69 lines
2.1 KiB
Python
69 lines
2.1 KiB
Python
import secrets
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from datetime import UTC, datetime, timedelta
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from typing import Optional
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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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# Ephemeral in-memory secret:
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# - Generated fresh on each backend process start
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# - Never written to disk
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# - Not configurable by the user
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SECRET_KEY = secrets.token_urlsafe(64)
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ALGORITHM = "HS256"
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ACCESS_TOKEN_EXPIRE_MINUTES = 60
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security = HTTPBearer() # Reads Authorization: Bearer <token>
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def create_access_token(
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subject: str,
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expires_delta: Optional[timedelta] = None,
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) -> str:
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"""
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Create a signed JWT for the given subject (e.g. "local-user").
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Tokens are valid only for the lifetime of this process, because the
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SECRET_KEY is regenerated each time the backend restarts.
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"""
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to_encode = {"sub": subject}
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expire = datetime.now(UTC) + (
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expires_delta or timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
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)
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to_encode.update({"exp": expire})
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return jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
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async def get_current_subject(
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credentials: HTTPAuthorizationCredentials = Depends(security),
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) -> str:
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"""
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FastAPI dependency to validate the JWT and return the subject.
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Use this as a dependency on routes that should be protected, e.g.:
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@router.get("/secure")
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async def secure_endpoint(current_subject: str = Depends(get_current_subject)):
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...
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"""
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token = credentials.credentials
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try:
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payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
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subject: Optional[str] = payload.get("sub")
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if subject is None:
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raise HTTPException(
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status_code=status.HTTP_401_UNAUTHORIZED,
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detail="Invalid token payload",
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)
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return subject
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except JWTError:
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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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)
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token = create_access_token("local-user")
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print(token)
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