(1.17+) Redundant position packet + UseItem packet inversion (move->useitem)

[MinesAndValleys]

Full output of /ncp version

https://paste.lucko.me/gPU5D3dfro

Describe the issue

I cannot jump while using right click in all cases.

How to reproduce the issue

Using right-click when jumping, especially when jumping to place a block below, it rubber bands back. Players have reported the water disappearing when they try to place water as they land to stop fall damage.

Extra links: video and/or debug log (instructions: https://github.com/Updated-NoCheatPlus/Docs/blob/master/Development/Debugging.md#on-the-fly-debug-output-for-individual-players)

https://paste.lucko.me/jHjipKnprV

Any possible config options changed or plugins that may cause interference?

[MinesAndValleys]

@Lysandr0 here's a video of me reproducing it. It's actually not every time, but more often when I right-click closer to when I jump.

https://cloudup.com/cINhAsSTxhP

[Lysandr0]

Does it happen with noslow off? (checks.moving.survivalfly.extended.noslow).

[MinesAndValleys]

I can still reproduce it with that disabled.

[Lysandr0]

Managed to reproduce it myself after a swift test. Should be tackled on Spigot/MC side, rather, but for now it looks like we'll need to add more convoluted workarounds to account for another vanilla bug (yet again). Similarly to lostground :) (Edit: Seems to be intended behaviour actually: apparently Mojang attempted to fix a bucket place desync issue by resending the player's position when right clicking(!?)).

https://user-images.githubusercontent.com/20213873/130325189-9bbbceec-e025-4444-8199-f3da9a8ed444.mov

[compieter-gh]

I think i also have a similar when attacking mobs/monsters

[Lysandr0]

It happens with left clicks as well? ... Haven't tested it personally.

[compieter-gh]

I'll make an video bout the issue.

[compieter-gh]

https://youtu.be/Vy1Nx3kTfy8 -- With hacks I can't seem to reproduce it without hacks although all the fight check are disabled so it shouldn't happen either way

[compieter-gh]

config.yml.zip

Also viaversion is on the proxy on a 1.17.1 server and the client 1.16.5

[Lysandr0]

The video doesn't tell much unfortunately. The setbacks you're experiencing are probably(if not for sure) due to the Criticals module which can trigger either MorePackets, if attacking too quickly the entity while moving, or SurvivalFly, depending on how the cheat is implemented :)

[Lysandr0]

Minor update for onlookers :p As stated in Discord by CaptainObvious, every time the client sends a use item packet it will also send a flying packet with the same position as before (since 1.17). This will result in a duplicate flying packet which we should skip/ignore somehow.

Update: from further observation, this also concerns MorePackets, not only SurvivalFly. Due to the extra position packet, it'll trigger if you keep the button pressed for long enough.

[ghost]

Preview: https://streamable.com/bo3x2h

[GunacP40]

Are there any updates on this? It's been a couple of months now. I'm having this issue as well.

[Lysandr0]

Unfortunately, Xaw3ep seems to be on hiatus right now, so we likely have to wait for a while... Unless someone wants to PR, of course. :p

[Lysandr0]

Fixed, hopefully this won't cause any new exploit/bypass to arise.