Cancel blocking AcceptTcpClient call

Question

As everyone may already know, the simplest way to accept incoming TCP connections in C# is by looping over TcpListener.AcceptTcpClient(). Additionally this way will block co

Answer 1

The following code will close/abort AcceptTcpClient when isRunning variable becomes false

public static bool isRunning;

delegate void mThread(ref book isRunning);
delegate void AccptTcpClnt(ref TcpClient client, TcpListener listener);

public static main()
{
   isRunning = true;
   mThread t = new mThread(StartListening);
   Thread masterThread = new Thread(() => t(this, ref isRunning));
   masterThread.IsBackground = true; //better to run it as a background thread
   masterThread.Start();
}

public static void AccptClnt(ref TcpClient client, TcpListener listener)
{
  if(client == null)
    client = listener.AcceptTcpClient(); 
}

public static void StartListening(ref bool isRunning)
{
  TcpListener listener = new TcpListener(new IPEndPoint(IPAddress.Any, portNum));

  try
  {
     listener.Start();

     TcpClient handler = null;
     while (isRunning)
     {
        AccptTcpClnt t = new AccptTcpClnt(AccptClnt);

        Thread tt = new Thread(() => t(ref handler, listener));
        tt.IsBackground = true;
        // the AcceptTcpClient() is a blocking method, so we are invoking it
        // in a separate dedicated thread 
        tt.Start(); 
        while (isRunning && tt.IsAlive && handler == null) 
        Thread.Sleep(500); //change the time as you prefer


        if (handler != null)
        {
           //handle the accepted connection here
        }        
        // as was suggested in comments, aborting the thread this way
        // is not a good practice. so we can omit the else if block
        // else if (!isRunning && tt.IsAlive)
        // {
        //   tt.Abort();
        //}                   
     }
     // when isRunning is set to false, the code exits the while(isRunning)
     // and listner.Stop() is called which throws SocketException 
     listener.Stop();           
  }
  // catching the SocketException as was suggested by the most
  // voted answer
  catch (SocketException e)
  {

  }

}