Scissors/patches/server/0045-Add-depth-limit-to-SNBT.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Telesphoreo <me@telesphoreo.me>
Date: Mon, 15 Apr 2024 23:40:27 -0500
Subject: [PATCH] Add depth limit to SNBT


diff --git a/src/main/java/net/minecraft/nbt/TagParser.java b/src/main/java/net/minecraft/nbt/TagParser.java
index c77860a141064aea6a0b510bb44d35fea90aee42..3be3dd61b8a27b3a8ca3c72ae5ffa2ea8fa00231 100644
--- a/src/main/java/net/minecraft/nbt/TagParser.java
+++ b/src/main/java/net/minecraft/nbt/TagParser.java
@@ -184,9 +184,47 @@ public class TagParser {
 
         this.expect('}');
         this.depth--; // Paper
-        return compoundTag;
+        return exceedsDepthLimit(compoundTag) ? new CompoundTag() : compoundTag; // Scissors - Add depth limit to SNBT
     }
 
+    // Scissors start - Add depth limit to SNBT
+    private boolean exceedsDepthLimit(Tag tag) {
+        return this.exceedsDepthLimit(0, tag);
+    }
+
+    private boolean exceedsDepthLimit(long depth, Tag tag) {
+        if (depth > 256) {
+            return true;
+        }
+
+        if (tag instanceof ListTag listTag) {
+            for (Tag childTag : listTag) {
+                boolean returnValue = this.exceedsDepthLimit(depth + 1, childTag);
+
+                if (returnValue) {
+                    return true;
+                }
+            }
+        } else if (tag instanceof CompoundTag compoundTag) {
+            for (String key : compoundTag.getAllKeys()) {
+                Tag childTag = compoundTag.get(key);
+
+                if (childTag == null) {
+                    continue;
+                }
+
+                boolean returnValue = this.exceedsDepthLimit(depth + 1, childTag);
+
+                if (returnValue) {
+                    return true;
+                }
+            }
+        }
+
+        return false;
+    }
+    // Scissors end
+
     private Tag readListTag() throws CommandSyntaxException {
         this.expect('[');
         this.reader.skipWhitespace();
@@ -220,7 +258,7 @@ public class TagParser {
 
             this.expect(']');
             this.depth--; // Paper
-            return listTag;
+            return exceedsDepthLimit(listTag) ? new ListTag() : listTag; // Scissors - Add depth limit to SNBT
         }
     }
 
@@ -245,7 +283,7 @@ public class TagParser {
     }
 
     private <T extends Number> List<T> readArray(TagType<?> arrayTypeReader, TagType<?> typeReader) throws CommandSyntaxException {
-        List<T> list = Lists.newArrayList();
+        List<Number> list = Lists.newArrayList(); // Scissors - List<T> -> List<Number>
 
         while (this.reader.peek() != ']') {
             int i = this.reader.getCursor();
@@ -257,11 +295,11 @@ public class TagParser {
             }
 
             if (typeReader == ByteTag.TYPE) {
-                list.add((T)(Byte)((NumericTag)tag).getAsByte()); // Paper - decompile fix
+                list.add(((NumericTag)tag).getAsByte()); // Scissors - Remove (T) cast
             } else if (typeReader == LongTag.TYPE) {
-                list.add((T)(Long)((NumericTag)tag).getAsLong()); // Paper - decompile fix
+                list.add(((NumericTag)tag).getAsLong()); // Scissors - Remove (T) cast
             } else {
-                list.add((T)(Integer)((NumericTag)tag).getAsInt()); // Paper - decompile fix
+                list.add(((NumericTag)tag).getAsInt()); // Scissors - Remove (T) cast
             }
 
             if (!this.hasElementSeparator()) {
@@ -274,7 +312,7 @@ public class TagParser {
         }
 
         this.expect(']');
-        return list;
+        return (List<T>) list; // Scissors - Cast to List<T>
     }
 
     private boolean hasElementSeparator() {