Choosing a person to communicate in C #

If you want to track users, I advise you to code your server application to handle all connections. Here's a quick example (note that this is not a complete example):

using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

private TcpListener tcpListener;
private Thread listenerThread;
volatile bool listening;

// Create a client struct/class to handle connection information and names
private List<Client> clients;

// In constructor
clients = new List<Client>();
tcpListener = new TcpListener(IPAddress.Any, 3000);
listening = true;
listenerThread = new Thread(new ThreadStart(ListenForClients));
listenerThread.Start();

// ListenForClients function
private void ListenForClients()
{
    // Start the TCP listener
    this.tcpListener.Start();

    TcpClient tcpClient;
    while (listening)
    {
        try
        {
            // Suspends while loop till a client connects
            tcpClient = this.tcpListener.AcceptTcpClient();

            // Create a thread to handle communication with client
            Thread clientThread = new Thread(new ParameterizedThreadStart(HandleMessage));
            clientThread.Start(tcpClient);
        }
        catch { // Handle errors }
    }
}

// Handling messages (Connect? Disconnect? You can customize!)
private void HandleMessage(object client)
{
    // Retrieve our client and initialize the network stream
    TcpClient tcpClient = (TcpClient)client;
    NetworkStream clientStream = tcpClient.GetStream();

    // Create our data
    byte[] byteMessage = new byte[4096];
    int bytesRead;
    string message;
    string[] data;

    // Set our encoder
    ASCIIEncoding encoder = new ASCIIEncoding();

    while (true)
    {
        // Retrieve the clients message
        bytesRead = 0;
        try { bytesRead = clientStream.Read(byteMessage, 0, 4096); }
        catch { break; }

        // Client had disconnected
        if (bytesRead == 0)
            break;

        // Decode the clients message
        message = encoder.GetString(byteMessage, 0, bytesRead);
        // Handle the message...
    }
}

      

        
        
        
      

    

Now again, please note that this is not a complete example and I know I kind of tried my best, but I hope this gives you an idea. The part of the message in the HandleMessage function can be the IP address of the users if they connect to the chat server / disconnect and other parameters you want to specify. This is code taken from an app I wrote for my dad's company so employees can communicate with each other right from the custom CRM I wrote. If you have any more questions, please comment.