MC-265520 Patch

What does this mod do?

This is a fabric mod which fixes MC-265520 in Minecraft versions <1.20.5.

What is MC-265520 about?

MC-265520 is about a race condition when switching between protocol states. The protocol states get switched while decoding packets and Minecraft expects the old protocol state when handling the switching packet on the main thread.

How does this mod solve the issue?

This mod moves the FlowControlHandler added because of MC-265209 in front of the handler which switches protocol states.
The mod also uses a custom FlowControlHandler (based on the old, MIT-licensed AutoReadHolderHandler of Velocity) instead of changing how the entire networking pipeline works (as Mojang did in 1.20.5).