public static async Task <SocksProxyRequest> ReadRequestAsync(Stream s)
{
SocksProxyRequest request = new SocksProxyRequest();
byte[] buffer = new byte[3];
await s.ReadBytesAsync(buffer, 0, 3);
request._version = buffer[0];
request._command = (SocksProxyRequestCommand)buffer[1];
request._dstEP = await SocksProxyServer.ReadEndPointAsync(s);
return(request);
}
private static async Task <EndPoint> RequestAsync(Stream s, SocksProxyRequest request)
{
await request.WriteToAsync(s);
await s.FlushAsync();
SocksProxyReply reply = await SocksProxyReply.ReadReplyAsync(s);
if (!reply.IsVersionSupported)
{
throw new SocksProxyException("Socks version 5 is not supported by the proxy server.");
}
if (reply.ReplyCode != SocksProxyReplyCode.Succeeded)
{
throw new SocksProxyException("Socks proxy server request failed: " + reply.ReplyCode.ToString(), reply.ReplyCode);
}
return(reply.BindEndPoint);
}
public async Task StartAsync()
{
bool dontDispose = false;
try
{
NetworkStream localNetworkStream = new NetworkStream(_localSocket);
Stream localStream = new WriteBufferedStream(localNetworkStream, 512);
#region authenticate
SocksProxyNegotiationRequest negotiationRequest = await SocksProxyNegotiationRequest.ReadRequestAsync(localStream).WithTimeout(CLIENT_WAIT_TIMEOUT);
if (!negotiationRequest.IsVersionSupported)
{
await new SocksProxyNegotiationReply(SocksProxyAuthenticationMethod.NoAcceptableMethods).WriteToAsync(localStream);
await localStream.FlushAsync();
return;
}
//match method and authenticate
bool methodMatched = false;
SocksProxyAuthenticationMethod serverMethod = _authenticationManager == null ? SocksProxyAuthenticationMethod.NoAuthenticationRequired : SocksProxyAuthenticationMethod.UsernamePassword;
foreach (SocksProxyAuthenticationMethod method in negotiationRequest.Methods)
{
if (method == serverMethod)
{
//method matches
await new SocksProxyNegotiationReply(method).WriteToAsync(localStream);
await localStream.FlushAsync();
switch (serverMethod)
{
case SocksProxyAuthenticationMethod.NoAuthenticationRequired:
methodMatched = true;
break;
case SocksProxyAuthenticationMethod.UsernamePassword:
//read method version
SocksProxyAuthenticationRequest authenticationRequest = await SocksProxyAuthenticationRequest.ReadRequestAsync(localStream).WithTimeout(CLIENT_WAIT_TIMEOUT);
if (!authenticationRequest.IsVersionSupported)
{
await new SocksProxyAuthenticationReply(SocksProxyAuthenticationStatus.Failure).WriteToAsync(localStream);
await localStream.FlushAsync();
return;
}
if (!_authenticationManager.Authenticate(authenticationRequest.Username, authenticationRequest.Password))
{
await new SocksProxyAuthenticationReply(SocksProxyAuthenticationStatus.Failure).WriteToAsync(localStream);
await localStream.FlushAsync();
return;
}
await new SocksProxyAuthenticationReply(SocksProxyAuthenticationStatus.Success).WriteToAsync(localStream);
await localStream.FlushAsync();
methodMatched = true;
break;
}
break;
}
}
if (!methodMatched)
{
//no method matched
await new SocksProxyNegotiationReply(SocksProxyAuthenticationMethod.NoAcceptableMethods).WriteToAsync(localStream);
await localStream.FlushAsync();
return;
}
#endregion
#region process request
//read request
SocksProxyRequest request = await SocksProxyRequest.ReadRequestAsync(localStream).WithTimeout(CLIENT_WAIT_TIMEOUT);
if (!request.IsVersionSupported)
{
await new SocksProxyReply(SocksProxyReplyCode.GeneralSocksServerFailure).WriteToAsync(localStream);
await localStream.FlushAsync();
return;
}
//process command
SocksProxyReplyCode reply;
EndPoint bindEP;
switch (request.Command)
{
case SocksProxyRequestCommand.Connect:
{
try
{
_remoteSocket = await _connectionManager.ConnectAsync(request.DestinationEndPoint);
reply = SocksProxyReplyCode.Succeeded;
bindEP = _remoteSocket.LocalEndPoint;
}
