Question

Im new to Sockets and C# in general and am having a difficult time implementing a simple upd listener function. I’ve spent alot of time searching the web tying unsuccessfully to intergate any of the numerious examples online. So any suggestions, links, examples would be greatly appreciated!

At this point, I have a third party application broadcasting over port 6600 a general UPD message containing information about the location of the application server (ServerName, IP Address, etc.). I’d like to design my listener client application to capture the UPD broadcast and generate a collection of the available servers which can be used to future processing.

The problem I’m having is that when I attempt to create the listener using listener.Listen(0) if fails and generates a general type error. If I attempt to us the UdpClient class my application hangs and never returns any data. The Code for both examples is listed below:

namespace UDPListener
{
    class Program
    {
        static void Main(string[] args)
        {
            Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
            listener.Bind(new IPEndPoint(IPAddress.Any, 6600));
            listener.Listen(6);
            Socket socket = listener.Accept();
            Stream netStream = new NetworkStream(socket);
            StreamReader reader = new StreamReader(netStream);

            string result = reader.ReadToEnd();
            Console.WriteLine(result);
            socket.Close();
            listener.Close();

        }
    }
}

And the UdpClient:

private void IdentifyServer()
    {
        //Creates a UdpClient for reading incoming data.
        UdpClient receivingUdpClient = new UdpClient(6600);

        //Creates an IPEndPoint to record the IP Address and port number of the sender.  
        // The IPEndPoint will allow you to read datagrams sent from any source.
        IPEndPoint RemoteIpEndPoint = new IPEndPoint(IPAddress.Any, 0);
        try
        {

            // Blocks until a message returns on this socket from a remote host.
            Byte[] receiveBytes = receivingUdpClient.Receive(ref RemoteIpEndPoint);

            string returnData = Encoding.ASCII.GetString(receiveBytes);

            Output.Text = ("This is the message you received " +
                                        returnData.ToString());
            Output.Text = ("This message was sent from " +
                                        RemoteIpEndPoint.Address.ToString() +
                                        " on their port number " +
                                        RemoteIpEndPoint.Port.ToString());
        }
        catch (Exception e)
        {
            MessageBox.Show(e.ToString());
        }

Answer 1

dtb was absolutely write! After much research and some help from a friend I realized that what I was actually looking for was a solution for Multicasting. I’ll include the links below.

@dtb, thanks for helping point me in the right direction!

http://www.codeproject.com/Articles/1705/IP-Multicasting-in-C

http://codeidol.com/csharp/csharp-network/IP-Multicasting/Csharp-IP-Multicast-Support/