75 lines
2.9 KiB
Python
75 lines
2.9 KiB
Python
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"""Simple shared-token auth for the yunke data-mirror API (Task 2.9).
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Trust model (per design doc §8 + plan Task 2.9):
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* **No token configured** (``Settings.api_token`` empty, the default) -> auth
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is DISABLED. This is a local/intranet tool; when no token is set we trust the
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network boundary and every request passes through. This keeps local dev and
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single-box deployments zero-config.
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* **Token configured** -> every request must present the same token via either
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the ``Authorization: Bearer <token>`` header or the ``?token=<token>`` query
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parameter. Missing / mismatched tokens get ``401 Unauthorized``.
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The dependency is applied globally on the FastAPI app (see
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:mod:`app.api.main`). ``GET /api/health`` is exempt so liveness probes can
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reach it without knowing the token — that exemption is encoded here in
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:data:`_PUBLIC_PATHS` so the rule lives with the auth logic itself.
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"""
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from __future__ import annotations
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import secrets
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from fastapi import HTTPException, Request, status
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from app.config import get_settings
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# Request paths that bypass auth even when a token is configured. Keep this
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# minimal so the protected surface is easy to reason about — currently just the
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# liveness probe.
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_PUBLIC_PATHS = frozenset({"/api/health"})
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async def require_auth(request: Request) -> None:
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"""No-op when ``api_token`` is unset; otherwise enforce a shared bearer token.
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Settings are read on every call (``get_settings`` is ``lru_cache``-ed, so
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this is cheap) so rotating the token — env change plus
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``get_settings.cache_clear()`` — takes effect without a process restart.
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The comparison uses :func:`secrets.compare_digest` on UTF-8 bytes to avoid
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a timing side channel and to tolerate non-ASCII token values.
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"""
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settings = get_settings()
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expected = settings.api_token
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if not expected:
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# No token configured -> trust the network boundary.
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return
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if request.url.path in _PUBLIC_PATHS:
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return
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presented = _extract_token(request)
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if presented is None or not secrets.compare_digest(
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presented.encode("utf-8"), expected.encode("utf-8")
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):
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raise HTTPException(
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status_code=status.HTTP_401_UNAUTHORIZED,
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detail="invalid or missing API token",
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headers={"WWW-Authenticate": "Bearer"},
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)
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def _extract_token(request: Request) -> str | None:
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"""Pull the presented token from the ``Authorization`` header or ``?token=``.
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Header wins when present and well-formed (``Bearer <value>``); otherwise we
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fall back to the ``token`` query parameter, which is convenient for
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browser-visible endpoints like media streaming.
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"""
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auth_header = request.headers.get("Authorization")
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if auth_header:
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scheme, _, value = auth_header.partition(" ")
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if scheme.lower() == "bearer" and value:
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return value
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return request.query_params.get("token")
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