Files
BanGUI/backend/app/routers/auth.py

209 lines
7.0 KiB
Python

"""Authentication router.
``POST /api/auth/login`` — verify master password and issue a session.
``POST /api/auth/logout`` — revoke the current session.
The session token is set as an ``HttpOnly`` ``SameSite=Lax`` cookie for
browser-based SPAs. The cookie is automatically included in all requests
and is inaccessible to JavaScript, protecting it from XSS attacks and
malicious scripts.
For programmatic API clients (non-browser), use ``POST /api/auth/token``
which returns a token in the response body for use in the ``Authorization``
header. This endpoint does not set a cookie.
Login attempts are rate-limited to 5 per minute per IP address to prevent
brute-force attacks. Requests exceeding the limit return ``429 Too Many Requests``
with a ``Retry-After`` header.
"""
from __future__ import annotations
import asyncio
import structlog
from fastapi import APIRouter, Request, Response, status
from app.dependencies import (
AuthDep,
LoginRateLimiterDep,
SessionCacheDep,
SessionServiceContextDep,
SettingsDep,
)
from app.exceptions import AuthenticationError, RateLimitError
from app.models.auth import LoginRequest, LoginResponse, LogoutResponse
from app.services import auth_service
from app.utils.client_ip import get_client_ip
from app.utils.constants import SESSION_COOKIE_NAME
log: structlog.stdlib.BoundLogger = structlog.get_logger()
router = APIRouter(prefix="/api/auth", tags=["auth"])
# Trusted proxy IPs that can set X-Forwarded-For header.
# By default, none are trusted. In production behind nginx, add the nginx container IP.
_TRUSTED_PROXIES: list[str] = []
@router.post(
"/login",
response_model=LoginResponse,
summary="Authenticate with the master password",
)
async def login(
body: LoginRequest,
response: Response,
request: Request,
session_ctx: SessionServiceContextDep,
settings: SettingsDep,
rate_limiter: LoginRateLimiterDep,
) -> LoginResponse:
"""Verify the master password and return a session token.
On success the token is also set as an ``HttpOnly`` ``SameSite=Lax``
cookie so the browser SPA benefits from automatic credential handling.
Rate limiting: Up to 5 login attempts per minute per client IP.
Requests exceeding this limit return ``429 Too Many Requests`` with
a ``Retry-After`` header.
Args:
body: Login request validated by Pydantic.
response: FastAPI response object used to set the cookie.
request: The incoming HTTP request (used to extract client IP).
session_ctx: Session service context containing db and repository.
settings: Application settings (used for session duration).
rate_limiter: The login rate limiter (per IP).
Returns:
:class:`~app.models.auth.LoginResponse` containing the token.
Raises:
AuthenticationError: if the password is incorrect.
RateLimitError: if the rate limit is exceeded.
"""
client_ip = get_client_ip(request, trusted_proxies=_TRUSTED_PROXIES)
if not rate_limiter.is_allowed(client_ip):
log.warning("login_rate_limit_exceeded", client_ip=client_ip)
raise RateLimitError("Too many login attempts. Please try again later.")
try:
signed_token, expires_at = await auth_service.login(
session_ctx.db,
password=body.password,
session_duration_minutes=settings.session_duration_minutes,
session_secret=settings.session_secret,
session_repo=session_ctx.session_repo,
)
except ValueError as exc:
# Add delay on wrong password to slow down brute-force attacks.
# The bcrypt checkpw already takes ~100ms at cost factor 12,
# but an extra 10 seconds makes automation much less feasible.
await asyncio.sleep(10.0)
log.warning("login_failed", client_ip=client_ip, error=str(exc))
raise AuthenticationError(str(exc)) from exc
response.set_cookie(
key=SESSION_COOKIE_NAME,
value=signed_token,
httponly=settings.session_cookie_httponly,
samesite=settings.session_cookie_samesite,
secure=settings.session_cookie_secure,
max_age=settings.session_duration_minutes * 60,
)
log.info("login_success", client_ip=client_ip)
return LoginResponse(expires_at=expires_at)
@router.get(
"/session",
summary="Validate the current session",
)
async def validate_session(
_: AuthDep,
) -> dict[str, bool]:
"""Validate the current session.
This endpoint requires a valid session and returns 200 if the session is
valid and still active. If the session is invalid, expired, or missing,
FastAPI's ``require_auth`` dependency returns 401 automatically.
The frontend calls this on mount to bootstrap its authentication state
from the backend rather than relying solely on cached ``sessionStorage``.
Args:
_: The injected session object (unused, but its presence triggers validation).
Returns:
A simple JSON object confirming the session is valid.
"""
return {"valid": True}
@router.post(
"/logout",
response_model=LogoutResponse,
summary="Revoke the current session",
)
async def logout(
request: Request,
response: Response,
session_ctx: SessionServiceContextDep,
settings: SettingsDep,
session_cache: SessionCacheDep,
) -> LogoutResponse:
"""Invalidate the active session.
The session token is read from the ``bangui_session`` cookie or the
``Authorization: Bearer`` header. If no token is present the request
is silently treated as a successful logout (idempotent).
Args:
request: FastAPI request (used to extract the token).
response: FastAPI response (used to clear the cookie).
session_ctx: Session service context containing db and repository.
settings: Application settings (used to unwrap signed tokens).
session_cache: Session cache for invalidation.
Returns:
:class:`~app.models.auth.LogoutResponse`.
"""
token = _extract_token(request)
if token:
raw_token = await auth_service.logout(
session_ctx.db,
token,
settings.session_secret,
session_repo=session_ctx.session_repo,
)
if raw_token:
session_cache.invalidate(raw_token)
session_cache.invalidate(token)
response.delete_cookie(key=SESSION_COOKIE_NAME)
return LogoutResponse()
# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------
def _extract_token(request: Request) -> str | None:
"""Extract the session token from cookie or Authorization header.
Args:
request: The incoming FastAPI request.
Returns:
The token string, or ``None`` if absent.
"""
token: str | None = request.cookies.get(SESSION_COOKIE_NAME)
if token:
return token
auth_header: str = request.headers.get("Authorization", "")
if auth_header.startswith("Bearer "):
return auth_header[len("Bearer "):]
return None