Myg wrote on 2025-01-01, 01:48:

So how exactly do you imagine this should work? I've been thinking about it a bit more and was curious what I could actually add to the equation per say.

I just asked ChatGPT "How do I write a TCP server in C# that accepts two connections and forward the incoming data from one connection to the other?"

Reply (I just added Task.WaitAll to the code, otherwise it terminates immediately):

1using System.Net;
2using System.Net.Sockets;
3
4class TcpServer
5{
6    private const int Port = 5000;  // Port number to listen on
7    private static TcpListener _tcpListener;
8    private static TcpClient _client1 = null;
9    private static TcpClient _client2 = null;
10
11    public static void Main(string[] args)
12    {
13        // Start the TCP listener
14        _tcpListener = new TcpListener(IPAddress.Any, Port);
15        _tcpListener.Start();
16
17        Console.WriteLine($"Server listening on port {Port}...");
18
19        // Accept exactly two client connections
20        AcceptClients().Wait();
21    }
22
23    private static async Task AcceptClients()
24    {
25        // Wait for the first client connection
26        _client1 = await _tcpListener.AcceptTcpClientAsync();
27        Console.WriteLine("First client connected.");
28
29        // Wait for the second client connection
30        _client2 = await _tcpListener.AcceptTcpClientAsync();
31        Console.WriteLine("Second client connected.");
32
33        // Handle the data forwarding between the two clients
34        var task1 = Task.Run(() => ForwardData(_client1, _client2)); // Forward from client1 to client2
35        var task2 = Task.Run(() => ForwardData(_client2, _client1)); // Forward from client2 to client1
36        Task.WaitAll([task1, task2], -1);
37    }
38
39    private static async Task ForwardData(TcpClient fromClient, TcpClient toClient)
40    {
41        using (fromClient)
42        using (toClient)
43        {
44            NetworkStream fromStream = fromClient.GetStream();
45            NetworkStream toStream = toClient.GetStream();
46
47            byte[] buffer = new byte[1024];
48            int bytesRead;
49
50            try
51            {
52                // Forward data from 'fromClient' to 'toClient'
53                while ((bytesRead = await fromStream.ReadAsync(buffer, 0, buffer.Length)) != 0)
54                {
55                    Console.WriteLine($"Forwarding {bytesRead} bytes from {fromClient.Client.RemoteEndPoint} to {toClient.Client.RemoteEndPoint}");
56
57                    // Write the data to the other client's stream
58                    await toStream.WriteAsync(buffer, 0, bytesRead);
59                    await toStream.FlushAsync();
60                }

61
62                Console.WriteLine("Client disconnected.");
63            }
64            catch (Exception ex)
65            {
66                Console.WriteLine($"Error in data forwarding: {ex.Message}");
67            }
68        }
69    }
70}

This works already well with unmodified versions of Dosbox 0.74.3 and Dosbox-Staging (tested with DOOM2):

1serial1 nullmodem port:5000 server:localhost
2sersetup.exe

Main issues are that this code cannot handle any reconnect right now.

I am fimilar with TCP servers/clients. I was just curious how to implement it on my server? How would I get the right people to send data to each other?

Myg wrote on 2025-01-05, 16:09:

I am fimilar with TCP servers/clients. I was just curious how to implement it on my server? How would I get the right people to send data to each other?

Maybe I get you wrong, but Nullmodem serial is a point to point connection, so data coming in from one client is always sent to the other client. In a LAN Dosbox already provides a client/server model. But it also works if both Dosbox instances connect to a server that just forwards the TCP packages. Since dosbox does not even use an envelope for the serial data, you could also forward the data between TCP and a physical serial port.

Or do you mean some kind of authentication or multiple nullmodem connections handled by the server at the same time?

Caligula wrote on 2025-01-05, 17:37:

Myg wrote on 2025-01-05, 16:09:

I am fimilar with TCP servers/clients. I was just curious how to implement it on my server? How would I get the right people to send data to each other?

Maybe I get you wrong, but Nullmodem serial is a point to point connection, so data coming in from one client is always sent to the other client. In a LAN Dosbox already provides a client/server model. But it also works if both Dosbox instances connect to a server that just forwards the TCP packages. Since dosbox does not even use an envelope for the serial data, you could also forward the data between TCP and a physical serial port.

Or do you mean some kind of authentication or multiple nullmodem connections handled by the server at the same time?

Yea, I considered this but it seems very inefficient. I will contemplate approaches. If I can't find one I will consider a basic relaying to all clients approach. Yes I was concerned about multiple nullmodem connections... I am also concerned about this approach doubling (at the least) latency of an already latant protocol.

Nice 😁