMarkNotFoundYet {
+			continue
+		} else if err != nil {
+			return err
+		}
+		_ = conn.receiveBuffer.Next(n)
+
+		// Use the derived key material to intialize the link crypto.
+		okm := ntor.Kdf(seed, framing.KeyLength*2)
+		conn.encoder = framing.NewEncoder(okm[:framing.KeyLength])
+		conn.decoder = framing.NewDecoder(okm[framing.KeyLength:])
+
+		return nil
+	}
+}
+
+func (conn *obfs4Conn) serverHandshake(sf *obfs4ServerFactory, sessionKey *ntor.Keypair) error {
+	if !conn.isServer {
+		return fmt.Errorf("serverHandshake called on client connection")
+	}
+
+	// Generate the server handshake, and arm the base timeout.
+	hs := newServerHandshake(sf.nodeID, sf.identityKey, sessionKey)
+	if err := conn.Conn.SetDeadline(time.Now().Add(serverHandshakeTimeout)); err != nil {
+		return err
+	}
+
+	// Consume the client handshake.
+	var hsBuf [maxHandshakeLength]byte
+	for {
+		n, err := conn.Conn.Read(hsBuf[:])
+		if err != nil {
+			// The Read() could have returned data and an error, but there is
+			// no point in continuing on an EOF or whatever.
+			return err
+		}
+		conn.receiveBuffer.Write(hsBuf[:n])
+
+		seed, err := hs.parseClientHandshake(sf.replayFilter, conn.receiveBuffer.Bytes())
+		if err == ErrMarkNotFoundYet {
+			continue
+		} else if err != nil {
+			return err
+		}
+		conn.receiveBuffer.Reset()
+
+		if err := conn.Conn.SetDeadline(time.Time{}); err != nil {
+			return nil
+		}
+
+		// Use the derived key material to intialize the link crypto.
+		okm := ntor.Kdf(seed, framing.KeyLength*2)
+		conn.encoder = framing.NewEncoder(okm[framing.KeyLength:])
+		conn.decoder = framing.NewDecoder(okm[:framing.KeyLength])
+
+		break
+	}
+
+	// Since the current and only implementation always sends a PRNG seed for
+	// the length obfuscation, this makes the amount of data received from the
+	// server inconsistent with the length sent from the client.
+	//
+	// Rebalance this by tweaking the client mimimum padding/server maximum
+	// padding, and sending the PRNG seed unpadded (As in, treat the PRNG seed
+	// as part of the server response).  See inlineSeedFrameLength in
+	// handshake_ntor.go.
+
+	// Generate/send the response.
+	blob, err := hs.generateHandshake()
+	if err != nil {
+		return err
+	}
+	var frameBuf bytes.Buffer
+	if _, err = frameBuf.Write(blob); err != nil {
+		return err
+	}
+
+	// Send the PRNG seed as the first packet.
+	if err := conn.makePacket(&frameBuf, packetTypePrngSeed, sf.lenSeed.Bytes()[:], 0); err != nil {
+		return err
+	}
+	if _, err = conn.Conn.Write(frameBuf.Bytes()); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (conn *obfs4Conn) Read(b []byte) (n int, err error) {
+	// If there is no payload from the previous Read() calls, consume data off
+	// the network.  Not all data received is guaranteed to be usable payload,
+	// so do this in a loop till data is present or an error occurs.
+	for conn.receiveDecodedBuffer.Len() == 0 {
+		err = conn.readPackets()
+		if err == framing.ErrAgain {
+			// Don't proagate this back up the call stack if we happen to break
+			// out of the loop.
+			err = nil
+			continue
+		} else if err != nil {
+			break
+		}
+	}
+
+	// Even if err is set, attempt to do the read anyway so that all decoded
+	// data gets relayed before the connection is torn down.
+	if conn.receiveDecodedBuffer.Len() > 0 {
+		var berr error
+		n, berr = conn.receiveDecodedBuffer.Read(b)
+		if err == nil {
+			// Only propagate berr if there are not more important (fatal)
+			// errors from the network/crypto/packet processing.
