From c801bfc35cf100dffe42a36980af7d715fa1bafd 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/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index cc1914d8c..606c0bed8 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -508,4 +508,10 @@ public class PaperWorldConfig {
         allowPermaChunkLoaders = getBoolean("game-mechanics.allow-permanent-chunk-loaders", allowPermaChunkLoaders);
         log("Allow Perma Chunk Loaders: " + (allowPermaChunkLoaders ? "enabled" : "disabled"));
     }
+
+    public boolean disableEnderpearlExploit = true;
+    private void disableEnderpearlExploit() {
+        disableEnderpearlExploit = getBoolean("game-mechanics.disable-unloaded-chunk-enderpearl-exploit", disableEnderpearlExploit);
+        log("Disable Unloaded Chunk Enderpearl Exploit: " + (disableEnderpearlExploit ? "enabled" : "disabled"));
+    }
 }
diff --git a/src/main/java/net/minecraft/server/EntityProjectile.java b/src/main/java/net/minecraft/server/EntityProjectile.java
index 01c7fcc8b..8e6428a0c 100644
--- a/src/main/java/net/minecraft/server/EntityProjectile.java
+++ b/src/main/java/net/minecraft/server/EntityProjectile.java
@@ -271,6 +271,7 @@ public abstract class EntityProjectile extends Entity implements IProjectile {
         if (this.shooterName != null && this.shooterName.isEmpty()) {
             this.shooterName = null;
         }
+        if (this instanceof EntityEnderPearl && this.world != null && this.world.paperConfig.disableEnderpearlExploit) { this.shooterName = null; } // Paper - Don't store shooter name for pearls to block enderpearl travel exploit
 
         this.shooter = this.getShooter();
     }
-- 
2.17.0