Fixes:
* On passable-violations useLoc might have been passed as newTo.
Reduce potential for accidental future misuse:
* Call useLoc.setWorld(null) as late as possible.
* Do not reset world of MoveInfo.useLoc in MoveInfo.set.
An implementation for NCPCompatBukkit is missing.
Note that the native access can not set lastYaw nor lastPitch in
PlayerConnection (private), but it could set lastYaw and lastPitch in
EntityPlayer.
Can't guarantee this actually helps with stuff like derp/magnet, because
we can not really set the outcome of a PlayerMoveEvent without
rubberbanding the whole planet. Hacks could send enough packets per tick
to keep freezing people - we might be able to keep track of yaw/pitch
correction and cancel (most) attacking for the same tick after yaw
correction (invalidate "same" with in-bounds yaw).
"Magnet" refers to a player seemingly freezing other nearby players onto
the spot, causing them to yaw-glitch, seemingly getting attracted by the
cheater.
Thanks again @Iceee for reporting and @Amaranth for finding cause +
suggested fix.
Not sure this both helps and prevents false positives, so it could get
redone a couple of times, might also result in being impossible to fix
with a plugin in an acceptable way.
- Never skip undoing changes. This is necessary to also process commands
that are not registered or that are fall-back aliases.
- Check adding all plugin commands always.
- Check for aliases as well for decision if to match a command.
These seem not to have been affected beforehand, due to the nature of
the SimpleCommandMap, however we don't want to exclusively rely on
fetching that one successfully.
Setting a set-back location with a null World will now lead to a
NullPointerException. Setting null worlds on set-back locations is not
intended by contract, however due to using temporary Location instances
with Entity.getLocation(Location) and setting the world to null
afterwards to prevent memory leaks, also considering the number of
places where setSetBack is used, this seems to be an appropriate measure
to track better or help excluding violations of that contract.
This does not change the used methods much, thus it will rather allow
much more cheating, however it allows some basic testing for false
positives. The reach implementation has been slightly optimized to run
faster. The current implementation is not final and only uses trace
elements that were added in the current tick, the latest is always
included.
Next steps will probably be:
* Stricter methods for an individual TraceEntry (demand near-exact hit).
* Don't allow random latency shifting. Maintain a window-thing.
* Probably get rid of the classic method for attacking other entities.
No change for the function of the plugin, except if there are new bugs.
Actual changes:
* Keep track of squared distance to the previous element in a trace.
* Balance mergeDist: prevent merging the latest entry, if the squared
distance from the latest to the second latest element is greater
than mergeDist. Never merge if there are only two entries in total.
* Add convenience methods for resetting and updating the trace.
* Maintain the moving traces actively. With intended use being
player-player interaction, we will not reset with every teleport.