+			err = berr
+		}
+	}
+
+	return
+}
+
+func (conn *obfs4Conn) Write(b []byte) (n int, err error) {
+	chopBuf := bytes.NewBuffer(b)
+	var payload [maxPacketPayloadLength]byte
+	var frameBuf bytes.Buffer
+
+	// Chop the pending data into payload frames.
+	for chopBuf.Len() > 0 {
+		// Send maximum sized frames.
+		rdLen := 0
+		rdLen, err = chopBuf.Read(payload[:])
+		if err != nil {
+			return 0, err
+		} else if rdLen == 0 {
+			panic(fmt.Sprintf("BUG: Write(), chopping length was 0"))
+		}
+		n += rdLen
+
+		err = conn.makePacket(&frameBuf, packetTypePayload, payload[:rdLen], 0)
+		if err != nil {
+			return 0, err
+		}
+	}
+
+	if conn.iatMode != iatParanoid {
+		// For non-paranoid IAT, pad once per burst.  Paranoid IAT handles
+		// things differently.
+		if err = conn.padBurst(&frameBuf, conn.lenDist.Sample()); err != nil {
+			return 0, err
+		}
+	}
+
+	// Write the pending data onto the network.  Partial writes are fatal,
+	// because the frame encoder state is advanced, and the code doesn't keep
+	// frameBuf around.  In theory, write timeouts and whatnot could be
+	// supported if this wasn't the case, but that complicates the code.
+	if conn.iatMode != iatNone {
+		var iatFrame [framing.MaximumSegmentLength]byte
+		for frameBuf.Len() > 0 {
+			iatWrLen := 0
+
+			switch conn.iatMode {
+			case iatEnabled:
+				// Standard (ScrambleSuit-style) IAT obfuscation optimizes for
+				// bulk transport and will write ~MTU sized frames when
+				// possible.
+				iatWrLen, err = frameBuf.Read(iatFrame[:])
+
+			case iatParanoid:
+				// Paranoid IAT obfuscation throws performance out of the
+				// window and will sample the length distribution every time a
+				// write is scheduled.
+				targetLen := conn.lenDist.Sample()
+				if frameBuf.Len() < targetLen {
+					// There's not enough data buffered for the target write,
+					// so padding must be inserted.
+					if err = conn.padBurst(&frameBuf, targetLen); err != nil {
+						return 0, err
+					}
+					if frameBuf.Len() != targetLen {
+						// Ugh, padding came out to a value that required more
+						// than one frame, this is relatively unlikely so just
+						// resample since there's enough data to ensure that
+						// the next sample will be written.
+						continue
+					}
+				}
+				iatWrLen, err = frameBuf.Read(iatFrame[:targetLen])
+			}
+			if err != nil {
+				return 0, err
+			} else if iatWrLen == 0 {
+				panic(fmt.Sprintf("BUG: Write(), iat length was 0"))
+			}
+
+			// Calculate the delay.  The delay resolution is 100 usec, leading
+			// to a maximum delay of 10 msec.
+			iatDelta := time.Duration(conn.iatDist.Sample() * 100)
+
+			// Write then sleep.
+			_, err = conn.Conn.Write(iatFrame[:iatWrLen])
+			if err != nil {
+				return 0, err
+			}
+			time.Sleep(iatDelta * time.Microsecond)
+		}
+	} else {
+		_, err = conn.Conn.Write(frameBuf.Bytes())
+	}
+
+	return
+}
+
+func (conn *obfs4Conn) SetDeadline(t time.Time) error {
+	return syscall.ENOTSUP
+}
+
+func (conn *obfs4Conn) SetWriteDeadline(t time.Time) error {
+	return syscall.ENOTSUP
+}
+
+func (conn *obfs4Conn) closeAfterDelay(sf *obfs4ServerFactory, startTime time.Time) {
+	// I-it's not like I w-wanna handshake with you or anything.  B-b-baka!
+	defer conn.Conn.Close()
+
+	delay := time.Duration(sf.closeDelay)*time.Second + serverHandshakeTimeout
+	deadline := startTime.Add(delay)
+	if time.Now().After(deadline) {
+		return
+	}
+
+	if err := conn.Conn.SetReadDeadline(deadline); err != nil {
+		return
+	}
+
+	// Consume and discard data on this connection until either the specified
+	// interval passes or a certain size has been reached.
