This should prevent bouncing higher and higher (cheat).
Missing:
* The bounce effect should be set considering the last yDistance, in
order to allow negative vertical velocity to work.
* Add workaorunds for gravity with exiting cobweb.
* Allow multiple times zero y-distance (cobweb several times, slime 2).
Cobweb may need adjusting the bounding box to check with, instead.
* The server might reset the fall distance with preceding micro-moves,
so use NoFall data already on checking pre-conditions for bounce.
* Cap the bounce effect slightly smaller.
* Renew the bounce effect under certain conditions.
* Gravity, odds.
Remaining:
* Two consecutive times yDist = 0 at the maximum of a jump.
MISSING:
* Micro move onto ground, fall distance resets before sf check is run.
Done:
* Split PlayerMoveEvent processing to from -> loc + from -> to. Just if
from isn't the same coordinates as player.getLocation. This
reduces the complexity of workarounds.
* You do take fall damage falling onto slime blocks while sneaking.
* Queue bounce effect, only if the move is valid. Skip NoFall then.
* Apply bounce effect once moving up, to allow overriding.
* Cover more odd cases.
Unrelated:
* Use data.debug instead of cc.debug.
Adjust workarounds, confine velocity activation to next tick.
Cases missing:
* Lost ground cases (yOnGround has been reduced, strikes here).
* Two consecutive yDist = 0.
This will preserve the order of debug messages sent from multiple
threads. As a side effect, this might be better for performance, given
that on constant input the logging task will stay registered, so there
is little overhead and the file-io is taken off the asynchronous packet
and chat handler threads.Hopefully the thread switching is less
expensive than the gain by not delaying chat/packet threads, in case of
servers with few cores. We might adapt the used policy later, based on
cores and/or config.
* Queue outgoing positions in order to detect ACK on incoming.
* Since we can't detect relative teleports, positions are only queued,
if they match an absolute location from a teleport event (Bukkit).
* The queue is kept simple: only store the latest position.
* Cancel incoming flying/pos/look until ACK is received.
Missing:
* Are yaw/pitch are ever sent back changed.
* Configuration to turn it off.
* Might use this to just skip all violation handling until ACK.
This is a quick go with little testing, roughly up to level 60. Above
that there may be more false positives, also "no jumping" is not
enforced there.
A suggestion for the future could be to just use/part-calculate an array
for all the typical effects.
Used to be 0.0625 for a while, but intentions are to cover ground-loss
as lostground workarounds. Later switch to calculate the distance to
ground (with a given max-distance).
For efficiency (several?) other cases will be removable, once we model
the per-move ground/medium properties more accurately also for the past
move(s). At least lostground_pyramid should be removed then.
Can't implement "dumb" access order, because we will have to move
entries to the front with setting and altering data, but we don't want
the data to be changed every time get is called, e.g. with piston
tracking.
Efficiency could be increased, using the entry as reference instead of
duplicate calls with coordinates.
Splits CoordMap into interface, abstract hash map, implementations.
Sketch Linked version, hinting at access order, e.g. with
tracking piston effects with timeouts.
Missing:
* Implementation of a linked version.
Cancelling redundant packets has to big problems:
* The normal case is to not run in the primary thread.
* For legit players a missed micro move could mean that survivalfly can
not detect ground properly.
Better approaches could be:
* Cancel asynchronous packets if they match the last sent one (only
simple hacks).
* Check for moves passing block borders, request block shapes and such
from the main thread.
* Detect actual cheating or unusual patterns instead.
* Queue packets for processing in the main thread.
Missing:
* Actually detect ACK packets for previous outgoing teleports.
* Do something upon detecting illegal coordinates (asynchronous
disconnect? queue kicking, config).
