update CHANGES

1. only enable menu items relevant to pac status
2. rename edit pac file into edit local pac file
3. users are allowed to enable online pac then input online pac url, not to input then enable

CHANGES

@@ -1,4 +1,17 @@
-2.3 2015-01-14
+2.5 2015-07-11
+- Support load balance
+- Support high availability
+
+2.4 2015-07-11
+- Support UDP relay
+- Support online PAC
+- Migrate update checker to GitHub releases
+- Other fixes
+
+2.3.1 2015-03-06
+- Support user rule
+
+2.3 2015-01-25
 - Use the same port for every profile
 - Use the same port for HTTP/Socks5/PAC
 - Fix GFWList PAC compatibility issue with IE11

CONTRIBUTING.md

@@ -4,24 +4,15 @@ How to Contribute
 Pull Requests
 -------------
 
-1. Pull requests are welcome. If you would like to add a large feature
-or make a significant change, make sure to open an issue to discuss with
-people first.
+1. Pull requests are welcome.
 2. Make sure to pass the unit tests. Write unit tests for new modules if
 needed.
 
 Issues
 ------
 
-1. Only bugs and feature requests are accepted here.
-2. We'll only work on important features. If the feature you're asking only
-benefits a few people, you'd better implement the feature yourself and send us
-a pull request, or ask some of your friends to do so.
-3. We don't answer questions of any other types here. Since very few people
-are watching the issue tracker here, you'll probably get no help from here.
-Read [Troubleshooting] and get help from forums or [mailing lists].
-4. Issues in languages other than English will be Google translated into English
-later.
+1. Nobody has reported any bugs but posted a lot of questions in the last
+few months. So we're closing the issue tracker.
 
 
 [Troubleshooting]: https://github.com/clowwindy/shadowsocks/wiki/Troubleshooting

README.md

@@ -6,32 +6,47 @@ Shadowsocks for Windows
 #### Features
 
 1. System proxy configuration
-2. Fast profile switching
-3. PAC mode and global mode
-4. Compatible with IE
-5. Only a single exe file of 200KB size
+2. PAC mode and global mode
+3. GFWList and user rules
+4. Supports HTTP proxy
+5. Supports server auto switching
+6. Supports UDP relay (see Usage)
 
 #### Download
 
-Download [latest release].
+Download a [latest release].
 
-For <= Windows 7, download Shadowsocks-win-x.x.x.zip.
+For >= Windows 8 or with .Net 4.0, download Shadowsocks-win-dotnet4.0-x.x.x.zip.
 
-For >= Windows 8, download Shadowsocks-win-dotnet4.0-x.x.x.zip, unless you have .Net 2.0 installed.
+For <= Windows 7 or with .Net 2.0, download Shadowsocks-win-x.x.x.zip.
 
-#### Usage
+#### Basic
 
-1. Find Shadowsocks icon in notification tray
+1. Find Shadowsocks icon in the notification tray
 2. You can add multiple servers in servers menu
-3. Select Enable System Proxy menu to enable system proxy
-4. After you saved PAC file with any editor, Shadowsocks will notify browsers
-about the change automatically
-5. Please disable other proxy addons in your browser, or set them to use
-system proxy
+3. Select Enable System Proxy menu to enable system proxy. Please disable other
+proxy addons in your browser, or set them to use system proxy
+4. You can also configure your browser proxy manually if you don't want to enable
+system proxy. Set Socks5 or HTTP proxy to 127.0.0.1:1080. You can change this
+port in Server -> Edit Servers
 
-### Develop
+#### PAC
 
-Visual Studio Express 2012 is recommended.
+1. You can change PAC rules by editing the PAC file. When you save the PAC file
+with any editor, Shadowsocks will notify browsers about the change automatically
+2. You can also update PAC file from GFWList (maintained by 3rd party)
+3. You can also use online PAC URL
+
+#### Server Auto Switching
+
+1. Load balance: choosing server randomly
+2. High availability: choosing the best server (low latency and packet loss)
+3. Write your own strategy by implement IStrategy interface and send us a pull request!
+
+#### UDP
+
+For UDP, you need to use SocksCap or ProxyCap to force programs you want
+to proxy to tunnel over Shadowsocks
 
 #### License
 
@@ -40,4 +55,4 @@ GPLv3
 
 [Appveyor]:       https://ci.appveyor.com/project/clowwindy/shadowsocks-csharp
 [Build Status]:   https://ci.appveyor.com/api/projects/status/gknc8l1lxy423ehv/branch/master
-[latest release]: https://sourceforge.net/projects/shadowsocksgui/files/dist/
+[latest release]: https://github.com/shadowsocks/shadowsocks-csharp/releases

shadowsocks-csharp/Controller/I18N.cs

@@ -18,6 +18,10 @@ namespace Shadowsocks.Controller
                 string[] lines = Regex.Split(Resources.cn, "\r\n|\r|\n");
                 foreach (string line in lines)
                 {
+                    if (line.StartsWith("#"))
+                    {
+                        continue;
+                    }
                     string[] kv = Regex.Split(line, "=");
                     if (kv.Length == 2)
                     {

shadowsocks-csharp/Controller/Listener.cs

@@ -1,143 +0,0 @@
-using Shadowsocks.Model;
-using System;
-using System.Collections.Generic;
-using System.Net;
-using System.Net.Sockets;
-using System.Text;
-
-namespace Shadowsocks.Controller
-{
-    public class Listener
-    {
-        public interface Service
-        {
-            bool Handle(byte[] firstPacket, int length, Socket socket);
-        }
-
-        Configuration _config;
-        bool _shareOverLAN;
-        Socket _socket;
-        IList<Service> _services;
-
-        public Listener(IList<Service> services)
-        {
-            this._services = services;
-        }
-
-        public void Start(Configuration config)
-        {
-            this._config = config;
-            this._shareOverLAN = config.shareOverLan;
-            try
-            {
-                // Create a TCP/IP socket.
-                _socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
-                _socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
-                IPEndPoint localEndPoint = null;
-                if (_shareOverLAN)
-                {
-                    localEndPoint = new IPEndPoint(IPAddress.Any, _config.localPort);
-                }
-                else
-                {
-                    localEndPoint = new IPEndPoint(IPAddress.Loopback, _config.localPort);
-                }
-
-                // Bind the socket to the local endpoint and listen for incoming connections.
-                _socket.Bind(localEndPoint);
-                _socket.Listen(1024);
-
-
-                // Start an asynchronous socket to listen for connections.
-                Console.WriteLine("Shadowsocks started");
-                _socket.BeginAccept(
-                    new AsyncCallback(AcceptCallback),
-                    _socket);
-            }
-            catch (SocketException)
-            {
-                _socket.Close();
-                throw;
-            }
-        }
-
-        public void Stop()
-        {
-            if (_socket != null)
-            {
-                _socket.Close();
-                _socket = null;
-            }
-        }
-
-        public void AcceptCallback(IAsyncResult ar)
-        {
-            Socket listener = (Socket)ar.AsyncState;
-            try
-            {
-                Socket conn = listener.EndAccept(ar);
-
-                byte[] buf = new byte[4096];
-                object[] state = new object[] {
-                    conn,
-                    buf
-                };
-
-                conn.BeginReceive(buf, 0, buf.Length, 0,
-                    new AsyncCallback(ReceiveCallback), state);
-            }
-            catch (ObjectDisposedException)
-            {
-            }
-            catch (Exception e)
-            {
-                Console.WriteLine(e);
-            }
-            finally
-            {
-                try
-                {
-                    listener.BeginAccept(
-                        new AsyncCallback(AcceptCallback),
-                        listener);
-                }
-                catch (ObjectDisposedException)
-                {
-                    // do nothing
-                }
-                catch (Exception e)
-                {
-                    Logging.LogUsefulException(e);
-                }
-            }
-        }
-
-
-        private void ReceiveCallback(IAsyncResult ar)
-        {
-            object[] state = (object[])ar.AsyncState;
-
-            Socket conn = (Socket)state[0];
-            byte[] buf = (byte[])state[1];
-            try
-            {
-                int bytesRead = conn.EndReceive(ar);
-                foreach (Service service in _services)
-                {
-                    if (service.Handle(buf, bytesRead, conn))
-                    {
-                        return;
-                    }
-                }
-                // no service found for this
-                // shouldn't happen
-                conn.Close();
-            }
-            catch (Exception e)
-            {
-                Console.WriteLine(e);
-                conn.Close();
-            }
-        }
-    }
-}

shadowsocks-csharp/Controller/Logging.cs

@@ -31,6 +31,14 @@ namespace Shadowsocks.Controller
             }
         }
 
+        public static void Debug(object o)
+        {
+
+#if DEBUG
+            Console.WriteLine(o);
+#endif
+        }
+
         public static void LogUsefulException(Exception e)
         {
             // just log useful exceptions, not all of them
@@ -55,6 +63,9 @@ namespace Shadowsocks.Controller
                     Console.WriteLine(e);
                 }
             }
+            else if (e is ObjectDisposedException)
+            {
+            }
             else
             {
                 Console.WriteLine(e);

shadowsocks-csharp/Controller/Service/GfwListUpdater.cs

@@ -16,6 +16,8 @@ namespace Shadowsocks.Controller
 
         private static string PAC_FILE = PACServer.PAC_FILE;
 