+	discarded := 0
+	var buf [framing.MaximumSegmentLength]byte
+	for discarded < int(sf.closeDelayBytes) {
+		n, err := conn.Conn.Read(buf[:])
+		if err != nil {
+			return
+		}
+		discarded += n
+	}
+}
+
+func (conn *obfs4Conn) padBurst(burst *bytes.Buffer, toPadTo int) (err error) {
+	tailLen := burst.Len() % framing.MaximumSegmentLength
+
+	padLen := 0
+	if toPadTo >= tailLen {
+		padLen = toPadTo - tailLen
+	} else {
+		padLen = (framing.MaximumSegmentLength - tailLen) + toPadTo
+	}
+
+	if padLen > headerLength {
+		err = conn.makePacket(burst, packetTypePayload, []byte{},
+			uint16(padLen-headerLength))
+		if err != nil {
+			return
+		}
+	} else if padLen > 0 {
+		err = conn.makePacket(burst, packetTypePayload, []byte{},
+			maxPacketPayloadLength)
+		if err != nil {
+			return
+		}
+		err = conn.makePacket(burst, packetTypePayload, []byte{},
+			uint16(padLen))
+		if err != nil {
+			return
+		}
+	}
+
+	return
+}
+
+func init() {
+	flag.BoolVar(&biasedDist, biasCmdArg, false, "Enable obfs4 using ScrambleSuit style table generation")
+}
+
+var _ base.ClientFactory = (*obfs4ClientFactory)(nil)
+var _ base.ServerFactory = (*obfs4ServerFactory)(nil)
+var _ base.Transport = (*Transport)(nil)
+var _ net.Conn = (*obfs4Conn)(nil)

vendor/gitlab.com/yawning/obfs4.git/transports/obfs4/packet.go

@@ -0,0 +1,175 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package obfs4
+
+import (
+	"crypto/sha256"
+	"encoding/binary"
+	"fmt"
+	"io"
+
+	"gitlab.com/yawning/obfs4.git/common/drbg"
+	"gitlab.com/yawning/obfs4.git/transports/obfs4/framing"
+)
+
+const (
+	packetOverhead          = 2 + 1
+	maxPacketPayloadLength  = framing.MaximumFramePayloadLength - packetOverhead
+	maxPacketPaddingLength  = maxPacketPayloadLength
+	seedPacketPayloadLength = seedLength
+
+	consumeReadSize = framing.MaximumSegmentLength * 16
+)
+
+const (
+	packetTypePayload = iota
+	packetTypePrngSeed
+)
+
+// InvalidPacketLengthError is the error returned when decodePacket detects a
+// invalid packet length/
+type InvalidPacketLengthError int
+
+func (e InvalidPacketLengthError) Error() string {
+	return fmt.Sprintf("packet: Invalid packet length: %d", int(e))
+}
+
+// InvalidPayloadLengthError is the error returned when decodePacket rejects the
+// payload length.
+type InvalidPayloadLengthError int
+
+func (e InvalidPayloadLengthError) Error() string {
+	return fmt.Sprintf("packet: Invalid payload length: %d", int(e))
+}
+
+var zeroPadBytes [maxPacketPaddingLength]byte
+
+func (conn *obfs4Conn) makePacket(w io.Writer, pktType uint8, data []byte, padLen uint16) error {
+	var pkt [framing.MaximumFramePayloadLength]byte
+
+	if len(data)+int(padLen) > maxPacketPayloadLength {
+		panic(fmt.Sprintf("BUG: makePacket() len(data) + padLen > maxPacketPayloadLength: %d + %d > %d",
+			len(data), padLen, maxPacketPayloadLength))
+	}
+
+	// Packets are:
+	//   uint8_t type      packetTypePayload (0x00)
+	//   uint16_t length   Length of the payload (Big Endian).
+	//   uint8_t[] payload Data payload.
+	//   uint8_t[] padding Padding.
