Added IPv6Synthesizer interface which allows the core tunnel to call into the host application to synthesize IPv6 addresses from IPv4 ones. This is used to correctly lookup IPs on DNS64/NAT64 networks.

MobileLibrary/Android/PsiphonTunnel/PsiphonTunnel.java

@@ -335,6 +335,9 @@ public class PsiphonTunnel extends Psi.PsiphonProvider.Stub {
         return DEFAULT_SECONDARY_DNS_SERVER;
     }
 
+    @Override
+    public String IPv6Synthesize(String IPv4Addr) { return IPv4Addr; }
+
     //----------------------------------------------------------------------------------------------
     // Psiphon Tunnel Core
     //----------------------------------------------------------------------------------------------
@@ -347,7 +350,8 @@ public class PsiphonTunnel extends Psi.PsiphonProvider.Stub {
                     loadPsiphonConfig(mHostService.getContext()),
                     embeddedServerEntries,
                     this,
-                    isVpnMode());
+                    isVpnMode(),
+                    false /* Do not use IPv6 synthesizer for android */);
         } catch (java.lang.Exception e) {
             throw new Exception("failed to start Psiphon library", e);
         }

MobileLibrary/iOS/PsiphonTunnel/PsiphonTunnel.xcodeproj/project.pbxproj

@@ -7,6 +7,8 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		4E89F7FE1E2ED3CE00005F4C /* LookupIPv6.c in Sources */ = {isa = PBXBuildFile; fileRef = 4E89F7FC1E2ED3CE00005F4C /* LookupIPv6.c */; };
+		4E89F7FF1E2ED3CE00005F4C /* LookupIPv6.h in Headers */ = {isa = PBXBuildFile; fileRef = 4E89F7FD1E2ED3CE00005F4C /* LookupIPv6.h */; };
 		660E0B7A1E2D6EB6002BF5D4 /* Psi in Frameworks */ = {isa = PBXBuildFile; fileRef = 660E0B791E2D6EB6002BF5D4 /* Psi */; };
 		662659271DD270E900872F6C /* Reachability.h in Headers */ = {isa = PBXBuildFile; fileRef = 662659251DD270E900872F6C /* Reachability.h */; };
 		662659281DD270E900872F6C /* Reachability.m in Sources */ = {isa = PBXBuildFile; fileRef = 662659261DD270E900872F6C /* Reachability.m */; };
@@ -60,6 +62,8 @@
 /* End PBXCopyFilesBuildPhase section */
 
 /* Begin PBXFileReference section */
+		4E89F7FC1E2ED3CE00005F4C /* LookupIPv6.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = LookupIPv6.c; sourceTree = "<group>"; };
+		4E89F7FD1E2ED3CE00005F4C /* LookupIPv6.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = LookupIPv6.h; sourceTree = "<group>"; };
 		660E0B791E2D6EB6002BF5D4 /* Psi */ = {isa = PBXFileReference; lastKnownFileType = archive.ar; name = Psi; path = PsiphonTunnel/Psi.framework/Versions/A/Psi; sourceTree = "<group>"; };
 		662659251DD270E900872F6C /* Reachability.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = Reachability.h; sourceTree = "<group>"; };
 		662659261DD270E900872F6C /* Reachability.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = Reachability.m; sourceTree = "<group>"; };
@@ -118,6 +122,8 @@
 			children = (
 				662659251DD270E900872F6C /* Reachability.h */,
 				662659261DD270E900872F6C /* Reachability.m */,
+				4E89F7FC1E2ED3CE00005F4C /* LookupIPv6.c */,
+				4E89F7FD1E2ED3CE00005F4C /* LookupIPv6.h */,
 			);
 			path = Reachability;
 			sourceTree = "<group>";
@@ -214,6 +220,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				6685BDCB1E2E882800F0E414 /* ref.h in Headers */,
+				4E89F7FF1E2ED3CE00005F4C /* LookupIPv6.h in Headers */,
 				66BDB05D1DC26CCC0079384C /* SBJson4StreamParser.h in Headers */,
 				6685BDD41E2EBB1000F0E414 /* GoPsi.objc.h in Headers */,
 				6685BDD51E2EBB1000F0E414 /* Universe.objc.h in Headers */,
@@ -337,6 +344,7 @@
 				66BDB0641DC26CCC0079384C /* SBJson4StreamWriter.m in Sources */,
 				66BDB0661DC26CCC0079384C /* SBJson4StreamWriterState.m in Sources */,
 				66BDB05C1DC26CCC0079384C /* SBJson4Parser.m in Sources */,
+				4E89F7FE1E2ED3CE00005F4C /* LookupIPv6.c in Sources */,
 				66BDB0681DC26CCC0079384C /* SBJson4Writer.m in Sources */,
 				66BDB0621DC26CCC0079384C /* SBJson4StreamTokeniser.m in Sources */,
 				66BDB0441DA6C7DD0079384C /* PsiphonTunnel.m in Sources */,

