Editing OpenSimulator Internals/Code Map/LLUDP (section)

== Incoming Packet Path ==

 PacketReceived(buffer)  -- called by OpenSimUDPBase for every UDP datagram

# Decoding: validates minimum length (7 bytes), computes header length (7/8/10 bytes depending on extra header flags), zero-decodes if MSG_ZEROCODED flag set, calls Packet.BuildPacket()
# Malformed packets are dropped and counted (IncomingMalformedPacketCount) -- logs a warning every 10000 as a probable network attack indicator
# Packet-to-client mapping:
#* If the endpoint has a pending queue (client still being created), the packet is queued rather than processed, except UseCircuitCode resends which are acked and dropped
#* If no client exists yet and the packet is UseCircuitCode, a pending queue is created and HandleUseCircuitCode() is dispatched via FireAndForget
#* Otherwise the client is looked up by endpoint via Scene.TryGetClient() -- unrecognized senders are counted as orphaned packets
# ACK receiving: appended ACKs and standalone PacketAck packets are applied to udpClient.NeedAcks
# ACK sending: reliable packets get their sequence number queued in PendingAcks; ACKs are flushed once 2*MTU bytes have been received since the last flush
# Duplicate detection: PacketArchive tracks recently seen reliable sequence numbers -- duplicates (resent or not) are dropped after the ack machinery has already run
# Ping handling: StartPingCheck/CompletePingCheck are handled inline and never reach the packet inbox
# Everything else is wrapped in an IncomingPacket and added to packetInbox (a BlockingCollection) for the IncomingPacketHandler thread to process

IncomingPacketHandler() thread: pulls from packetInbox with a 4500ms timeout, calls client.ProcessInPacket() for each. Exceptions in one client's packet do not crash the loop.

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