+	pkt[0] = pktType
+	binary.BigEndian.PutUint16(pkt[1:], uint16(len(data)))
+	if len(data) > 0 {
+		copy(pkt[3:], data[:])
+	}
+	copy(pkt[3+len(data):], zeroPadBytes[:padLen])
+
+	pktLen := packetOverhead + len(data) + int(padLen)
+
+	// Encode the packet in an AEAD frame.
+	var frame [framing.MaximumSegmentLength]byte
+	frameLen, err := conn.encoder.Encode(frame[:], pkt[:pktLen])
+	if err != nil {
+		// All encoder errors are fatal.
+		return err
+	}
+	wrLen, err := w.Write(frame[:frameLen])
+	if err != nil {
+		return err
+	} else if wrLen < frameLen {
+		return io.ErrShortWrite
+	}
+
+	return nil
+}
+
+func (conn *obfs4Conn) readPackets() (err error) {
+	// Attempt to read off the network.
+	rdLen, rdErr := conn.Conn.Read(conn.readBuffer)
+	conn.receiveBuffer.Write(conn.readBuffer[:rdLen])
+
+	var decoded [framing.MaximumFramePayloadLength]byte
+	for conn.receiveBuffer.Len() > 0 {
+		// Decrypt an AEAD frame.
+		decLen := 0
+		decLen, err = conn.decoder.Decode(decoded[:], conn.receiveBuffer)
+		if err == framing.ErrAgain {
+			break
+		} else if err != nil {
+			break
+		} else if decLen < packetOverhead {
+			err = InvalidPacketLengthError(decLen)
+			break
+		}
+
+		// Decode the packet.
+		pkt := decoded[0:decLen]
+		pktType := pkt[0]
+		payloadLen := binary.BigEndian.Uint16(pkt[1:])
+		if int(payloadLen) > len(pkt)-packetOverhead {
+			err = InvalidPayloadLengthError(int(payloadLen))
+			break
+		}
+		payload := pkt[3 : 3+payloadLen]
+
+		switch pktType {
+		case packetTypePayload:
+			if payloadLen > 0 {
+				conn.receiveDecodedBuffer.Write(payload)
+			}
+		case packetTypePrngSeed:
+			// Only regenerate the distribution if we are the client.
+			if len(payload) == seedPacketPayloadLength && !conn.isServer {
+				var seed *drbg.Seed
+				seed, err = drbg.SeedFromBytes(payload)
+				if err != nil {
+					break
+				}
+				conn.lenDist.Reset(seed)
+				if conn.iatDist != nil {
+					iatSeedSrc := sha256.Sum256(seed.Bytes()[:])
+					iatSeed, err := drbg.SeedFromBytes(iatSeedSrc[:])
+					if err != nil {
+						break
+					}
+					conn.iatDist.Reset(iatSeed)
+				}
+			}
+		default:
+			// Ignore unknown packet types.
+		}
+	}
+
+	// Read errors (all fatal) take priority over various frame processing
+	// errors.
