1 files changed, 86 insertions, 0 deletions
diff --git a/patches/server/0677-Fix-dangerous-end-portal-logic.patch b/patches/server/0677-Fix-dangerous-end-portal-logic.patch
new file mode 100644
index 0000000000..430c5ca9a1
--- /dev/null
+++ b/patches/server/0677-Fix-dangerous-end-portal-logic.patch
@@ -0,0 +1,86 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Spottedleaf <[email protected]>
+Date: Fri, 4 Jun 2021 17:06:52 -0400
+Subject: [PATCH] Fix dangerous end portal logic
+
+End portals could teleport entities during move calls. Stupid
+logic given the caller will never expect that kind of thing,
+and will result in all kinds of dupes.
+
+Move the tick logic into the post tick, where portaling was
+designed to happen in the first place.
+
+diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
+index 56d8939c34e0edd74ee2980a41a889bb3ccf659e..6970bb9951e83d5e1a76bad8ca4a7cb16d7fdd92 100644
+--- a/src/main/java/net/minecraft/world/entity/Entity.java
++++ b/src/main/java/net/minecraft/world/entity/Entity.java
+@@ -388,6 +388,36 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, i
+         return chunkMap.playerEntityTrackerTrackMaps[type.ordinal()].getObjectsInRange(MCUtil.getCoordinateKey(this));
+     }
+     // Paper end - optimise entity tracking
++    // Paper start - make end portalling safe
++    public BlockPos portalBlock;
++    public ServerLevel portalWorld;
++    public void tickEndPortal() {
++        BlockPos pos = this.portalBlock;
++        ServerLevel world = this.portalWorld;
++        this.portalBlock = null;
++        this.portalWorld = null;
++
++        if (pos == null || world == null || world != this.level) {
++            return;
++        }
++
++        if (this.isPassenger() || this.isVehicle() || !this.canChangeDimensions() || this.isRemoved() || !this.valid || !this.isAlive()) {
++            return;
++        }
++
++        ResourceKey<Level> resourcekey = world.getTypeKey() == LevelStem.END ? Level.OVERWORLD : Level.END; // CraftBukkit - SPIGOT-6152: send back to main overworld in custom ends
++        ServerLevel worldserver = world.getServer().getLevel(resourcekey);
++
++        org.bukkit.event.entity.EntityPortalEnterEvent event = new org.bukkit.event.entity.EntityPortalEnterEvent(this.getBukkitEntity(), new org.bukkit.Location(world.getWorld(), pos.getX(), pos.getY(), pos.getZ()));
++        event.callEvent();
++
++        if (this instanceof ServerPlayer) {
++            ((ServerPlayer)this).changeDimension(worldserver, PlayerTeleportEvent.TeleportCause.END_PORTAL);
++            return;
++        }
++        this.teleportTo(worldserver, null);
++    }
++    // Paper end - make end portalling safe
+ 
+     public Entity(EntityType<?> type, Level world) {
+         this.id = Entity.ENTITY_COUNTER.incrementAndGet();
+@@ -2531,6 +2561,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, i
+             }
+ 
+             this.processPortalCooldown();
++            this.tickEndPortal(); // Paper - make end portalling safe
+         }
+     }
+ 
+diff --git a/src/main/java/net/minecraft/world/level/block/EndPortalBlock.java b/src/main/java/net/minecraft/world/level/block/EndPortalBlock.java
+index b8305112c759ecb62ef9ad972e57ff85ceff20dc..19892cb3cb290add4f094dc87bb22106e4f07a24 100644
+--- a/src/main/java/net/minecraft/world/level/block/EndPortalBlock.java
++++ b/src/main/java/net/minecraft/world/level/block/EndPortalBlock.java
+@@ -53,16 +53,10 @@ public class EndPortalBlock extends BaseEntityBlock {
+                 // return; // CraftBukkit - always fire event in case plugins wish to change it
+             }
+ 
+-            // CraftBukkit start - Entity in portal
+-            EntityPortalEnterEvent event = new EntityPortalEnterEvent(entity.getBukkitEntity(), new org.bukkit.Location(world.getWorld(), pos.getX(), pos.getY(), pos.getZ()));
+-            world.getCraftServer().getPluginManager().callEvent(event);
+-
+-            if (entity instanceof ServerPlayer) {
+-                ((ServerPlayer) entity).changeDimension(worldserver, PlayerTeleportEvent.TeleportCause.END_PORTAL);
+-                return;
+-            }
+-            // CraftBukkit end
+-            entity.changeDimension(worldserver);
++            // Paper start - move all of this logic into portal tick
++            entity.portalWorld = ((ServerLevel)world);
++            entity.portalBlock = pos.immutable();
++            // Paper end - move all of this logic into portal tick
+         }
+ 
+     }