From ab452f9cd59aa0e074a0b65d0a91148dd0b4932d Mon Sep 17 00:00:00 2001
From: Sudzzy <originmc@outlook.com>
Date: Thu, 3 Mar 2016 02:50:31 -0600
Subject: [PATCH] Configurable inter-world teleportation safety

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 c98286999..4a2d29674 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -188,4 +188,9 @@ 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/net/minecraft/server/PlayerList.java b/src/main/java/net/minecraft/server/PlayerList.java
index 90cb2d277..8b3c2d287 100644
--- a/src/main/java/net/minecraft/server/PlayerList.java
+++ b/src/main/java/net/minecraft/server/PlayerList.java
@@ -798,7 +798,7 @@ public abstract class PlayerList {
         exitWorld.getTravelAgent().adjustExit(entityplayer, exit, velocity);
 
         entityplayer.worldChangeInvuln = true; // CraftBukkit - Set teleport invulnerability only if player changing worlds
-        this.moveToWorld(entityplayer, exitWorld.dimension, true, exit, true); // SPIGOT-3864
+        this.moveToWorld(entityplayer, exitWorld.dimension, true, exit, !exitWorld.paperConfig.disableTeleportationSuffocationCheck); // SPIGOT-3864 // Paper GH-1149 - Tie suffocation check to config option
         if (entityplayer.motX != velocity.getX() || entityplayer.motY != velocity.getY() || entityplayer.motZ != velocity.getZ()) {
             entityplayer.getBukkitEntity().setVelocity(velocity);
         }
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
index 06e79b4b3..650523614 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -660,7 +660,8 @@ 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;
     }
-- 
2.18.0