Fundamental compression issue (cpu overload)

I found a fundamental problem in the minecraft networking affecting all versions that have network compression.

By precompressing big packets and sending them to the server you can overload the cpu cores the networking threads (netty threads) are running on.

This affects vanilla and all kind of mods, forks and proxys like BungeeCord

I found no good way to fix this issue myself in BungeeCord (I am colloborator on the BungeeCord project)

But it can be fixed for upcoming versions of minecraft.

A solution to this issue would be to add a possibility for servers to disable compressed packets from client while allowing the server to compress the packets and forcing the clientto decompress these.

This could be easily impled by adding a new field to the SetCompression packet that is sent from the server to the client.

This would be a very simple way to fix this network security issue.

Here is a video where i added those overload exploit into a client mod

I precompressed PluginMessages or CustomPayload packets here and spammed them to the server

https://www.youtube.com/watch?v=I5HsPTQ7VjY

In the begining i did it on vanilla after with a bungeecord proxy (you can ignore the bungeecord test)

Note that there a packets you can insert even more data so it will start lagging at a much smaller packet sending rate