public static void Receive_Callback(IAsyncResult result)
{
StunSession session = (StunSession)result.AsyncState;
Socket socket = session.TcpSocket;
int read = socket.EndReceive(result);
if (read > 0)
{
session.Position += read;
// if we have at least 4 bytes we can check the length
if (session.Position > 3)
{
// extract length and compare with buffer position, we may have a full message
byte[] lengthBytes = new byte[2];
Array.Copy(session.SocketBuffer, 2, lengthBytes, 0, 2);
if (BitConverter.IsLittleEndian)
{
Array.Reverse(lengthBytes);
}
ushort length = BitConverter.ToUInt16(lengthBytes, 0);
if (length + 20 == session.Position)
{
StunMessage message = new StunMessage(session.SocketBuffer);
// TODO: work out how to process message :)
// we're now on a secondary thread in a static method, with no access to the "server"
}
else
{
session.TcpSocket.BeginReceive(session.SocketBuffer, session.Position, session.SocketBuffer.Length - session.Position, SocketFlags.None, new AsyncCallback(Receive_Callback), session);
}
}
}
else
{
socket.Close();
}
}
public void Start()
{
TcpListener tcpServer = new TcpListener(IPAddress.Parse(options.ListenAddress), options.TcpPort);
UdpClient udpClient = new UdpClient(new IPEndPoint(IPAddress.Parse(options.ListenAddress), options.UdpPort));
Task[] tasks = new Task[2]; // UDP receive, TCP accept
List <StunSession> sessions = new List <StunSession>();
// TODO: this is taken from an console app I used for UDP testing, refactor
// Task t = Task.Run(async () =>
// {
while (true)
{
// TODO: need to add logic to manage tasks for when UDP and/or TCP requests come in
// if the tasks are not already outstanding (i.e. awaiting from a previous loop) then
// add, otherwise just check for completion
// if task is already outstanding there is nothing to do but check if it's complete
if (tasks[0] == null)
{
tasks[0] = udpClient.ReceiveAsync();
}
if (tasks[1] == null)
{
tasks[2] = tcpServer.AcceptSocketAsync();
}
// check for any new connections
int task = Task.WaitAny(tasks, 5);
if (task == 0)
{
// UDP client sent a request
UdpReceiveResult result = ((Task <UdpReceiveResult>)tasks[0]).Result;
// done with the task so null it ready for next loop iteration
tasks[0] = null;
// TODO: store this somewhere for future reference
IPEndPoint remoteEndpoint = result.RemoteEndPoint;
// TODO: add some validation of magic number, 32-bit alignment etc.
byte[] buffer = result.Buffer;
StunMessage message = new StunMessage(buffer);
// process the message
ProcessMessage(message);
}
else if (task == 1)
{
// accepting a connection - create a new session object and start tracking
StunSession session = new StunSession();
sessions.Add(session);
session.TcpSocket = ((Task <Socket>)tasks[1]).Result;
// done with the task so null it ready for next loop iteration
tasks[1] = null;
// add task to receive TCP packet
// tcpReceiveTasks.Add(session.TcpSocket.ReceiveAsync(session.SocketBuffer, SocketFlags.None));
session.TcpSocket.BeginReceive(session.SocketBuffer, session.Position, session.SocketBuffer.Length - session.Position, SocketFlags.None, new AsyncCallback(Receive_Callback), session);
}
}
// });
// Console.WriteLine("Press any key to quit it");
// Console.ReadKey();
}