FastAPI从入门到实战（15）——OAuth2 密码模式和 FastAPI 的 OAuth2PasswordBearer

from typing import Optional

from fastapi import APIRouter, Depends, HTTPException
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from pydantic import BaseModel
from starlette import status

app15 = APIRouter()

"""OAuth2 密码模式和 FastAPI 的 OAuth2PasswordBearer"""

"""
OAuth2PasswordBearer是接收URL作为参数的一个类：客户端会向该URL发送username和password参数，然后得到一个Token值
OAuth2PasswordBearer并不会创建相应的URL路径操作，只是指明客户端用来请求Token的URL地址
当请求到来的时候，FastAPI会检查请求的Authorization头信息，如果没有找到Authorization头信息，或者头信息的内容不是Bearer token，它会返回401状态码(UNAUTHORIZED)
"""

oauth2_schema = OAuth2PasswordBearer(tokenUrl="/chapter15/token")  # 请求Token的URL地址 http://127.0.0.1:8082/chapter15/token
print(oauth2_schema)


@app15.get("/oauth2_password_bearer")
async def oauth2_password_bearer(token: str = Depends(oauth2_schema)):
    return {"token": token}


"""基于 Password 和 Bearer token 的 OAuth2 认证"""

fake_users_db = {
    "john snow": {
        "username": "john snow",
        "full_name": "John Snow",
        "email": "[email protected]",
        "hashed_password": "fakehashedsecret",
        "disabled": False,
    },
    "alice": {
        "username": "alice",
        "full_name": "Alice Wonderson",
        "email": "[email protected]",
        "hashed_password": "fakehashedsecret2",
        "disabled": True,
    },
}


def fake_hash_password(password: str):
    return "fakehashed" + password


class User(BaseModel):
    username: str
    email: Optional[str] = None
    full_name: Optional[str] = None
    disabled: Optional[bool] = None


class UserInDB(User):
    hashed_password: str


@app15.post("/token")
async def login(form_data: OAuth2PasswordRequestForm = Depends()):
    user_dict = fake_users_db.get(form_data.username)
    if not user_dict:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Incorrect username or password")
    user = UserInDB(**user_dict)
    hashed_password = fake_hash_password(form_data.password)
    if not hashed_password == user.hashed_password:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Incorrect username or password")
    return {"access_token": user.username, "token_type": "bearer"}


def get_user(db, username: str):
    if username in db:
        user_dict = db[username]
        return UserInDB(**user_dict)


def fake_decode_token(token: str):
    user = get_user(fake_users_db, token)
    return user


async def get_current_user(token: str = Depends(oauth2_schema)):
    user = fake_decode_token(token)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid authentication credentials",
            headers={"WWW-Authenticate": "Bearer"},  # OAuth2的规范，如果认证失败，请求头中返回“WWW-Authenticate”
        )
    return user


async def get_current_active_user(current_user: User = Depends(get_current_user)):
    if current_user.disabled:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Inactive user")
    return current_user


@app15.get("/users/me")
async def read_users_me(current_user: User = Depends(get_current_active_user)):
    return current_user