FastAPI 使用JWT认证的中间件

FastAPI 使用 JWT 认证的中间件 fastapi 的中间件还是太少，单独开发 JWT 需要，starlette 本身提供认证相关实现，只需要自定义一个 AuthenticationBackend 即可，本次我们实现使用中间价方式拆包 JWT 的令牌，获取 payload 里面的用户信息

私有定义的 payload 内容格式如下

{
"usid": "SkDQBhEjUfygRSeEBech", //UUID Short
"uname": "test user name", //Username
"mid":"700010001" // Member ID
}

调用代码

app = FastAPI()
app.add_middleware(AuthenticationMiddleware,backend=JWTAuthenticationBackend(secret_key="YOUR_SECRET_KEY"))

完整的代码

import jwt

from starlette.authentication import (
AuthenticationBackend, AuthenticationError, BaseUser, AuthCredentials,
UnauthenticatedUser )

class JWTUser(BaseUser):
def __init__(self, user_id_short: str, member_number: str, user_name: str,token: str, payload: dict) -> None:
self.user_name = user_name
self.user_id_short = user_id_short
self.member_number = member_number
self.token = token
self.payload = payload

@property
def is\_authenticated(self) -> bool:
    return True

@property
def display\_name(self) -> str:
    return self.user\_name   ## 会员名处理，加\*？

@property
def display\_user\_id\_short(self) -> str:
    return self.user\_id\_short   ## 会员id处理

@property
def display\_member\_number(self) -> str:
    return self.member\_number  ## 会员号处理，加\*？

class JWTAuthenticationBackend(AuthenticationBackend):

def \_\_init\_\_(self, secret\_key: str, algorithm: str = 'HS256', prefix: str = 'JWT', user\_name\_field:str = 'uname' , user\_id\_field: str = 'usid',member\_number\_field: str = 'mid'):
    self.secret\_key = secret\_key
    self.algorithm = algorithm
    self.prefix = prefix
    self.user\_name\_field = user\_name\_field
    self.user\_id\_field = user\_id\_field
    self.member\_number\_field = member\_number\_field
    

@classmethod
def get\_token\_from\_header(cls, authorization: str, prefix: str):
    """
    Parses the Authorization header and returns only the token
    :param authorization:
    :return:
    """
    try:
        scheme, token = authorization.split()
    except ValueError:
        raise AuthenticationError('Could not separate Authorization scheme and token')
    if scheme.lower() != prefix.lower():
        raise AuthenticationError(f'Authorization scheme {scheme} is not supported')
    return token

async def authenticate(self, request):
    if "Authorization" not in request.headers:
        return None

    auth = request.headers\["Authorization"\]
    token = self.get\_token\_from\_header(authorization=auth, prefix=self.prefix)
    try:
        payload = jwt.decode(token, key=self.secret\_key, algorithms=self.algorithm)
    except jwt.InvalidTokenError as e:
        raise AuthenticationError(str(e))

    return AuthCredentials(\["jwt\_authenticated"\]), JWTUser(user\_id\_short=payload\[self.user\_id\_field\], member\_number=payload\[self.member\_number\_field\],user\_name=payload\[self.user\_name\_field\],token=token,
                                                       payload=payload)

class JWTWebSocketAuthenticationBackend(AuthenticationBackend):

def \_\_init\_\_(self, secret\_key: str, algorithm: str = 'HS256', query\_param\_name: str = 'jwt',
             user\_name\_field:str = 'uname' , user\_id\_field: str = 'usid',member\_number\_field: str = 'mid'):
    self.secret\_key = secret\_key
    self.algorithm = algorithm
    self.query\_param\_name = query\_param\_name
    self.user\_name\_field = user\_name\_field
    self.user\_id\_field = user\_id\_field
    self.member\_number\_field = member\_number\_field

async def authenticate(self, request):
    if self.query\_param\_name not in request.query\_params:
        return AuthCredentials(), UnauthenticatedUser()

    token = request.query\_params\[self.query\_param\_name\]

    try:
        payload = jwt.decode(token, key=self.secret\_key, algorithms=self.algorithm)
    except jwt.InvalidTokenError as e:
        raise AuthenticationError(str(e))

    return AuthCredentials(\["jwt\_authenticated"\]), JWTUser(user\_id\_short=payload\[self.user\_id\_field\], member\_number=payload\[self.member\_number\_field\],user\_name=payload\[self.user\_name\_field\],token=token,
                                                       payload=payload)