+        private static string USER_RULE_FILE = PACServer.USER_RULE_FILE;
+
         public event EventHandler<ResultEventArgs> UpdateCompleted;
 
         public event ErrorEventHandler Error;
@@ -35,7 +37,17 @@ namespace Shadowsocks.Controller
             try
             {
                 List<string> lines = ParseResult(e.Result);
-
+                if (File.Exists(USER_RULE_FILE))
+                {
+                    string local = File.ReadAllText(USER_RULE_FILE, Encoding.UTF8);
+                    string[] rules = local.Split(new char[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries);
+                    foreach(string rule in rules)
+                    {
+                        if (rule.StartsWith("!") || rule.StartsWith("["))
+                            continue;
+                        lines.Add(rule);
+                    }
+                }
                 string abpContent = Utils.UnGzip(Resources.abp_js);
                 abpContent = abpContent.Replace("__RULES__", SimpleJson.SimpleJson.SerializeObject(lines));
                 if (File.Exists(PAC_FILE))

shadowsocks-csharp/Controller/Service/Listener.cs

@@ -0,0 +1,218 @@
+using Shadowsocks.Model;
+using System;
+using System.Collections.Generic;
+using System.Net;
+using System.Net.NetworkInformation;
+using System.Net.Sockets;
+using System.Text;
+
+namespace Shadowsocks.Controller
+{
+    public class Listener
+    {
+        public interface Service
+        {
+            bool Handle(byte[] firstPacket, int length, Socket socket, object state);
+        }
+
+        public class UDPState
+        {
+            public byte[] buffer = new byte[4096];
+            public EndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
+        }
+
+        Configuration _config;
+        bool _shareOverLAN;
+        Socket _tcpSocket;
+        Socket _udpSocket;
+        IList<Service> _services;
+
+        public Listener(IList<Service> services)
+        {
+            this._services = services;
+        }
+
+        private bool CheckIfPortInUse(int port)
+        {
+            IPGlobalProperties ipProperties = IPGlobalProperties.GetIPGlobalProperties();
+            IPEndPoint[] ipEndPoints = ipProperties.GetActiveTcpListeners();
+
+            foreach (IPEndPoint endPoint in ipEndPoints)
+            {
+                if (endPoint.Port == port)
+                {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        public void Start(Configuration config)
+        {
+            this._config = config;
+            this._shareOverLAN = config.shareOverLan;
+
+            if (CheckIfPortInUse(_config.localPort))
+                throw new Exception(I18N.GetString("Port already in use"));
+
+            try
+            {
+                // Create a TCP/IP socket.
+                _tcpSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+                _udpSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
+                _tcpSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
+                _udpSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
+                IPEndPoint localEndPoint = null;
+                if (_shareOverLAN)
+                {
+                    localEndPoint = new IPEndPoint(IPAddress.Any, _config.localPort);
+                }
+                else
+                {
+                    localEndPoint = new IPEndPoint(IPAddress.Loopback, _config.localPort);
+                }
+
+                // Bind the socket to the local endpoint and listen for incoming connections.
+                _tcpSocket.Bind(localEndPoint);
+                _udpSocket.Bind(localEndPoint);
+                _tcpSocket.Listen(1024);
+
+
+                // Start an asynchronous socket to listen for connections.
+                Console.WriteLine("Shadowsocks started");
+                _tcpSocket.BeginAccept(
+                    new AsyncCallback(AcceptCallback),
+                    _tcpSocket);
+                UDPState udpState = new UDPState();
+                _udpSocket.BeginReceiveFrom(udpState.buffer, 0, udpState.buffer.Length, 0, ref udpState.remoteEndPoint, new AsyncCallback(RecvFromCallback), udpState);
+            }
+            catch (SocketException)
+            {
+                _tcpSocket.Close();
+                throw;
+            }
+        }
+
+        public void Stop()
+        {
+            if (_tcpSocket != null)
+            {
+                _tcpSocket.Close();
+                _tcpSocket = null;
+            }
+            if (_udpSocket != null)
+            {
+                _udpSocket.Close();
+                _udpSocket = null;
+            }
+        }
+
+        public void RecvFromCallback(IAsyncResult ar)
+        {
+            UDPState state = (UDPState)ar.AsyncState;
+            try
+            {
+                int bytesRead = _udpSocket.EndReceiveFrom(ar, ref state.remoteEndPoint);
+                foreach (Service service in _services)
+                {
+                    if (service.Handle(state.buffer, bytesRead, _udpSocket, state))
+                    {
+                        break;
+                    }
+                }
+            }
+            catch (ObjectDisposedException)
+            {
+            }
+            catch (Exception)
+            {
+            }
+            finally
+            {
+                try
+                {
+                    _udpSocket.BeginReceiveFrom(state.buffer, 0, state.buffer.Length, 0, ref state.remoteEndPoint, new AsyncCallback(RecvFromCallback), state);
+                }
+                catch (ObjectDisposedException)
+                {
+                    // do nothing
+                }
+                catch (Exception)
+                {
+                }
+            }
+        }
+
+        public void AcceptCallback(IAsyncResult ar)
+        {
+            Socket listener = (Socket)ar.AsyncState;
+            try
+            {
+                Socket conn = listener.EndAccept(ar);
+
+                byte[] buf = new byte[4096];
+                object[] state = new object[] {
+                    conn,
+                    buf
+                };
+
+                conn.BeginReceive(buf, 0, buf.Length, 0,
+                    new AsyncCallback(ReceiveCallback), state);
+            }
+            catch (ObjectDisposedException)
+            {
+            }
+            catch (Exception e)
+            {
+                Console.WriteLine(e);
+            }
+            finally
+            {
+                try
+                {
+                    listener.BeginAccept(
+                        new AsyncCallback(AcceptCallback),
+                        listener);
+                }
+                catch (ObjectDisposedException)
+                {
+                    // do nothing
+                }
+                catch (Exception e)
+                {
+                    Logging.LogUsefulException(e);
+                }
+            }
+        }
+
+
+        private void ReceiveCallback(IAsyncResult ar)
+        {
+            object[] state = (object[])ar.AsyncState;
+
+            Socket conn = (Socket)state[0];
+            byte[] buf = (byte[])state[1];
+            try
+            {
+                int bytesRead = conn.EndReceive(ar);
+                foreach (Service service in _services)
+                {
+                    if (service.Handle(buf, bytesRead, conn, null))
+                    {
+                        return;
+                    }
+                }
+                // no service found for this
+                if (conn.ProtocolType == ProtocolType.Tcp)
+                {
+                    conn.Close();
+                }
+            }
+            catch (Exception e)
+            {
+                Console.WriteLine(e);
+                conn.Close();
+            }
+        }
+    }
+}

shadowsocks-csharp/Controller/Service/PACServer.cs

@@ -16,6 +16,8 @@ namespace Shadowsocks.Controller
     {
         public static string PAC_FILE = "pac.txt";
 
+        public static string USER_RULE_FILE = "user-rule.txt";
+
         FileSystemWatcher watcher;
         private Configuration _config;
 
@@ -31,8 +33,12 @@ namespace Shadowsocks.Controller
             this._config = config;
         }
 
-        public bool Handle(byte[] firstPacket, int length, Socket socket)
+        public bool Handle(byte[] firstPacket, int length, Socket socket, object state)
         {
+            if (socket.ProtocolType != ProtocolType.Tcp)
+            {
+                return false;
+            }
             try
             {
                 string request = Encoding.UTF8.GetString(firstPacket, 0, length);
@@ -94,6 +100,19 @@ namespace Shadowsocks.Controller
             }
         }
 
+        internal string TouchUserRuleFile()
+        {
+            if (File.Exists(USER_RULE_FILE))
+            {
+                return USER_RULE_FILE;
+            }
+            else
+            {
+                File.WriteAllText(USER_RULE_FILE, Resources.user_rule);
+                return USER_RULE_FILE;
+            }
+        }
+
         private string GetPACContent()
         {
             if (File.Exists(PAC_FILE))

shadowsocks-csharp/Controller/Service/PortForwarder.cs

@@ -15,8 +15,12 @@ namespace Shadowsocks.Controller
             this._targetPort = targetPort;
         }
 
-        public bool Handle(byte[] firstPacket, int length, Socket socket)
+        public bool Handle(byte[] firstPacket, int length, Socket socket, object state)
         {
+            if (socket.ProtocolType != ProtocolType.Tcp)
+            {
+                return false;
+            }
             new Handler().Start(firstPacket, length, socket, this._targetPort);
             return true;
         }

shadowsocks-csharp/Controller/Service/TCPRelay.cs

@@ -5,20 +5,26 @@ using System.Net.Sockets;
 using System.Net;
 using Shadowsocks.Encryption;
 using Shadowsocks.Model;
+using Shadowsocks.Controller.Strategy;
+using System.Timers;
 
 namespace Shadowsocks.Controller
 {
 
-    class Local : Listener.Service
+    class TCPRelay : Listener.Service
     {
-        private Configuration _config;
-        public Local(Configuration config)
+        private ShadowsocksController _controller;
+        public TCPRelay(ShadowsocksController controller)
         {
-            this._config = config;
+            this._controller = controller;
         }
 
-        public bool Handle(byte[] firstPacket, int length, Socket socket)
+        public bool Handle(byte[] firstPacket, int length, Socket socket, object state)
         {
+            if (socket.ProtocolType != ProtocolType.Tcp)
+            {
+                return false;
+            }
             if (length < 2 || firstPacket[0] != 5)
             {
                 return false;
@@ -26,9 +32,7 @@ namespace Shadowsocks.Controller
             socket.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, true);
             Handler handler = new Handler();
             handler.connection = socket;
-            Server server = _config.GetCurrentServer();
-            handler.encryptor = EncryptorFactory.GetEncryptor(server.method, server.password);
-            handler.server = server;
+            handler.controller = _controller;
 
             handler.Start(firstPacket, length);
             return true;
@@ -43,12 +47,20 @@ namespace Shadowsocks.Controller
         // Client  socket.
         public Socket remote;
         public Socket connection;
+        public ShadowsocksController controller;
+        private int retryCount = 0;
+        private bool connected;
 
+        private byte command;
         private byte[] _firstPacket;
         private int _firstPacketLength;
         // Size of receive buffer.
         public const int RecvSize = 16384;
         public const int BufferSize = RecvSize + 32;
+
+        private int totalRead = 0;
+        private int totalWrite = 0;
+
         // remote receive buffer
         private byte[] remoteRecvBuffer = new byte[RecvSize];
         // remote send buffer
@@ -66,36 +78,20 @@ namespace Shadowsocks.Controller
         private object encryptionLock = new object();
         private object decryptionLock = new object();
 
