PaperMC/patches/server/0469-Fix-villager-boat-exploit.patch
Bjarne Koll c5a10665b8
Remove wall-time / unused skip tick protection (#11412)
Spigot still maintains some partial implementation of "tick skipping", a
practice in which the MinecraftServer.currentTick field is updated not
by an increment of one per actual tick, but instead set to
System.currentTimeMillis() / 50. This behaviour means that the tracked
tick may "skip" a tick value in case a previous tick took more than the
expected 50ms.

To compensate for this in important paths, spigot/craftbukkit
implements "wall-time". Instead of incrementing/decrementing ticks on
block entities/entities by one for each call to their tick() method,
they instead increment/decrement important values, like
an ItemEntity's age or pickupDelay, by the difference of
`currentTick - lastTick`, where `lastTick` is the value of
`currentTick` during the last tick() call.

These "fixes" however do not play nicely with minecraft's simulation
distance as entities/block entities implementing the above behaviour
would "catch up" their values when moving from a non-ticking chunk to a
ticking one as their `lastTick` value remains stuck on the last tick in
a ticking chunk and hence lead to a large "catch up" once ticked again.

Paper completely removes the "tick skipping" behaviour (See patch
"Further-improve-server-tick-loop"), making the above precautions
completely unnecessary, which also rids paper of the previous described
incompatibility with non-ticking chunks.
2024-09-19 16:36:07 +02:00

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1.5 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jason Penilla <11360596+jpenilla@users.noreply.github.com>
Date: Mon, 11 Jan 2021 12:43:51 -0800
Subject: [PATCH] Fix villager boat exploit
diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index 98eb00a8ee23543714d424d3ff5ca19887d6db19..9436a9614dea81d14c4f77cc21ca91f85ca87152 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -595,6 +595,14 @@ public abstract class PlayerList {
PlayerList.LOGGER.debug("Removing player mount");
entityplayer.stopRiding();
entity.getPassengersAndSelf().forEach((entity1) -> {
+ // Paper start - Fix villager boat exploit
+ if (entity1 instanceof net.minecraft.world.entity.npc.AbstractVillager villager) {
+ final net.minecraft.world.entity.player.Player human = villager.getTradingPlayer();
+ if (human != null) {
+ villager.setTradingPlayer(null);
+ }
+ }
+ // Paper end - Fix villager boat exploit
entity1.setRemoved(Entity.RemovalReason.UNLOADED_WITH_PLAYER, EntityRemoveEvent.Cause.PLAYER_QUIT); // CraftBukkit - add Bukkit remove cause
});
}