Core/Netcode: Fix a possible infinite loop after 829be0b82 (which was accidentally merged in this morning)

src/server/game/Server/WorldSession.cpp

@@ -224,7 +224,17 @@ bool WorldSession::Update(uint32 diff, PacketFilter& updater)
     WorldPacket* packet = NULL;
     //! Delete packet after processing by default
     bool deletePacket = true;
-    while (m_Socket && !m_Socket->IsClosed() && _recvQueue.next(packet, updater))
+    //! To prevent infinite loop
+    bool delayedPackets = false;
+    WorldPacket* firstDelayedPacket = NULL;
+    //! If _recvQueue.peek() == firstDelayedPacket it means that in this Update call, we've processed all
+    //! *properly timed* packets, and we're now at the part of the queue where we find
+    //! delayed packets that were re-enqueued due to improper timing. To prevent an infinite
+    //! loop caused by re-enqueueing the same packets over and over again, we stop updating this session
+    //! and continue updating others. The re-enqueued packets will be handled in the next Update call for this session.
+    while (m_Socket && !m_Socket->IsClosed() && 
+            !_recvQueue.empty() && _recvQueue.peek(true) != firstDelayedPacket &&
+            _recvQueue.next(packet, updater))
     {
         if (packet->GetOpcode() >= NUM_MSG_TYPES)
         {
@@ -246,9 +256,11 @@ bool WorldSession::Update(uint32 diff, PacketFilter& updater)
                             //! the client to be in world yet. We will re-add the packets to the bottom of the queue and process them later.
                             if (!m_playerRecentlyLogout)
                             {
+                                //! Prevent infinite loop
+                                if (!firstDelayedPacket)
+                                    firstDelayedPacket = packet;
                                 //! Because checking a bool is faster than reallocating memory
                                 deletePacket = false;
-                                //! Re-enqueue
                                 QueuePacket(packet);
                                 //! Log
                                 sLog->outDebug(LOG_FILTER_NETWORKIO, "Re-enqueueing packet with opcode %s (0x%.4X) with with status STATUS_LOGGEDIN. "