try

[xairoy]

Hallo,
I am developing an application where there is a source which sends UDP datagrams at a constant Interval (2 datagrams per second). I am receiving these datagrams in the following code:

EP = New IPEndPoint(IPAddress.Any, clsUDP.nListenOnPort)  
 
(' clsUDP.nListenOnPort=6466)
 
UDPInput = New UdpClient(EP)
While clsMisc.ListenforUDP
  Try
 
byt = UDPInput.Receive(EP)
..................
 Catch ex As Exception
        MessageBox.Show(ex.ToString)
  End Try
End While
 
 UDPInput.Close()
 
UDPInput = Nothing
EP = Nothing

the flag clsMisc.ListenforUDP is true as long as the application runs. This is set to false when an user Logs off.
This is working properly when a user logs in and logs off three times consecutively. But when an user logs in fourth time. I found out by debugging that the program hangs
after
byt = UDPInput.Receive(EP)
this line. I have also tried with asynchronous connection (Beginreceive and end receive) and also with
UDPInput.Client.SetSocketOption(SocketOptionLevel. Socket, SocketOptionName.ReceiveBuffer, 0) to flush the buffer before I read the byt but in vain. It is always the fourh time that the problem arises.

I am trying this to solve for the last 3 days without success. I shall be grateful if somebody helps me.
Thanks.
Roy

[tlhintoq]

TIP: When you are writing your question, there is a button on the tool bar that wraps the [code] tags around your copy/pasted code. It helps a bunch. Its the button with a '#' on it. More on tags. They're cool. Check'em out.

[tlhintoq]

Let me be clear: I do C#, not VB so some code translation on your part may be required.

Your code logic seems to be quite close to my own for UDP datagrams

        public void StartListener()
        {
            IPAddress IPlisten = new IPAddress(new byte[] { 127, 0, 0, 1 });
            if(ListenIP != null) IPAddress.TryParse(ListenIP, out IPlisten);
            IPEndPoint groupEP = new IPEndPoint(IPlisten, ListenPort);
            done = false;
 
            try
            {
                while (!done)
                {
                    Console.WriteLine("Waiting for broadcast");
                    byte[] bytes = listener.Receive(ref groupEP);
                    ReceivedMsg(bytes); // Raise custom event with received bytes
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }
            finally
            {
                if (listener != null) listener.Close();
            }
        }
 

My line 13 would correspond to your line 9 where the received packet is assigned to a byte array.

I'm not sure what you mean by "hangs up after this line". It is the nature of the .Receive method to stop and wait for an incoming packet.

I run my UDP Listener on its own thread because it halts execution. When a packet is received I then raise a custom event ("ReceivedMsg") with the byte array that came in. Then the loop (lines 10-15) iterates and the .Receive again halts all execution until another packet is received.

I hope this helps.