How to configure socket connect timeout

I found this. Simpler than the accepted answer, and works with .NET Framework 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.");
}
 
//... 

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).

it might be too late but there is neat solution based on Task.WaitAny (c# 5 +) :

 public static bool ConnectWithTimeout(this Socket socket, string host, int port, int timeout)
        {
            bool connected = false;
            Task result = socket.ConnectAsync(host, port);               
            int index = Task.WaitAny(new[] { result }, timeout);
            connected = socket.Connected;
            if (!connected) {
              socket.Close();
            }

            return connected;
        }

I solved the problem by using Socket.ConnectAsync Method instead of Socket.Connect Method. After invoking the Socket.ConnectAsync(SocketAsyncEventArgs), start a timer (timer_connection), if time is up, check whether socket connection is connected (if(m_clientSocket.Connected)), if not, pop up timeout error.

private void connect(string ipAdd,string port)
    {
        try
        {
            SocketAsyncEventArgs e=new SocketAsyncEventArgs();


            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.
            e.RemoteEndPoint = ipEnd;
            e.UserToken = m_clientSocket;
            e.Completed+=new EventHandler<SocketAsyncEventArgs>(e_Completed);                
            m_clientSocket.ConnectAsync(e);

            if (timer_connection != null)
            {
                timer_connection.Dispose();
            }
            else
            {
                timer_connection = new Timer();
            }
            timer_connection.Interval = 2000;
            timer_connection.Tick+=new EventHandler(timer_connection_Tick);
            timer_connection.Start();
        }
        catch (SocketException se)
        {
            lb_connectStatus.Text = "Connection Failed";
            MessageBox.Show(se.Message);
        }
    }
private void e_Completed(object sender,SocketAsyncEventArgs e)
    {
        lb_connectStatus.Text = "Connection Established";
        WaitForServerData();
    }
    private void timer_connection_Tick(object sender, EventArgs e)
    {
        if (!m_clientSocket.Connected)
        {
            MessageBox.Show("Connection Timeout");
            //m_clientSocket = null;

            timer_connection.Stop();
        }
    }

Check this out on MSDN. It does not appear that you can do this with the implemented properties in the Socket class.

The poster on MSDN actually solved his problem using threading. He had a main thread which called out to other threads which run the connection code for a couple seconds and then check the Connected property of the socket:

I created another method wich actually connected the socket ... had the main thread sleep for 2 seconds and then check on the connecting method (wich is run in a separate thread) if the socket was connected good otherwise throw an exception "Timed out " and that;s all. Thanks again for the repleies.

What are you trying to do, and why can't it wait for 15-30 seconds before timing out?

I worked with Unity and had some problem with the BeginConnect and other async methods from socket.

There is something than I don't understand but the code samples before doesn't work for me.

So I wrote this piece of code to make it work. I test it on an adhoc network with android and pc, also in local on my computer. Hope it can help.

using System.Net.Sockets;
using System.Threading;
using System.Net;
using System;
using System.Diagnostics;

class ConnexionParameter : Guardian
{
    public TcpClient client;
    public string address;
    public int port;
    public Thread principale;
    public Thread thisthread = null;
    public int timeout;

    private EventWaitHandle wh = new AutoResetEvent(false);

    public ConnexionParameter(TcpClient client, string address, int port, int timeout, Thread principale)
    {
        this.client = client;
        this.address = address;
        this.port = port;
        this.principale = principale;
        this.timeout = timeout;
        thisthread = new Thread(Connect);
    }


    public void Connect()
    {
        WatchDog.Start(timeout, this);
        try
        {
            client.Connect(IPAddress.Parse(address), port);

        }
        catch (Exception)
        {
            UnityEngine.Debug.LogWarning("Unable to connect service (Training mode? Or not running?)");
        }
        OnTimeOver();
        //principale.Resume();
    }

    public bool IsConnected = true;
    public void OnTimeOver()
    {
        try
        {
            if (!client.Connected)
            {
                    /*there is the trick. The abort method from thread doesn't
 make the connection stop immediately(I think it's because it rise an exception
 that make time to stop). Instead I close the socket while it's trying to
 connect , that make the connection method return faster*/
                IsConnected = false;

                client.Close();
            }
            wh.Set();

        }
        catch(Exception)
        {
            UnityEngine.Debug.LogWarning("Connexion already closed, or forcing connexion thread to end. Ignore.");
        }
    }


    public void Start()
    {

        thisthread.Start();
        wh.WaitOne();
        //principale.Suspend();
    }

    public bool Get()
    {
        Start();
        return IsConnected;
    }
}


public static class Connexion
{


    public static bool Connect(this TcpClient client, string address, int port, int timeout)
    {
        ConnexionParameter cp = new ConnexionParameter(client, address, port, timeout, Thread.CurrentThread);
        return cp.Get();
    }

//http://stackoverflow.com/questions/19653588/timeout-at-acceptsocket
    public static Socket AcceptSocket(this TcpListener tcpListener, int timeoutms, int pollInterval = 10)
    {
        TimeSpan timeout = TimeSpan.FromMilliseconds(timeoutms);
        var stopWatch = new Stopwatch();
        stopWatch.Start();
        while (stopWatch.Elapsed < timeout)
        {
            if (tcpListener.Pending())
                return tcpListener.AcceptSocket();

            Thread.Sleep(pollInterval);
        }
        return null;
    }


}

and there a very simple watchdog on C# to make it work:

using System.Threading;

public interface Guardian
{
    void OnTimeOver();
}

public class WatchDog {

    int m_iMs;
    Guardian m_guardian;

    public WatchDog(int a_iMs, Guardian a_guardian)
    {
        m_iMs = a_iMs;
        m_guardian = a_guardian;
        Thread thread = new Thread(body);
        thread.Start(this);
    }


    private void body(object o)
    {
        WatchDog watchdog = (WatchDog)o;
        Thread.Sleep(watchdog.m_iMs);
        watchdog.m_guardian.OnTimeOver();
    }

    public static void Start(int a_iMs, Guardian a_guardian)
    {
        new WatchDog(a_iMs, a_guardian);
    }
}

There should be a ReceiveTimeout property in the Socket class.

Socket.ReceiveTimeout Property