+        private DateTime _startConnectTime;
+
+        public void CreateRemote()
+        {
+            Server server = controller.GetAServer(IStrategyCallerType.TCP, (IPEndPoint)connection.RemoteEndPoint);
+            this.encryptor = EncryptorFactory.GetEncryptor(server.method, server.password);
+            this.server = server;
+        }
+
         public void Start(byte[] firstPacket, int length)
         {
             this._firstPacket = firstPacket;
             this._firstPacketLength = length;
-            try
-            {
-                // 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];
-                }
-                IPEndPoint remoteEP = new IPEndPoint(ipAddress, server.server_port);
-
-
-                remote = new Socket(ipAddress.AddressFamily,
-                    SocketType.Stream, ProtocolType.Tcp);
-                remote.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, true);
-
-                // Connect to the remote endpoint.
-                remote.BeginConnect(remoteEP,
-                    new AsyncCallback(ConnectCallback), null);
-            }
-            catch (Exception e)
-            {
-                Logging.LogUsefulException(e);
-                this.Close();
-            }
+            this.HandshakeReceive();
         }
 
         private void CheckClose()
@@ -135,7 +131,7 @@ namespace Shadowsocks.Controller
                     remote.Shutdown(SocketShutdown.Both);
                     remote.Close();
                 }
-                catch (SocketException e)
+                catch (Exception e)
                 {
                     Logging.LogUsefulException(e);
                 }
@@ -144,33 +140,14 @@ namespace Shadowsocks.Controller
             {
                 lock (decryptionLock)
                 {
-                    ((IDisposable)encryptor).Dispose();
+                    if (encryptor != null)
+                    {
+                        ((IDisposable)encryptor).Dispose();
+                    }
                 }
             }
         }
 
-        private void ConnectCallback(IAsyncResult ar)
-        {
-            if (closed)
-            {
-                return;
-            }
-            try
-            {
-                // Complete the connection.
-                remote.EndConnect(ar);
-
-                //Console.WriteLine("Socket connected to {0}",
-                //    remote.RemoteEndPoint.ToString());
-
-                HandshakeReceive();
-            }
-            catch (Exception e)
-            {
-                Logging.LogUsefulException(e);
-                this.Close();
-            }
-        }
 
         private void HandshakeReceive()
         {
@@ -241,11 +218,19 @@ namespace Shadowsocks.Controller
             try
             {
                 int bytesRead = connection.EndReceive(ar);
-
-                if (bytesRead > 0)
+                
+                if (bytesRead >= 3)
                 {
-                    byte[] response = { 5, 0, 0, 1, 0, 0, 0, 0, 0, 0 };
-                    connection.BeginSend(response, 0, response.Length, 0, new AsyncCallback(StartPipe), null);
+                    command = connetionRecvBuffer[1];
+                    if (command == 1)
+                    {
+                        byte[] response = { 5, 0, 0, 1, 0, 0, 0, 0, 0, 0 };
+                        connection.BeginSend(response, 0, response.Length, 0, new AsyncCallback(ResponseCallback), null);
+                    }
+                    else if (command == 3)
+                    {
+                        HandleUDPAssociate();
+                    }
                 }
                 else
                 {
@@ -260,8 +245,209 @@ namespace Shadowsocks.Controller
             }
         }
 
+        private void HandleUDPAssociate()
+        {
+            IPEndPoint endPoint = (IPEndPoint)connection.LocalEndPoint;
+            byte[] address = endPoint.Address.GetAddressBytes();
+            int port = endPoint.Port;
+            byte[] response = new byte[4 + address.Length + 2];
+            response[0] = 5;
+            if (endPoint.AddressFamily == AddressFamily.InterNetwork)
+            {
+                response[3] = 1;
+            }
+            else if (endPoint.AddressFamily == AddressFamily.InterNetworkV6)
+            {
+                response[3] = 4;
+            }
+            address.CopyTo(response, 4);
+            response[response.Length - 1] = (byte)(port & 0xFF);
+            response[response.Length - 2] = (byte)((port >> 8) & 0xFF);
+            connection.BeginSend(response, 0, response.Length, 0, new AsyncCallback(ReadAll), true);
+        }
 
-        private void StartPipe(IAsyncResult ar)
+        private void ReadAll(IAsyncResult ar)
+        {
+
+            if (closed)
+            {
+                return;
+            }
+            try
+            {
+                if (ar.AsyncState != null)
+                {
+                    connection.EndSend(ar);
+                    connection.BeginReceive(connetionRecvBuffer, 0, RecvSize, 0,
+                        new AsyncCallback(ReadAll), null);
+                }
+                else
+                {
+                    int bytesRead = connection.EndReceive(ar);
+                    if (bytesRead > 0)
+                    {
+                        connection.BeginReceive(connetionRecvBuffer, 0, RecvSize, 0,
+                            new AsyncCallback(ReadAll), null);
+                    }
+                    else
+                    {
+                        this.Close();
+                    }
+                }
+            }
+            catch (Exception e)
+            {
+                Logging.LogUsefulException(e);
+                this.Close();
+            }
+        }
+
+        private void ResponseCallback(IAsyncResult ar)
+        {
+            try
+            {
+                connection.EndSend(ar);
+
+                StartConnect();
+            }
+            catch (Exception e)
+            {
+                Logging.LogUsefulException(e);
+                this.Close();
+            }
+        }
+
+        private class ServerTimer : Timer
+        {
+            public Server Server;
+
+            public ServerTimer(int p) :base(p)
+            {
+            }
+        }
+
+        private void StartConnect()
+        {
+            try
+            {
+                CreateRemote();
+
+                // 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];
+                }
+                IPEndPoint remoteEP = new IPEndPoint(ipAddress, server.server_port);
+
+
+                remote = new Socket(ipAddress.AddressFamily,
+                    SocketType.Stream, ProtocolType.Tcp);
+                remote.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, true);
+
+                _startConnectTime = DateTime.Now;
+                ServerTimer connectTimer = new ServerTimer(3000);
+                connectTimer.AutoReset = false;
+                connectTimer.Elapsed += connectTimer_Elapsed;
+                connectTimer.Enabled = true;
+                connectTimer.Server = server;
+
+                connected = false;
+                // Connect to the remote endpoint.
+                remote.BeginConnect(remoteEP,
+                    new AsyncCallback(ConnectCallback), connectTimer);
+            }
+            catch (Exception e)
+            {
+                Logging.LogUsefulException(e);
+                this.Close();
+            }
+        }
+
+        private void connectTimer_Elapsed(object sender, ElapsedEventArgs e)
+        {
+            if (connected)
+            {
+                return;
+            }
+            Server server = ((ServerTimer)sender).Server;
+            IStrategy strategy = controller.GetCurrentStrategy();
+            if (strategy != null)
+            {
+                strategy.SetFailure(server);
+            }
+            Console.WriteLine(String.Format("{0} timed out", server.FriendlyName()));
+            remote.Close();
+            RetryConnect();
+        }
+
+        private void RetryConnect()
+        {
+            if (retryCount < 4)
+            {
+                Logging.Debug("Connection failed, retrying");
+                StartConnect();
+                retryCount++;
+            }
+            else
+            {
+                this.Close();
+            }
+        }
+
+        private void ConnectCallback(IAsyncResult ar)
+        {
+            Server server = null;
+            if (closed)
+            {
+                return;
+            }
+            try
+            {
+                ServerTimer timer = (ServerTimer)ar.AsyncState;
+                server = timer.Server;
+                timer.Elapsed -= connectTimer_Elapsed;
+                timer.Enabled = false;
+                timer.Dispose();
+
+                // Complete the connection.
+                remote.EndConnect(ar);
+
+                connected = true;
+
+                //Console.WriteLine("Socket connected to {0}",
+                //    remote.RemoteEndPoint.ToString());
+
+                var latency = DateTime.Now - _startConnectTime;
+                IStrategy strategy = controller.GetCurrentStrategy();
+                if (strategy != null)
+                {
+                    strategy.UpdateLatency(server, latency);
+                }
+
+                StartPipe();
+            }
+            catch (ArgumentException e)
+            {
+            }
+            catch (Exception e)
+            {
+                if (server != null)
+                {
+                    IStrategy strategy = controller.GetCurrentStrategy();
+                    if (strategy != null)
+                    {
+                        strategy.SetFailure(server);
+                    }
+                }
+                Logging.LogUsefulException(e);
+                RetryConnect();
+            }
+        }
+
+        private void StartPipe()
         {
             if (closed)
             {
@@ -269,7 +455,6 @@ namespace Shadowsocks.Controller
             }
             try
             {
-                connection.EndReceive(ar);
                 remote.BeginReceive(remoteRecvBuffer, 0, RecvSize, 0,
                     new AsyncCallback(PipeRemoteReceiveCallback), null);
                 connection.BeginReceive(connetionRecvBuffer, 0, RecvSize, 0,
@@ -291,6 +476,7 @@ namespace Shadowsocks.Controller
             try
             {
                 int bytesRead = remote.EndReceive(ar);
+                totalRead += bytesRead;
 
                 if (bytesRead > 0)
                 {
@@ -304,6 +490,12 @@ namespace Shadowsocks.Controller
                         encryptor.Decrypt(remoteRecvBuffer, bytesRead, remoteSendBuffer, out bytesToSend);
                     }
                     connection.BeginSend(remoteSendBuffer, 0, bytesToSend, 0, new AsyncCallback(PipeConnectionSendCallback), null);
+
+                    IStrategy strategy = controller.GetCurrentStrategy();
+                    if (strategy != null)
+                    {
+                        strategy.UpdateLastRead(this.server);
+                    }
                 }
                 else
                 {
@@ -311,6 +503,13 @@ namespace Shadowsocks.Controller
                     connection.Shutdown(SocketShutdown.Send);
                     connectionShutdown = true;
                     CheckClose();
+
+                    if (totalRead == 0)
+                    {
+                        // closed before anything received, reports as failure
+                        // disable this feature
+                        // controller.GetCurrentStrategy().SetFailure(this.server);
+                    }
                 }
             }
             catch (Exception e)
@@ -329,6 +528,7 @@ namespace Shadowsocks.Controller
             try
             {
                 int bytesRead = connection.EndReceive(ar);
+                totalWrite += bytesRead;
 
