From bbf37c133d002558a9e031cf699579d96ded9e3c Mon Sep 17 00:00:00 2001
From: Zach Brown <zach.brown@destroystokyo.com>
Date: Mon, 18 Jul 2016 17:57:36 -0500
Subject: [PATCH] Less strict skull validation

Spigot's solution removes all unsigned skins from Skulls. While this does work to achieve its original goal, it is often
overzealous and removes many plugin created and other skulls. We can be more specific in our checks to avoid this.

This does technically reveal how the exploit works, however given that it already appears to be well-known throughout
malicious communities, and the current solution breaks legitimate skulls, we don't feel particularly bad about it this
time.

diff --git a/src/main/java/net/minecraft/server/ItemSkull.java b/src/main/java/net/minecraft/server/ItemSkull.java
index 4a9cb67..b2af87a 100644
--- a/src/main/java/net/minecraft/server/ItemSkull.java
+++ b/src/main/java/net/minecraft/server/ItemSkull.java
@@ -135,11 +135,24 @@ public class ItemSkull extends Item {
             boolean valid = true;
 
             NBTTagList textures = nbttagcompound.getCompound("SkullOwner").getCompound("Properties").getList("textures", 10); // Safe due to method contracts
+            // Paper start - Less strict validation
+            for (NBTBase texture : textures.list) {
+                if (texture instanceof NBTTagCompound && !((NBTTagCompound) texture).hasKeyOfType("Signature", 8)) {
+                    if (((NBTTagCompound) texture).getString("Value").trim().length() > 0) {
+                        continue;
+                    }
+
+                    valid = false;
+                }
+            }
+            /*
             for (int i = 0; i < textures.size(); i++) {
                 if (textures.get(i) instanceof NBTTagCompound && !((NBTTagCompound) textures.get(i)).hasKeyOfType("Signature", 8)) {
                     valid = false;
                 }
             }
+            */
+            // Paper end
 
             if (!valid) {
                 nbttagcompound.remove("SkullOwner");
-- 
2.9.2.windows.1