check_resource_allowed treats /api/../admin as under /api

What happened

check_resource_allowed pads trailing slashes and then does requested_path.startswith(configured_path). It does not collapse . / ...

On main @ 08a3bc8 these return True:

• requested https://example.com/api/../admin vs configured https://example.com/api
• requested https://example.com/mcp/.. vs configured https://example.com/mcp
• requested https://example.com/api/%2e%2e/admin vs configured https://example.com/api

tests/shared/test_auth_utils.py already rejects /api123 vs /api (path-boundary). Dot-segments are not covered.

What I expected

A requested path that walks out of the configured prefix should not match. /api/foo/../v1 vs /api can still match after normalisation, because it stays under /api.

How to reproduce

from mcp.shared.auth_utils import check_resource_allowed

check_resource_allowed("https://example.com/api/../admin", "https://example.com/api")
# True today. I expected False.

I can send a PR that percent-decodes once, runs posixpath.normpath, then keeps the existing trailing-slash prefix rule. Happy to do that if you want it.

Written with AI assistance. I read auth_utils.py next to the path-boundary tests and reproduced it locally.

auth_utils.py の check_resource_allowed から始め、tests/shared/test_auth_utils.py にある既存のパス境界のケースを確認します。ドットセグメント、パーセントエンコードされたドットセグメント、および設定されたプレフィックス配下に留まるパスのカバレッジを追加し、その後、関連する auth utility テストを実行します。設定されたプレフィックスから抜けるパスが一致せず、その配下に留まる正規化されたパスは引き続き一致すれば完了です。