From b2affdcf88b6869b90a344285caa181e07b6aa79 Mon Sep 17 00:00:00 2001 From: Belugary <53219544+Belugary@users.noreply.github.com> Date: Tue, 12 May 2026 16:57:44 +0800 Subject: [PATCH] fix(image): scope local_id lookup by chat_id + use real column name (#82) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * fix(image): scope local_id lookup by chat_id + use real column name `ImageResolver.get_image_md5` made two wrong assumptions about the production `MessageResourceInfo` schema, which made the decode_image MCP tool always fail with "无法找到 local_id=X 的图片信息": 1. The column is `message_local_id`, not `local_id`. The current query throws `sqlite3.OperationalError: no such column: local_id`, but the exception is swallowed by `except Exception: pass`, masking the real failure as a silent miss. 2. `message_local_id` is not globally unique. In production it repeats across chats, and within an active chat the same local_id can recur up to 7 times (observed on a real DB). The production schema scopes by `chat_id`, resolved from `ChatName2Id.rowid WHERE user_name = ?`. Fix: `get_image_md5` now takes `(username, local_id)`: - Resolve `username -> chat_id` via `ChatName2Id`. - Query `MessageResourceInfo` filtered by `chat_id + message_local_id + message_local_type == 3` (image type; high bits are session flags, so use `% 2^32`), ordered by `message_create_time DESC LIMIT 1`. External callers (`mcp_server.decode_image_tool` / `list_chat_images_tool`) already pass `username` through `ImageResolver.decode_image()` / `list_chat_images()`, so the public API is unchanged. Only the internal helper signature shifts. The existing test fixture in `test_decode_image_v2` used the same wrong schema as the buggy code (`CREATE TABLE MessageResourceInfo (local_id INTEGER PRIMARY KEY, packed_info BLOB)`), so the tests passed against a self-consistent fiction. The fixture is rebuilt to match real columns plus `ChatName2Id`, and three regression tests are added: - cross-chat collision (same local_id in 3 chats; must pick the right one and not the type=43 video row) - same-chat reuse (same local_id, two timestamps; must pick the newer) - unknown chat (username not in ChatName2Id; structured error, no crash) All 154 tests pass locally (151 baseline + 3 new). * fix(image): surface get_image_md5 errors and use read-only DB open Two follow-ups on top of the chat_id scoping fix: 1. The bare `except Exception: pass` was the original failure mode: it silently swallowed `OperationalError: no such column: local_id` when the production schema diverged from the old `local_id` column name, masking the bug this PR fixes. Print the exception to stderr so future schema drift surfaces immediately instead of returning a misleading "image not found" error. 2. Open message_resource.db with `file:...?mode=ro` URI to match the rest of the project (monitor_web.py uses this idiom in 9 places). The DB is read-only for our purposes and a running WeChat may still hold it; using URI ro avoids any chance of lock contention. Co-Authored-By: Claude Opus 4.7 (1M context) --------- Co-authored-by: Claude Opus 4.7 (1M context) --- decode_image.py | 42 ++++++++--- tests/test_decode_image_v2.py | 132 ++++++++++++++++++++++++++++++++-- 2 files changed, 157 insertions(+), 17 deletions(-) diff --git a/decode_image.py b/decode_image.py index 5f7be00..43e8e89 100644 --- a/decode_image.py +++ b/decode_image.py @@ -335,22 +335,42 @@ class ImageResolver: self.aes_key = aes_key self.xor_key = xor_key - def get_image_md5(self, local_id): - """通过 local_id 查 message_resource.db 获取图片文件 MD5""" + def get_image_md5(self, username, local_id): + """通过 (username, local_id) 查 message_resource.db 获取图片 MD5 + + message_local_id 在 MessageResourceInfo 中跨 chat 重复 (不全局唯一), + 必须用 chat_id 缩小范围;同一 chat 内活跃聊天也会复用 local_id + (实测最高同 chat 7 条同 local_id 的记录), 默认取最新一条。 + + message_local_type 上 32 bit 是版本/会话 flag, 用 % 2^32 取低位匹配 + 图片类型 3, 同 monitor_web.py 里 push 路径的写法。 + """ path = self.cache.get("message/message_resource.db") if not path: return None - conn = sqlite3.connect(path) + conn = sqlite3.connect(f"file:{path}?mode=ro", uri=True) try: + chat_row = conn.execute( + "SELECT rowid FROM ChatName2Id WHERE user_name = ?", + (username,) + ).fetchone() + if not chat_row: + return None + chat_id = chat_row[0] + row = conn.execute( - "SELECT packed_info FROM MessageResourceInfo WHERE local_id = ?", - (local_id,) + "SELECT packed_info FROM MessageResourceInfo " + "WHERE chat_id = ? AND message_local_id = ? " + "AND (message_local_type = 3 OR message_local_type % 4294967296 = 3) " + "ORDER BY message_create_time DESC LIMIT 1", + (chat_id, local_id) ).fetchone() if row and row[0]: return extract_md5_from_packed_info(row[0]) - except Exception: - pass + except Exception as e: + print(f"[get_image_md5] {type(e).__name__}: {e}", + file=sys.stderr, flush=True) finally: conn.close() @@ -381,10 +401,10 @@ class ImageResolver: Returns: dict with keys: success, path, format, md5, error """ - # 1. 获取 MD5 - file_md5 = self.get_image_md5(local_id) + # 1. 获取 MD5 (chat-scoped: 同 local_id 跨 chat 重复) + file_md5 = self.get_image_md5(username, local_id) if not file_md5: - return {'success': False, 'error': f'无法从 message_resource.db 找到 local_id={local_id} 的图片信息'} + return {'success': False, 'error': f'无法从 message_resource.db 找到 {username} local_id={local_id} 的图片信息'} # 2. 找 .dat 文件 dat_files = self.find_dat_files(username, file_md5) @@ -448,7 +468,7 @@ class ImageResolver: results = [] for local_id, create_time in rows: - file_md5 = self.get_image_md5(local_id) + file_md5 = self.get_image_md5(username, local_id) info = { 'local_id': local_id, 'create_time': create_time, diff --git a/tests/test_decode_image_v2.py b/tests/test_decode_image_v2.py index 95ee556..15e1132 100644 --- a/tests/test_decode_image_v2.py +++ b/tests/test_decode_image_v2.py @@ -70,23 +70,68 @@ class _FakeCache: return self._mapping.get(rel_key) -def _make_resource_db(path, local_id, file_md5): - """构造最小 message_resource.db,只含一条 packed_info 记录。 +def _make_resource_db(path, local_id, file_md5, username="wxid_test123", + chat_id=1, message_create_time=1700000000, + message_local_type=3, extra_rows=()): + """构造最小 message_resource.db, 表 schema 对齐真实微信结构。 + + 真实表里 message_local_id 不全局唯一 (跨 chat 重复, 活跃 chat 内也会复用), + 解析必须用 ChatName2Id.rowid -> chat_id 限定 + message_local_type=3 过滤图片。 packed_info 里嵌入 extract_md5_from_packed_info 期望的 protobuf marker (\\x12\\x22\\x0a\\x20) 加 32 字节 ASCII hex MD5。 + + Args: + extra_rows: 额外 (chat_id, message_local_id, message_local_type, + message_create_time, file_md5) 元组列表, 用于构造同 local_id + 跨 chat / 同 chat 多版本的歧义场景。 """ marker = b'\x12\x22\x0a\x20' - packed = b'\x00' * 8 + marker + file_md5.encode('ascii') + b'\x00' * 4 + def _packed(md5_hex): + return b'\x00' * 8 + marker + md5_hex.encode('ascii') + b'\x00' * 4 + conn = sqlite3.connect(path) try: + conn.execute(""" + CREATE TABLE MessageResourceInfo ( + message_id INTEGER PRIMARY KEY, + chat_id INTEGER, + sender_id INTEGER, + message_local_type INTEGER, + message_create_time INTEGER, + message_local_id INTEGER, + message_svr_id INTEGER, + message_origin_source INTEGER, + packed_info BLOB + ) + """) conn.execute( - "CREATE TABLE MessageResourceInfo (local_id INTEGER PRIMARY KEY, packed_info BLOB)" + "CREATE TABLE ChatName2Id (user_name TEXT PRIMARY KEY, update_time INTEGER)" ) conn.execute( - "INSERT INTO MessageResourceInfo VALUES (?, ?)", - (local_id, packed), + "INSERT INTO ChatName2Id (rowid, user_name, update_time) VALUES (?, ?, ?)", + (chat_id, username, message_create_time), ) + next_msg_id = 1 + conn.execute( + "INSERT INTO MessageResourceInfo " + "(message_id, chat_id, sender_id, message_local_type, message_create_time, " + " message_local_id, message_svr_id, message_origin_source, packed_info) " + "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)", + (next_msg_id, chat_id, 0, message_local_type, message_create_time, + local_id, 0, 0, _packed(file_md5)), + ) + next_msg_id += 1 + for extra in extra_rows: + ex_chat_id, ex_local_id, ex_type, ex_ctime, ex_md5 = extra + conn.execute( + "INSERT INTO MessageResourceInfo " + "(message_id, chat_id, sender_id, message_local_type, message_create_time, " + " message_local_id, message_svr_id, message_origin_source, packed_info) " + "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)", + (next_msg_id, ex_chat_id, 0, ex_type, ex_ctime, ex_local_id, 0, 0, _packed(ex_md5)), + ) + next_msg_id += 1 conn.commit() finally: conn.close() @@ -335,6 +380,81 @@ class TestImageResolverV2(unittest.TestCase): self.assertTrue(result['success'], msg=result) self.assertEqual(result['format'], 'png') + def test_decode_image_disambiguates_local_id_across_chats(self): + """同 local_id 跨 chat 重复时, 必须按 username -> chat_id 选对; 否则会拿到 + 别的 chat 的 MD5 (或视频 type=43 的 packed_info), 解出错图。 + + 生产 DB 上同一个 message_local_id 实测会出现在 5+ 个不同 chat 里, + 其中混有图片 (type=3) / 视频 (type=43) / 群聊 / 私聊, 必须 chat-scoped + + type 过滤才能定位。 + """ + os.unlink(self.db_path) + other_md5 = "f" * 32 + video_md5 = "a" * 32 + _make_resource_db( + self.db_path, self.local_id, self.file_md5, + username=self.username, chat_id=7, + message_create_time=1778487726, + extra_rows=[ + # 另一个 chat 同 local_id 同图片类型, MD5 不同 —— 选错就拿这个 + (5, self.local_id, 3, 1700000000, other_md5), + # 又一个 chat 同 local_id 但是视频 (type=43), 应被 type 过滤 + (132, self.local_id, 43, 1750000000, video_md5), + ], + ) + # 给冲突 chat 也注册 user_name, 否则 chat-scope 等价 + conn = sqlite3.connect(self.db_path) + conn.execute( + "INSERT INTO ChatName2Id (rowid, user_name, update_time) VALUES (5, ?, 0), (132, ?, 0)", + ("other_chat_wxid", "video_chat_wxid"), + ) + conn.commit() + conn.close() + + resolver = ImageResolver( + self.wechat_base, self.out_dir, self.cache, + aes_key=TEST_AES_KEY, xor_key=TEST_XOR_KEY, + ) + result = resolver.decode_image(self.username, self.local_id) + self.assertTrue(result['success'], msg=result) + # 必须拿目标 chat 的 MD5, 不是 other_chat 也不是视频 + self.assertEqual(result['md5'], self.file_md5) + + def test_decode_image_picks_latest_when_same_chat_local_id_reused(self): + """活跃 chat 里 local_id 会被复用 (实测同 chat 同 local_id 最多 7 条); + 默认应返回 message_create_time 最新的那张, 对应用户最近一次 reference。 + """ + os.unlink(self.db_path) + old_md5 = "c" * 32 + # self.file_md5 / self.local_id 在 _make_resource_db 默认插入为 "latest" 那条 + _make_resource_db( + self.db_path, self.local_id, self.file_md5, + username=self.username, chat_id=1, + message_create_time=1778487726, + extra_rows=[ + # 同 chat 同 local_id 但更早, 不应该被选中 + (1, self.local_id, 3, 1700000000, old_md5), + ], + ) + + resolver = ImageResolver( + self.wechat_base, self.out_dir, self.cache, + aes_key=TEST_AES_KEY, xor_key=TEST_XOR_KEY, + ) + result = resolver.decode_image(self.username, self.local_id) + self.assertTrue(result['success'], msg=result) + self.assertEqual(result['md5'], self.file_md5) + + def test_decode_image_unknown_chat_returns_error(self): + """username 在 ChatName2Id 里找不到时, 应返回结构化错误而不是 crash 或乱选 row。""" + resolver = ImageResolver( + self.wechat_base, self.out_dir, self.cache, + aes_key=TEST_AES_KEY, xor_key=TEST_XOR_KEY, + ) + result = resolver.decode_image("wxid_does_not_exist", self.local_id) + self.assertFalse(result['success']) + self.assertIn('wxid_does_not_exist', result['error']) + def test_decode_image_v1_no_aes_key_uses_fixed_key(self): # V1 magic 不会被 is_v2_format guard 拦截 (V1 magic 是 \x07\x08V1, V2 是 \x07\x08V2); # 即便 ImageResolver(aes_key=None), V1 文件也应通过 decrypt_dat_file 内置固定 key 解密