+	if rdErr != nil {
+		return rdErr
+	}
+
+	return
+}

vendor/gitlab.com/yawning/obfs4.git/transports/obfs4/statefile.go

@@ -0,0 +1,260 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package obfs4
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"strconv"
+	"strings"
+
+	"git.torproject.org/pluggable-transports/goptlib.git"
+	"gitlab.com/yawning/obfs4.git/common/csrand"
+	"gitlab.com/yawning/obfs4.git/common/drbg"
+	"gitlab.com/yawning/obfs4.git/common/ntor"
+)
+
+const (
+	stateFile  = "obfs4_state.json"
+	bridgeFile = "obfs4_bridgeline.txt"
+
+	certSuffix = "=="
+	certLength = ntor.NodeIDLength + ntor.PublicKeyLength
+)
+
+type jsonServerState struct {
+	NodeID     string `json:"node-id"`
+	PrivateKey string `json:"private-key"`
+	PublicKey  string `json:"public-key"`
+	DrbgSeed   string `json:"drbg-seed"`
+	IATMode    int    `json:"iat-mode"`
+}
+
+type obfs4ServerCert struct {
+	raw []byte
+}
+
+func (cert *obfs4ServerCert) String() string {
+	return strings.TrimSuffix(base64.StdEncoding.EncodeToString(cert.raw), certSuffix)
+}
+
+func (cert *obfs4ServerCert) unpack() (*ntor.NodeID, *ntor.PublicKey) {
+	if len(cert.raw) != certLength {
+		panic(fmt.Sprintf("cert length %d is invalid", len(cert.raw)))
+	}
+
+	nodeID, _ := ntor.NewNodeID(cert.raw[:ntor.NodeIDLength])
+	pubKey, _ := ntor.NewPublicKey(cert.raw[ntor.NodeIDLength:])
+
+	return nodeID, pubKey
+}
+
+func serverCertFromString(encoded string) (*obfs4ServerCert, error) {
+	decoded, err := base64.StdEncoding.DecodeString(encoded + certSuffix)
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode cert: %s", err)
+	}
+
+	if len(decoded) != certLength {
+		return nil, fmt.Errorf("cert length %d is invalid", len(decoded))
+	}
+
+	return &obfs4ServerCert{raw: decoded}, nil
+}
+
+func serverCertFromState(st *obfs4ServerState) *obfs4ServerCert {
+	cert := new(obfs4ServerCert)
+	cert.raw = append(st.nodeID.Bytes()[:], st.identityKey.Public().Bytes()[:]...)
+	return cert
+}
+
+type obfs4ServerState struct {
+	nodeID      *ntor.NodeID
+	identityKey *ntor.Keypair
+	drbgSeed    *drbg.Seed
+	iatMode     int
+
+	cert *obfs4ServerCert
+}
+
+func (st *obfs4ServerState) clientString() string {
+	return fmt.Sprintf("%s=%s %s=%d", certArg, st.cert, iatArg, st.iatMode)
+}
+
+func serverStateFromArgs(stateDir string, args *pt.Args) (*obfs4ServerState, error) {
+	var js jsonServerState
+	var nodeIDOk, privKeyOk, seedOk bool
+
+	js.NodeID, nodeIDOk = args.Get(nodeIDArg)
+	js.PrivateKey, privKeyOk = args.Get(privateKeyArg)
+	js.DrbgSeed, seedOk = args.Get(seedArg)
+	iatStr, iatOk := args.Get(iatArg)
+
+	// Either a private key, node id, and seed are ALL specified, or
+	// they should be loaded from the state file.
+	if !privKeyOk && !nodeIDOk && !seedOk {
+		if err := jsonServerStateFromFile(stateDir, &js); err != nil {
+			return nil, err
+		}
+	} else if !privKeyOk {
+		return nil, fmt.Errorf("missing argument '%s'", privateKeyArg)
+	} else if !nodeIDOk {
+		return nil, fmt.Errorf("missing argument '%s'", nodeIDArg)
+	} else if !seedOk {
+		return nil, fmt.Errorf("missing argument '%s'", seedArg)
+	}
+
+	// The IAT mode should be independently configurable.
+	if iatOk {
+		// If the IAT mode is specified, attempt to parse and apply it
+		// as an override.
+		iatMode, err := strconv.Atoi(iatStr)
+		if err != nil {
+			return nil, fmt.Errorf("malformed iat-mode '%s'", iatStr)
+		}
+		js.IATMode = iatMode
+	}
+
+	return serverStateFromJSONServerState(stateDir, &js)
+}
+
+func serverStateFromJSONServerState(stateDir string, js *jsonServerState) (*obfs4ServerState, error) {
+	var err error
+
+	st := new(obfs4ServerState)
+	if st.nodeID, err = ntor.NodeIDFromHex(js.NodeID); err != nil {
+		return nil, err
+	}
+	if st.identityKey, err = ntor.KeypairFromHex(js.PrivateKey); err != nil {
+		return nil, err
+	}
+	if st.drbgSeed, err = drbg.SeedFromHex(js.DrbgSeed); err != nil {
+		return nil, err
+	}
+	if js.IATMode < iatNone || js.IATMode > iatParanoid {
+		return nil, fmt.Errorf("invalid iat-mode '%d'", js.IATMode)
+	}
+	st.iatMode = js.IATMode
+	st.cert = serverCertFromState(st)
+
+	// Generate a human readable summary of the configured endpoint.
