From 97aa493a6d38781247226e4c8b22304905ee0297 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 fe56f01035..af6b97708a 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -414,4 +414,10 @@ public class PaperWorldConfig {
     private void disableSprintInterruptionOnAttack() {
         disableSprintInterruptionOnAttack = getBoolean("game-mechanics.disable-sprint-interruption-on-attack", false);
     }
+
+    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 fc8c0cab55..dd8af4be80 100644
--- a/src/main/java/net/minecraft/server/EntityProjectile.java
+++ b/src/main/java/net/minecraft/server/EntityProjectile.java
@@ -242,6 +242,7 @@ public abstract class EntityProjectile extends Entity implements IProjectile {
         if (nbttagcompound.hasKeyOfType("owner", 10)) {
             this.shooterId = GameProfileSerializer.b(nbttagcompound.getCompound("owner"));
         }
+        if (this instanceof EntityEnderPearl && this.world != null && this.world.paperConfig.disableEnderpearlExploit) { this.shooterId = null; } // Paper - Don't store shooter name for pearls to block enderpearl travel exploit
 
     }
 
-- 
2.19.0