Unified ipv4, ipv6 and domain connections.

-Use dual-mode socket & DnsEndPoint to handle all domain name connection.
-Move all socket creation into one single function.

So that we could treat domain name just like ipv4 & ipv6 address.
This also solves the async domain solving problem because the os will
hanlde it for us.

shadowsocks-csharp/Controller/Service/PortForwarder.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Net;
 using System.Net.Sockets;
+using Shadowsocks.Util;
 
 namespace Shadowsocks.Controller
 {
@@ -45,14 +46,9 @@ namespace Shadowsocks.Controller
                 this._local = socket;
                 try
                 {
-                    // TODO async resolving
-                    IPAddress ipAddress;
-                    bool parsed = IPAddress.TryParse("127.0.0.1", out ipAddress);
-                    IPEndPoint remoteEP = new IPEndPoint(ipAddress, targetPort);
+                    EndPoint remoteEP = SocketUtil.GetEndPoint("localhost", targetPort);
 
-
-                    _remote = new Socket(ipAddress.AddressFamily,
-                        SocketType.Stream, ProtocolType.Tcp);
+                    _remote = SocketUtil.CreateSocket(remoteEP);
                     _remote.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, true);
 
                     // Connect to the remote endpoint.

shadowsocks-csharp/Controller/Service/TCPRelay.cs

@@ -9,6 +9,7 @@ using Shadowsocks.Controller.Strategy;
 using Shadowsocks.Encryption;
 using Shadowsocks.Model;
 using Shadowsocks.Proxy;
+using Shadowsocks.Util;
 
 namespace Shadowsocks.Controller
 {
@@ -363,24 +364,11 @@ namespace Shadowsocks.Controller
                 CreateRemote();
 
                 // Setting up proxy
-                IPEndPoint proxyEP;
+                EndPoint proxyEP;
                 if (_config.useProxy)
                 {
-                    IPAddress ipAddress;
-                    bool parsed = IPAddress.TryParse(_config.proxyServer, out ipAddress);
-                    if (!parsed)
-                    {
-                        /*
-                         * TODO really necessary to resolve a proxy's address? Maybe from local hosts?
-                         * also we may simplify it by using dual-mode socket with 
-                         * the approach described in DirectConnect.BeginConnectDest
-                         */
-                        IPHostEntry ipHostInfo = Dns.GetHostEntry(_config.proxyServer);
-                        ipAddress = ipHostInfo.AddressList[0];
-                    }
-
                     remote = new Socks5Proxy();
-                    proxyEP = new IPEndPoint(ipAddress, _config.proxyPort);
+                    proxyEP = SocketUtil.GetEndPoint(_config.proxyServer, _config.proxyPort);
                 }
                 else
                 {
@@ -395,7 +383,7 @@ namespace Shadowsocks.Controller
                 proxyTimer.Enabled = true;
 
                 proxyTimer.Proxy = remote;
-                proxyTimer.DestEndPoint = ProxyUtils.GetEndPoint(server.server, server.server_port);
+                proxyTimer.DestEndPoint = SocketUtil.GetEndPoint(server.server, server.server_port);
                 proxyTimer.Server = server;
 
                 _proxyConnected = false;

shadowsocks-csharp/Controller/Service/UDPRelay.cs

@@ -7,6 +7,7 @@ using System.Runtime.CompilerServices;
 using Shadowsocks.Controller.Strategy;
 using Shadowsocks.Encryption;
 using Shadowsocks.Model;
+using Shadowsocks.Util;
 
 namespace Shadowsocks.Controller
 {
@@ -56,7 +57,7 @@ namespace Shadowsocks.Controller
             private byte[] _buffer = new byte[1500];
 
             private IPEndPoint _localEndPoint;
-            private IPEndPoint _remoteEndPoint;
+            private EndPoint _remoteEndPoint;
 
             public UDPHandler(Socket local, Server server, IPEndPoint localEndPoint)
             {
@@ -64,16 +65,8 @@ namespace Shadowsocks.Controller
                 _server = server;
                 _localEndPoint = localEndPoint;
 
-                // TODO async resolving
-                IPAddress ipAddress;
-                bool parsed = IPAddress.TryParse(server.server, out ipAddress);
-                if (!parsed)
-                {
-                    IPHostEntry ipHostInfo = Dns.GetHostEntry(server.server);
-                    ipAddress = ipHostInfo.AddressList[0];
-                }
-                _remoteEndPoint = new IPEndPoint(ipAddress, server.server_port);
-                _remote = new Socket(_remoteEndPoint.AddressFamily, SocketType.Dgram, ProtocolType.Udp);
+                _remoteEndPoint = SocketUtil.GetEndPoint(server.server, server.server_port);
+                _remote = SocketUtil.CreateSocket(_remoteEndPoint, ProtocolType.Udp);
             }
 
             public void Send(byte[] data, int length)

shadowsocks-csharp/Proxy/DirectConnect.cs

@@ -2,6 +2,7 @@
 using System.Net;
 using System.Net.Sockets;
 using System.Threading;
+using Shadowsocks.Util;
 
