Files
api/src/cartsnitch_api/auth/dependencies.py
T
Barcode Betty 89293d1811 fix(api): hash session token with SHA-256 before DB lookup
Better-Auth v1.2+ stores SHA-256(raw_token) in the sessions.token
column. The cookie/Bearer header carries the raw token, so the API was
doing a plain-text lookup that would never match a hashed value —
causing all authenticated endpoints to return 401.

- Add hashlib import and hash token in _validate_session_token()
- Update conftest._create_test_user_and_session() to store hashed tokens
- Update test_expired_session_rejected() to store hashed tokens

Co-Authored-By: Paperclip <noreply@paperclip.ing>
2026-04-04 19:00:09 +00:00

98 lines
3.2 KiB
Python

"""FastAPI dependency injection for authentication.
Validates Better-Auth session tokens from cookies or Bearer header.
Sessions are verified by querying the shared sessions table directly.
"""
import hashlib
from datetime import UTC, datetime
from fastapi import Cookie, Depends, Header, HTTPException, Request, status
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from sqlalchemy import text
from sqlalchemy.ext.asyncio import AsyncSession
from cartsnitch_api.config import settings
from cartsnitch_api.database import get_db
# Keep Bearer scheme as optional — Better-Auth primarily uses cookies,
# but we support Bearer tokens for service-to-service or mobile clients.
bearer_scheme = HTTPBearer(auto_error=False)
# Better-Auth session cookie name
SESSION_COOKIE_NAME = "better-auth.session_token"
# Secure prefix used by better-auth on HTTPS deployments
SECURE_SESSION_COOKIE_NAME = "__Secure-better-auth.session_token"
async def _validate_session_token(token: str, db: AsyncSession) -> str:
"""Validate a Better-Auth session token against the sessions table.
Better-Auth v1.2+ stores SHA-256(raw_token) in the DB.
The cookie/Bearer header carries the raw token, so we hash before lookup.
"""
token_hash = hashlib.sha256(token.encode()).hexdigest()
result = await db.execute(
text("SELECT user_id, expires_at FROM sessions WHERE token = :token"),
{"token": token_hash},
)
row = result.first()
if not row:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Invalid session token",
)
user_id, expires_at = row
if expires_at.tzinfo is None:
# Treat naive datetimes as UTC
expires_at = expires_at.replace(tzinfo=UTC)
if expires_at < datetime.now(UTC):
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Session expired",
)
return str(user_id)
async def get_current_user(
request: Request,
credentials: HTTPAuthorizationCredentials | None = Depends(bearer_scheme),
db: AsyncSession = Depends(get_db),
) -> str:
"""Extract and validate the session token from cookie or Authorization header.
Checks in order:
1. Better-Auth session cookie (primary — web clients)
2. Bearer token in Authorization header (fallback — API clients)
"""
token: str | None = None
# 1. Check session cookie — prefer __Secure- variant (HTTPS) over plain (HTTP dev)
cookie_token = request.cookies.get(SECURE_SESSION_COOKIE_NAME) or request.cookies.get(SESSION_COOKIE_NAME)
if cookie_token:
token = cookie_token
# 2. Fall back to Bearer header
if not token and credentials:
token = credentials.credentials
if not token:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Authentication required",
)
return await _validate_session_token(token, db)
async def verify_service_key(x_service_key: str = Header()) -> None:
if x_service_key != settings.service_key:
raise HTTPException(
status_code=status.HTTP_403_FORBIDDEN,
detail="Invalid service key",
)