MobileLibrary/iOS/PsiphonTunnel/PsiphonTunnel/PsiphonTunnel.m

@@ -19,6 +19,7 @@
 
 #import <CoreTelephony/CTTelephonyNetworkInfo.h>
 #import <CoreTelephony/CTCarrier.h>
+#import "LookupIPv6.h"
 #import "Psi-meta.h"
 #import "PsiphonTunnel.h"
 #import "Reachability.h"
@@ -62,6 +63,9 @@
 
         // Not supported on iOS.
         const BOOL useDeviceBinder = FALSE;
+
+        // Must always use IPv6Synthesizer for iOS
+        const BOOL useIPv6Synthesizer = TRUE;
         
         NSString *configStr = [self getConfig];
         if (configStr == nil) {
@@ -76,6 +80,7 @@
                            embeddedServerEntries,
                            self,
                            useDeviceBinder,
+                           useIPv6Synthesizer,
                            &e);
             
             [self logMessage:[NSString stringWithFormat: @"GoPsiStart: %@", res ? @"TRUE" : @"FALSE"]];
@@ -555,6 +560,17 @@
     return (netstat != NotReachable) ? 1 : 0;
 }
 
+- (NSString *)iPv6Synthesize:(NSString *)IPv4Addr {
+    // This function is called to synthesize an ipv6 address from an ipv4 one on a DNS64/NAT64 network
+    char *result = getIPv6ForIPv4([IPv4Addr UTF8String]);
+    if (result != NULL) {
+        NSString *IPv6Addr = [NSString stringWithUTF8String:result];
+        free(result);
+        return IPv6Addr;
+    }
+    return @"";
+}
+
 - (void)notice:(NSString *)noticeJSON {
     [self handlePsiphonNotice:noticeJSON];
 }

MobileLibrary/iOS/PsiphonTunnel/PsiphonTunnel/Reachability/LookupIPv6.c

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2016, Psiphon Inc.
+ * All rights reserved.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "LookupIPv6.h"
+
+#include <netdb.h>
+#include <arpa/inet.h>
+#include <err.h>
+#include <stdlib.h>
+#include <string.h>
+
+char *getIPv6ForIPv4(const char *ipv4_str) {
+    char *ipv6_str = NULL;
+    struct addrinfo hints, *res, *res0;
+    int error;
+    
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_family = PF_UNSPEC;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_flags = AI_DEFAULT;
+    error = getaddrinfo(ipv4_str, NULL, &hints, &res0);
+    if (error) {
+        /* NOTREACHED */
+        return NULL;
+    }
+
+    for (res = res0; res; res = res->ai_next) {
+        if (res->ai_addr->sa_family != AF_INET6) {
+            continue;
+        }
+        struct sockaddr_in6 *sockaddr = (struct sockaddr_in6*)res->ai_addr;
+        ipv6_str = (char *)malloc(sizeof(char)*(INET6_ADDRSTRLEN)); // INET6_ADDRSTRLEN includes null terminating character
+        inet_ntop(AF_INET6, &(sockaddr->sin6_addr), ipv6_str, INET6_ADDRSTRLEN);
+        break;
+    }
+    
+    freeaddrinfo(res0);
+    return ipv6_str;
+}

