Question

I am currently using this function to send data from the server to the clients

private static void send_message(string ip, string message)
{
    byte[] packetData = System.Text.UTF8Encoding.UTF8.GetBytes(message);

    int port = 11000;

    IPEndPoint ep = new IPEndPoint(IPAddress.Parse(ip), port);
    Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
    client.SendTo(packetData, ep);
}

But this would mean a destination IP/port can only have one client open to receive the data, because having two clients open would mean one client can retrieve data that was meant for another (if I’m correct).. how do I solve this?

Receiving function:

private static Int32 port = 11000;
private static UdpClient udpClient = new UdpClient(port);

public static void receive_threaded()
{
    Thread t = new Thread(() =>
    {
        while (true)
        {
            IPEndPoint remoteIPEndPoint = new IPEndPoint(IPAddress.Any, port);
            byte[] content = udpClient.Receive(ref remoteIPEndPoint);

            if (content.Length > 0)
            {
                string message = Encoding.UTF8.GetString(content);
                parseMessage(message);
            }
        }
    });
    t.Start();
}

Answer 1

1) You should implement some kind of protocol so that your server has a “well known” port to accept connections. Use this port to inform your client ANOTHER port where the client must connect. Use a different port for each client.

Your client conects to the server at 11000. Your server assigns a unique port for the client, let’s say 11001 for the firts client. Then the server opens a connection at 11001. The client closes connection at 11000 and opens a new connection at 11001 to receive the data.

2) Why UDP?