From a83d01f64fcfef076c79ea5da00a7663fd2b2c32 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 1ba09df9c..6fc3b7621 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -187,4 +187,9 @@ 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 23562388a..23cab725d 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 18f68b925..aacf8ea7f 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