From 63cc3f948a55521ede6dbf7c1a1b9f49bce2b729 Mon Sep 17 00:00:00 2001
From: lil David <1337lilDavid@gmail.com>
Date: Sun, 1 Sep 2024 13:18:50 -0500
Subject: [PATCH] Verify symbol data hash when patching

---
 data.py | 12 +++++++++---
 rom.py  | 14 +++++++++++---
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/data.py b/data.py
index 836286a..152512b 100644
--- a/data.py
+++ b/data.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import hashlib
 from io import StringIO
 import itertools
 import json
@@ -89,15 +90,20 @@ def data_path(file_name: str):
     6, 6, 5, 6, 5, 6, 6, 6, 6, 6, 6, 8, 8, 8, 8, 8
 ]
 
+symbols_hash = None
 ram_symbols = None
 rom_symbols = None
 
 
 def _get_symbols():
-    global ram_symbols, rom_symbols
+    global ram_symbols, rom_symbols, symbols_hash
 
-    symbol_data = data_path("extracted_symbols.json").decode("utf-8")
-    symbols = json.loads(symbol_data)
+    symbol_data = data_path("extracted_symbols.json")
+    hasher = hashlib.md5()
+    hasher.update(symbol_data)
+    symbols_hash = hasher.hexdigest()
+
+    symbols = json.loads(symbol_data.decode("utf-8"))
     ram_symbols = symbols["ewram"] | symbols["iwram"]
     rom_symbols = symbols["rom"]
 
diff --git a/rom.py b/rom.py
index 89fc788..2ef49aa 100644
--- a/rom.py
+++ b/rom.py
@@ -5,14 +5,14 @@
 
 from pathlib import Path
 import struct
-from typing import TYPE_CHECKING, Sequence, Tuple
+from typing import TYPE_CHECKING, Sequence
 
 from BaseClasses import ItemClassification, Location
 import Utils
-from worlds.Files import APPatchExtension, APProcedurePatch, APTokenMixin, APTokenTypes
+from worlds.Files import APPatchExtension, APProcedurePatch, APTokenMixin, APTokenTypes, InvalidDataError
 
 from . import rom_data
-from .data import encode_str, get_rom_address, get_symbol, get_width_of_encoded_string
+from .data import encode_str, get_rom_address, get_width_of_encoded_string, symbols_hash
 from .items import AP_MZM_ID_BASE, ItemID, ItemType, item_data_table
 from .nonnative_items import get_zero_mission_sprite
 from .options import ChozodiaAccess, DisplayNonLocalItems, Goal
@@ -27,6 +27,13 @@
 class MZMPatchExtensions(APPatchExtension):
     game = "Metroid Zero Mission"
 
+    @staticmethod
+    def check_symbol_hash(caller: APProcedurePatch, rom: bytes, hash: str):
+        if hash != symbols_hash:
+            raise InvalidDataError("Memory addresses don't match. This patch was generated with a "
+                                   "different version of the apworld.")
+        return rom
+
     @staticmethod
     def add_decompressed_graphics(caller: APProcedurePatch, rom: bytes):
         return rom_data.add_item_sprites(rom)
@@ -53,6 +60,7 @@ class MZMProcedurePatch(APProcedurePatch, APTokenMixin):
     def __init__(self, *args, **kwargs):
         super(MZMProcedurePatch, self).__init__(*args, **kwargs)
         self.procedure = [
+            ("check_symbol_hash", [symbols_hash]),
             ("apply_bsdiff4", ["basepatch.bsdiff"]),
             ("apply_tokens", ["token_data.bin"]),
             ("add_decompressed_graphics", []),