From 1e37ab83bd78027f61a60f51dd2dc6207ffc0ca7 Mon Sep 17 00:00:00 2001
From: Sudzzy <originmc@outlook.com>
Date: Thu, 3 Mar 2016 02:50:31 -0600
Subject: [PATCH] Fix inter-world teleportation glitches

People are able to abuse the way Bukkit handles teleportation across worlds since it provides a built in teleportation safety check.

To abuse the safety check, players are required to get into a location deemed unsafe by Bukkit e.g. be within a chest or door block. While they are in this block, they accept a teleport request from a player within a different world. Once the player teleports, Minecraft will recursively search upwards for a safe location, this could eventually land within a player's skybase.

Example setup to perform the glitch: http://puu.sh/ng3PC/cf072dcbdb.png
The wanted destination was on top of the emerald block however the player ended on top of the diamond block. This only is the case if the player is teleporting between worlds.

diff --git a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index ed63854..7005d69 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -245,4 +245,9 @@ public class PaperWorldConfig {
     private void portalSearchRadius() {
         portalSearchRadius = getInt("portal-search-radius", 128);
     }
+
+    public boolean disableTeleportationSuffocationCheck;
+    private void disableTeleportationSuffocationCheck() {
+        disableTeleportationSuffocationCheck = getBoolean("disable-teleportation-suffocation-check", false);
+    }
 }
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
index b597ae2..44d2698 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -577,7 +577,8 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         if (fromWorld == toWorld) {
             entity.playerConnection.teleport(to);
         } else {
-            server.getHandle().moveToWorld(entity, toWorld.dimension, true, to, true);
+            // Paper - Configurable suffocation check
+            server.getHandle().moveToWorld(entity, toWorld.dimension, true, to, !toWorld.paperConfig.disableTeleportationSuffocationCheck);
         }
         return true;
     }
-- 
2.9.3