+	if err = newBridgeFile(stateDir, st); err != nil {
+		return nil, err
+	}
+
+	// Write back the possibly updated server state.
+	return st, writeJSONServerState(stateDir, js)
+}
+
+func jsonServerStateFromFile(stateDir string, js *jsonServerState) error {
+	fPath := path.Join(stateDir, stateFile)
+	f, err := ioutil.ReadFile(fPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			if err = newJSONServerState(stateDir, js); err == nil {
+				return nil
+			}
+		}
+		return err
+	}
+
+	if err := json.Unmarshal(f, js); err != nil {
+		return fmt.Errorf("failed to load statefile '%s': %s", fPath, err)
+	}
+
+	return nil
+}
+
+func newJSONServerState(stateDir string, js *jsonServerState) (err error) {
+	// Generate everything a server needs, using the cryptographic PRNG.
+	var st obfs4ServerState
+	rawID := make([]byte, ntor.NodeIDLength)
+	if err = csrand.Bytes(rawID); err != nil {
+		return
+	}
+	if st.nodeID, err = ntor.NewNodeID(rawID); err != nil {
+		return
+	}
+	if st.identityKey, err = ntor.NewKeypair(false); err != nil {
+		return
+	}
+	if st.drbgSeed, err = drbg.NewSeed(); err != nil {
+		return
+	}
+	st.iatMode = iatNone
+
+	// Encode it into JSON format and write the state file.
+	js.NodeID = st.nodeID.Hex()
+	js.PrivateKey = st.identityKey.Private().Hex()
+	js.PublicKey = st.identityKey.Public().Hex()
+	js.DrbgSeed = st.drbgSeed.Hex()
+	js.IATMode = st.iatMode
+
+	return writeJSONServerState(stateDir, js)
+}
+
+func writeJSONServerState(stateDir string, js *jsonServerState) error {
+	var err error
+	var encoded []byte
+	if encoded, err = json.Marshal(js); err != nil {
+		return err
+	}
+	if err = ioutil.WriteFile(path.Join(stateDir, stateFile), encoded, 0600); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func newBridgeFile(stateDir string, st *obfs4ServerState) error {
+	const prefix = "# obfs4 torrc client bridge line\n" +
+		"#\n" +
+		"# This file is an automatically generated bridge line based on\n" +
+		"# the current obfs4proxy configuration.  EDITING IT WILL HAVE\n" +
+		"# NO EFFECT.\n" +
+		"#\n" +
+		"# Before distributing this Bridge, edit the placeholder fields\n" +
+		"# to contain the actual values:\n" +
+		"#  <IP ADDRESS>  - The public IP address of your obfs4 bridge.\n" +
+		"#  <PORT>        - The TCP/IP port of your obfs4 bridge.\n" +
+		"#  <FINGERPRINT> - The bridge's fingerprint.\n\n"
+
+	bridgeLine := fmt.Sprintf("Bridge obfs4 <IP ADDRESS>:<PORT> <FINGERPRINT> %s\n",
+		st.clientString())
+
+	tmp := []byte(prefix + bridgeLine)
+	if err := ioutil.WriteFile(path.Join(stateDir, bridgeFile), tmp, 0600); err != nil {
+		return err
+	}
+
+	return nil
+}

vendor/vendor.json

@@ -2,6 +2,12 @@
 	"comment": "",
 	"ignore": "test",
 	"package": [
+		{
