psiphon-tunnel-core/replace/webrtc/settingengine.go

// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT

//go:build !js
// +build !js

package webrtc

import (
	"context"
	"crypto/x509"
	"io"
	"net"
	"time"

	"github.com/pion/dtls/v2"
	dtlsElliptic "github.com/pion/dtls/v2/pkg/crypto/elliptic"
	"github.com/pion/ice/v2"
	"github.com/pion/logging"
	"github.com/pion/transport/v2"
	"github.com/pion/transport/v2/packetio"
	"github.com/pion/transport/v2/vnet"
	"golang.org/x/net/proxy"
)

// SettingEngine allows influencing behavior in ways that are not
// supported by the WebRTC API. This allows us to support additional
// use-cases without deviating from the WebRTC API elsewhere.
type SettingEngine struct {
	ephemeralUDP struct {
		PortMin uint16
		PortMax uint16
	}
	detach struct {
		DataChannels bool
	}
	timeout struct {
		ICEDisconnectedTimeout    *time.Duration
		ICEFailedTimeout          *time.Duration
		ICEKeepaliveInterval      *time.Duration
		ICEHostAcceptanceMinWait  *time.Duration
		ICESrflxAcceptanceMinWait *time.Duration
		ICEPrflxAcceptanceMinWait *time.Duration
		ICERelayAcceptanceMinWait *time.Duration
	}
	candidates struct {
		ICELite                  bool
		ICENetworkTypes          []NetworkType
		InterfaceFilter          func(string) bool
		IPFilter                 func(net.IP) bool
		NAT1To1IPs               []string
		NAT1To1IPCandidateType   ICECandidateType
		MulticastDNSMode         ice.MulticastDNSMode
		MulticastDNSHostName     string
		UsernameFragment         string
		Password                 string
		IncludeLoopbackCandidate bool
	}
	replayProtection struct {
		DTLS  *uint
		SRTP  *uint
		SRTCP *uint
	}
	dtls struct {
		insecureSkipHelloVerify   bool
		disableInsecureSkipVerify bool
		retransmissionInterval    time.Duration
		ellipticCurves            []dtlsElliptic.Curve
		connectContextMaker       func() (context.Context, func())
		extendedMasterSecret      dtls.ExtendedMasterSecretType
		clientAuth                *dtls.ClientAuthType
		clientCAs                 *x509.CertPool
		rootCAs                   *x509.CertPool
		keyLogWriter              io.Writer
	}
	sctp struct {
		maxReceiveBufferSize uint32
	}
	sdpMediaLevelFingerprints                 bool
	answeringDTLSRole                         DTLSRole
	disableCertificateFingerprintVerification bool
	disableSRTPReplayProtection               bool
	disableSRTCPReplayProtection              bool
	net                                       transport.Net
	BufferFactory                             func(packetType packetio.BufferPacketType, ssrc uint32) io.ReadWriteCloser
	LoggerFactory                             logging.LoggerFactory
	iceTCPMux                                 ice.TCPMux
	iceUDPMux                                 ice.UDPMux
	iceProxyDialer                            proxy.Dialer
	iceDisableActiveTCP                       bool
	disableMediaEngineCopy                    bool
	srtpProtectionProfiles                    []dtls.SRTPProtectionProfile
	receiveMTU                                uint

	// [Psiphon] from https://github.com/pion/webrtc/pull/2298
	iceUDPMuxSrflx ice.UniversalUDPMux
}

// getReceiveMTU returns the configured MTU. If SettingEngine's MTU is configured to 0 it returns the default
func (e *SettingEngine) getReceiveMTU() uint {
	if e.receiveMTU != 0 {
		return e.receiveMTU
	}

	return receiveMTU
}

// DetachDataChannels enables detaching data channels. When enabled
// data channels have to be detached in the OnOpen callback using the
// DataChannel.Detach method.
func (e *SettingEngine) DetachDataChannels() {
	e.detach.DataChannels = true
}

