Fixed UDP hello message drop on azure environment w/ fixed tests

DarkRift.Client/BichannelClientConnection.cs

@@ -30,7 +30,7 @@ public sealed class BichannelClientConnection : NetworkClientConnection, IDispos
         ///     The IP address of the remote client.
         /// </summary>
         public IPEndPoint RemoteUdpEndPoint { get; }
-        
+
         /// <summary>
         ///     Whether Nagel's algorithm should be disabled or not.
         /// </summary>
@@ -113,7 +113,7 @@ public BichannelClientConnection(IPVersion ipVersion, IPAddress ipAddress, int p
 
             tcpSocket = new Socket(addressFamily, SocketType.Stream, ProtocolType.Tcp);
             udpSocket = new Socket(tcpSocket.AddressFamily, SocketType.Dgram, ProtocolType.Udp);
-            
+
             NoDelay = noDelay;
         }
 
@@ -172,6 +172,7 @@ public override void Connect()
                         : "Malformatted TCP auth token from server.";
                     throw new DarkRiftConnectionException(errorMessage, SocketError.ConnectionAborted);
                 }
+
                 if (protocolVersion > BichannelProtocolVersion)
                 {
                     tcpSocket.Shutdown(SocketShutdown.Both);
@@ -183,7 +184,7 @@ public override void Connect()
                 udpSocket.Send(buffer);
 
                 //Receive response from server to initiate the connection
-                int udpAcknowledgmentSize = protocolVersion >= 1 ? 8 : 1;
+                int udpAcknowledgmentSize = protocolVersion >= 1 ? 12 : 1;
                 byte[] udpBuffer = new byte[udpAcknowledgmentSize];
                 udpSocket.ReceiveTimeout = 5000;
 
@@ -198,23 +199,24 @@ public override void Connect()
                 }
                 finally
                 {
-                    udpSocket.ReceiveTimeout = 0;   //Reset to infinite
+                    udpSocket.ReceiveTimeout = 0; //Reset to infinite
                 }
 
                 bool failedUdpReceive = receivedUdp != udpAcknowledgmentSize;
                 if (!failedUdpReceive)
                 {
                     if (protocolVersion != 0)
                     {
-                        for (int i = 0; i < udpAcknowledgmentSize; ++i)
+                        for (int i = 1; i < buffer.Length; i++)
                         {
-                            if (udpBuffer[i] != buffer[i + 1])
+                            if (udpBuffer[i - 1] != buffer[i])
                             {
                                 failedUdpReceive = true;
                                 break;
                             }
                         }
                     }
+
                     if (protocolVersion == 0)
                     {
                         if (udpBuffer[0] != 0)
@@ -722,7 +724,6 @@ private void UdpReceiveCompleted(object sender, SocketAsyncEventArgs e)
                     // Leave the loop
                     return;
                 }
-
             } while (!completingAsync);
         }
 

DarkRift.Server/Plugins/Listeners/Bichannel/BichannelListenerBase.cs

@@ -82,7 +82,7 @@ protected struct PendingConnection
         ///     The UDP connections to the server.
         /// </summary>
         protected Dictionary<EndPoint, BichannelServerConnection> UdpConnections { get; } = new Dictionary<EndPoint, BichannelServerConnection>();
-       
+
         /// <summary>
         ///     The maximum size the client can ask a TCP body to be without being striked.
         /// </summary>
@@ -194,7 +194,7 @@ protected void HandleTcpConnection(Socket acceptSocket)
             try
             {
                 //Send token via TCP
-                byte[] buffer = new byte[9];                    //Version, Token * 8
+                byte[] buffer = new byte[9]; //Version, Token * 8
                 buffer[0] = (byte)BichannelProtocolVersion;
                 BigEndianHelper.WriteBytes(buffer, 1, token);
                 acceptSocket.Send(buffer);
@@ -313,20 +313,26 @@ protected void HandleUdpConnection(MessageBuffer buffer, EndPoint remoteEndPoint
 
                 // Send message back to client to say hi
                 // This MemoryBuffer is not supposed to be disposed here! It's disposed when the message is sent!
-                int numBytesOfHello = BichannelProtocolVersion >= 1? 8 : 1; // This used to be 1 which caused issues with some ISPs.
+                // HelloBuffer size is must be at least 12 bytes even when the actual token is shorter
+                // otherwise the message is dropped in some environments. namely ACI
+                int numBytesOfHello = BichannelProtocolVersion >= 1 ? 12 : 1; // This used to be 1 which caused issues with some ISPs.
                 MessageBuffer helloBuffer = MessageBuffer.Create(numBytesOfHello);
                 helloBuffer.Count = numBytesOfHello;
 
                 if (BichannelProtocolVersion >= 1)
                 {
-                    for (int i = 0; i < numBytesOfHello; ++i)
+                    // Copy TCP token
+                    for (int i = 0; i < 8; i++)
                         helloBuffer.Buffer[i] = buffer.Buffer[i + 1];
+                    // Zero remaining bytes (as we might want to use them somehow in the future)
+                    for (int i = 8; i < numBytesOfHello; ++i)
+                        helloBuffer.Buffer[i] = 0;
                 }
                 else
                 {
                     helloBuffer.Buffer[0] = 0;
                 }
-                
+
                 connection.SendMessageUnreliable(helloBuffer);
 
                 //Inform everyone
@@ -360,7 +366,7 @@ internal void UnregisterUdpConnection(BichannelServerConnection connection)
             lock (UdpConnections)
                 UdpConnections.Remove(connection.RemoteUdpEndPoint);
         }
-        
+
         /// <summary>
         ///     Sends a buffer to the given endpoint using the UDP socket.
         /// </summary>

DarkRift.SystemTesting/PartialMessagingSteps.cs

@@ -79,12 +79,14 @@ public void GivenTheHandshakeHasCompeleted()
             udpSocket.Send(tcpBuffer);
 
             // Receive punchthrough
-            byte[] udpBuffer = new byte[8];
+            byte[] udpBuffer = new byte[12];
             int receivedUdp = udpSocket.Receive(udpBuffer);
 
-            Assert.AreEqual(8, receivedUdp);
+            Assert.AreEqual(12, receivedUdp);
             for (int i = 0; i < 8; ++i)
                 Assert.AreEqual(tcpBuffer[i + 1], udpBuffer[i], $"Token byte {i} mismatch");
+            for (int i = 8; i < 12; ++i)
+                Assert.AreEqual(0, udpBuffer[i]);
 
             // Stupid race condition to attach the MessageReceived handler
             System.Threading.Thread.Sleep(100);