Listen to UPnP Broadcast with UdpClient

问题

Just trying to receive a UPnP broadcast from a device in my local network. I did find a lot of similar questions and tried a bunch of suggestions, none of theme where successful. I do see the UDP packets with Wireshark, so they are actually received on my computer. Any suggestions?

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;

public class UDPListener
{
    private const int listenPort = 1900;

    private static void StartListener()
    {
        bool done = false;

        IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Any, listenPort);

        UdpClient listener = new UdpClient();
        listener.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);        
        listener.Client.Bind(localEndPoint);
        listener.JoinMulticastGroup(IPAddress.Parse("239.255.255.250"));
        listener.MulticastLoopback = true;

        IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, 0);

        try
        {
            while (!done)
            {
                Console.WriteLine("Waiting for broadcast");
                var bytes = listener.Receive(ref groupEP);

                Console.WriteLine("Received broadcast from {0} :\n {1}\n",
                   groupEP.ToString(),
                   Encoding.ASCII.GetString(bytes, 0, bytes.Length));

            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
        finally
        {
            listener.Close();
        }
    }

    public static int Main()
    {
        StartListener();

        return 0;
    }
}

回答1:

Thanks to Try and Error I did got it working by specifying my local address while binding to the multicast group. I hardcoded the address in the example since It's is just a sandbox application. Using IPAddress.Any does not work. I don't know exactly why. For future reference and other poor souls who might looking for similar stuff:

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;

public class UDPListener
{
    private static void StartListener()
    {
        bool done = false;

        IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Any, 1900);

        UdpClient listener = new UdpClient();
        listener.Client.Bind(localEndPoint);
        listener.JoinMulticastGroup(IPAddress.Parse("239.255.255.250"), IPAddress.Parse("10.32.4.129"));

        IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, 0);

        try
        {
            while (!done)
            {
                Console.WriteLine("Waiting for broadcast");
                var bytes = listener.Receive(ref groupEP);

                Console.WriteLine("Received broadcast from {0} :\n {1}\n",
                   groupEP.ToString(),
                   Encoding.ASCII.GetString(bytes, 0, bytes.Length));
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
        finally
        {
            listener.Close();
        }
    }

    public static int Main()
    {
        StartListener();

        return 0;
    }
}

来源：https://stackoverflow.com/questions/35793032/listen-to-upnp-broadcast-with-udpclient

标签

broadcast

upnp