73 lines
2.4 KiB
Python
73 lines
2.4 KiB
Python
 
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"""JWT authentication utilities for BadNote."""
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from datetime import datetime, timedelta, timezone
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from uuid import uuid4
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from fastapi import Depends, HTTPException, status
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from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
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from jose import JWTError, jwt
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from passlib.context import CryptContext
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from .config import settings
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pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
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bearer_scheme = HTTPBearer()
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def hash_password(password: str) -> str:
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"""Hash a plaintext password with bcrypt."""
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return pwd_context.hash(password)
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def verify_password(password: str, password_hash: str) -> bool:
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"""Verify a password against its hash."""
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return pwd_context.verify(password, password_hash)
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# A precomputed hash used to spend roughly the same time verifying a password
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# for a non-existent user as for an existing one, so login response timing does
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# not leak whether a username exists.
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_DUMMY_HASH = pwd_context.hash("badnote-dummy-password")
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def dummy_verify() -> None:
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"""Run a throwaway bcrypt verification to equalise login timing."""
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pwd_context.verify("badnote-dummy-password", _DUMMY_HASH)
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def create_access_token(user_id: str) -> str:
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"""Create a JWT access token for the given user_id."""
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expire = datetime.now(timezone.utc) + timedelta(hours=settings.jwt_expiry_hours)
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payload = {
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"sub": user_id,
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"exp": expire,
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"iat": datetime.now(timezone.utc),
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"jti": str(uuid4()),
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}
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return jwt.encode(payload, settings.jwt_secret, algorithm="HS256")
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def decode_access_token(token: str) -> dict:
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"""Decode and validate a JWT token. Returns the payload dict."""
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try:
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payload = jwt.decode(token, settings.jwt_secret, algorithms=["HS256"])
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return payload
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except JWTError as exc:
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raise HTTPException(
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status_code=status.HTTP_401_UNAUTHORIZED,
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detail="Invalid or expired token",
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) from exc
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async def get_current_user(
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credentials: HTTPAuthorizationCredentials = Depends(bearer_scheme),
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) -> str:
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"""FastAPI dependency: extract user_id from Bearer token."""
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payload = decode_access_token(credentials.credentials)
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user_id: str | None = payload.get("sub")
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if user_id is None:
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raise HTTPException(
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status_code=status.HTTP_401_UNAUTHORIZED,
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detail="Token missing subject",
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)
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return user_id
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