From 4a30598e11988808422e02822c399e739869d129 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 c982869995..4a2d296746 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 4320efaef5..9f2c7d3f45 100644
--- a/src/main/java/net/minecraft/server/PlayerList.java
+++ b/src/main/java/net/minecraft/server/PlayerList.java
@@ -792,7 +792,7 @@ 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 8db92714ea..86f485e6ff 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -701,7 +701,8 @@ 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