Question

Hello i got this code from here to receive data on a multicast address

 Socket sock = new Socket(AddressFamily.InterNetwork,
            SocketType.Dgram, ProtocolType.Udp);
 Console.WriteLine("Ready to receive…");
 IPEndPoint iep = new IPEndPoint(IPAddress.Any, 9050);
 EndPoint ep = (EndPoint)iep;
 sock.Bind(iep);
 sock.SetSocketOption(SocketOptionLevel.IP, 
            SocketOptionName.AddMembership, 
            new MulticastOption(IPAddress.Parse("224.100.0.1")));
 byte[] data = new byte[1024];
 int recv = sock.ReceiveFrom(data, ref ep);
 string stringData = Encoding.ASCII.GetString(data, 0, recv);
 Console.WriteLine("received: {0} from: {1}", stringData, ep.ToString());
 sock.Close();

Now this works when i receive a packet, then the sock.ReceiveFrom is triggered but after that the receiver shuts down (even if i remove the sock.Close line).
What i want is that the receiver displays or saves me the data but continue listening for more packets.

What would be a good way to do this?

Answer 1

You have to code some kind of loop or use the async methods BeginReceive/EndReceive.
As soon as your local sock variable gets out of scope, it might be collected by gc and get disposed.

byte[] data = new byte[1024];

while (true) {
    // this blocks until some bytes are received
    int recv = sock.ReceiveFrom(data, ref ep);
    string stringData = Encoding.ASCII.GetString(data, 0, recv);
    Console.WriteLine("received: {0} from: {1}", stringData, ep.ToString());
}