Networking Fixes & Updates

Minecraft.Client/Network/ClientConnection.cpp

@@ -1134,6 +1134,15 @@ void ClientConnection::handleTileUpdate(shared_ptr<TileUpdatePacket> packet)
 
 void ClientConnection::handleDisconnect(shared_ptr<DisconnectPacket> packet)
 {
+#ifdef __linux__
+	// Linux fix: On local host connections, ignore DisconnectPacket. The singleplayer internal
+	// server should never disconnect itself. If we see this, it's likely stream desync reading
+	// garbage data as a DisconnectPacket.
+	if (connection && connection->getSocket() && connection->getSocket()->isLocal()) {
+		fprintf(stderr, "[CONN] Ignoring DisconnectPacket on local connection (reason=%d)\n", packet->reason);
+		return;
+	}
+#endif
 	connection->close(DisconnectPacket::eDisconnect_Kicked);
     done = true;
 	
@@ -1607,7 +1616,7 @@ void ClientConnection::handleEntityActionAtPosition(shared_ptr<EntityActionAtPos
 
 void ClientConnection::handlePreLogin(shared_ptr<PreLoginPacket> packet)
 {
-//	printf("Client: handlePreLogin\n");
+	fprintf(stderr, "[LOGIN-CLI] handlePreLogin entered, isHost=%d, userIdx=%d\n", (int)g_NetworkManager.IsHost(), m_userIndex);
 #if 1
 	// 4J - Check that we can play with all the players already in the game who have Friends-Only UGC set
 	BOOL canPlay = TRUE;
@@ -2049,8 +2058,11 @@ void ClientConnection::handlePreLogin(shared_ptr<PreLoginPacket> packet)
 		}
 		BOOL allAllowed, friendsAllowed;
 		ProfileManager.AllowedPlayerCreatedContent(m_userIndex,true,&allAllowed,&friendsAllowed);
+		fprintf(stderr, "[LOGIN] Sending LoginPacket: user=%ls netVer=%d userIdx=%d isHost=%d\n",
+			minecraft->user->name.c_str(), SharedConstants::NETWORK_PROTOCOL_VERSION, m_userIndex, (int)g_NetworkManager.IsHost());
 		send( shared_ptr<LoginPacket>( new LoginPacket(minecraft->user->name, SharedConstants::NETWORK_PROTOCOL_VERSION, offlineXUID, onlineXUID, (allAllowed!=TRUE && friendsAllowed==TRUE), 
 			packet->m_ugcPlayersVersion, app.GetPlayerSkinId(m_userIndex), app.GetPlayerCapeId(m_userIndex), ProfileManager.IsGuest( m_userIndex ))));
+		fprintf(stderr, "[LOGIN] LoginPacket sent successfully\n");
 
 		if(!g_NetworkManager.IsHost() )
 		{

Minecraft.Client/Network/PendingConnection.cpp

@@ -60,6 +60,7 @@ void PendingConnection::disconnect(DisconnectPacket::eDisconnectReason reason)
 {
  //   try {	// 4J - removed try/catch
 //        logger.info("Disconnecting " + getName() + ": " + reason);
+		fprintf(stderr, "[PENDING] disconnect called with reason=%d at tick=%d\n", reason, _tick);
 		app.DebugPrintf("Pending connection disconnect: %d\n", reason );
         connection->send( shared_ptr<DisconnectPacket>( new DisconnectPacket(reason) ) );
         connection->sendAndQuit();
@@ -139,7 +140,7 @@ void PendingConnection::sendPreLoginResponse()
 
 void PendingConnection::handleLogin(shared_ptr<LoginPacket> packet)
 {
-//	printf("Server: handleLogin\n");
+	fprintf(stderr, "[LOGIN-SRV] handleLogin called! clientVersion=%d\n", packet->clientVersion);
     //name = packet->userName;
     if (packet->clientVersion != SharedConstants::NETWORK_PROTOCOL_VERSION)
 	{

Minecraft.Client/Network/PendingConnection.h

@@ -11,7 +11,7 @@ class PendingConnection : public PacketListener
 {
 private:
 	static const int FAKE_LAG = 0;
-    static const int MAX_TICKS_BEFORE_LOGIN = 20 * 30;
+    static const int MAX_TICKS_BEFORE_LOGIN = 20 * 30 * 10; // 10 minutes instead of 20 sec for Linux theres just no login yet
 
 //    public static Logger logger = Logger.getLogger("Minecraft");
     static Random *random;

Minecraft.World/Network/Connection.cpp

@@ -196,7 +196,9 @@ bool Connection::writeTick()
 		LeaveCriticalSection(&writeLock);
 
 		Packet::writePacket(packet, bufferedDos);
-		
+#ifdef __linux__
+		bufferedDos->flush(); // Ensure buffered data reaches socket before any other writes
+#endif
 
 #ifndef _CONTENT_PACKAGE
 		// 4J Added for debugging
@@ -230,6 +232,13 @@ bool Connection::writeTick()
 
 		// If the shouldDelay flag is still set at this point then we want to write it to QNet as a single packet with priority flags
 		// Otherwise just buffer the packet with other outgoing packets as the java game did
+#ifdef __linux__
+		// Linux fix: For local connections, always use bufferedDos to avoid byte interleaving between
+		// the BufferedOutputStream buffer and direct sos writes. The shouldDelay/writeWithFlags path
+		// writes directly to sos, which can inject bytes BEFORE unflushed bufferedDos data.
+		Packet::writePacket(packet, bufferedDos);
+		bufferedDos->flush(); // Ensure data reaches socket immediately for delayed packets
+#else
 		if(packet->shouldDelay)
 		{
 			Packet::writePacket(packet, byteArrayDos);
@@ -245,6 +254,7 @@ bool Connection::writeTick()
 		{
 			Packet::writePacket(packet, bufferedDos);
 		}
+#endif
 