// SetSRTPProtectionProfiles allows the user to override the default SRTP Protection Profiles
// The default srtp protection profiles are provided by the function `defaultSrtpProtectionProfiles`
func (e *SettingEngine) SetSRTPProtectionProfiles(profiles ...dtls.SRTPProtectionProfile) {
	e.srtpProtectionProfiles = profiles
}

// SetICETimeouts sets the behavior around ICE Timeouts
//
// disconnectedTimeout:
//
//	Duration without network activity before an Agent is considered disconnected. Default is 5 Seconds
//
// failedTimeout:
//
//	Duration without network activity before an Agent is considered failed after disconnected. Default is 25 Seconds
//
// keepAliveInterval:
//
//	How often the ICE Agent sends extra traffic if there is no activity, if media is flowing no traffic will be sent. Default is 2 seconds
func (e *SettingEngine) SetICETimeouts(disconnectedTimeout, failedTimeout, keepAliveInterval time.Duration) {
	e.timeout.ICEDisconnectedTimeout = &disconnectedTimeout
	e.timeout.ICEFailedTimeout = &failedTimeout
	e.timeout.ICEKeepaliveInterval = &keepAliveInterval
}

// SetHostAcceptanceMinWait sets the ICEHostAcceptanceMinWait
func (e *SettingEngine) SetHostAcceptanceMinWait(t time.Duration) {
	e.timeout.ICEHostAcceptanceMinWait = &t
}

// SetSrflxAcceptanceMinWait sets the ICESrflxAcceptanceMinWait
func (e *SettingEngine) SetSrflxAcceptanceMinWait(t time.Duration) {
	e.timeout.ICESrflxAcceptanceMinWait = &t
}

// SetPrflxAcceptanceMinWait sets the ICEPrflxAcceptanceMinWait
func (e *SettingEngine) SetPrflxAcceptanceMinWait(t time.Duration) {
	e.timeout.ICEPrflxAcceptanceMinWait = &t
}

// SetRelayAcceptanceMinWait sets the ICERelayAcceptanceMinWait
func (e *SettingEngine) SetRelayAcceptanceMinWait(t time.Duration) {
	e.timeout.ICERelayAcceptanceMinWait = &t
}

// SetEphemeralUDPPortRange limits the pool of ephemeral ports that
// ICE UDP connections can allocate from. This affects both host candidates,
// and the local address of server reflexive candidates.
//
// When portMin and portMax are left to the 0 default value, pion/ice candidate
// gatherer replaces them and uses 1 for portMin and 65535 for portMax.
func (e *SettingEngine) SetEphemeralUDPPortRange(portMin, portMax uint16) error {
	if portMax < portMin {
		return ice.ErrPort
	}

	e.ephemeralUDP.PortMin = portMin
	e.ephemeralUDP.PortMax = portMax
	return nil
}

// SetLite configures whether or not the ice agent should be a lite agent
func (e *SettingEngine) SetLite(lite bool) {
	e.candidates.ICELite = lite
}

// SetNetworkTypes configures what types of candidate networks are supported
// during local and server reflexive gathering.
func (e *SettingEngine) SetNetworkTypes(candidateTypes []NetworkType) {
	e.candidates.ICENetworkTypes = candidateTypes
}

// SetInterfaceFilter sets the filtering functions when gathering ICE candidates
// This can be used to exclude certain network interfaces from ICE. Which may be
// useful if you know a certain interface will never succeed, or if you wish to reduce
// the amount of information you wish to expose to the remote peer
func (e *SettingEngine) SetInterfaceFilter(filter func(string) bool) {
	e.candidates.InterfaceFilter = filter
}

// SetIPFilter sets the filtering functions when gathering ICE candidates
// This can be used to exclude certain ip from ICE. Which may be
// useful if you know a certain ip will never succeed, or if you wish to reduce
// the amount of information you wish to expose to the remote peer
func (e *SettingEngine) SetIPFilter(filter func(net.IP) bool) {
	e.candidates.IPFilter = filter
}

