minecraft/conn.go: replay RequestChunkRadius received before StartGame - #462
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RestartFU wants to merge 1 commit into
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minecraft/conn.go: replay RequestChunkRadius received before StartGame#462RestartFU wants to merge 1 commit into
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A client that sends RequestChunkRadius after login completes but before StartGame() is called has the packet routed to the user read queue, so handleRequestChunkRadius never runs. The client then waits forever for ChunkRadiusUpdated and never sends SetLocalPlayerAsInitialised, leaving StartGame blocked. On a proxy the window between login and StartGame spans the downstream dial + handshake, making this easy to hit under load. Stash such a packet and replay it through handle() right after startGame(), which expects IDRequestChunkRadius at that point. The packet is still delivered to the user so proxies keep forwarding it downstream.
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A client that sends
RequestChunkRadiusafter the login sequence completes but beforeStartGame()is called has the packet routed to the user read queue, sohandleRequestChunkRadiusnever runs. The client then waits forever forChunkRadiusUpdated, never sendsSetLocalPlayerAsInitialised, andStartGameblocks indefinitely — a deadlock with no timeout on either side.In a plain server this window is microseconds, but on proxies (which read packets from the accepted connection while dialing the downstream server) it spans the whole downstream dial + handshake, and some clients (observed with Android/console timing) send
RequestChunkRadiusearly enough to hit it.Fix: stash such a packet and replay it through
handle()right afterstartGame(), which expectsIDRequestChunkRadiusat that point. The packet is still delivered to the user read queue, so proxies that forward it downstream see no behavior change; servers that callStartGameimmediately are unaffected (the stash stays nil).