C# SOCKS5 Proxy

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• RB

  Roei Bar17y agoPosted Aug 8, 2009, 3:22 PM

  hey,
  here is a sample Socks5 Client:
  
  
  public class ConnectionException:ApplicationException
  {
  public ConnectionException(string message)
      :base(message)
  {
  }
  }
  
  ///

  
  /// Provides sock5 functionality to clients (Connect only).
  ///

  
  public class SocksProxy
  {
  
  private SocksProxy(){}
  
  #region ErrorMessages
  private static string[] errorMsgs=    {
                                          "Operation completed successfully.",
                                          "General SOCKS server failure.",
                                          "Connection not allowed by ruleset.",
                                          "Network unreachable.",
                                          "Host unreachable.",
                                          "Connection refused.",
                                          "TTL expired.",
                                          "Command not supported.",
                                          "Address type not supported.",
                                          "Unknown error."
                                      };
  #endregion
  
  
  public static Socket ConnectToSocks5Proxy(string proxyAdress, ushort proxyPort, string destAddress, ushort destPort,
      string userName, string password)
  {
      IPAddress destIP = null;
      IPAddress proxyIP = null;
      byte[] request = new byte[257];
      byte[] response = new byte[257];
      ushort nIndex;
  
      try
      {
          proxyIP =  IPAddress.Parse(proxyAdress);
      }
      catch(FormatException)
      {    // get the IP address
          proxyIP = Dns.GetHostByAddress(proxyAdress).AddressList[0];
      }
  
      // Parse destAddress (assume it in string dotted format "212.116.65.112" )
      try
      {
          destIP = IPAddress.Parse(destAddress);
      }
      catch(FormatException)
      {
          // wrong assumption its in domain name format "www.microsoft.com"
      }
  
      IPEndPoint proxyEndPoint = new IPEndPoint(proxyIP,proxyPort);
  
      // open a TCP connection to SOCKS server...
      Socket s = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
      s.Connect(proxyEndPoint);   
  
      nIndex = 0;
      request[nIndex++]=0x05; // Version 5.
      request[nIndex++]=0x02; // 2 Authentication methods are in packet...
      request[nIndex++]=0x00; // NO AUTHENTICATION REQUIRED
      request[nIndex++]=0x02; // USERNAME/PASSWORD
      // Send the authentication negotiation request...
      s.Send(request,nIndex,SocketFlags.None);
  
      // Receive 2 byte response...
      int nGot = s.Receive(response,2,SocketFlags.None);   
      if (nGot!=2)
          throw new ConnectionException("Bad response received from proxy server.");
  
      if (response[1]==0xFF)
      {    // No authentication method was accepted close the socket.
          s.Close();
          throw new ConnectionException("None of the authentication method was accepted by proxy server.");
      }
     
      byte[] rawBytes;
  
      if (/*response[1]==0x02*/true)
      {//Username/Password Authentication protocol
          nIndex = 0;
          request[nIndex++]=0x05; // Version 5.
         
          // add user name
          request[nIndex++]=(byte)userName.Length;
          rawBytes = Encoding.Default.GetBytes(userName);
          rawBytes.CopyTo(request,nIndex);
          nIndex+=(ushort)rawBytes.Length;
  
          // add password
          request[nIndex++]=(byte)password.Length;
          rawBytes = Encoding.Default.GetBytes(password);
          rawBytes.CopyTo(request,nIndex);
          nIndex+=(ushort)rawBytes.Length;
  
          // Send the Username/Password request
          s.Send(request,nIndex,SocketFlags.None);
          // Receive 2 byte response...
          nGot = s.Receive(response,2,SocketFlags.None);   
          if (nGot!=2)
              throw new ConnectionException("Bad response received from proxy server.");
          if (response[1] != 0x00)
              throw new ConnectionException("Bad Usernaem/Password.");
      }
      // This version only supports connect command.
      // UDP and Bind are not supported.
  
      // Send connect request now...
      nIndex = 0;
      request[nIndex++]=0x05;    // version 5.
      request[nIndex++]=0x01;    // command = connect.
      request[nIndex++]=0x00;    // Reserve = must be 0x00
  
      if (destIP != null)
      {// Destination adress in an IP.
          switch(destIP.AddressFamily)
          {
              case AddressFamily.InterNetwork:
                  // Address is IPV4 format
                  request[nIndex++]=0x01;
                  rawBytes = destIP.GetAddressBytes();
                  rawBytes.CopyTo(request,nIndex);
                  nIndex+=(ushort)rawBytes.Length;
                  break;
              case AddressFamily.InterNetworkV6:
                  // Address is IPV6 format
                  request[nIndex++]=0x04;
                  rawBytes = destIP.GetAddressBytes();
                  rawBytes.CopyTo(request,nIndex);
                  nIndex+=(ushort)rawBytes.Length;
                  break;
          }
      }
      else
      {// Dest. address is domain name.
          request[nIndex++]=0x03;    // Address is full-qualified domain name.
          request[nIndex++]=Convert.ToByte(destAddress.Length); // length of address.
          rawBytes = Encoding.Default.GetBytes(destAddress);
          rawBytes.CopyTo(request,nIndex);
          nIndex+=(ushort)rawBytes.Length;
      }
  
      // using big-edian byte order
      byte[] portBytes = BitConverter.GetBytes(destPort);
      for (int i=portBytes.Length-1;i>=0;i--)
          request[nIndex++]=portBytes[i];
     
      // send connect request.
      s.Send(request,nIndex,SocketFlags.None);
      s.Receive(response);    // Get variable length response...
      if (response[1]!=0x00)
          throw new ConnectionException(errorMsgs[response[1]]);
      // Success Connected...
      return s;
  }
  }
  
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