                 if (bytesRead > 0)
                 {
@@ -342,6 +542,13 @@ namespace Shadowsocks.Controller
                         encryptor.Encrypt(connetionRecvBuffer, bytesRead, connetionSendBuffer, out bytesToSend);
                     }
                     remote.BeginSend(connetionSendBuffer, 0, bytesToSend, 0, new AsyncCallback(PipeRemoteSendCallback), null);
+
+
+                    IStrategy strategy = controller.GetCurrentStrategy();
+                    if (strategy != null)
+                    {
+                        strategy.UpdateLastWrite(this.server);
+                    }
                 }
                 else
                 {

shadowsocks-csharp/Controller/Service/UDPRelay.cs

@@ -0,0 +1,200 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Shadowsocks.Encryption;
+using Shadowsocks.Model;
+using System.Net.Sockets;
+using System.Net;
+using System.Runtime.CompilerServices;
+using Shadowsocks.Controller.Strategy;
+
+namespace Shadowsocks.Controller
+{
+    class UDPRelay : Listener.Service
+    {
+        private ShadowsocksController _controller;
+        private LRUCache<IPEndPoint, UDPHandler> _cache;
+        public UDPRelay(ShadowsocksController controller)
+        {
+            this._controller = controller;
+            this._cache = new LRUCache<IPEndPoint, UDPHandler>(512);  // todo: choose a smart number
+        }
+
+        public bool Handle(byte[] firstPacket, int length, Socket socket, object state)
+        {
+            if (socket.ProtocolType != ProtocolType.Udp)
+            {
+                return false;
+            }
+            if (length < 4)
+            {
+                return false;
+            }
+            Listener.UDPState udpState = (Listener.UDPState)state;
+            IPEndPoint remoteEndPoint = (IPEndPoint)udpState.remoteEndPoint;
+            UDPHandler handler = _cache.get(remoteEndPoint);
+            if (handler == null)
+            {
+                handler = new UDPHandler(socket, _controller.GetAServer(IStrategyCallerType.UDP, remoteEndPoint), remoteEndPoint);
+                _cache.add(remoteEndPoint, handler);
+            }
+            handler.Send(firstPacket, length);
+            handler.Receive();
+            return true;
+        }
+
+        public class UDPHandler
+        {
+            private Socket _local;
+            private Socket _remote;
+
+            private Server _server;
+            private byte[] _buffer = new byte[1500];
+
+            private IPEndPoint _localEndPoint;
+            private IPEndPoint _remoteEndPoint;
+
+            public UDPHandler(Socket local, Server server, IPEndPoint localEndPoint)
+            {
+                _local = local;
+                _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);
+
+            }
+            public void Send(byte[] data, int length)
+            {
+                IEncryptor encryptor = EncryptorFactory.GetEncryptor(_server.method, _server.password);
+                byte[] dataIn = new byte[length - 3];
+                Array.Copy(data, 3, dataIn, 0, length - 3);
+                byte[] dataOut = new byte[length - 3 + 16];
+                int outlen;
+                encryptor.Encrypt(dataIn, dataIn.Length, dataOut, out outlen);
+                _remote.SendTo(dataOut, _remoteEndPoint);
+            }
+            public void Receive()
+            {
+                EndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
+                _remote.BeginReceiveFrom(_buffer, 0, _buffer.Length, 0, ref remoteEndPoint, new AsyncCallback(RecvFromCallback), null);
+            }
+            public void RecvFromCallback(IAsyncResult ar)
+            {
+                try
+                {
+                    EndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
+                    int bytesRead = _remote.EndReceiveFrom(ar, ref remoteEndPoint);
+
+                    byte[] dataOut = new byte[bytesRead];
+                    int outlen;
+
+                    IEncryptor encryptor = EncryptorFactory.GetEncryptor(_server.method, _server.password);
+                    encryptor.Decrypt(_buffer, bytesRead, dataOut, out outlen);
+
+                    byte[] sendBuf = new byte[outlen + 3];
+                    Array.Copy(dataOut, 0, sendBuf, 3, outlen);
+
+                    _local.SendTo(sendBuf, outlen + 3, 0, _localEndPoint);
+                    Receive();
+                }
+                catch (ObjectDisposedException)
+                {
+                }
+                catch (Exception)
+                {
+                }
+                finally
+                {
+                }
+            }
+            public void Close()
+            {
+                try
+                {
+                    _remote.Close();
+                }
+                catch (ObjectDisposedException)
+                {
+                }
+                catch (Exception)
+                {
+                }
+                finally
+                {
+                }
+            }
+        }
+    }
+    // cc by-sa 3.0 http://stackoverflow.com/a/3719378/1124054
+    class LRUCache<K, V> where V : UDPRelay.UDPHandler
+    {
+        private int capacity;
+        private Dictionary<K, LinkedListNode<LRUCacheItem<K, V>>> cacheMap = new Dictionary<K, LinkedListNode<LRUCacheItem<K, V>>>();
+        private LinkedList<LRUCacheItem<K, V>> lruList = new LinkedList<LRUCacheItem<K, V>>();
+
+        public LRUCache(int capacity)
+        {
+            this.capacity = capacity;
+        }
+
+        [MethodImpl(MethodImplOptions.Synchronized)]
+        public V get(K key)
+        {
+            LinkedListNode<LRUCacheItem<K, V>> node;
+            if (cacheMap.TryGetValue(key, out node))
+            {
+                V value = node.Value.value;
+                lruList.Remove(node);
+                lruList.AddLast(node);
+                return value;
+            }
+            return default(V);
+        }
+
+        [MethodImpl(MethodImplOptions.Synchronized)]
+        public void add(K key, V val)
+        {
+            if (cacheMap.Count >= capacity)
+            {
+                RemoveFirst();
+            }
+
+            LRUCacheItem<K, V> cacheItem = new LRUCacheItem<K, V>(key, val);
+            LinkedListNode<LRUCacheItem<K, V>> node = new LinkedListNode<LRUCacheItem<K, V>>(cacheItem);
+            lruList.AddLast(node);
+            cacheMap.Add(key, node);
+        }
+
+        private void RemoveFirst()
+        {
+            // Remove from LRUPriority
+            LinkedListNode<LRUCacheItem<K, V>> node = lruList.First;
+            lruList.RemoveFirst();
+
+            // Remove from cache
+            cacheMap.Remove(node.Value.key);
+            node.Value.value.Close();
+        }
+    }
+
+    class LRUCacheItem<K, V>
+    {
+        public LRUCacheItem(K k, V v)
+        {
+            key = k;
+            value = v;
+        }
+        public K key;
+        public V value;
+    }
+
+}

shadowsocks-csharp/Controller/Service/UpdateChecker.cs

@@ -6,24 +6,25 @@ using System.Net;
 using System.Reflection;
 using System.Text;
 using System.Text.RegularExpressions;
-using System.Xml;
+using SimpleJson;
 
 namespace Shadowsocks.Controller
 {
     public class UpdateChecker
     {
-        private const string UpdateURL = "https://sourceforge.net/api/file/index/project-id/1817190/path/dist/mtime/desc/limit/10/rss";
+        private const string UpdateURL = "https://api.github.com/repos/shadowsocks/shadowsocks-csharp/releases";
 
         public string LatestVersionNumber;
         public string LatestVersionURL;
         public event EventHandler NewVersionFound;
 
-        public const string Version = "2.3";
+        public const string Version = "2.5";
 
         public void CheckUpdate(Configuration config)
         {
             // TODO test failures
             WebClient http = new WebClient();
+            http.Headers.Add("User-Agent", "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.3319.102 Safari/537.36");
             http.Proxy = new WebProxy(IPAddress.Loopback.ToString(), config.localPort);
             http.DownloadStringCompleted += http_DownloadStringCompleted;
             http.DownloadStringAsync(new Uri(UpdateURL));
@@ -119,23 +120,25 @@ namespace Shadowsocks.Controller
             {
                 string response = e.Result;
 
-                XmlDocument xmlDoc = new XmlDocument();
-                xmlDoc.LoadXml(response);
-                XmlNodeList elements = xmlDoc.GetElementsByTagName("media:content");
+                JsonArray result = (JsonArray)SimpleJson.SimpleJson.DeserializeObject(e.Result);
+
                 List<string> versions = new List<string>();
-                foreach (XmlNode el in elements)
+                foreach (JsonObject release in result)
                 {
-                    foreach (XmlAttribute attr in el.Attributes)
+                    if ((bool)release["prerelease"])
                     {
-                        if (attr.Name == "url")
+                        continue;
+                    }
+                    foreach (JsonObject asset in (JsonArray)release["assets"])
+                    {
+                        string url = (string)asset["browser_download_url"];
+                        if (IsNewVersion(url))
                         {
-                            if (IsNewVersion(attr.Value))
-                            {
-                                versions.Add(attr.Value);
-                            }
+                            versions.Add(url);
                         }
                     }
                 }
+
                 if (versions.Count == 0)
                 {
                     return;

shadowsocks-csharp/Controller/ShadowsocksController.cs

@@ -5,6 +5,8 @@ using System.Collections.Generic;
 using System.Text;
 using System.Threading;
 using System.Net.Sockets;
+using Shadowsocks.Controller.Strategy;
+using System.Net;
 
 namespace Shadowsocks.Controller
 {
@@ -20,6 +22,7 @@ namespace Shadowsocks.Controller
         private Listener _listener;
         private PACServer _pacServer;
         private Configuration _config;
+        private StrategyManager _strategyManager;
         private PolipoRunner polipoRunner;
         private GFWListUpdater gfwListUpdater;
         private bool stopped = false;
@@ -38,6 +41,7 @@ namespace Shadowsocks.Controller
         
