//
// Send a command over UDP
//
public static void SendUDP(object sender, DoWorkEventArgs ea)
{
const int MAX_RECVBUFFER_SIZE = 2048;
// Create a new socket instance
// Since this socket is only used within the WiFi network, the preference is on the NonCellular side,
// to not send the UDP broadcast into the Internet, it wouldn't be delivered...
Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
socket.SetNetworkPreference(NetworkSelectionCharacteristics.NonCellular);
SocketAsyncEventArgs socketEventArg = new SocketAsyncEventArgs();
// Let's assume that the local network broadcast address can be created by changing the last digit to 255
// - Like 192.168.0.xx -> 192.168.0.255
// WP8 does support sending to IPAddress.Broadcast, i.e. "255.255.255.255", but there's something
// wrong with the socket handling:
// - Cannot use 'SendToAsync', but have to use 'ConnectAsync' instead
// - Cannot receive any data using the same socket (code seems OK, but nothing is received)
byte[] localBroadcastAddressBytes = FindMyIPAddress().GetAddressBytes();
localBroadcastAddressBytes[3] = 255;
IPAddress localBroadcast = new IPAddress(localBroadcastAddressBytes);
socketEventArg.RemoteEndPoint = new IPEndPoint(localBroadcast, UDPPort);
socketEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(delegate(object s, SocketAsyncEventArgs e)
{
switch (e.LastOperation)
{
case SocketAsyncOperation.SendTo: // The broadcast was sent successfully, now start listening on the same socket
Socket sock = e.UserToken as Socket;
socketEventArg.SetBuffer(new Byte[MAX_RECVBUFFER_SIZE], 0, MAX_RECVBUFFER_SIZE);
sock.ReceiveFromAsync(socketEventArg);
break;
case SocketAsyncOperation.ReceiveFrom: // Received a response to the broadcast
if (e.SocketError == System.Net.Sockets.SocketError.Success)
{
// Retrieve the data from the buffer
var response = Encoding.UTF8.GetString(e.Buffer, e.Offset, e.BytesTransferred);
response = response.Trim('\0');
System.Diagnostics.Debug.WriteLine("Received JSON data: " + response);
// Is this is an 'identify' or 'command' response?
HeatPumpIdentifyResponse identifyResponse = (HeatPumpIdentifyResponse)JsonFunctions.DeserializeFromStringToJson(response, typeof(HeatPumpIdentifyResponse));
System.Diagnostics.Debug.WriteLine("Response to command: " + identifyResponse.command + ": " + response);
// Run the notification handler (if found)
if (App.ViewModel.notificationHandlers.ContainsKey(identifyResponse.command))
{
System.Diagnostics.Debug.WriteLine("Found handler for command " + identifyResponse.command);
App.ViewModel.notificationHandlers[identifyResponse.command](response);
}
}
break;
}
});
// Add the data to be sent into the send buffer
byte[] payload = Encoding.UTF8.GetBytes((string)ea.Argument);
socketEventArg.SetBuffer(payload, 0, payload.Length);
// Add the socket as the UserToken for use within the event handler
socketEventArg.UserToken = socket;
// Send the UDP broadcast
socket.SendToAsync(socketEventArg);
}