MobileLibrary/iOS/PsiphonTunnel/PsiphonTunnel/Reachability/LookupIPv6.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2016, Psiphon Inc.
+ * All rights reserved.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef LookupIPv6_h
+#define LookupIPv6_h
+
+char *getIPv6ForIPv4(const char *ipv4_str);
+
+#endif /* LookupIPv6_h */

MobileLibrary/psi/psi.go

@@ -37,6 +37,7 @@ type PsiphonProvider interface {
 	Notice(noticeJSON string)
 	HasNetworkConnectivity() int
 	BindToDevice(fileDescriptor int) error
+	IPv6Synthesize(IPv4Addr string) string
 	GetPrimaryDnsServer() string
 	GetSecondaryDnsServer() string
 }
@@ -49,7 +50,7 @@ var controllerWaitGroup *sync.WaitGroup
 func Start(
 	configJson, embeddedServerEntryList string,
 	provider PsiphonProvider,
-	useDeviceBinder bool) error {
+	useDeviceBinder bool, useIPv6Synthesizer bool) error {
 
 	controllerMutex.Lock()
 	defer controllerMutex.Unlock()
@@ -69,6 +70,10 @@ func Start(
 		config.DnsServerGetter = provider
 	}
 
+	if useIPv6Synthesizer {
+		config.IPv6Synthesizer = provider
+	}
+
 	psiphon.SetNoticeOutput(psiphon.NewNoticeReceiver(
 		func(notice []byte) {
 			provider.Notice(string(notice))

psiphon/TCPConn.go

@@ -104,6 +104,22 @@ func interruptibleTCPDial(addr string, config *DialConfig) (*TCPConn, error) {
 	// when tcpDial, amoung other things, when makes a blocking syscall.Connect()
 	// call.
 	go func() {
+		if config.IPv6Synthesizer != nil {
+			// Synthesize an ipv6 address from an ipv4 one
+			// This is for compatibility on DNS64/NAT64 networks
+			host, port, err := net.SplitHostPort(addr)
+			if err != nil {
+				return
+			}
+			ip := net.ParseIP(host)
+			if ip != nil && len(ip) == net.IPv4len {
+				synthesizedAddr := config.IPv6Synthesizer.IPv6Synthesize(host)
+				if synthesizedAddr != "" {
+					addr = net.JoinHostPort(synthesizedAddr, port)
+				}
+			}
+		}
+
 		var netConn net.Conn
 		var err error
 		if config.UpstreamProxyUrl != "" {

psiphon/TCPConn_bind.go

@@ -78,12 +78,23 @@ func tcpDial(addr string, config *DialConfig, dialResult chan error) (net.Conn,
 		return nil, common.ContextError(err)
 	}
 
-	// TODO: IPv6 support
-	var ip [4]byte
-	copy(ip[:], ipAddrs[index].To4())
+	var ip []byte
+	var domain int
+	ipAddr := ipAddrs[index]
+
+	// Get address type (IPv4 or IPv6)
+	if len(ipAddr) == net.IPv4len {
+		ip = make([]byte, 4)
+		copy(ip[:], ipAddr.To4())
+		domain = syscall.AF_INET
+	} else if len(ipAddr) == net.IPv6len {
+		ip = make([]byte, 16)
+		copy(ip[:], ipAddr.To16())
+		domain = syscall.AF_INET6
+	}
 
 	// Create a socket and bind to device, when configured to do so
-	socketFd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, 0)
+	socketFd, err := syscall.Socket(domain, syscall.SOCK_STREAM, 0)
 	if err != nil {
 		return nil, common.ContextError(err)
 	}
@@ -100,8 +111,18 @@ func tcpDial(addr string, config *DialConfig, dialResult chan error) (net.Conn,
 		}
 	}
 