+			"checksumSHA1": "U+FCQqriNrAjZd1HTErRvII8Co0=",
+			"path": "git.torproject.org/pluggable-transports/goptlib.git",
+			"revision": "781a46c66d2ddbc3509354ae7f1fccab74cb9927",
+			"revisionTime": "2019-04-11T18:29:08Z"
+		},
 		{
 			"checksumSHA1": "+Bo3QheGAtKFk7QPb+pdIEZNiYI=",
 			"path": "github.com/AndreasBriese/bbloom",
@@ -208,6 +214,12 @@
 			"revision": "ecdeabc65495df2dec95d7c4a4c3e021903035e5",
 			"revisionTime": "2017-10-02T20:02:53Z"
 		},
+		{
+			"checksumSHA1": "haOootYK2tDd6cG3F/ot4wg4al4=",
+			"path": "github.com/dchest/siphash",
+			"revision": "a21c2e7914a8fe0db087fa007cbe804967665dfc",
+			"revisionTime": "2020-11-09T08:17:23Z"
+		},
 		{
 			"checksumSHA1": "LE/UfJmiAXFbHwf4fNIRnFuMHUM=",
 			"path": "github.com/deckarep/golang-set",
@@ -370,6 +382,12 @@
 			"revision": "0fb14efe8c47ae851c0034ed7a448854d3d34cf3",
 			"revisionTime": "2018-02-01T23:52:37Z"
 		},
+		{
+			"checksumSHA1": "eGEk/t876DJsabi73ReGQSmNxVI=",
+			"path": "github.com/jinzhu/copier",
+			"revision": "632e723a6687dc925c0c4a99ea86d36e00ff2fb5",
+			"revisionTime": "2020-10-25T03:57:56Z"
+		},
 		{
 			"checksumSHA1": "z8MqG1rnemNMAoCpATKO9HpA0M8=",
 			"path": "github.com/juju/ratelimit",
@@ -428,6 +446,12 @@
 			"revision": "fce601fe55579125e1b3cb0b992287e7290f7b83",
 			"revisionTime": "2017-01-06T18:23:40Z"
 		},
+		{
+			"checksumSHA1": "PSwMdiyt8i4JTvrfwFkRRPZ2Itc=",
+			"path": "github.com/mroth/weightedrand",
+			"revision": "953da99f62a7995b5b73a21940be7af2a0be59cc",
+			"revisionTime": "2020-10-29T23:44:42Z"
+		},
 		{
 			"checksumSHA1": "N6I3i0LIjQckurgTeH3b2A5YTec=",
 			"path": "github.com/oschwald/maxminddb-golang",
@@ -526,16 +550,40 @@
 			"tree": true
 		},
 		{
-			"checksumSHA1": "kt4nwBTlAIn0dET5SqLdWXLLuso=",
+			"checksumSHA1": "TtIN/5Wshp+L7WdSLIRLlH+QzYI=",
+			"path": "github.com/refraction-networking/gotapdance",
+			"revision": "74051a40dbbb06cb0558ccb00dfe03c3f8f4a6a6",
+			"revisionTime": "2020-12-11T19:02:02Z"
+		},
+		{
+			"checksumSHA1": "ObZZJpjQl2BISlIiES82BW8jbEE=",
+			"path": "github.com/refraction-networking/gotapdance/ed25519/edwards25519",
+			"revision": "74051a40dbbb06cb0558ccb00dfe03c3f8f4a6a6",
+			"revisionTime": "2020-12-11T19:02:02Z"
+		},
+		{
+			"checksumSHA1": "VoyDh1KIIVE+OJbehDNJ91tf4Vw=",
+			"path": "github.com/refraction-networking/gotapdance/ed25519/extra25519",
+			"revision": "74051a40dbbb06cb0558ccb00dfe03c3f8f4a6a6",
+			"revisionTime": "2020-12-11T19:02:02Z"
+		},
+		{
+			"checksumSHA1": "HV1A1VNKaVd2yHQmzhy05WJ4JNY=",
 			"path": "github.com/refraction-networking/gotapdance/protobuf",
-			"revision": "3a6e1938ad70af3e91081cd036e3ed05995d67e7",
-			"revisionTime": "2019-09-09T20:29:46Z"
+			"revision": "74051a40dbbb06cb0558ccb00dfe03c3f8f4a6a6",