// SetNAT1To1IPs sets a list of external IP addresses of 1:1 (D)NAT
// and a candidate type for which the external IP address is used.
// This is useful when you host a server using Pion on an AWS EC2 instance
// which has a private address, behind a 1:1 DNAT with a public IP (e.g.
// Elastic IP). In this case, you can give the public IP address so that
// Pion will use the public IP address in its candidate instead of the private
// IP address. The second argument, candidateType, is used to tell Pion which
// type of candidate should use the given public IP address.
// Two types of candidates are supported:
//
// ICECandidateTypeHost:
//
//	The public IP address will be used for the host candidate in the SDP.
//
// ICECandidateTypeSrflx:
//
//	A server reflexive candidate with the given public IP address will be added to the SDP.
//
// Please note that if you choose ICECandidateTypeHost, then the private IP address
// won't be advertised with the peer. Also, this option cannot be used along with mDNS.
//
// If you choose ICECandidateTypeSrflx, it simply adds a server reflexive candidate
// with the public IP. The host candidate is still available along with mDNS
// capabilities unaffected. Also, you cannot give STUN server URL at the same time.
// It will result in an error otherwise.
func (e *SettingEngine) SetNAT1To1IPs(ips []string, candidateType ICECandidateType) {
	e.candidates.NAT1To1IPs = ips
	e.candidates.NAT1To1IPCandidateType = candidateType
}

// SetIncludeLoopbackCandidate enable pion to gather loopback candidates, it is useful
// for some VM have public IP mapped to loopback interface
func (e *SettingEngine) SetIncludeLoopbackCandidate(include bool) {
	e.candidates.IncludeLoopbackCandidate = include
}

// SetAnsweringDTLSRole sets the DTLS role that is selected when offering
// The DTLS role controls if the WebRTC Client as a client or server. This
// may be useful when interacting with non-compliant clients or debugging issues.
//
// DTLSRoleActive:
//
//	Act as DTLS Client, send the ClientHello and starts the handshake
//
// DTLSRolePassive:
//
//	Act as DTLS Server, wait for ClientHello
func (e *SettingEngine) SetAnsweringDTLSRole(role DTLSRole) error {
	if role != DTLSRoleClient && role != DTLSRoleServer {
		return errSettingEngineSetAnsweringDTLSRole
	}

	e.answeringDTLSRole = role
	return nil
}

// SetVNet sets the VNet instance that is passed to pion/ice
//
// VNet is a virtual network layer for Pion, allowing users to simulate
// different topologies, latency, loss and jitter. This can be useful for
// learning WebRTC concepts or testing your application in a lab environment
// Deprecated: Please use SetNet()
func (e *SettingEngine) SetVNet(vnet *vnet.Net) {
	e.SetNet(vnet)
}

// SetNet sets the Net instance that is passed to pion/ice
//
// Net is an network interface layer for Pion, allowing users to replace
// Pions network stack with a custom implementation.
func (e *SettingEngine) SetNet(net transport.Net) {
	e.net = net
}

// SetICEMulticastDNSMode controls if pion/ice queries and generates mDNS ICE Candidates
func (e *SettingEngine) SetICEMulticastDNSMode(multicastDNSMode ice.MulticastDNSMode) {
	e.candidates.MulticastDNSMode = multicastDNSMode
}

// SetMulticastDNSHostName sets a static HostName to be used by pion/ice instead of generating one on startup
//
// This should only be used for a single PeerConnection. Having multiple PeerConnections with the same HostName will cause
// undefined behavior
func (e *SettingEngine) SetMulticastDNSHostName(hostName string) {
	e.candidates.MulticastDNSHostName = hostName
}

