public void HandlePackets()
{
IPEndPoint receive_ep = new IPEndPoint(IPAddress.Any, 0);
var mtu_special = Encoding.ASCII.GetBytes("MTU ");
while (!listener_stop.WaitOne(0))
{
try
{
byte[] buf = Socket.Receive(ref receive_ep);
byte[] tuple = EndPointToTuple(receive_ep);
if (Sessions.ContainsKey(tuple))
{
var session = Sessions[tuple];
bool mtu_probe = true;
for (int i = 0; i < 4; i++)
{
if (buf[i] != mtu_special[i])
{
mtu_probe = false;
break;
}
}
if (mtu_probe)
{
session.GoodMTUs.Add(buf.Length);
session.LastMTUProbe = DateTime.Now;
continue;
}
if (session.L7FragmentationCapable && !session.NegotiatingMTU)
{
session.HandleFragment(buf);
}
else
{
session.Push(buf);
}
}
else
{
var session = new UdpSession(Socket, this, receive_ep);
Message syn_msg = null;
try
{
syn_msg = Message.Parse(buf);
}
catch (Exception ex)
{
Log.Info("Ignored improper connection attempt with message {0}/0x{1:X2}", syn_msg?.Type, syn_msg?.Subtype);
continue;
}
if (syn_msg == null || syn_msg.Type != MessageType.Control || syn_msg.Subtype != UdpSession.SYN)
{
Log.Info("Ignored improper connection attempt with message {0}/0x{1:X2}", syn_msg?.Type, syn_msg?.Subtype);
continue;
}
Sessions[tuple] = session;
Utilities.StartThread(delegate
{
var syn_ack_msg = new Message(MessageType.Control, UdpSession.SYN_ACK);
syn_ack_msg.Store["capabilities"] = new byte[] { (byte)UdpCapabilities.L7Fragmentation };
session.Send(syn_ack_msg.Serialize());
var ack_msg = session.ReceiveMessage(UdpSession.HANDSHAKE_TIMEOUT);
if (ack_msg == null || ack_msg.Type != MessageType.Control || ack_msg.Subtype != UdpSession.ACK)
{
Log.Info("Ignored improper connection attempt with message {0}/0x{1:X2}", ack_msg?.Type, ack_msg?.Subtype);
Sessions.Remove(tuple);
return;
}
if (ack_msg.Store.ContainsKey("capabilities"))
{
session.L7FragmentationCapable = ack_msg.Store["capabilities"].Contains((byte)UdpCapabilities.L7Fragmentation);
}
Log.Info("Accepted UDP connection on {0}{1}", receive_ep, QueueConnections ? ", queueing session" : "");
if (session.L7FragmentationCapable)
{
Log.Info("Negotiating MTU...");
session.NegotiateMTU();
}
if (QueueConnections)
{
Queue.Add(new UdpTunnel(session));
}
});
}
}
catch (SocketException ex)
{
Log.Error(ex);
}
catch (Exception ex)
{
Log.Error(ex);
}
}
}
internal void Close(UdpSession session)
{
Sessions.Remove(EndPointToTuple(session.EndPoint));
}