Receive and process continuous packets using UDP

Question

This is my current setup (using UDP):

void OnDataReceived(IAsyncResult result) { IPEndPoint ep = new IPEndPoint(IPAddress.Any, 0); byte[] buffer = socket.EndReceive(result, ref ep); Packet p = new Packet(Encoding.ASCII.GetString(buffer, 0, buffer.Length)); //process packet socket.BeginReceive(new AsyncCallback(OnDataReceived), socket); } 

I was wondering what would happen if I immediately call socket.BeginReceive after calling EndReceive, and then process the packet to get a continuous stream of packets as follows:

 void OnDataReceived(IAsyncResult result) { IPEndPoint ep = new IPEndPoint(IPAddress.Any, 0); byte[] buffer = socket.EndReceive(result, ref ep); socket.BeginReceive(new AsyncCallback(OnDataReceived), socket); Packet p = new Packet(Encoding.ASCII.GetString(buffer, 0, buffer.Length)); //process packets } 

If a packet is received as soon as I call BeginReceive, will this conflict with the current packet processing?

Also, if this does not contradict the switch to TCP, do it disfunctional?

Answer 1

It looks like you are creating some kind of recursive handler. I'm not sure how this will work, perhaps not in a good way. I usually use a separate reader stream that listens for incoming data and passes it to the event. It has served me well in the past. I have not studied using async for this, though.

Here is a sample code on how to use a separate thread to process incoming UDP data. It is not complete, but should give you an idea of ​​how to configure it.

  private Thread _udpReadThread; private volatile bool _terminateThread; public event DataEventHandler OnDataReceived; public delegate void DataEventHandler(object sender, DataEventArgs e); private void CreateUdpReadThread() { _udpReadThread = new Thread(UdpReadThread) { Name = "UDP Read thread" }; _udpReadThread.Start(new IPEndPoint(IPAddress.Any, 1234)); } private void UdpReadThread(object endPoint) { var myEndPoint = (EndPoint)endPoint; var udpListener = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); udpListener.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true); // Important to specify a timeout value, otherwise the socket ReceiveFrom() // will block indefinitely if no packets are received and the thread will never terminate udpListener.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 100); udpListener.Bind(myEndPoint); try { while (!_terminateThread) { try { var buffer = new byte[1024]; var size = udpListener.ReceiveFrom(buffer, ref myEndPoint); Array.Resize(ref buffer, size); // Let any consumer(s) handle the data via an event FireOnDataReceived(((IPEndPoint)(myEndPoint)).Address, buffer); } catch (SocketException socketException) { // Handle socket errors } } } finally { // Close Socket udpListener.Shutdown(SocketShutdown.Both); udpListener.Close(); } } public class DataEventArgs : EventArgs { public byte[] Data { get; private set; } public IPAddress IpAddress { get; private set; } public DataEventArgs(IPAddress ipaddress, byte[] data) { IpAddress = ipaddress; Data = data; } }