How to configure socket connect timeout

Question

When the Client tries to connect to a disconnected IP address, there is a long timeout over 15 seconds... How can we reduce this timeout? What is the method to configure it?

The code I'm using to set up a socket connection is as following:

try
{
    m_clientSocket = new Socket(
         AddressFamily.InterNetwork,
         SocketType.Stream,
         ProtocolType.Tcp);

    IPAddress ip = IPAddress.Parse(serverIp);
    int iPortNo = System.Convert.ToInt16(serverPort);
    IPEndPoint ipEnd = new IPEndPoint(ip, iPortNo);

    m_clientSocket.Connect(ipEnd);
    if (m_clientSocket.Connected)
    {
        lb_connectStatus.Text = "Connection Established";
        WaitForServerData();
    }
}
catch (SocketException se)
{
    lb_connectStatus.Text = "Connection Failed";
    MessageBox.Show(se.Message);
}

Answer 1

There should be a ReceiveTimeout property in the Socket class.

Socket.ReceiveTimeout Property

Answer 2

I had the Same problem when connecting to a Socket and I came up with the below solution ,It works Fine for me. `

private bool CheckConnectivityForProxyHost(string hostName, int port)
       {
           if (string.IsNullOrEmpty(hostName))
               return false;

           bool isUp = false;
           Socket testSocket = null;

           try
           {

               testSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
               IPAddress ip = null;
               if (testSocket != null && NetworkingCollaboratorBase.GetResolvedConnecionIPAddress(hostName, out ip))//Use a method to resolve your IP
               {
                   IPEndPoint ipEndPoint = new IPEndPoint(ip, port);

                   isUp = false;
//time out 5 Sec
                  CallWithTimeout(ConnectToProxyServers, 5000, testSocket, ipEndPoint);

                       if (testSocket != null && testSocket.Connected)
                       {
                           isUp = true;
                       }
                   }

               }
           }
           catch (Exception ex)
           {
               isUp = false;
           }
           finally
           {
               try
               {
                   if (testSocket != null)
                   {
                       testSocket.Shutdown(SocketShutdown.Both);
                   }
               }
               catch (Exception ex)
               {

               }
               finally
               {
                   if (testSocket != null)
                       testSocket.Close();
               }

           }

           return isUp;
       }


 private void CallWithTimeout(Action<Socket, IPEndPoint> action, int timeoutMilliseconds, Socket socket, IPEndPoint ipendPoint)
       {
           try
           {
               Action wrappedAction = () =>
               {
                   action(socket, ipendPoint);
               };

               IAsyncResult result = wrappedAction.BeginInvoke(null, null);

               if (result.AsyncWaitHandle.WaitOne(timeoutMilliseconds))
               {
                   wrappedAction.EndInvoke(result);
               }

           }
           catch (Exception ex)
           {

           }
       }

  private void ConnectToProxyServers(Socket testSocket, IPEndPoint ipEndPoint)
       {
           try
           {
               if (testSocket == null || ipEndPoint == null)
                   return;

                   testSocket.Connect(ipEndPoint);

           }
           catch (Exception ex)
           {

           }
       } 

Answer 3

My take:

public static class SocketExtensions
{
    /// <summary>
    /// Connects the specified socket.
    /// </summary>
    /// <param name="socket">The socket.</param>
    /// <param name="endpoint">The IP endpoint.</param>
    /// <param name="timeout">The timeout.</param>
    public static void Connect(this Socket socket, EndPoint endpoint, TimeSpan timeout)
    {
        var result = socket.BeginConnect(endpoint, null, null);

        bool success = result.AsyncWaitHandle.WaitOne(timeout, true);
        if (success)
        {
            socket.EndConnect(result);
        }
        else
        {
            socket.Close();
            throw new SocketException(10060); // Connection timed out.
        }
    }
}

Answer 4

I just wrote an extension class in order to allow timeouts in connections. Use it exactly as you would use the standard Connect() methods, with an extra parameter named timeout.

using System;
using System.Net;
using System.Net.Sockets;

/// <summary>
/// Extensions to Socket class
/// </summary>
public static class SocketExtensions
{
    /// <summary>
    /// Connects the specified socket.
    /// </summary>
    /// <param name="socket">The socket.</param>
    /// <param name="host">The host.</param>
    /// <param name="port">The port.</param>
    /// <param name="timeout">The timeout.</param>
    public static void Connect(this Socket socket, string host, int port, TimeSpan timeout)
    {
        AsyncConnect(socket, (s, a, o) => s.BeginConnect(host, port, a, o), timeout);
    }

    /// <summary>
    /// Connects the specified socket.
    /// </summary>
    /// <param name="socket">The socket.</param>
    /// <param name="addresses">The addresses.</param>
    /// <param name="port">The port.</param>
    /// <param name="timeout">The timeout.</param>
    public static void Connect(this Socket socket, IPAddress[] addresses, int port, TimeSpan timeout)
    {
        AsyncConnect(socket, (s, a, o) => s.BeginConnect(addresses, port, a, o), timeout);
    }

    /// <summary>
    /// Asyncs the connect.
    /// </summary>
    /// <param name="socket">The socket.</param>
    /// <param name="connect">The connect.</param>
    /// <param name="timeout">The timeout.</param>
    private static void AsyncConnect(Socket socket, Func<Socket, AsyncCallback, object, IAsyncResult> connect, TimeSpan timeout)
    {
        var asyncResult = connect(socket, null, null);
        if (!asyncResult.AsyncWaitHandle.WaitOne(timeout))
        {
            try
            {
                socket.EndConnect(asyncResult);
            }
            catch (SocketException)
            { }
            catch (ObjectDisposedException)
            { }
        }
    }

Answer 5

I dont program in C# but in C, we solve the same problem by making the socket non-blocking and then putting the fd in a select/poll loop with a timeout value equal to the amount of time we are willing to wait for the connect to succeed.

I found this for Visual C++ and the explanation there also bends towards the select/poll mechanism I explained before.

In my experience, you cannot change connect timeout values per socket. You change it for all (by tuning OS parameters).

Answer 6

I found this. Simpler than the accepted answer, and works with .NET v2

Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

// Connect using a timeout (5 seconds)

IAsyncResult result = socket.BeginConnect( sIP, iPort, null, null );

bool success = result.AsyncWaitHandle.WaitOne( 5000, true );

if ( socket.Connected )
{
    socket.EndConnect( result );
}
else 
{
     // NOTE, MUST CLOSE THE SOCKET

     socket.Close();
     throw new ApplicationException("Failed to connect server.");
}

//...