UDP 所有客户端的 ReceiveAsync 中断

Question

I have created a simple C# UDP server/client model where multiple clients can connect to the same server. They all use the same EndPoint to connect to: IPEndPoint(IPAddress.Any, 0); When this happens, I spawn a new task that listens for incoming messages on the given remoteEndPoint using

SocketReceiveFromResult dataReceived = await socket.ReceiveFromAsync(buffer, SocketFlags.None, endpoint).RemoteEndPoint;

This works great and new connections can connect and start sending messages to the server, which then relays those messages to the other clients. When I then close one of the client connections, I Close() the socket from that client but I then get a SocketException in the ReceiveLoop Task that says "An existing connection was forcibly closed by the remote host." This wouldn't be a problem at all, but it happens for all the connections, even the initial port that listens for incoming requests.

 try
 {
     if (isConnected)
     {
         UdpProtocol.RequestFromData requestFromData = await socket.ReceiveFromAsync(buffer, SocketFlags.None, endpoint);
         onMessageReceived?.Invoke(requestFromData.JsonObject);
      }
 }
 catch (SocketException exception)
 {
     onConnectionClosed?.Invoke();
 }

How do I terminate the connection properly without causing all other client connections to also terminate?

Answer 1

After searching for a long time, I came upon this thread: C# UDP An existing connection was forcibly closed by the remote host

apparently, UDP sockets listen to "ICMP messages and throwing exceptions when they are received. If the port is no longer listening (after the hard crash), the ICMP message causes the 'forcibly closed' exception."

This code works to create a socket that doesn't listen for such events.

        socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
        const int SIO_UDP_CONNRESET = -1744830452;
        socket.IOControl((IOControlCode)SIO_UDP_CONNRESET, new byte[] { 0, 0, 0, 0 }, null);
        socket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.PacketInformation, true);
        IPEndPoint server = new IPEndPoint(IPAddress.Any, 30000);
        socket.Bind(server);

putting it here solely for future references.