         // when user clicked Edit PAC, and PAC file has already created
         public event EventHandler<PathEventArgs> PACFileReadyToOpen;
+        public event EventHandler<PathEventArgs> UserRuleFileReadyToOpen;
 
         public event EventHandler<GFWListUpdater.ResultEventArgs> UpdatePACFromGFWListCompleted;
 
@@ -48,6 +52,7 @@ namespace Shadowsocks.Controller
         public ShadowsocksController()
         {
             _config = Configuration.Load();
+            _strategyManager = new StrategyManager(this);
         }
 
         public void Start()
@@ -69,11 +74,44 @@ namespace Shadowsocks.Controller
         }
 
         // always return copy
-        public Configuration GetConfiguration()
+        public Configuration GetConfigurationCopy()
         {
             return Configuration.Load();
         }
 
+        // always return current instance
+        public Configuration GetCurrentConfiguration()
+        {
+            return _config;
+        }
+
+        public IList<IStrategy> GetStrategies()
+        {
+            return _strategyManager.GetStrategies();
+        }
+
+        public IStrategy GetCurrentStrategy()
+        {
+            foreach (var strategy in _strategyManager.GetStrategies())
+            {
+                if (strategy.ID == this._config.strategy)
+                {
+                    return strategy;
+                }
+            }
+            return null;
+        }
+
+        public Server GetAServer(IStrategyCallerType type, IPEndPoint localIPEndPoint)
+        {
+            IStrategy strategy = GetCurrentStrategy();
+            if (strategy != null)
+            {
+                return strategy.GetAServer(type, localIPEndPoint);
+            }
+            return GetCurrentServer();
+        }
+
         public void SaveServers(List<Server> servers, int localPort)
         {
             _config.configs = servers;
@@ -133,6 +171,14 @@ namespace Shadowsocks.Controller
         public void SelectServerIndex(int index)
         {
             _config.index = index;
+            _config.strategy = null;
+            SaveConfig(_config);
+        }
+
+        public void SelectStrategy(string strategyID)
+        {
+            _config.index = -1;
+            _config.strategy = strategyID;
             SaveConfig(_config);
         }
 
@@ -166,6 +212,15 @@ namespace Shadowsocks.Controller
             }
         }
 
+        public void TouchUserRuleFile()
+        {
+            string userRuleFilename = _pacServer.TouchUserRuleFile();
+            if (UserRuleFileReadyToOpen != null)
+            {
+                UserRuleFileReadyToOpen(this, new PathEventArgs() { Path = userRuleFilename });
+            }
+        }
+
         public string GetQRCodeForCurrentServer()
         {
             Server server = GetCurrentServer();
@@ -182,6 +237,28 @@ namespace Shadowsocks.Controller
             }
         }
 
+        public void SavePACUrl(string pacUrl)
+        {
+            _config.pacUrl = pacUrl;
+            UpdateSystemProxy();
+            SaveConfig(_config);
+            if (ConfigChanged != null)
+            {
+                ConfigChanged(this, new EventArgs());
+            }
+        }
+
+        public void UseOnlinePAC(bool useOnlinePac)
+        {
+            _config.useOnlinePac = useOnlinePac;
+            UpdateSystemProxy();
+            SaveConfig(_config);
+            if (ConfigChanged != null)
+            {
+                ConfigChanged(this, new EventArgs());
+            }
+        }
+
         protected void Reload()
         {
             // some logic in configuration updated the config when saving, we need to read it again
@@ -216,11 +293,18 @@ namespace Shadowsocks.Controller
             polipoRunner.Stop();
             try
             {
+                foreach (var strategy in GetStrategies())
+                {
+                    strategy.ReloadServers();
+                }
+
                 polipoRunner.Start(_config);
 
-                Local local = new Local(_config);
+                TCPRelay tcpRelay = new TCPRelay(this);
+                UDPRelay udpRelay = new UDPRelay(this);
                 List<Listener.Service> services = new List<Listener.Service>();
-                services.Add(local);
+                services.Add(tcpRelay);
+                services.Add(udpRelay);
                 services.Add(_pacServer);
                 services.Add(new PortForwarder(polipoRunner.RunningPort));
                 _listener = new Listener(services);

shadowsocks-csharp/Controller/Strategy/BalancingStrategy.cs

@@ -0,0 +1,71 @@
+using Shadowsocks.Controller;
+using Shadowsocks.Model;
+using System;
+using System.Collections.Generic;
+using System.Net;
+using System.Text;
+
+namespace Shadowsocks.Controller.Strategy
+{
+    class BalancingStrategy : IStrategy
+    {
+        ShadowsocksController _controller;
+        Random _random;
+
+        public BalancingStrategy(ShadowsocksController controller)
+        {
+            _controller = controller;
+            _random = new Random();
+        }
+
+        public string Name
+        {
+            get { return I18N.GetString("Load Balance"); }
+        }
+
+        public string ID
+        {
+            get { return "com.shadowsocks.strategy.balancing"; }
+        }
+
+        public void ReloadServers()
+        {
+            // do nothing
+        }
+
+        public Server GetAServer(IStrategyCallerType type, IPEndPoint localIPEndPoint)
+        {
+            var configs = _controller.GetCurrentConfiguration().configs;
+            int index;
+            if (type == IStrategyCallerType.TCP)
+            {
+                index = _random.Next();
+            }
+            else
+            {
+                index = localIPEndPoint.GetHashCode();
+            }
+            return configs[index % configs.Count];
+        }
+
+        public void UpdateLatency(Model.Server server, TimeSpan latency)
+        {
+            // do nothing
+        }
+
+        public void UpdateLastRead(Model.Server server)
+        {
+            // do nothing
+        }
+
+        public void UpdateLastWrite(Model.Server server)
+        {
+            // do nothing
+        }
+
+        public void SetFailure(Model.Server server)
+        {
+            // do nothing
+        }
+    }
+}

shadowsocks-csharp/Controller/Strategy/HighAvailabilityStrategy.cs

@@ -0,0 +1,177 @@
+using Shadowsocks.Model;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Shadowsocks.Controller.Strategy
+{
+    class HighAvailabilityStrategy : IStrategy
+    {
+        protected Server _currentServer;
+        protected Dictionary<Server, ServerStatus> _serverStatus;
+        ShadowsocksController _controller;
+        Random _random;
+
+        public class ServerStatus
+        {
+            // time interval between SYN and SYN+ACK
+            public TimeSpan latency;
+            public DateTime lastTimeDetectLatency;
+
+            // last time anything received
+            public DateTime lastRead;
+
+            // last time anything sent
+            public DateTime lastWrite;
+
+            // connection refused or closed before anything received
+            public DateTime lastFailure;
+
+            public Server server;
+
+            public double score;
+        }
+
+        public HighAvailabilityStrategy(ShadowsocksController controller)
+        {
+            _controller = controller;
+            _random = new Random();
+            _serverStatus = new Dictionary<Server, ServerStatus>();
+        }
+
+        public string Name
+        {
+            get { return I18N.GetString("High Availability"); }
+        }
+
+        public string ID
+        {
+            get { return "com.shadowsocks.strategy.ha"; }
+        }
+
+        public void ReloadServers()
+        {
+            // make a copy to avoid locking
+            var newServerStatus = new Dictionary<Server, ServerStatus>(_serverStatus);
+
+            foreach (var server in _controller.GetCurrentConfiguration().configs)
+            {
+                if (!newServerStatus.ContainsKey(server))
+                {
+                    var status = new ServerStatus();
+                    status.server = server;
+                    status.lastFailure = DateTime.MinValue;
+                    status.lastRead = DateTime.Now;
+                    status.lastWrite = DateTime.Now;
+                    status.latency = new TimeSpan(0, 0, 0, 0, 10);
+                    status.lastTimeDetectLatency = DateTime.Now;
+                    newServerStatus[server] = status;
+                }
+            }
+            _serverStatus = newServerStatus;
+
+            ChooseNewServer();
+        }
+
+        public Server GetAServer(IStrategyCallerType type, System.Net.IPEndPoint localIPEndPoint)
+        {
+            if (type == IStrategyCallerType.TCP)
+            {
+                ChooseNewServer();
+            }
+            return _currentServer;
+        }
+
+        /**
+         * once failed, try after 5 min
+         * and (last write - last read) < 5s
+         * and (now - last read) <  5s  // means not stuck
+         * and latency < 200ms, try after 30s
+         */
+        public void ChooseNewServer()
+        {
+            Server oldServer = _currentServer;
+            List<ServerStatus> servers = new List<ServerStatus>(_serverStatus.Values);
+            DateTime now = DateTime.Now;
+            foreach (var status in servers)
+            {
+                // all of failure, latency, (lastread - lastwrite) normalized to 1000, then
+                // 100 * failure - 2 * latency - 0.5 * (lastread - lastwrite)
+                status.score =
+                    100 * 1000 * Math.Min(5 * 60, (now - status.lastFailure).TotalSeconds)
+                    -2 * 5 * (Math.Min(2000, status.latency.TotalMilliseconds) / (1 + (now - status.lastTimeDetectLatency).TotalSeconds / 30 / 10) +
+                    -0.5 * 200 * Math.Min(5, (status.lastRead - status.lastWrite).TotalSeconds));
+                Logging.Debug(String.Format("server: {0} latency:{1} score: {2}", status.server.FriendlyName(), status.latency, status.score));
+            }
+            ServerStatus max = null;
+            foreach (var status in servers)
+            {
+                if (max == null)
+                {
+                    max = status;
+                }
+                else
+                {
+                    if (status.score >= max.score)
+                    {
+                        max = status;
+                    }
+                }
+            }
+            if (max != null)
+            {
+                _currentServer = max.server;
+                if (_currentServer != oldServer)
+                {
+                    Console.WriteLine("HA switching to server: {0}", _currentServer.FriendlyName());
+                }
+                Logging.Debug(String.Format("choosing server: {0}", _currentServer.FriendlyName()));
+            }
+        }
+
+        public void UpdateLatency(Model.Server server, TimeSpan latency)
+        {
+            Logging.Debug(String.Format("latency: {0} {1}", server.FriendlyName(), latency));
+
+            ServerStatus status;
+            if (_serverStatus.TryGetValue(server, out status))
+            {
+                status.latency = latency;
+                status.lastTimeDetectLatency = DateTime.Now;
+            }
+        }
+
+        public void UpdateLastRead(Model.Server server)
+        {
+            Logging.Debug(String.Format("last read: {0}", server.FriendlyName()));
+
+            ServerStatus status;
+            if (_serverStatus.TryGetValue(server, out status))
+            {
+                status.lastRead = DateTime.Now;
+            }
+        }
+
+        public void UpdateLastWrite(Model.Server server)
+        {
+            Logging.Debug(String.Format("last write: {0}", server.FriendlyName()));
+
+            ServerStatus status;
+            if (_serverStatus.TryGetValue(server, out status))
+            {
+                status.lastWrite = DateTime.Now;
+            }
+        }
+
+        public void SetFailure(Model.Server server)
+        {
+            Logging.Debug(String.Format("failure: {0}", server.FriendlyName()));
+
+            ServerStatus status;
+            if (_serverStatus.TryGetValue(server, out status))
+            {
+                status.lastFailure = DateTime.Now;
+            }
+        }
+    }
+}

