Paper/patches/server/0194-Block-Enderpearl-Travel-Exploit.patch
Spottedleaf 01a13871de
Rewrite chunk system (#8177)
Patch documentation to come

Issues with the old system that are fixed now:
- World generation does not scale with cpu cores effectively.
- Relies on the main thread for scheduling and maintaining chunk state, dropping chunk load/generate rates at lower tps.
- Unreliable prioritisation of chunk gen/load calls that block the main thread.
- Shutdown logic is utterly unreliable, as it has to wait for all chunks to unload - is it guaranteed that the chunk system is in a state on shutdown that it can reliably do this? Watchdog shutdown also typically failed due to thread checks, which is now resolved.
- Saving of data is not unified (i.e can save chunk data without saving entity data, poses problems for desync if shutdown is really abnormal.
- Entities are not loaded with chunks. This caused quite a bit of headache for Chunk#getEntities API, but now the new chunk system loads entities with chunks so that they are ready whenever the chunk loads in. Effectively brings the behavior back to 1.16 era, but still storing entities in their own separate regionfiles.

The above list is not complete. The patch documentation will complete it.

New chunk system hard relies on starlight and dataconverter, and most importantly the new concurrent utilities in ConcurrentUtil.

Some of the old async chunk i/o interface (i.e the old file io thread reroutes _some_ calls to the new file io thread) is kept for plugin compat reasons. It will be removed in the next major version of minecraft.

The old legacy chunk system patches have been moved to the removed folder in case we need them again.
2022-09-26 01:02:51 -07:00

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Mon, 30 Apr 2018 17:15:26 -0400
Subject: [PATCH] Block Enderpearl Travel Exploit
Players are able to use alt accounts and enderpearls to travel
long distances utilizing the pearls in unloaded chunks and loading
the chunk later when convenient.
This disables that by not saving the thrower when the chunk is unloaded.
This is mainly useful for survival servers that do not allow freeform teleporting.
diff --git a/src/main/java/net/minecraft/server/level/ServerLevel.java b/src/main/java/net/minecraft/server/level/ServerLevel.java
index 4d96a196511621d56507cfb35923bd5270f83716..cc0ff0df8c41cd379ed7536c3e5051f64c7cd3a8 100644
--- a/src/main/java/net/minecraft/server/level/ServerLevel.java
+++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
@@ -2199,6 +2199,12 @@ public class ServerLevel extends Level implements WorldGenLevel {
public void onTickingEnd(Entity entity) {
ServerLevel.this.entityTickList.remove(entity);
+ // Paper start - Reset pearls when they stop being ticked
+ if (paperConfig().fixes.disableUnloadedChunkEnderpearlExploit && entity instanceof net.minecraft.world.entity.projectile.ThrownEnderpearl pearl) {
+ pearl.cachedOwner = null;
+ pearl.ownerUUID = null;
+ }
+ // Paper end
}
public void onTrackingStart(Entity entity) {
diff --git a/src/main/java/net/minecraft/world/entity/projectile/Projectile.java b/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
index cf8498165065c7db1be9cf7de492c1a41817cbf1..f550686d1ae45a9ecb406e999d02dba0cf022c58 100644
--- a/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
+++ b/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
@@ -88,6 +88,7 @@ public abstract class Projectile extends Entity {
protected void readAdditionalSaveData(CompoundTag nbt) {
if (nbt.hasUUID("Owner")) {
this.ownerUUID = nbt.getUUID("Owner");
+ if (this instanceof ThrownEnderpearl && this.level != null && this.level.paperConfig().fixes.disableUnloadedChunkEnderpearlExploit) { this.ownerUUID = null; } // Paper - Don't store shooter name for pearls to block enderpearl travel exploit
}
this.leftOwner = nbt.getBoolean("LeftOwner");