+			"revisionTime": "2020-12-11T19:02:02Z"
 		},
 		{
-			"checksumSHA1": "vcO0kZzwAtxZ0Jk2nhrPdE16myI=",
+			"checksumSHA1": "4BHfngLYV4TDRnjnW2h8dRHmjH8=",
 			"path": "github.com/refraction-networking/gotapdance/tapdance",
-			"revision": "3a6e1938ad70af3e91081cd036e3ed05995d67e7",
-			"revisionTime": "2019-09-09T20:29:46Z"
+			"revision": "74051a40dbbb06cb0558ccb00dfe03c3f8f4a6a6",
+			"revisionTime": "2020-12-11T19:02:02Z"
+		},
+		{
+			"checksumSHA1": "fv2fYuM1BN+zb4/TEktcVTqKhnI=",
+			"path": "github.com/refraction-networking/gotapdance/tapdance/phantoms",
+			"revision": "74051a40dbbb06cb0558ccb00dfe03c3f8f4a6a6",
+			"revisionTime": "2020-12-11T19:02:02Z"
 		},
 		{
 			"checksumSHA1": "OagdWaWcbCBQZR5bBGgGaK3nddE=",
@@ -603,6 +651,54 @@
 			"revision": "795b5e3961ea1912fde60af417ad85e86acc0d6a",
 			"revisionTime": "2016-03-03T16:20:51Z"
 		},
+		{
+			"checksumSHA1": "0hAOhCdLVxSQA1Q0JohD8Bhn7K4=",
+			"path": "gitlab.com/yawning/obfs4.git/common/csrand",
+			"revision": "816cff15f425d0cb87a1b996366989aa01833f99",
+			"revisionTime": "2019-01-20T16:14:28Z"
+		},
+		{
+			"checksumSHA1": "/XPowaH9OlO1DP0PoLFz0aix+SM=",
+			"path": "gitlab.com/yawning/obfs4.git/common/drbg",
+			"revision": "816cff15f425d0cb87a1b996366989aa01833f99",
+			"revisionTime": "2019-01-20T16:14:28Z"
+		},
+		{
+			"checksumSHA1": "v60BfXtdH8GnFjObFmnSeLCFaOk=",
+			"path": "gitlab.com/yawning/obfs4.git/common/ntor",
+			"revision": "816cff15f425d0cb87a1b996366989aa01833f99",
+			"revisionTime": "2019-01-20T16:14:28Z"
+		},
+		{
+			"checksumSHA1": "ionu/jUjAwvpK7ApMCqGDSEZCuY=",
+			"path": "gitlab.com/yawning/obfs4.git/common/probdist",
+			"revision": "816cff15f425d0cb87a1b996366989aa01833f99",
+			"revisionTime": "2019-01-20T16:14:28Z"
+		},
+		{
+			"checksumSHA1": "FzzCEnbgv9Va+2hf6a1NSDn9+js=",
+			"path": "gitlab.com/yawning/obfs4.git/common/replayfilter",
+			"revision": "816cff15f425d0cb87a1b996366989aa01833f99",
+			"revisionTime": "2019-01-20T16:14:28Z"
+		},
+		{
+			"checksumSHA1": "qkgbPdXEwvk3XRcsTYVaJvW0vNs=",
+			"path": "gitlab.com/yawning/obfs4.git/transports/base",
+			"revision": "816cff15f425d0cb87a1b996366989aa01833f99",
+			"revisionTime": "2019-01-20T16:14:28Z"
+		},
+		{
+			"checksumSHA1": "QluTzp5bKaIyF5QCwlS8Vg7asls=",
+			"path": "gitlab.com/yawning/obfs4.git/transports/obfs4",
+			"revision": "816cff15f425d0cb87a1b996366989aa01833f99",
+			"revisionTime": "2019-01-20T16:14:28Z"
+		},
+		{
+			"checksumSHA1": "/cd1rCHqtzxLYCjMNDSxS4xpm20=",
+			"path": "gitlab.com/yawning/obfs4.git/transports/obfs4/framing",
+			"revision": "816cff15f425d0cb87a1b996366989aa01833f99",
+			"revisionTime": "2019-01-20T16:14:28Z"
+		},
 		{
 			"checksumSHA1": "VrTiQbtu3FoRCY9h3HwjvtGVksw=",
 			"path": "go.uber.org/atomic",