 namespace Shadowsocks.Proxy
 {
@@ -52,39 +53,14 @@ namespace Shadowsocks.Proxy
 
         public void BeginConnectDest(EndPoint destEndPoint, AsyncCallback callback, object state)
         {
-            EndPoint realEndPoint = DestEndPoint = destEndPoint;
-
-            /*
-             * On windows vista or later, dual-mode socket is supported, so that
-             * we don't need to resolve a DnsEndPoint manually.
-             * We could just create a dual-mode socket and pass the DnsEndPoint
-             * directly to it's BeginConnect and the system will handle it correctlly
-             * so that we won't worry about async resolving any more.
-             * 
-             * see: https://blogs.msdn.microsoft.com/webdev/2013/01/08/dual-mode-sockets-never-create-an-ipv4-socket-again/
-             * 
-             * But it seems that we can't use this feature because DnsEndPoint
-             * doesn't have a specific AddressFamily before it has been
-             * resolved (we don't know whether it's ipv4 or ipv6) and we don't have
-             * a dual-mode socket to use on windows xp :(
-             */
-            var dep = realEndPoint as DnsEndPoint;
-            if (dep != null)
-            {
-                // need to resolve manually
-                // TODO async resolving
-                IPHostEntry ipHostInfo = Dns.GetHostEntry(dep.Host);
-                IPAddress ipAddress = ipHostInfo.AddressList[0];
-
-                realEndPoint = new IPEndPoint(ipAddress, dep.Port);
-            }
+            DestEndPoint = destEndPoint;
 
             if (_remote == null)
             {
-                _remote = new Socket(realEndPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
+                _remote = SocketUtil.CreateSocket(destEndPoint);
                 _remote.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, true);
             }
-            _remote.BeginConnect(realEndPoint, callback, state);
+            _remote.BeginConnect(destEndPoint, callback, state);
         }
 
         public void EndConnectDest(IAsyncResult asyncResult)

shadowsocks-csharp/Proxy/IProxy.cs

@@ -35,20 +35,4 @@ namespace Shadowsocks.Proxy
 
         void Close();
     }
-
-    public static class ProxyUtils
-    {
-        public static EndPoint GetEndPoint(string host, int port)
-        {
-            IPAddress ipAddress;
-            bool parsed = IPAddress.TryParse(host, out ipAddress);
-            if (parsed)
-            {
-                return new IPEndPoint(ipAddress, port);
-            }
-
-            // maybe is a domain name
-            return new DnsEndPoint(host, port);
-        }
-    }
 }

shadowsocks-csharp/Proxy/Socks5Proxy.cs

@@ -6,6 +6,7 @@ using System.Net.Sockets;
 using System.Text;
 using System.Threading;
 using Shadowsocks.Controller;
+using Shadowsocks.Util;
 
 namespace Shadowsocks.Proxy
 {
@@ -51,7 +52,7 @@ namespace Shadowsocks.Proxy
 
         public void BeginConnectProxy(EndPoint remoteEP, AsyncCallback callback, object state)
         {
-            _remote = new Socket(remoteEP.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
+            _remote = SocketUtil.CreateSocket(remoteEP);
             _remote.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, true);
 
             var st = new Socks5State();

shadowsocks-csharp/Util/SocketUtil.cs

@@ -0,0 +1,66 @@
+using System;
+using System.Net;
+using System.Net.Sockets;
+
+namespace Shadowsocks.Util
+{
+    public static class SocketUtil
+    {
+        private class DnsEndPoint2 : DnsEndPoint
+        {
+            public DnsEndPoint2(string host, int port) : base(host, port)
+            {
+            }
+
+            public DnsEndPoint2(string host, int port, AddressFamily addressFamily) : base(host, port, addressFamily)
+            {
+            }
+
+            public override string ToString()
+            {
+                return this.Host + ":" + this.Port;
+            }
+        }
+
+        public static EndPoint GetEndPoint(string host, int port)
+        {
+            IPAddress ipAddress;
+            bool parsed = IPAddress.TryParse(host, out ipAddress);
+            if (parsed)
+            {
+                return new IPEndPoint(ipAddress, port);
+            }
+
+            // maybe is a domain name
+            return new DnsEndPoint2(host, port);
+        }
+
+        public static Socket CreateSocket(EndPoint endPoint, ProtocolType protocolType = ProtocolType.Tcp)
+        {
+            SocketType socketType;
+            switch (protocolType)
+            {
+                case ProtocolType.Tcp:
+                    socketType = SocketType.Stream;
+                    break;
+                case ProtocolType.Udp:
+                    socketType = SocketType.Dgram;
+                    break;
+                default:
+                    throw new NotSupportedException("Protocol " + protocolType + " doesn't supported!");
+            }
+
+            if (endPoint is DnsEndPoint)
+            {
+                var socket = new Socket(AddressFamily.InterNetworkV6, socketType, protocolType);
+                socket.SetSocketOption(SocketOptionLevel.IPv6, (SocketOptionName)27, false);
+
+                return socket;
+            }
+            else
+            {
+                return new Socket(endPoint.AddressFamily, socketType, protocolType);
+            }
+        }
+    }
+}

shadowsocks-csharp/shadowsocks-csharp.csproj

@@ -176,6 +176,7 @@
     <Compile Include="Controller\Strategy\IStrategy.cs" />
     <Compile Include="Proxy\Socks5Proxy.cs" />
     <Compile Include="StringEx.cs" />
+    <Compile Include="Util\SocketUtil.cs" />
     <Compile Include="Util\Util.cs" />
     <Compile Include="View\ConfigForm.cs">
       <SubType>Form</SubType>