Where is UdpClient.CancelReceive?

Question

I'm implementing a simple local-network discovery protocol, so I call UdpClient.Send and then UdpClient.BeginReceive. In case more than one response is pending, I call UdpClient.BeginReceive at the end of the callback. Something like this:

UdpClient client = new UdpClient(AddressFamily.InterNetwork);
client.EnableBroadcast = true;
client.Send(request, request.Length, broadcastEndPoint);
client.BeginReceive(Callback, client);

...and then in Callback:

void Callback(IAsyncResult ar)
{
    UdpClient client = (UdpClient)ar.AsyncState;
    IPEndPoint remoteEndPoint = null;
    byte[] response = client.EndReceive(ar, ref remoteEndPoint);

    // Do something with response

    client.BeginReceive(Callback, client);
}

My problem is that my main loop calls client.Close while there's still a receive pending. The receive completes, and then my next call to BeginReceive throws an exception: System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host

Why doesn't UdpClient have a CancelReceive method? What can I do instead?

Answer 1

I have the same problem. How did you solve it ?

Answer 2

Instead or to overcome this exception create bool and set it before issuing the close command, use that bool to check in callback

like this

bool isClosing=false; void Callback(IAsyncResult ar) { if(isClosing) return; }

set the bool 'isClosing' before issuing the close command

Hope this works