Allow enabling sand duping (#10191)

Because this exploit has been widely known for years and has not been fixed by Mojang, we decided that it was worth allowing people to toggle it on/off due to how easy it is to make it configurable.

It should be noted that this decision does not promise all future exploits will be configurable. 

1 files changed, 22 insertions, 0 deletions

diff --git a/patches/server/0534-Fix-PlayerItemConsumeEvent-cancelling-properly.patch b/patches/server/0534-Fix-PlayerItemConsumeEvent-cancelling-properly.patch
new file mode 100644
index 0000000000..23fd145ca7
--- /dev/null
+++ b/patches/server/0534-Fix-PlayerItemConsumeEvent-cancelling-properly.patch
@@ -0,0 +1,22 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: chickeneer <[email protected]>
+Date: Fri, 19 Mar 2021 00:33:15 -0500
+Subject: [PATCH] Fix PlayerItemConsumeEvent cancelling properly
+
+When the active item is not cleared, the item is still readied
+for use and will repeatedly trigger the PlayerItemConsumeEvent
+till their item is switched.
+This patch clears the active item when the event is cancelled
+
+diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
+index 26ac98e0dbcac5d20a013cc1b8f5d70133e23154..dad6481439c54567fd6135b39c9209e74a3acba0 100644
+--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
++++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
+@@ -3880,6 +3880,7 @@ public abstract class LivingEntity extends Entity implements Attackable {
+                         this.level().getCraftServer().getPluginManager().callEvent(event);
+ 
+                         if (event.isCancelled()) {
++                            this.stopUsingItem(); // Paper - event is using an item, clear active item to reset its use
+                             // Update client
+                             ((ServerPlayer) this).getBukkitEntity().updateInventory();
+                             ((ServerPlayer) this).getBukkitEntity().updateScaledHealth();