Socket Async UDP - How to handle client crash

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Greetings all.

I have almost no experience with Network programming on C#.
I have an Asynchronous UDP socket on a server that sends data to clients.

If one of the client crashes i get the next Socket Error:

Message = "An existing connection was forcibly closed by the remote host"
ErrorCode = 10054
SocketErrorCode = ConnectionReset

How do you handle this exception???
I cant close the socket because there are other clients still receiving messages. I also cant ignore the ICMP message, because i need remove the client from a local list.

The code:

 public void Initialize()
        {
            receiveSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

            receiveEndPoint = new IPEndPoint(IPAddress.Any, receivePort);
            receiveSocket.Bind(receiveEndPoint);
            receivePort = (receiveSocket.LocalEndPoint as IPEndPoint).Port;
            receiveBuffer = new byte[BufferSize];
            receiveAsyncResult = receiveSocket.BeginReceiveFrom(receiveBuffer, 0, receiveBuffer.Length, SocketFlags.None, ref receiveEndPoint, new AsyncCallback(NetworkMessageReceivedCallback), receiveSocket);
          ........
          ......
        }
protected void NetworkMessageReceivedCallback(IAsyncResult asyncResult)
        {
            EndPoint remoteEndPoint = null;
            byte[] bytes = null;
            try
            {
                // Finish receiving the message.
                remoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
                int bytesRead = receiveSocket.EndReceiveFrom(asyncResult, ref remoteEndPoint);
                
                // Copy off to a local buffer. 
                bytes = new Byte[BufferSize];
                Buffer.BlockCopy(receiveBuffer, 0, bytes, 0, bytesRead);
               // Continue to hear from port
                receiveAsyncResult = receiveSocket.BeginReceiveFrom(receiveBuffer, 0, receiveBuffer.Length, SocketFlags.None,
                    ref receiveEndPoint, new AsyncCallback(NetworkMessageReceivedCallback), receiveSocket);
            }
            catch (SocketException socketException)
            {

                if (OnForceDisconnect != null) { OnForceDisconnect(remoteEndPoint); }
              
               // Continue to hear from port
                receiveAsyncResult = receiveSocket.BeginReceiveFrom(receiveBuffer, 0, receiveBuffer.Length, SocketFlags.None,
                    ref receiveEndPoint, new AsyncCallback(NetworkMessageReceivedCallback), receiveSocket);
                 
            }
           ..........
           }

Thanks

Posted 19-May-10 12:32pm

eco2709

Updated 19-May-10 12:48pm

Henry Minute

v2

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Jarno Burger · Answer 1 · 2010-08-03T02:53:00

My thingies that i found out with the same probs , these are my hints :

1
I found out that visual studio debug can do a break in debugmode , but that i wouldnt matter so much if this would happen. cause the rest was still connected.

2
I placed the beginrecieve also in a try catch.

3
And i also check if network packets can still be send or recieved.

4

if (ex.SocketErrorCode == SocketError.ConnectionReset)
{
   JTracer.Write(ex, "connection got broken , nothing serious");
}
   else
{
   pTracer.ThrowError(ex, "begin recieve error");
}