security-measures.py

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
from passlib.context import CryptContext
from datetime import datetime, timedelta
from pydantic import BaseModel
import os

# Secret key for JWT encoding/decoding
SECRET_KEY = os.getenv("JWT_SECRET_KEY")
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

class User(BaseModel):
    username: str

class Token(BaseModel):
    access_token: str
    token_type: str

def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)

def get_password_hash(password):
    return pwd_context.hash(password)

def create_access_token(data: dict):
    to_encode = data.copy()
    expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

async def get_current_user(token: str = Depends(oauth2_scheme)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        return User(username=username)
    except JWTError:
        raise credentials_exception

# Example usage in a FastAPI route
@app.post("/token")
async def login(form_data: OAuth2PasswordRequestForm = Depends()):
    # Implement user authentication logic here
    # For demonstration purposes, we'll use a hardcoded user
    if form_data.username != "demo" or form_data.password != "password":
        raise HTTPException(status_code=400, detail="Incorrect username or password")
    access_token = create_access_token(data={"sub": form_data.username})
    return {"access_token": access_token, "token_type": "bearer"}

@app.get("/protected-route")
async def protected_route(current_user: User = Depends(get_current_user)):
    return {"message": f"Hello, {current_user.username}!"}