catch (SocketException ex)
{
switch (ex.SocketErrorCode)
{
case SocketError.NetworkUnreachable:
reply = SocksProxyReplyCode.NetworkUnreachable;
break;
case SocketError.HostUnreachable:
reply = SocksProxyReplyCode.HostUnreachable;
break;
case SocketError.ConnectionRefused:
reply = SocksProxyReplyCode.ConnectionRefused;
break;
default:
reply = SocksProxyReplyCode.GeneralSocksServerFailure;
break;
}
bindEP = new IPEndPoint(IPAddress.Any, 0);
}
}
break;
case SocksProxyRequestCommand.Bind:
{
_bindHandler = await _connectionManager.GetBindHandlerAsync(request.DestinationEndPoint.AddressFamily);
reply = _bindHandler.ReplyCode;
bindEP = _bindHandler.ProxyLocalEndPoint;
}
break;
case SocksProxyRequestCommand.UdpAssociate:
{
switch (_localSocket.LocalEndPoint.AddressFamily)
{
case AddressFamily.InterNetwork:
case AddressFamily.InterNetworkV6:
EndPoint localEP = new IPEndPoint((_localSocket.LocalEndPoint as IPEndPoint).Address, 0);
_udpRelaySocket = new Socket(localEP.AddressFamily, SocketType.Dgram, ProtocolType.Udp);
_udpRelaySocket.Bind(localEP);
reply = SocksProxyReplyCode.Succeeded;
bindEP = _udpRelaySocket.LocalEndPoint as IPEndPoint;
break;
default:
reply = SocksProxyReplyCode.AddressTypeNotSupported;
bindEP = new IPEndPoint(IPAddress.Any, 0);
break;
}
}
break;
default:
reply = SocksProxyReplyCode.CommandNotSupported;
bindEP = new IPEndPoint(IPAddress.Any, 0);
break;
}
//send response
await new SocksProxyReply(reply, bindEP).WriteToAsync(localStream);
await localStream.FlushAsync();
if (reply != SocksProxyReplyCode.Succeeded)
{
return; //nothing to do further
}
//final command process
switch (request.Command)
{
case SocksProxyRequestCommand.Connect:
{
//pipe sockets
_ = _localSocket.CopyToAsync(_remoteSocket).ContinueWith(delegate(Task prevTask) { Dispose(); });
_ = _remoteSocket.CopyToAsync(_localSocket).ContinueWith(delegate(Task prevTask) { Dispose(); });
dontDispose = true;
}
break;
case SocksProxyRequestCommand.Bind:
{
try
{
_remoteSocket = await _bindHandler.AcceptAsync().WithTimeout(CLIENT_WAIT_TIMEOUT);
}
catch (SocksProxyException ex)
{
//send second reply
await new SocksProxyReply(ex.ReplyCode, _bindHandler.ProxyLocalEndPoint).WriteToAsync(localStream);
await localStream.FlushAsync();
}
catch
{
//send second reply
await new SocksProxyReply(SocksProxyReplyCode.GeneralSocksServerFailure, _bindHandler.ProxyLocalEndPoint).WriteToAsync(localStream);
await localStream.FlushAsync();
}
if (_remoteSocket != null)
{
_bindHandler.Dispose();
//send second reply
await new SocksProxyReply(SocksProxyReplyCode.Succeeded, _bindHandler.ProxyRemoteEndPoint).WriteToAsync(localStream);
await localStream.FlushAsync();
//pipe sockets
_ = _localSocket.CopyToAsync(_remoteSocket).ContinueWith(delegate(Task prevTask) { Dispose(); });
_ = _remoteSocket.CopyToAsync(_localSocket).ContinueWith(delegate(Task prevTask) { Dispose(); });
dontDispose = true;
}
}
break;
case SocksProxyRequestCommand.UdpAssociate:
{
EndPoint localEP = null;
switch (_localSocket.LocalEndPoint.AddressFamily)
{
case AddressFamily.InterNetwork:
localEP = new IPEndPoint(IPAddress.Any, 0);
break;
case AddressFamily.InterNetworkV6:
localEP = new IPEndPoint(IPAddress.IPv6Any, 0);
break;
default:
throw new NotSupportedException();
}
using (IProxyServerUdpAssociateHandler udpRemoteHandler = await _connectionManager.GetUdpAssociateHandlerAsync(localEP))
{
using (IProxyServerUdpAssociateHandler udpLocalHandler = new SocksProxyUdpAssociateHandler(_localSocket, _udpRelaySocket, new IPEndPoint((_localSocket.RemoteEndPoint as IPEndPoint).Address, (request.DestinationEndPoint as IPEndPoint).Port)))
{
_ = CopyToAsync(udpRemoteHandler, udpLocalHandler);
await CopyToAsync(udpLocalHandler, udpRemoteHandler);
}
}
}
break;
}
#endregion
}
finally
{
if (!dontDispose)
{
Dispose();
}
}
}