Question

I am wondering whether I can set a timeout value for UdpClient receive method.

I want to use block mode, but because sometimes udp will lost packet, my program udpClient.receive will hang there forever.

any good ideas how I can manage that?

Answer 1

What Filip is referring to is nested within the socket that UdpClient contains (UdpClient.Client.ReceiveTimeout).

You can also use the async methods to do this, but manually block execution:

var timeToWait = TimeSpan.FromSeconds(10);

var udpClient = new UdpClient( portNumber );
var asyncResult = udpClient.BeginReceive( null, null );
asyncResult.AsyncWaitHandle.WaitOne( timeToWait );
if (asyncResult.IsCompleted)
{
    try
    {
        IPEndPoint remoteEP = null;
        byte[] receivedData = udpClient.EndReceive( asyncResult, ref remoteEP );
        // EndReceive worked and we have received data and remote endpoint
    }
    catch (Exception ex)
    {
        // EndReceive failed and we ended up here
    }
} 
else
{
    // The operation wasn't completed before the timeout and we're off the hook
}