UDP socket on Universal Windows not receiving data

Question

I have a WPF application that receives data through a UDP socket. Now I need to port it to Universal Windows Platform, but the socket does not receive the incoming data.

private void Init()
{
    socket = new Socket(SocketType.Dgram, ProtocolType.Udp);
    socket.Bind(new IPEndPoint(IPAddress.Parse("192.168.0.1"), 55156));

    socketAsyncArgs = new SocketAsyncEventArgs();
    buffer = new byte[4096];
    socketAsyncArgs.SetBuffer(buffer, 0, buffer.Length);
    socketAsyncArgs.Completed += Receive_Completed;
}

private void Receive()
{
    bool isPending = socket.ReceiveAsync(socketAsyncArgs);
    if ( ! isPending)
        Receive_Completed(socket, socketAsyncArgs);
}

The Receive_Completed method is never called. The same code works well in a WPF project. I used WireShark to verify the packets are coming. I also tried using Windows.Networking.Sockets.DatagramSocket with the same result - the socket does not receive any data.

Answer 1

I found the solution. Apparently, you have to specifically enable that the application will be receiving incoming network traffic. The UWP project in Visual Studio contains a file named Package.appxmanifest. Double click it, select the Capabilities tab and check Internet (Client & Server). More about that at the MSDN - Networking basics.

Answer 2

Don't you have to connect First? I dont about socket.bind but you have to set an IPEndPoint in socketAsyncArgs.RemoteEndPoint. And please don't call Receive_Completed!!! its an event it should be triggered automatically.

I tested you code with a server and worked(but in TCP and Stream mode)

private void Init()
{
    socket = new Socket(SocketType.Dgram, ProtocolType.Udp);

    socketAsyncArgs = new SocketAsyncEventArgs();
    socketAsyncArgs.RemoteEndPoint = new IPEndPoint(IPAddress.Parse("192.168.0.1"), 55156);
    buffer = new byte[4096];
    socketAsyncArgs.SetBuffer(buffer, 0, buffer.Length);
    socketAsyncArgs.Completed += Receive_Completed;
}

private void Receive()
{
    bool isPending = socket.ConnectAsync(socketAsyncArgs);
    if (!isPending)
        isPending = socket.ReceiveAsync(socketAsyncArgs);
}