public void Connect(string ip, int port)
{
// not if already started
if (Connecting || Connected)
{
Log.Warning("Telepathy Client can not create connection because an existing connection is connecting or connected");
return;
}
// overwrite old thread's state object. create a new one to avoid
// data races where an old dieing thread might still modify the
// current state! fixes all the flaky tests!
state = new ClientConnectionState(MaxMessageSize);
// We are connecting from now until Connect succeeds or fails
state.Connecting = true;
// create a TcpClient with perfect IPv4, IPv6 and hostname resolving
// support.
//
// * TcpClient(hostname, port): works but would connect (and block)
// already
// * TcpClient(AddressFamily.InterNetworkV6): takes Ipv4 and IPv6
// addresses but only connects to IPv6 servers (e.g. Telepathy).
// does NOT connect to IPv4 servers (e.g. Mirror Booster), even
// with DualMode enabled.
// * TcpClient(): creates IPv4 socket internally, which would force
// Connect() to only use IPv4 sockets.
//
// => the trick is to clear the internal IPv4 socket so that Connect
// resolves the hostname and creates either an IPv4 or an IPv6
// socket as needed (see TcpClient source)
state.client.Client = null; // clear internal IPv4 socket until Connect()
// client.Connect(ip, port) is blocking. let's call it in the thread
// and return immediately.
// -> this way the application doesn't hang for 30s if connect takes
// too long, which is especially good in games
// -> this way we don't async client.BeginConnect, which seems to
// fail sometimes if we connect too many clients too fast
state.receiveThread = new Thread(() => {
ReceiveThreadFunction(state, ip, port, MaxMessageSize, NoDelay, SendTimeout, ReceiveTimeout, ReceiveQueueLimit);
});
state.receiveThread.IsBackground = true;
state.receiveThread.Start();
}
// the thread function
// STATIC to avoid sharing state!
// => pass ClientState object. a new one is created for each new thread!
// => avoids data races where an old dieing thread might still modify
// the current thread's state :/
static void ReceiveThreadFunction(ClientConnectionState state, string ip, int port, int MaxMessageSize, bool NoDelay, int SendTimeout, int ReceiveTimeout, int ReceiveQueueLimit)
{
Thread sendThread = null;
// absolutely must wrap with try/catch, otherwise thread
// exceptions are silent
try
{
// connect (blocking)
state.client.Connect(ip, port);
state.Connecting = false; // volatile!
// set socket options after the socket was created in Connect()
// (not after the constructor because we clear the socket there)
state.client.NoDelay = NoDelay;
state.client.SendTimeout = SendTimeout;
state.client.ReceiveTimeout = ReceiveTimeout;
// start send thread only after connected
// IMPORTANT: DO NOT SHARE STATE ACROSS MULTIPLE THREADS!
sendThread = new Thread(() => { ThreadFunctions.SendLoop(0, state.client, state.sendPipe, state.sendPending); });
sendThread.IsBackground = true;
sendThread.Start();
// run the receive loop
// (receive pipe is shared across all loops)
ThreadFunctions.ReceiveLoop(0, state.client, MaxMessageSize, state.receivePipe, ReceiveQueueLimit);
}
catch (SocketException exception)
{
// this happens if (for example) the ip address is correct
// but there is no server running on that ip/port
Log.Info("Client Recv: failed to connect to ip=" + ip + " port=" + port + " reason=" + exception);
// add 'Disconnected' event to receive pipe so that the caller
// knows that the Connect failed. otherwise they will never know
state.receivePipe.Enqueue(0, EventType.Disconnected, default);
}
catch (ThreadInterruptedException)
{
// expected if Disconnect() aborts it
}
catch (ThreadAbortException)
{
// expected if Disconnect() aborts it
}
catch (ObjectDisposedException)
{
// expected if Disconnect() aborts it and disposed the client
// while ReceiveThread is in a blocking Connect() call
}
catch (Exception exception)
{
// something went wrong. probably important.
Log.Error("Client Recv Exception: " + exception);
}
// sendthread might be waiting on ManualResetEvent,
// so let's make sure to end it if the connection
// closed.
// otherwise the send thread would only end if it's
// actually sending data while the connection is
// closed.
sendThread?.Interrupt();
// Connect might have failed. thread might have been closed.
// let's reset connecting state no matter what.
state.Connecting = false;
// if we got here then we are done. ReceiveLoop cleans up already,
// but we may never get there if connect fails. so let's clean up
// here too.
state.client?.Close();
}