shadowsocks-csharp/Controller/Strategy/IStrategy.cs

@@ -0,0 +1,56 @@
+using Shadowsocks.Model;
+using System;
+using System.Collections.Generic;
+using System.Net;
+using System.Text;
+
+namespace Shadowsocks.Controller.Strategy
+{
+    public enum IStrategyCallerType
+    {
+        TCP,
+        UDP
+    }
+
+    /*
+     * IStrategy
+     * 
+     * Subclasses must be thread-safe
+     */
+    public interface IStrategy
+    {
+        string Name { get; }
+        
+        string ID { get; }
+
+        /*
+         * Called when servers need to be reloaded, i.e. new configuration saved 
+         */
+        void ReloadServers();
+
+        /*
+         * Get a new server to use in TCPRelay or UDPRelay
+         */
+        Server GetAServer(IStrategyCallerType type, IPEndPoint localIPEndPoint);
+
+        /*
+         * TCPRelay will call this when latency of a server detected
+         */
+        void UpdateLatency(Server server, TimeSpan latency);
+
+        /*
+         * TCPRelay will call this when reading from a server
+         */
+        void UpdateLastRead(Server server);
+
+        /*
+         * TCPRelay will call this when writing to a server
+         */
+        void UpdateLastWrite(Server server);
+
+        /*
+         * TCPRelay will call this when fatal failure detected
+         */
+        void SetFailure(Server server);
+    }
+}

shadowsocks-csharp/Controller/Strategy/StrategyManager.cs

@@ -0,0 +1,23 @@
+using Shadowsocks.Controller;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Shadowsocks.Controller.Strategy
+{
+    class StrategyManager
+    {
+        List<IStrategy> _strategies;
+        public StrategyManager(ShadowsocksController controller)
+        {
+            _strategies = new List<IStrategy>();
+            _strategies.Add(new BalancingStrategy(controller));
+            _strategies.Add(new HighAvailabilityStrategy(controller));
+            // TODO: load DLL plugins
+        }
+        public IList<IStrategy> GetStrategies()
+        {
+            return _strategies;
+        }
+    }
+}

shadowsocks-csharp/Controller/System/SystemProxy.cs

@@ -49,9 +49,14 @@ namespace Shadowsocks.Controller
                     }
                     else
                     {
+                        string pacUrl;
+                        if (config.useOnlinePac && !string.IsNullOrEmpty(config.pacUrl))
+                            pacUrl = config.pacUrl;
+                        else
+                            pacUrl = "http://127.0.0.1:" + config.localPort.ToString() + "/pac?t=" + GetTimestamp(DateTime.Now);
                         registry.SetValue("ProxyEnable", 0);
                         registry.SetValue("ProxyServer", "");
-                        registry.SetValue("AutoConfigURL", "http://127.0.0.1:" + config.localPort.ToString() + "/pac?t=" + GetTimestamp(DateTime.Now));
+                        registry.SetValue("AutoConfigURL", pacUrl);
                     }
                 }
                 else

shadowsocks-csharp/Data/cn.txt

@@ -1,4 +1,9 @@
+# translation for Simplified Chinese
+
 Shadowsocks=Shadowsocks
+
+# Menu items
+
 Enable System Proxy=启用系统代理
 Mode=系统代理模式
 PAC=PAC 模式
@@ -7,13 +12,22 @@ Servers=服务器
 Edit Servers...=编辑服务器...
 Start on Boot=开机启动
 Allow Clients from LAN=允许来自局域网的连接
-Edit PAC File...=编辑 PAC 文件...
+Local PAC=使用本地 PAC
+Online PAC=使用在线 PAC
+Edit Local PAC File...=编辑本地 PAC 文件...
+Update Local PAC from GFWList=从 GFWList 更新本地 PAC
+Edit User Rule for GFWList...=编辑 GFWList 的用户规则...
 Show QRCode...=显示二维码...
 Scan QRCode from Screen...=扫描屏幕上的二维码...
 Show Logs...=显示日志...
 About...=关于...
 Quit=退出
 Edit Servers=编辑服务器
+Load Balance=负载均衡
+High Availability=高可用
+
+# Config Form
+
 &Add=添加(&A)
 &Delete=删除(&D)
 Server=服务器
@@ -26,7 +40,19 @@ Remarks=备注
 OK=确定
 Cancel=取消
 New server=未配置的服务器
+
+# QRCode Form
+
 QRCode=二维码
+
+# PAC Url Form
+
+Edit Online PAC URL=编辑在线 PAC 网址
+Edit Online PAC URL...=编辑在线 PAC 网址...
+Please input PAC Url=请输入 PAC 网址
+
+# Messages
+
 Shadowsocks Error: {0}=Shadowsocks 错误: {0}
 Port already in use=端口已被占用
 Illegal port number format=非法端口格式
@@ -34,17 +60,17 @@ Please add at least one server=请添加至少一个服务器
 Server IP can not be blank=服务器 IP 不能为空
 Password can not be blank=密码不能为空
 Port out of range=端口超出范围
+Port can't be 8123=端口不能为 8123
 Shadowsocks {0} Update Found=Shadowsocks {0} 更新
 Click here to download=点击这里下载
 Shadowsocks is here=Shadowsocks 在这里
 You can turn on/off Shadowsocks in the context menu=可以在右键菜单中开关 Shadowsocks
 System Proxy Enabled=系统代理已启用
 System Proxy Disabled=系统代理未启用
-Update PAC from GFWList=从 GFWList 更新 PAC
 Failed to update PAC file =更新 PAC 文件失败
 PAC updated=更新 PAC 成功
 No updates found. Please report to GFWList if you have problems with it.=未发现更新。如有问题请提交给 GFWList。
-No QRCode found. Try to zoom in or move it to the center of the screen.=找不到二维码，尝试把它放大或者移动到靠近屏幕中间的位置
+No QRCode found. Try to zoom in or move it to the center of the screen.=未发现二维码，尝试把它放大或移动到靠近屏幕中间的位置
 Failed to decode QRCode=无法解析二维码
 Failed to update registry=无法修改注册表
 System Proxy On: =系统代理已启用：

shadowsocks-csharp/Data/user-rule.txt

@@ -0,0 +1,2 @@
+! Put user rules line by line in this file.
+! See https://adblockplus.org/en/filter-cheatsheet

shadowsocks-csharp/Model/Configuration.cs

@@ -11,12 +11,17 @@ namespace Shadowsocks.Model
     public class Configuration
     {
         public List<Server> configs;
+
+        // when strategy is set, index is ignored
+        public string strategy;
         public int index;
         public bool global;
         public bool enabled;
         public bool shareOverLan;
         public bool isDefault;
         public int localPort;
+        public string pacUrl;
+        public bool useOnlinePac;
 
         private static string CONFIG_FILE = "gui-config.json";
 
@@ -77,9 +82,9 @@ namespace Shadowsocks.Model
             {
                 config.index = config.configs.Count - 1;
             }
-            if (config.index < 0)
+            if (config.index < -1)
             {
-                config.index = 0;
+                config.index = -1;
             }
             config.isDefault = false;
             try
@@ -116,6 +121,10 @@ namespace Shadowsocks.Model
             {
                 throw new ArgumentException(I18N.GetString("Port out of range"));
             }
+            if (port == 8123)
+            {
+                throw new ArgumentException(I18N.GetString("Port can't be 8123"));
+            }
         }
 
         private static void CheckPassword(string password)

shadowsocks-csharp/Model/Server.cs

@@ -18,6 +18,17 @@ namespace Shadowsocks.Model
         public string method;
         public string remarks;
 