// SetICECredentials sets a staic uFrag/uPwd to be used by pion/ice
//
// This is useful if you want to do signalless WebRTC session, or having a reproducible environment with static credentials
func (e *SettingEngine) SetICECredentials(usernameFragment, password string) {
	e.candidates.UsernameFragment = usernameFragment
	e.candidates.Password = password
}

// DisableCertificateFingerprintVerification disables fingerprint verification after DTLS Handshake has finished
func (e *SettingEngine) DisableCertificateFingerprintVerification(isDisabled bool) {
	e.disableCertificateFingerprintVerification = isDisabled
}

// SetDTLSReplayProtectionWindow sets a replay attack protection window size of DTLS connection.
func (e *SettingEngine) SetDTLSReplayProtectionWindow(n uint) {
	e.replayProtection.DTLS = &n
}

// SetSRTPReplayProtectionWindow sets a replay attack protection window size of SRTP session.
func (e *SettingEngine) SetSRTPReplayProtectionWindow(n uint) {
	e.disableSRTPReplayProtection = false
	e.replayProtection.SRTP = &n
}

// SetSRTCPReplayProtectionWindow sets a replay attack protection window size of SRTCP session.
func (e *SettingEngine) SetSRTCPReplayProtectionWindow(n uint) {
	e.disableSRTCPReplayProtection = false
	e.replayProtection.SRTCP = &n
}

// DisableSRTPReplayProtection disables SRTP replay protection.
func (e *SettingEngine) DisableSRTPReplayProtection(isDisabled bool) {
	e.disableSRTPReplayProtection = isDisabled
}

// DisableSRTCPReplayProtection disables SRTCP replay protection.
func (e *SettingEngine) DisableSRTCPReplayProtection(isDisabled bool) {
	e.disableSRTCPReplayProtection = isDisabled
}

// SetSDPMediaLevelFingerprints configures the logic for DTLS Fingerprint insertion
// If true, fingerprints will be inserted in the sdp at the fingerprint
// level, instead of the session level. This helps with compatibility with
// some webrtc implementations.
func (e *SettingEngine) SetSDPMediaLevelFingerprints(sdpMediaLevelFingerprints bool) {
	e.sdpMediaLevelFingerprints = sdpMediaLevelFingerprints
}

// SetICETCPMux enables ICE-TCP when set to a non-nil value. Make sure that
// NetworkTypeTCP4 or NetworkTypeTCP6 is enabled as well.
func (e *SettingEngine) SetICETCPMux(tcpMux ice.TCPMux) {
	e.iceTCPMux = tcpMux
}

// SetICEUDPMux allows ICE traffic to come through a single UDP port, drastically
// simplifying deployments where ports will need to be opened/forwarded.
// UDPMux should be started prior to creating PeerConnections.
func (e *SettingEngine) SetICEUDPMux(udpMux ice.UDPMux) {
	e.iceUDPMux = udpMux
}

// [Psiphon] from https://github.com/pion/webrtc/pull/2298
// SetICEUDPMuxSrflx allows ICE traffic from server reflexive candidates to be
// multiplexed onto a single port.
func (e *SettingEngine) SetICEUDPMuxSrflx(udpMuxSrflx ice.UniversalUDPMux) {
	e.iceUDPMuxSrflx = udpMuxSrflx
}

// SetICEProxyDialer sets the proxy dialer interface based on golang.org/x/net/proxy.
func (e *SettingEngine) SetICEProxyDialer(d proxy.Dialer) {
	e.iceProxyDialer = d
}

// DisableActiveTCP disables using active TCP for ICE. Active TCP is enabled by default
func (e *SettingEngine) DisableActiveTCP(isDisabled bool) {
	e.iceDisableActiveTCP = isDisabled
}

// DisableMediaEngineCopy stops the MediaEngine from being copied. This allows a user to modify
// the MediaEngine after the PeerConnection has been constructed. This is useful if you wish to
// modify codecs after signaling. Make sure not to share MediaEngines between PeerConnections.
func (e *SettingEngine) DisableMediaEngineCopy(isDisabled bool) {
	e.disableMediaEngineCopy = isDisabled
}

