From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 1 Jul 2020 03:12:06 -0400
Subject: [PATCH] Clean up duplicated GameProfile Properties

We had a bug where we accidently cloned properties resulting in skulls
growing to large sizes and preventing login.

This now automatically cleans up the extra properties.

diff --git a/src/main/java/net/minecraft/nbt/NbtUtils.java b/src/main/java/net/minecraft/nbt/NbtUtils.java
index fdf78f7ab15a8c81699c6c0e5d0333c482c7d0a3..050ee055b9a2a0767f58d6677ad7f2d927fbaa54 100644
--- a/src/main/java/net/minecraft/nbt/NbtUtils.java
+++ b/src/main/java/net/minecraft/nbt/NbtUtils.java
@@ -92,7 +92,8 @@ public final class NbtUtils {
                 for(String string2 : compoundTag.getAllKeys()) {
                     ListTag listTag = compoundTag.getList(string2, 10);
 
-                    for(int i = 0; i < listTag.size(); ++i) {
+                    if (listTag.size() == 0) continue; // Paper - remove duplicate properties
+                    for (int i = listTag.size() - 1; i < listTag.size(); ++i) { // Paper - remove duplicate properties
                         CompoundTag compoundTag2 = listTag.getCompound(i);
                         String string3 = compoundTag2.getString("Value");
                         if (compoundTag2.contains("Signature", 8)) {
diff --git a/src/main/java/net/minecraft/world/item/PlayerHeadItem.java b/src/main/java/net/minecraft/world/item/PlayerHeadItem.java
index 7fb2cc8d49a2d8f256f625cb99b66ef8efc3fc0e..f9980110a4614bb0206dce3dc796d9459069b750 100644
--- a/src/main/java/net/minecraft/world/item/PlayerHeadItem.java
+++ b/src/main/java/net/minecraft/world/item/PlayerHeadItem.java
@@ -53,6 +53,18 @@ public class PlayerHeadItem extends StandingAndWallBlockItem {
             });
             // CraftBukkit start
         } else {
+            // Paper start - clean up old duplicated properties
+            CompoundTag properties = nbt.getCompound("SkullOwner").getCompound("Properties");
+            for (String key : properties.getAllKeys()) {
+                net.minecraft.nbt.ListTag values = properties.getList(key, 10);
+                if (values.size() > 1) {
+                    net.minecraft.nbt.Tag texture = values.get(values.size() - 1);
+                    values = new net.minecraft.nbt.ListTag();
+                    values.add(texture);
+                    properties.put(key, values);
+                }
+            }
+            // Paper end
             net.minecraft.nbt.ListTag textures = nbt.getCompound("SkullOwner").getCompound("Properties").getList("textures", 10); // Safe due to method contracts
             for (int i = 0; i < textures.size(); i++) {
                 if (textures.get(i) instanceof CompoundTag && !((CompoundTag) textures.get(i)).contains("Signature", 8) && ((CompoundTag) textures.get(i)).getString("Value").trim().isEmpty()) {