+        public override int GetHashCode()
+        {
+            return server.GetHashCode() ^ server_port;
+        }
+
+        public override bool Equals(object obj)
+        {
+            Server o2 = (Server)obj;
+            return this.server == o2.server && this.server_port == o2.server_port;
+        }
+
         public string FriendlyName()
         {
             if (string.IsNullOrEmpty(server))

shadowsocks-csharp/Properties/Resources.Designer.cs

@@ -1,7 +1,7 @@
 //------------------------------------------------------------------------------
 // <auto-generated>
 //     This code was generated by a tool.
-//     Runtime Version:4.0.30319.18444
+//     Runtime Version:4.0.30319.34209
 //
 //     Changes to this file may cause incorrect behavior and will be lost if
 //     the code is regenerated.
@@ -71,36 +71,30 @@ namespace Shadowsocks.Properties {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to Shadowsocks=Shadowsocks
-        ///Enable=启用代理
-        ///Mode=代理模式
+        ///   Looks up a localized string similar to # translation for Simplified Chinese
+        ///
+        ///Shadowsocks=Shadowsocks
+        ///
+        ///# Menu items
+        ///
+        ///Enable System Proxy=启用系统代理
+        ///Mode=系统代理模式
         ///PAC=PAC 模式
         ///Global=全局模式
         ///Servers=服务器
         ///Edit Servers...=编辑服务器...
         ///Start on Boot=开机启动
-        ///Share over LAN=在局域网共享代理
-        ///Edit PAC File...=编辑 PAC 文件...
+        ///Allow Clients from LAN=允许来自局域网的连接
+        ///Local PAC=使用本地 PAC
+        ///Online PAC=使用在线 PAC
+        ///Edit Local PAC File...=编辑本地 PAC 文件...
+        ///Update Local PAC from GFWList=从 GFWList 更新本地 PAC
+        ///Edit User Rule for GFWList...=编辑 GFWList 的用户规则...
         ///Show QRCode...=显示二维码...
         ///Scan QRCode from Screen...=扫描屏幕上的二维码...
         ///Show Logs...=显示日志...
         ///About...=关于...
-        ///Quit=退出
-        ///Edit Servers=编辑服务器
-        ///&amp;Add=添加(&amp;A)
-        ///&amp;Delete=删除(&amp;D)
-        ///Server=服务器
-        ///Server IP=服务器 IP
-        ///Server Port=服务器端口
-        ///Password=密码
-        ///Encryption=加密
-        ///Proxy Port=代理端口
-        ///Remarks=备注
-        ///OK=确定
-        ///Cancel=取消
-        ///New server=未配置的服务器
-        ///QRCode=二维码
-        ///Shadowsocks Error: {0}=Shadowsocks [rest of string was truncated]&quot;;.
+        ///Quit=退出 [rest of string was truncated]&quot;;.
         /// </summary>
         internal static string cn {
             get {
@@ -119,7 +113,8 @@ namespace Shadowsocks.Properties {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to proxyAddress = &quot;__POLIPO_BIND_IP__&quot;
+        ///   Looks up a localized string similar to proxyAddress = &quot;__POLIPO_BIND_IP__&quot;
+        ///proxyPort = 8123
         ///
         ///socksParentProxy = &quot;127.0.0.1:__SOCKS_PORT__&quot;
         ///socksProxyType = socks5
@@ -194,5 +189,16 @@ namespace Shadowsocks.Properties {
                 return ((System.Drawing.Bitmap)(obj));
             }
         }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to ! Put user rules line by line in this file.
+        ///! See https://adblockplus.org/en/filter-cheatsheet
+        ///.
+        /// </summary>
+        internal static string user_rule {
+            get {
+                return ResourceManager.GetString("user_rule", resourceCulture);
+            }
+        }
     }
 }

shadowsocks-csharp/Properties/Resources.resx

@@ -148,4 +148,7 @@
   <data name="ssw128" type="System.Resources.ResXFileRef, System.Windows.Forms">
     <value>..\Resources\ssw128.png;System.Drawing.Bitmap, System.Drawing, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a</value>
   </data>
+  <data name="user_rule" type="System.Resources.ResXFileRef, System.Windows.Forms">
+    <value>..\data\user-rule.txt;System.String, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089;utf-8</value>
+  </data>
 </root>

shadowsocks-csharp/View/ConfigForm.cs

@@ -133,10 +133,14 @@ namespace Shadowsocks.View
 
         private void LoadCurrentConfiguration()
         {
-            _modifiedConfiguration = controller.GetConfiguration();
+            _modifiedConfiguration = controller.GetConfigurationCopy();
             LoadConfiguration(_modifiedConfiguration);
             _oldSelectedIndex = _modifiedConfiguration.index;
-            ServersListBox.SelectedIndex = _modifiedConfiguration.index;
+            if (_oldSelectedIndex < 0)
+            {
+                _oldSelectedIndex = 0;
+            }
+            ServersListBox.SelectedIndex = _oldSelectedIndex;
             LoadSelectedServer();
         }
 

shadowsocks-csharp/View/MenuViewController.cs

@@ -35,6 +35,12 @@ namespace Shadowsocks.View
         private MenuItem ServersItem;
         private MenuItem globalModeItem;
         private MenuItem PACModeItem;
+        private MenuItem localPACItem;
+        private MenuItem onlinePACItem;
+        private MenuItem editLocalPACItem;
+        private MenuItem updateFromGFWListItem;
+        private MenuItem editGFWUserRuleItem;
+        private MenuItem editOnlinePACItem;
         private ConfigForm configForm;
         private string _urlToOpen;
 
@@ -46,7 +52,8 @@ namespace Shadowsocks.View
 
             controller.EnableStatusChanged += controller_EnableStatusChanged;
             controller.ConfigChanged += controller_ConfigChanged;
-            controller.PACFileReadyToOpen += controller_PACFileReadyToOpen;
+            controller.PACFileReadyToOpen += controller_FileReadyToOpen;
+            controller.UserRuleFileReadyToOpen += controller_FileReadyToOpen;
             controller.ShareOverLANStatusChanged += controller_ShareOverLANStatusChanged;
             controller.EnableGlobalChanged += controller_EnableGlobalChanged;
             controller.Errored += controller_Errored;
@@ -64,9 +71,9 @@ namespace Shadowsocks.View
 
             LoadCurrentConfiguration();
 
-            updateChecker.CheckUpdate(controller.GetConfiguration());
+            updateChecker.CheckUpdate(controller.GetConfigurationCopy());
 
-            if (controller.GetConfiguration().isDefault)
+            if (controller.GetConfigurationCopy().isDefault)
             {
                 _isFirstRun = true;
                 ShowConfigForm();
@@ -99,7 +106,7 @@ namespace Shadowsocks.View
             {
                 icon = Resources.ss24;
             }
-            Configuration config = controller.GetConfiguration();
+            Configuration config = controller.GetConfigurationCopy();
             bool enabled = config.enabled;
             bool global = config.global;
             if (!enabled)
@@ -117,12 +124,21 @@ namespace Shadowsocks.View
             }
             _notifyIcon.Icon = Icon.FromHandle(icon.GetHicon());
 
+            string serverInfo = null;
+            if (controller.GetCurrentStrategy() != null)
+            {
+                serverInfo = controller.GetCurrentStrategy().Name;
+            }
+            else
+            {
+                serverInfo = config.GetCurrentServer().FriendlyName();
+            }
             // we want to show more details but notify icon title is limited to 63 characters
             string text = I18N.GetString("Shadowsocks") + " " + UpdateChecker.Version + "\n" +
                 (enabled ?
                     I18N.GetString("System Proxy On: ") + (global ? I18N.GetString("Global") : I18N.GetString("PAC")) :
                     String.Format(I18N.GetString("Running: Port {0}"), config.localPort))  // this feedback is very important because they need to know Shadowsocks is running
-                + "\n" + config.GetCurrentServer().FriendlyName();
+                + "\n" + serverInfo;
             _notifyIcon.Text = text.Substring(0, Math.Min(63, text.Length));
         }
 
@@ -150,11 +166,18 @@ namespace Shadowsocks.View
                     CreateMenuItem("Show QRCode...", new EventHandler(this.QRCodeItem_Click)),
                     CreateMenuItem("Scan QRCode from Screen...", new EventHandler(this.ScanQRCodeItem_Click))
                 }),
+                CreateMenuGroup("PAC ", new MenuItem[] {
+                    this.localPACItem = CreateMenuItem("Local PAC", new EventHandler(this.LocalPACItem_Click)),
+                    this.onlinePACItem = CreateMenuItem("Online PAC", new EventHandler(this.OnlinePACItem_Click)),
+                    new MenuItem("-"),
+                    this.editLocalPACItem = CreateMenuItem("Edit Local PAC File...", new EventHandler(this.EditPACFileItem_Click)),
+                    this.updateFromGFWListItem = CreateMenuItem("Update Local PAC from GFWList", new EventHandler(this.UpdatePACFromGFWListItem_Click)),
+                    this.editGFWUserRuleItem = CreateMenuItem("Edit User Rule for GFWList...", new EventHandler(this.EditUserRuleFileForGFWListItem_Click)),
+                    this.editOnlinePACItem = CreateMenuItem("Edit Online PAC URL...", new EventHandler(this.UpdateOnlinePACURLItem_Click)),
+                }),
                 new MenuItem("-"),
                 this.AutoStartupItem = CreateMenuItem("Start on Boot", new EventHandler(this.AutoStartupItem_Click)),
                 this.ShareOverLANItem = CreateMenuItem("Allow Clients from LAN", new EventHandler(this.ShareOverLANItem_Click)),
-                CreateMenuItem("Edit PAC File...", new EventHandler(this.EditPACFileItem_Click)),
-                CreateMenuItem("Update PAC from GFWList", new EventHandler(this.UpdatePACFromGFWListItem_Click)),
                 new MenuItem("-"),
                 CreateMenuItem("Show Logs...", new EventHandler(this.ShowLogItem_Click)),
                 CreateMenuItem("About...", new EventHandler(this.AboutItem_Click)),
@@ -171,22 +194,22 @@ namespace Shadowsocks.View
 
         private void controller_EnableStatusChanged(object sender, EventArgs e)
         {
-            enableItem.Checked = controller.GetConfiguration().enabled;
+            enableItem.Checked = controller.GetConfigurationCopy().enabled;
             modeItem.Enabled = enableItem.Checked;
         }
 
         void controller_ShareOverLANStatusChanged(object sender, EventArgs e)
         {
-            ShareOverLANItem.Checked = controller.GetConfiguration().shareOverLan;
+            ShareOverLANItem.Checked = controller.GetConfigurationCopy().shareOverLan;
         }
 
         void controller_EnableGlobalChanged(object sender, EventArgs e)
         {
-            globalModeItem.Checked = controller.GetConfiguration().global;
+            globalModeItem.Checked = controller.GetConfigurationCopy().global;
             PACModeItem.Checked = !globalModeItem.Checked;
         }
 
