Paper/patches/server-remapped/0757-Fix-dangerous-end-portal-logic.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <spottedleaf@users.noreply.github.com>
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/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index 779b926921fd435620cbbc69ed6f9931a422b652..25711ab723386db0f448c54e18ef069bfcd0dd99 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -1020,6 +1020,7 @@ public class ServerPlayer extends Player implements ContainerListener {
         return b(destination, TeleportCause.UNKNOWN);
     }
 
+    @Nullable public final Entity changeDimension(ServerLevel worldserver, PlayerTeleportEvent.TeleportCause cause) { return this.b(worldserver, cause); } // Paper - OBFHELPER
     @Nullable
     public Entity b(ServerLevel worldserver, PlayerTeleportEvent.TeleportCause cause) {
         // CraftBukkit end
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index d055b362459e5b4658aa220e16118ee6174c0de4..2462a78d976937cf4737f1ce0bfde2b2b7d5b1f7 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -312,6 +312,37 @@ public abstract class Entity implements Nameable, CommandSource, net.minecraft.s
     }
     // 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.removed || !this.valid || !this.isAlive()) {
+            return;
+        }
+
+        ResourceKey<Level> resourcekey = world.getTypeKey() == DimensionType.END_LOCATION ? 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();
         this.passengers = Lists.newArrayList();
@@ -2297,6 +2328,7 @@ public abstract class Entity implements Nameable, CommandSource, net.minecraft.s
             }
 
             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 2231680140d0e3c4c10b6722fd13fe0ee55ce294..52884b87b25bef8abfa824f40d02efe3f947f330 100644
--- a/src/main/java/net/minecraft/world/level/block/EndPortalBlock.java
+++ b/src/main/java/net/minecraft/world/level/block/EndPortalBlock.java
@@ -3,7 +3,6 @@ package net.minecraft.world.level.block;
 import net.minecraft.core.BlockPos;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.server.level.ServerLevel;
-import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.level.BlockGetter;
 import net.minecraft.world.level.Level;
@@ -50,16 +49,10 @@ 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).b(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
         }
 
     }