From a6a74a356098b9ba2b0a30e99e7792b198f5f325 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 ba5332c3..d1acf678 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -513,4 +513,10 @@ 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 01c7fcc8..8e6428a0 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