-        void controller_PACFileReadyToOpen(object sender, ShadowsocksController.PathEventArgs e)
+        void controller_FileReadyToOpen(object sender, ShadowsocksController.PathEventArgs e)
         {
             string argument = @"/select, " + e.Path;
 
@@ -229,7 +252,7 @@ namespace Shadowsocks.View
 
         private void LoadCurrentConfiguration()
         {
-            Configuration config = controller.GetConfiguration();
+            Configuration config = controller.GetConfigurationCopy();
             UpdateServersMenu();
             enableItem.Checked = config.enabled;
             modeItem.Enabled = config.enabled;
@@ -237,6 +260,9 @@ namespace Shadowsocks.View
             PACModeItem.Checked = !config.global;
             ShareOverLANItem.Checked = config.shareOverLan;
             AutoStartupItem.Checked = AutoStartup.Check();
+            onlinePACItem.Checked = onlinePACItem.Enabled && config.useOnlinePac;
+            localPACItem.Checked = !onlinePACItem.Checked;
+            UpdatePACItemsEnabledStatus();
         }
 
         private void UpdateServersMenu()
@@ -246,20 +272,33 @@ namespace Shadowsocks.View
             {
                 items.RemoveAt(0);
             }
-
-            Configuration configuration = controller.GetConfiguration();
-            for (int i = 0; i < configuration.configs.Count; i++)
+            int i = 0;
+            foreach (var strategy in controller.GetStrategies())
+            {
+                MenuItem item = new MenuItem(strategy.Name);
+                item.Tag = strategy.ID;
+                item.Click += AStrategyItem_Click;
+                items.Add(i, item);
+                i++;
+            }
+            int strategyCount = i;
+            Configuration configuration = controller.GetConfigurationCopy();
+            foreach (var server in configuration.configs)
             {
-                Server server = configuration.configs[i];
                 MenuItem item = new MenuItem(server.FriendlyName());
-                item.Tag = i;
+                item.Tag = i - strategyCount;
                 item.Click += AServerItem_Click;
                 items.Add(i, item);
+                i++;
             }
 
-            if (configuration.index >= 0 && configuration.index < configuration.configs.Count)
+            foreach (MenuItem item in items)
             {
-                items[configuration.index].Checked = true;
+                if (item.Tag != null && (item.Tag.ToString() == configuration.index.ToString() || item.Tag.ToString() == configuration.strategy))
+                {
+                    item.Checked = true;
+                }
+
             }
         }
 
@@ -352,12 +391,23 @@ namespace Shadowsocks.View
             controller.UpdatePACFromGFWList();
         }
 
+        private void EditUserRuleFileForGFWListItem_Click(object sender, EventArgs e)
+        {
+            controller.TouchUserRuleFile();
+        }
+
         private void AServerItem_Click(object sender, EventArgs e)
         {
             MenuItem item = (MenuItem)sender;
             controller.SelectServerIndex((int)item.Tag);
         }
 
+        private void AStrategyItem_Click(object sender, EventArgs e)
+        {
+            MenuItem item = (MenuItem)sender;
+            controller.SelectStrategy((string)item.Tag);
+        }
+
         private void ShowLogItem_Click(object sender, EventArgs e)
         {
             string argument = Logging.LogFile;
@@ -473,5 +523,65 @@ namespace Shadowsocks.View
 				MessageBox.Show(I18N.GetString("Failed to update registry"));
 			}
 		}
+
+        private void LocalPACItem_Click(object sender, EventArgs e)
+        {
+            if (!localPACItem.Checked)
+            {
+                localPACItem.Checked = true;
+                onlinePACItem.Checked = false;
+                controller.UseOnlinePAC(false);
+                UpdatePACItemsEnabledStatus();
+            }
+        }
+
+        private void OnlinePACItem_Click(object sender, EventArgs e)
+        {
+            if (!onlinePACItem.Checked)
+            {
+                if (String.IsNullOrEmpty(controller.GetConfigurationCopy().pacUrl))
+                {
+                    UpdateOnlinePACURLItem_Click(sender, e);
+                }
+                if (!String.IsNullOrEmpty(controller.GetConfigurationCopy().pacUrl))
+                {
+                    localPACItem.Checked = false;
+                    onlinePACItem.Checked = true;
+                    controller.UseOnlinePAC(true);
+                }
+                UpdatePACItemsEnabledStatus();
+            }
+        }
+
+        private void UpdateOnlinePACURLItem_Click(object sender, EventArgs e)
+        {
+            string origPacUrl = controller.GetConfigurationCopy().pacUrl;
+            string pacUrl = Microsoft.VisualBasic.Interaction.InputBox(
+                I18N.GetString("Please input PAC Url"),
+                I18N.GetString("Edit Online PAC URL"),
+                origPacUrl, -1, -1);
+            if (!string.IsNullOrEmpty(pacUrl) && pacUrl != origPacUrl)
+            {
+                controller.SavePACUrl(pacUrl);
+            }
+        }
+
+        private void UpdatePACItemsEnabledStatus()
+        {
+            if (this.localPACItem.Checked)
+            {
+                this.editLocalPACItem.Enabled = true;
+                this.updateFromGFWListItem.Enabled = true;
+                this.editGFWUserRuleItem.Enabled = true;
+                this.editOnlinePACItem.Enabled = false;
+            }
+            else
+            {
+                this.editLocalPACItem.Enabled = false;
+                this.updateFromGFWListItem.Enabled = false;
+                this.editGFWUserRuleItem.Enabled = false;
+                this.editOnlinePACItem.Enabled = true;
+            }
+        }
     }
 }

shadowsocks-csharp/shadowsocks-csharp.csproj

@@ -63,6 +63,7 @@
     <ApplicationManifest>app.manifest</ApplicationManifest>
   </PropertyGroup>
   <ItemGroup>
+    <Reference Include="Microsoft.VisualBasic" />
     <Reference Include="System" />
     <Reference Include="System.Data" />
     <Reference Include="System.Drawing" />
@@ -123,14 +124,16 @@
     <Compile Include="3rd\zxing\ResultPoint.cs" />
     <Compile Include="3rd\zxing\ResultPointCallback.cs" />
     <Compile Include="3rd\zxing\WriterException.cs" />
-    <Compile Include="Controller\AutoStartup.cs" />
+    <Compile Include="Controller\Strategy\HighAvailabilityStrategy.cs" />
+    <Compile Include="Controller\System\AutoStartup.cs" />
     <Compile Include="Controller\FileManager.cs" />
-    <Compile Include="Controller\GFWListUpdater.cs" />
+    <Compile Include="Controller\Service\GFWListUpdater.cs" />
     <Compile Include="Controller\I18N.cs" />
-    <Compile Include="Controller\Listener.cs" />
+    <Compile Include="Controller\Service\Listener.cs" />
     <Compile Include="Controller\Logging.cs" />
-    <Compile Include="Controller\PortForwarder.cs" />
-    <Compile Include="Controller\UpdateChecker.cs" />
+    <Compile Include="Controller\Service\PortForwarder.cs" />
+    <Compile Include="Controller\Service\UDPRelay.cs" />
+    <Compile Include="Controller\Service\UpdateChecker.cs" />
     <Compile Include="Encryption\EncryptorBase.cs" />
     <Compile Include="Encryption\EncryptorFactory.cs" />
     <Compile Include="Encryption\IVEncryptor.cs" />
@@ -140,7 +143,7 @@
     <Compile Include="Encryption\SodiumEncryptor.cs" />
     <Compile Include="Encryption\TableEncryptor.cs" />
     <Compile Include="Encryption\IEncryptor.cs" />
-    <Compile Include="Controller\PACServer.cs" />
+    <Compile Include="Controller\Service\PACServer.cs" />
     <Compile Include="Model\Server.cs" />
     <Compile Include="Model\Configuration.cs" />
     <Compile Include="Properties\Resources.Designer.cs">
@@ -148,6 +151,9 @@
       <DesignTime>True</DesignTime>
       <DependentUpon>Resources.resx</DependentUpon>
     </Compile>
+    <Compile Include="Controller\Strategy\BalancingStrategy.cs" />
+    <Compile Include="Controller\Strategy\StrategyManager.cs" />
+    <Compile Include="Controller\Strategy\IStrategy.cs" />
     <Compile Include="Util\Util.cs" />
     <Compile Include="View\ConfigForm.cs">
       <SubType>Form</SubType>
@@ -155,12 +161,12 @@
     <Compile Include="View\ConfigForm.Designer.cs">
       <DependentUpon>ConfigForm.cs</DependentUpon>
     </Compile>
-    <Compile Include="Controller\Local.cs" />
-    <Compile Include="Controller\PolipoRunner.cs" />
+    <Compile Include="Controller\Service\TCPRelay.cs" />
+    <Compile Include="Controller\Service\PolipoRunner.cs" />
     <Compile Include="Program.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Controller\ShadowsocksController.cs" />
-    <Compile Include="Controller\SystemProxy.cs" />
+    <Compile Include="Controller\System\SystemProxy.cs" />
     <Compile Include="View\MenuViewController.cs" />
     <Compile Include="View\QRCodeForm.cs">
       <SubType>Form</SubType>
@@ -198,6 +204,7 @@
     <None Include="Resources\ss24.png" />
     <None Include="Resources\ssw128.png" />
     <Content Include="Data\cn.txt" />
+    <Content Include="Data\user-rule.txt" />
     <Content Include="shadowsocks.ico" />
     <None Include="Data\polipo_config.txt" />
   </ItemGroup>