Correct use of UDP DatagramSocket

问题

I have the following code (snips provided below) in my base class for handling a UDP socket. I am adding support for WinRT (controlled by the #define for WINRT). I have everything working for .Net, but something is going wrong with my WinRT implementation. When I send the data, it is not being received on the server side. Any idea what is going wrong? I don't see any errors on the client side, just nothing shows up on the server. I have successfully gotten my TCP socket class working, using the DataWriter in a similar way.

        public UdpSocketClient(IPEndPoint remoteEndPoint, int localPort)
        {
            this.remoteEndPoint = remoteEndPoint;
#if WINRT
            this.socket = new DatagramSocket();
            this.socket.MessageReceived += ReceiveCallback;

            // Bind to any port
            Logger.Debug("{0}: UdpSocketClient created. Binding to port {1}.", this, (localPort == 0) ? "[any]" : localPort.ToString());
            IAsyncAction bindAction = this.socket.BindEndpointAsync(new HostName("localhost"), localPort == 0 ? "0" : localPort.ToString());
            bindAction.AsTask().Wait();
            Logger.Trace("{0}: Bind Complete to port {1}", this, this.socket.Information.LocalServiceName);

            // Get IOutputStream
            Logger.Trace("{0}: Getting output stream to {1}.", this, remoteEndPoint);
            IAsyncOperation<IOutputStream> asyncOutput = this.socket.GetOutputStreamAsync(remoteEndPoint.address, remoteEndPoint.port.ToString());
            asyncOutput.AsTask().Wait();
            Logger.Trace("{0}: Got output stream.", this);

            // Create DataWriter
            dataWriter = new DataWriter(asyncOutput.GetResults());
#else
            ...
#endif
        }


        public void SendBuffer(ByteBuffer buffer, int wait = 0)
        {
#if WINRT
            Logger.Trace("{0}: Sending buffer. Wait = {1}", this, wait);
            for (int i = 0; i < buffer.WriteSize(); i++)
                dataWriter.WriteByte(buffer.Buffer()[i]);
            DataWriterStoreOperation op = dataWriter.StoreAsync();
            if (wait != 0) op.AsTask().Wait(wait);
            else op.AsTask().Wait();
            Logger.Trace("{0}: Sending complete.", this);
#else
        ...
#endif
        }

Some relevant logs:

04/23 19:08:57.504 DEBUG: Area Sync: UdpSocketClient created. Binding to port [any].
04/23 19:08:57.505 TRACE: Area Sync: Bind Complete to port 59518
04/23 19:08:57.506 TRACE: Area Sync: Getting output stream to 71.227.179.128:1302.
04/23 19:08:57.507 TRACE: Area Sync: Got output stream.

04/23 19:08:57.604 TRACE: Area Sync: Sending contact packet.
04/23 19:08:57.604 TRACE: Area Sync: Sending buffer. Wait = 0
04/23 19:08:57.605 TRACE: Area Sync: Sending complete.

回答1:

I figured it out. Apparently it doesn't like my bind code. The documentation says that you should be able to pass null into the bind, but I always got an exception for that. So, it works if I use the ConnectAsync API:

        public UdpSocketClient(IPEndPoint remoteEndPoint, int localPort)
        {
            this.remoteEndPoint = remoteEndPoint;
#if WINRT
            this.socket = new DatagramSocket();
            this.socket.MessageReceived += ReceiveCallback;

            Logger.Trace("{0}: Connecting to {1}.", this, remoteEndPoint);
            IAsyncAction connectAction = this.socket.ConnectAsync(remoteEndPoint.address, remoteEndPoint.port.ToString());
            connectAction.AsTask().Wait();
            Logger.Trace("{0}: Connect Complete. Status {1}, ErrorCode {2}", this, connectAction.Status, 
                connectAction.ErrorCode != null ? connectAction.ErrorCode.Message : "None");

            dataWriter = new DataWriter(this.socket.OutputStream);
#else
            ...
#endif
        }

来源：https://stackoverflow.com/questions/10290945/correct-use-of-udp-datagramsocket