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.

== AT ==
public net.minecraft.world.entity.projectile.Projectile cachedOwner
public net.minecraft.world.entity.projectile.Projectile ownerUUID

diff --git a/src/main/java/net/minecraft/server/level/ServerLevel.java b/src/main/java/net/minecraft/server/level/ServerLevel.java
index 97554ab72743cf2b8e87c7f3c35579f669c2308a..6d75010bf837a791f5fe04aacb973246410bbd66 100644
--- a/src/main/java/net/minecraft/server/level/ServerLevel.java
+++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
@@ -2354,6 +2354,12 @@ 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 fbbb1fa3d5f4ace67fee96aa235cec3b39deb7b1..e8620ad6be2dda7fe288f884c4ae88a924be4a62 100644
--- a/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
+++ b/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
@@ -101,6 +101,7 @@ public abstract class Projectile extends Entity implements TraceableEntity {
         if (nbt.hasUUID("Owner")) {
             this.ownerUUID = nbt.getUUID("Owner");
             this.cachedOwner = null;
+            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");