-	sockAddr := syscall.SockaddrInet4{Addr: ip, Port: port}
-	err = syscall.Connect(socketFd, &sockAddr)
+	// Connect socket fd to the address
+	if domain == syscall.AF_INET {
+		var inet4Addr [4]byte
+		copy(inet4Addr[:], ip)
+		servAddr := syscall.SockaddrInet4{Addr: inet4Addr, Port: port}
+		err = syscall.Connect(socketFd, &servAddr)
+	} else if domain == syscall.AF_INET6 {
+		var inet6Addr [16]byte
+		copy(inet6Addr[:], ip)
+		servAddr := syscall.SockaddrInet6{Addr: inet6Addr, Port: port}
+		err = syscall.Connect(socketFd, &servAddr)
+	}
 	if err != nil {
 		syscall.Close(socketFd)
 		return nil, common.ContextError(err)

psiphon/config.go

@@ -230,6 +230,11 @@ type Config struct {
 	// deployments.
 	DeviceBinder DeviceBinder
 
+	// IPv6Synthesizer is an interface that allows the core tunnel to call
+	// into the host application to synthesize IPv6 addresses from IPv4 ones. This
+	// is used to correctly lookup IPs on DNS64/NAT64 networks.
+	IPv6Synthesizer IPv6Synthesizer
+
 	// DnsServerGetter is an interface that enables the core tunnel to call
 	// into the host application to discover the native network DNS server settings.
 	// This parameter is only applicable to library deployments.

psiphon/controller.go

@@ -100,6 +100,7 @@ func NewController(config *Config) (controller *Controller, err error) {
 		PendingConns:                  untunneledPendingConns,
 		DeviceBinder:                  config.DeviceBinder,
 		DnsServerGetter:               config.DnsServerGetter,
+		IPv6Synthesizer:               config.IPv6Synthesizer,
 		UseIndistinguishableTLS:       config.UseIndistinguishableTLS,
 		TrustedCACertificatesFilename: config.TrustedCACertificatesFilename,
 		DeviceRegion:                  config.DeviceRegion,

psiphon/feedback.go

@@ -113,6 +113,7 @@ func SendFeedback(configJson, diagnosticsJson, b64EncodedPublicKey, uploadServer
 		UpstreamProxyCustomHeaders:    config.UpstreamProxyCustomHeaders,
 		PendingConns:                  nil,
 		DeviceBinder:                  nil,
+		IPv6Synthesizer:               nil,
 		DnsServerGetter:               nil,
 		UseIndistinguishableTLS:       config.UseIndistinguishableTLS,
 		TrustedCACertificatesFilename: config.TrustedCACertificatesFilename,

psiphon/net.go

@@ -79,6 +79,7 @@ type DialConfig struct {
 	// current active untunneled network DNS server.
 	DeviceBinder    DeviceBinder
 	DnsServerGetter DnsServerGetter
+	IPv6Synthesizer IPv6Synthesizer
 
 	// UseIndistinguishableTLS specifies whether to try to use an
 	// alternative stack for TLS. From a circumvention perspective,
@@ -123,6 +124,11 @@ type DnsServerGetter interface {
 	GetSecondaryDnsServer() string
 }
 
+// IPv6Synthesizer defines the interface to the external IPv6Synthesize provider
+type IPv6Synthesizer interface {
+	IPv6Synthesize(IPv4Addr string) string
+}
+
 // TimeoutError implements the error interface
 type TimeoutError struct{}
 

psiphon/tunnel.go

@@ -629,6 +629,7 @@ func dialSsh(
 		PendingConns:                  pendingConns,
 		DeviceBinder:                  config.DeviceBinder,
 		DnsServerGetter:               config.DnsServerGetter,
+		IPv6Synthesizer:               config.IPv6Synthesizer,
 		UseIndistinguishableTLS:       config.UseIndistinguishableTLS,
 		TrustedCACertificatesFilename: config.TrustedCACertificatesFilename,
 		DeviceRegion:                  config.DeviceRegion,