mirror of
https://github.com/TronoSfera/backup_service.git
synced 2026-05-18 10:03:32 +03:00
129 lines
4.4 KiB
Python
129 lines
4.4 KiB
Python
"""Authentication utilities for the backup service.
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This module implements password hashing, JSON Web Token (JWT) generation and
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verification, and FastAPI dependencies for authenticating API calls. Users
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authenticate via the ``/api/login`` endpoint by providing their username and
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password; upon successful authentication a signed JWT is returned. The JWT
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must be included in the ``Authorization: Bearer <token>`` header for
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subsequent requests.
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The JWT contains the user's ID and role (admin flag). Token expiration is
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configurable via the ``ACCESS_TOKEN_EXPIRE_MINUTES`` environment variable.
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"""
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from __future__ import annotations
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import os
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import datetime
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import hashlib
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from typing import Optional
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from jose import JWTError, jwt
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from passlib.context import CryptContext
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from passlib.handlers import bcrypt as passlib_bcrypt
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from fastapi import Depends, HTTPException, Request, status
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from fastapi.security import OAuth2PasswordBearer
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from sqlalchemy.orm import Session
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from . import models
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from .database import get_db
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# Configuration
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SECRET_KEY = os.getenv("SECRET_KEY", "CHANGE_ME")
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ALGORITHM = "HS256"
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ACCESS_TOKEN_EXPIRE_MINUTES = int(os.getenv("ACCESS_TOKEN_EXPIRE_MINUTES", "60"))
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def _build_password_context() -> CryptContext:
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"""Create a password hashing context with a safe backend fallback."""
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try:
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passlib_bcrypt.bcrypt.set_backend("builtin")
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passlib_bcrypt.bcrypt_sha256.set_backend("builtin")
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passlib_bcrypt.bcrypt_sha256.hash("passlib-backend-check")
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return CryptContext(schemes=["bcrypt_sha256", "bcrypt"], deprecated="auto")
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except Exception:
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# bcrypt backends can fail with newer bcrypt releases; fall back to pbkdf2.
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return CryptContext(schemes=["pbkdf2_sha256"], deprecated="auto")
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pwd_context = _build_password_context()
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def _normalize_bcrypt_password(password: str) -> str:
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"""Normalize passwords to avoid bcrypt's 72-byte length limit.
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Some bcrypt backends raise a ValueError for passwords longer than 72 bytes.
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Instead of truncating, hash the original bytes with SHA-256 to preserve
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entropy while ensuring the input length stays within bcrypt limits.
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"""
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encoded = password.encode("utf-8")
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if len(encoded) <= 72:
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return password
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return hashlib.sha256(encoded).hexdigest()
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oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/login", auto_error=False)
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def hash_password(password: str) -> str:
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normalized = _normalize_bcrypt_password(password)
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return pwd_context.hash(normalized)
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def verify_password(plain_password: str, hashed_password: str) -> bool:
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normalized = _normalize_bcrypt_password(plain_password)
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return pwd_context.verify(normalized, hashed_password)
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def create_access_token(data: dict, expires_delta: Optional[datetime.timedelta] = None) -> str:
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to_encode = data.copy()
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expire = datetime.datetime.utcnow() + (
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expires_delta or datetime.timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
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)
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to_encode.update({"exp": expire})
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encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
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return encoded_jwt
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async def get_current_user(
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request: Request,
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token: str | None = Depends(oauth2_scheme),
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db: Session = Depends(get_db),
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) -> models.User:
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"""Retrieve the current user from a JWT token."""
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credentials_exception = HTTPException(
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status_code=status.HTTP_401_UNAUTHORIZED,
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detail="Could not validate credentials",
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headers={"WWW-Authenticate": "Bearer"},
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)
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raw_token = token or request.cookies.get("access_token")
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if not raw_token:
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raise credentials_exception
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try:
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payload = jwt.decode(raw_token, SECRET_KEY, algorithms=[ALGORITHM])
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user_id: int | None = payload.get("sub")
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if user_id is None:
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raise credentials_exception
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except JWTError as e:
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raise credentials_exception from e
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user = db.query(models.User).filter(models.User.id == user_id).first()
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if user is None:
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raise credentials_exception
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return user
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async def get_current_active_user(
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current_user: models.User = Depends(get_current_user),
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) -> models.User:
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return current_user
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async def get_current_admin(
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current_user: models.User = Depends(get_current_user),
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) -> models.User:
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if not current_user.is_admin:
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raise HTTPException(
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status_code=status.HTTP_403_FORBIDDEN,
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detail="Not enough privileges",
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)
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return current_user
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