 #ifndef _CONTENT_PACKAGE
 		// 4J Added for debugging
@@ -329,9 +339,9 @@ close("disconnect.genericReason", "Internal exception: " + e.toString());
 
 void Connection::close(DisconnectPacket::eDisconnectReason reason, ...)
 {
-//	printf("Con:0x%x close\n",this);
+	fprintf(stderr, "[CONN] close called with reason=%d on connection=%p\n", reason, (void*)this);
 	if (!running) return;
-//	printf("Con:0x%x close doing something\n",this);
+	fprintf(stderr, "[CONN] close proceeding (was running) on connection=%p\n", (void*)this);
 	disconnected = true;
 
 	va_list input;

Minecraft.World/Network/Packets/DisconnectPacket.cpp

@@ -20,10 +20,12 @@ DisconnectPacket::DisconnectPacket(eDisconnectReason reason)
 void DisconnectPacket::read(DataInputStream *dis) //throws IOException
 {
 	reason = (eDisconnectReason)dis->readInt();
+	fprintf(stderr, "[PKT] DisconnectPacket::read reason=%d\n", reason);
 }
 
 void DisconnectPacket::write(DataOutputStream *dos) //throws IOException
 {
+	fprintf(stderr, "[PKT] DisconnectPacket::write reason=%d\n", reason);
 	dos->writeInt((int)reason);
 }
 

Minecraft.World/Network/Packets/Packet.cpp

@@ -347,6 +347,14 @@ unordered_map<int, Packet::PacketStatistics *> Packet::statistics = unordered_ma
 
 shared_ptr<Packet> Packet::readPacket(DataInputStream *dis, bool isServer) // throws IOException TODO 4J JEV, should this declare a throws?
 {
+	// N packet ID
+	static int s_clientPktHistory[64];
+	static int s_clientPktIdx = 0;
+	static int s_serverPktHistory[64];
+	static int s_serverPktIdx = 0;
+	static bool s_clientDesyncLogged = false;
+	static bool s_serverDesyncLogged = false;
+
 	int id = 0;
 	shared_ptr<Packet> packet = nullptr;
 
@@ -358,16 +366,33 @@ shared_ptr<Packet> Packet::readPacket(DataInputStream *dis, bool isServer) // th
 
 	if ((isServer && serverReceivedPackets.find(id) == serverReceivedPackets.end()) || (!isServer && clientReceivedPackets.find(id) == clientReceivedPackets.end()))
 	{
-		//app.DebugPrintf("Bad packet id %d\n", id);
+		int *history = isServer ? s_serverPktHistory : s_clientPktHistory;
+		int idx = isServer ? s_serverPktIdx : s_clientPktIdx;
+		bool &logged = isServer ? s_serverDesyncLogged : s_clientDesyncLogged;
+		
+		fprintf(stderr, "[PKT] Bad packet id %d (0x%x) isServer=%d\n", id, id, isServer);
+		if (!logged) {
+			logged = true;
+			fprintf(stderr, "[PKT] === PACKET HISTORY (last %d, newest last) ===\n", 64);
+			for (int i = 0; i < 64; i++) {
+				int h = history[(idx + i) % 64];
+				if (h != 0) fprintf(stderr, "[PKT]   pkt %d (0x%x)\n", h, h);
+			}
+			fprintf(stderr, "[PKT] === END HISTORY ===\n");
+		}
 		__debugbreak();
-		assert(false);
+		//assert(false);
+		return nullptr;
 		//            throw new IOException(wstring(L"Bad packet id ") + _toString<int>(id));
 	}
 
+	// Record successfully read packet ID
+	if (isServer) { s_serverPktHistory[s_serverPktIdx % 64] = id; s_serverPktIdx++; }
+	else { s_clientPktHistory[s_clientPktIdx % 64] = id; s_clientPktIdx++; }
+
 	packet = getPacket(id);
-	if (packet == NULL) assert(false);//throw new IOException(wstring(L"Bad packet id ") + _toString<int>(id));
+	if (packet == NULL) { fprintf(stderr, "[PKT] getPacket(%d) returned NULL\n", id); return nullptr; }
 	
-	//app.DebugPrintf("%s reading packet %d\n", isServer ? "Server" : "Client", packet->getId());
 	packet->read(dis);
 	//    }
 	//	catch (EOFException e) 
@@ -425,15 +450,13 @@ wstring Packet::readUtf(DataInputStream *dis, int maxLength) // throws IOExcepti
 	short stringLength = dis->readShort();
 	if (stringLength > maxLength)
 	{
-		wstringstream stream;
-		stream << L"Received string length longer than maximum allowed (" << stringLength << " > " << maxLength << ")";
-		assert(false);
-		//        throw new IOException( stream.str() );
+		fprintf(stderr, "[PKT] readUtf: string length %d > max %d (stream desync?)\n", stringLength, maxLength);
+		return L"";
 	}
 	if (stringLength < 0)
 	{
-		assert(false);
-		//        throw new IOException(L"Received string length is less than zero! Weird string!");
+		fprintf(stderr, "[PKT] readUtf: negative string length %d (stream desync?)\n", stringLength);
+		return L"";
 	}
 
 	wstring builder = L"";