improve ttl hack (fix #371). Also some code clean

Author: RevenantX

LibSample/HolePunchServerTest.cs

@@ -121,23 +121,32 @@ public void Run()
                 Console.WriteLine("Success C2. Connecting to C1: {0}, connection created: {1}", point, peer != null);
             };
 
-            _c1 = new NetManager(netListener);
-            _c1.NatPunchEnabled = true;
+            _c1 = new NetManager(netListener)
+            {
+                IPv6Enabled = false,
+                NatPunchEnabled = true
+            };
             _c1.NatPunchModule.Init(natPunchListener1);
             _c1.Start();
 
-            _c2 = new NetManager(netListener);
-            _c2.NatPunchEnabled = true;
+            _c2 = new NetManager(netListener)
+            {
+                IPv6Enabled = false,
+                NatPunchEnabled = true
+            };
             _c2.NatPunchModule.Init(natPunchListener2);
             _c2.Start();
 
-            _puncher = new NetManager(netListener);
+            _puncher = new NetManager(netListener)
+            {
+                IPv6Enabled = false,
+                NatPunchEnabled = true
+            };
             _puncher.Start(ServerPort);
-            _puncher.NatPunchEnabled = true;
             _puncher.NatPunchModule.Init(this);
 
-            _c1.NatPunchModule.SendNatIntroduceRequest(NetUtils.MakeEndPoint("::1", ServerPort), "token1");
-            _c2.NatPunchModule.SendNatIntroduceRequest(NetUtils.MakeEndPoint("::1", ServerPort), "token1");
+            _c1.NatPunchModule.SendNatIntroduceRequest("localhost", ServerPort, "token1");
+            _c2.NatPunchModule.SendNatIntroduceRequest("localhost", ServerPort, "token1");
 
             // keep going until ESCAPE is pressed
             Console.WriteLine("Press ESC to quit");

LibSample/SpeedBench.cs

@@ -158,9 +158,9 @@ void INetEventListener.OnPeerDisconnected(NetPeer peer, DisconnectInfo disconnec
             }
         }
         private const string DATA = "The quick brown fox jumps over the lazy dog";
-        private static int MAX_LOOP_COUNT = 750;
-        private static int UNRELIABLE_MESSAGES_PER_LOOP = 1000;
-        private static int RELIABLE_MESSAGES_PER_LOOP = 350;
+        private const int MAX_LOOP_COUNT = 750;
+        private const int UNRELIABLE_MESSAGES_PER_LOOP = 1000;
+        private const int RELIABLE_MESSAGES_PER_LOOP = 350;
         private static bool CLIENT_RUNNING = true;
 
         public void Run()

LiteNetLib.Tests/CommunicationTest.cs

@@ -157,7 +157,7 @@ public void ConnectionFailedTest()
             NetManager client = ManagerStack.Client(1);
 
             var result = false;
-            DisconnectInfo disconnectInfo = default(DisconnectInfo);
+            DisconnectInfo disconnectInfo = default;
 
             ManagerStack.ClientListener(1).PeerDisconnectedEvent += (peer, info) => 
             {

LiteNetLib/NatPunchModule.cs

@@ -192,17 +192,15 @@ private void HandleNatIntroduction(NetDataReader dr)
             writer.Put((byte)PacketProperty.NatPunchMessage);
             writer.Put(hostByte);
             writer.Put(token);
-            if (hostByte == HostByte)
-            {
-                _socket.Ttl = 2;
-                _socket.SendTo(writer.Data, 0, writer.Length, remoteExternal, ref errorCode);
-                _socket.Ttl = NetConstants.SocketTTL;
-            }
-            else
-            {
-                _socket.SendTo(writer.Data, 0, writer.Length, remoteExternal, ref errorCode);
-            }
-    
+
+            // hack for some routers
+            _socket.Ttl = 2;
+            _socket.SendTo(new []{(byte)PacketProperty.Empty}, 0, 1, remoteExternal, ref errorCode);
+
+            // actual send
+            _socket.Ttl = NetConstants.SocketTTL;
+            _socket.SendTo(writer.Data, 0, writer.Length, remoteExternal, ref errorCode);
+
             NetDebug.Write(NetLogLevel.Trace, "[NAT] external punch sent to " + remoteExternal);
         }
 

LiteNetLib/NetManager.cs

@@ -892,6 +892,10 @@ private void DataReceived(byte[] reusableBuffer, int count, IPEndPoint remoteEnd
                     return;
             }
 
+            //empty packet
+            if (reusableBuffer[0] == (byte) PacketProperty.Empty)
+                return;
+
             //Try read packet
             NetPacket packet = NetPacketPool.GetPacket(count);
             if (!packet.FromBytes(reusableBuffer, 0, count))

LiteNetLib/NetPacket.cs

@@ -23,7 +23,8 @@ internal enum PacketProperty : byte
         Merged,
         ShutdownOk,
         PeerNotFound,
-        InvalidProtocol
+        InvalidProtocol,
+        Empty
     }
 
     internal sealed class NetPacket
@@ -120,6 +121,8 @@ public static int GetHeaderSize(PacketProperty property)
                     return NetConstants.HeaderSize + 8;
                 case PacketProperty.Pong:
                     return NetConstants.HeaderSize + 10;
+                case PacketProperty.Empty:
+                    return 1;
                 default:
                     return NetConstants.HeaderSize;
             }