Paper/patches/server/0680-Fix-sticky-pistons-and-BlockPistonRetractEvent.patch
Owen 89d51d5f29
Allow enabling sand duping (#10191)
Because this exploit has been widely known for years and has not been fixed by Mojang, we decided that it was worth allowing people to toggle it on/off due to how easy it is to make it configurable.

It should be noted that this decision does not promise all future exploits will be configurable.
2024-03-03 17:05:34 -05:00

86 lines
5.5 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Wed, 22 Dec 2021 09:51:48 -0800
Subject: [PATCH] Fix sticky pistons and BlockPistonRetractEvent
There is an explicit check in the handling code for empty pistons that
prevents sticky pistons from firing the event. However when we look back
at the history we see that this check was originally added so that ONLY
sticky pistons would fire the retract event. I'm not sure why.
https://hub.spigotmc.org/stash/projects/SPIGOT/repos/craftbukkit/commits/1092acbddf07edfa4100bc6824504ac75088e913
Over the course of several updates, the meaning of that field appears to
have changed from "is NOT sticky" to "is sticky". So now its having the
opposite effect. Only normal pistons fire the retraction event. And like
all things in CB, it's just been carried around since.
If we are to believe the history, the correct fix for this issue is to
flip it so it only fires for sticky pistons, but that puts us in a
bind. It's already firing for non-sticky pistons, changing it now would
likely result in breakage. Furthermore, there is little documentation as
to WHY that was ever intended to be the case.
Instead we opt to remove the check entirely so that the event fires for
all piston types.
Co-authored-by: Zach Brown <zach@zachbr.io>
Co-authored-by: Madeline Miller <mnmiller1@me.com>
diff --git a/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java b/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
index 0dbdcd443fe8a299119ea5ba3acb1a0412856184..3dfe79684f662ac7cae4583bfe03a633438b4df7 100644
--- a/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
+++ b/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
@@ -159,15 +159,15 @@ public class PistonBaseBlock extends DirectionalBlock {
}
// CraftBukkit start
- if (!this.isSticky) {
- org.bukkit.block.Block block = world.getWorld().getBlockAt(pos.getX(), pos.getY(), pos.getZ());
- BlockPistonRetractEvent event = new BlockPistonRetractEvent(block, ImmutableList.<org.bukkit.block.Block>of(), CraftBlock.notchToBlockFace(enumdirection));
- world.getCraftServer().getPluginManager().callEvent(event);
-
- if (event.isCancelled()) {
- return;
- }
- }
+ // if (!this.isSticky) { // Paper - Fix sticky pistons and BlockPistonRetractEvent; Move further down
+ // org.bukkit.block.Block block = world.getWorld().getBlockAt(pos.getX(), pos.getY(), pos.getZ());
+ // BlockPistonRetractEvent event = new BlockPistonRetractEvent(block, ImmutableList.<org.bukkit.block.Block>of(), CraftBlock.notchToBlockFace(enumdirection));
+ // world.getCraftServer().getPluginManager().callEvent(event);
+ //
+ // if (event.isCancelled()) {
+ // return;
+ // }
+ // }
// PAIL: checkME - what happened to setTypeAndData?
// CraftBukkit end
world.blockEvent(pos, this, b0, enumdirection.get3DDataValue());
@@ -244,6 +244,13 @@ public class PistonBaseBlock extends DirectionalBlock {
BlockState iblockdata2 = (BlockState) ((BlockState) Blocks.MOVING_PISTON.defaultBlockState().setValue(MovingPistonBlock.FACING, enumdirection)).setValue(MovingPistonBlock.TYPE, this.isSticky ? PistonType.STICKY : PistonType.DEFAULT);
+ // Paper start - Fix sticky pistons and BlockPistonRetractEvent; Move empty piston retract call to fix multiple event fires
+ if (!this.isSticky) {
+ if (!new BlockPistonRetractEvent(CraftBlock.at(world, pos), java.util.Collections.emptyList(), CraftBlock.notchToBlockFace(enumdirection)).callEvent()) {
+ return false;
+ }
+ }
+ // Paper end - Fix sticky pistons and BlockPistonRetractEvent
world.setBlock(pos, iblockdata2, 20);
world.setBlockEntity(MovingPistonBlock.newMovingBlockEntity(pos, iblockdata2, (BlockState) this.defaultBlockState().setValue(PistonBaseBlock.FACING, Direction.from3DDataValue(data & 7)), enumdirection, false, true));
world.blockUpdated(pos, iblockdata2.getBlock());
@@ -270,6 +277,13 @@ public class PistonBaseBlock extends DirectionalBlock {
if (type == 1 && !iblockdata3.isAir() && PistonBaseBlock.isPushable(iblockdata3, world, blockposition1, enumdirection.getOpposite(), false, enumdirection) && (iblockdata3.getPistonPushReaction() == PushReaction.NORMAL || iblockdata3.is(Blocks.PISTON) || iblockdata3.is(Blocks.STICKY_PISTON))) {
this.moveBlocks(world, pos, enumdirection, false);
} else {
+ // Paper start - Fix sticky pistons and BlockPistonRetractEvent; fire BlockPistonRetractEvent for sticky pistons retracting nothing (air)
+ if (type == TRIGGER_CONTRACT && iblockdata2.isAir()) {
+ if (!new BlockPistonRetractEvent(CraftBlock.at(world, pos), java.util.Collections.emptyList(), CraftBlock.notchToBlockFace(enumdirection)).callEvent()) {
+ return false;
+ }
+ }
+ // Paper end - Fix sticky pistons and BlockPistonRetractEvent
world.removeBlock(pos.relative(enumdirection), false);
}
}