// SetReceiveMTU sets the size of read buffer that copies incoming packets. This is optional.
// Leave this 0 for the default receiveMTU
func (e *SettingEngine) SetReceiveMTU(receiveMTU uint) {
	e.receiveMTU = receiveMTU
}

// SetDTLSRetransmissionInterval sets the retranmission interval for DTLS.
func (e *SettingEngine) SetDTLSRetransmissionInterval(interval time.Duration) {
	e.dtls.retransmissionInterval = interval
}

// SetDTLSInsecureSkipHelloVerify sets the skip HelloVerify flag for DTLS.
// If true and when acting as DTLS server, will allow client to skip hello verify phase and
// receive ServerHello after initial ClientHello. This will mean faster connect times,
// but will have lower DoS attack resistance.
func (e *SettingEngine) SetDTLSInsecureSkipHelloVerify(skip bool) {
	e.dtls.insecureSkipHelloVerify = skip
}

// SetDTLSDisableInsecureSkipVerify sets the disable skip insecure verify flag for DTLS.
// This controls whether a client verifies the server's certificate chain and host name.
func (e *SettingEngine) SetDTLSDisableInsecureSkipVerify(disable bool) {
	e.dtls.disableInsecureSkipVerify = disable
}

// SetDTLSEllipticCurves sets the elliptic curves for DTLS.
func (e *SettingEngine) SetDTLSEllipticCurves(ellipticCurves ...dtlsElliptic.Curve) {
	e.dtls.ellipticCurves = ellipticCurves
}

// SetDTLSConnectContextMaker sets the context used during the DTLS Handshake.
// It can be used to extend or reduce the timeout on the DTLS Handshake.
// If nil, the default dtls.ConnectContextMaker is used. It can be implemented as following.
//
//	func ConnectContextMaker() (context.Context, func()) {
//		return context.WithTimeout(context.Background(), 30*time.Second)
//	}
func (e *SettingEngine) SetDTLSConnectContextMaker(connectContextMaker func() (context.Context, func())) {
	e.dtls.connectContextMaker = connectContextMaker
}

// SetDTLSExtendedMasterSecret sets the extended master secret type for DTLS.
func (e *SettingEngine) SetDTLSExtendedMasterSecret(extendedMasterSecret dtls.ExtendedMasterSecretType) {
	e.dtls.extendedMasterSecret = extendedMasterSecret
}

// SetDTLSClientAuth sets the client auth type for DTLS.
func (e *SettingEngine) SetDTLSClientAuth(clientAuth dtls.ClientAuthType) {
	e.dtls.clientAuth = &clientAuth
}

// SetDTLSClientCAs sets the client CA certificate pool for DTLS certificate verification.
func (e *SettingEngine) SetDTLSClientCAs(clientCAs *x509.CertPool) {
	e.dtls.clientCAs = clientCAs
}

// SetDTLSRootCAs sets the root CA certificate pool for DTLS certificate verification.
func (e *SettingEngine) SetDTLSRootCAs(rootCAs *x509.CertPool) {
	e.dtls.rootCAs = rootCAs
}

// SetDTLSKeyLogWriter sets the destination of the TLS key material for debugging.
// Logging key material compromises security and should only be use for debugging.
func (e *SettingEngine) SetDTLSKeyLogWriter(writer io.Writer) {
	e.dtls.keyLogWriter = writer
}

// SetSCTPMaxReceiveBufferSize sets the maximum receive buffer size.
// Leave this 0 for the default maxReceiveBufferSize.
func (e *SettingEngine) SetSCTPMaxReceiveBufferSize(maxReceiveBufferSize uint32) {
	e.sctp.maxReceiveBufferSize = maxReceiveBufferSize
}