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.

Comienza en auth_utils.py, en check_resource_allowed, y revisa los casos existentes de límites de ruta en tests/shared/test_auth_utils.py. Añade cobertura para segmentos de punto, segmentos de punto codificados mediante porcentaje y rutas que permanecen bajo el prefijo configurado; después, ejecuta las pruebas relevantes de las utilidades de auth. Está terminado cuando las rutas que escapan del prefijo configurado no coinciden, mientras que las rutas normalizadas que permanecen bajo él sí lo hacen.