django rest framework_jwt之认证的源码流程剖析

视图代码

class UserViewset(BaseView):
    '''
        create:
        创建用户
        retrieve：

    '''
    queryset = User.objects.all()
    authentication_classes = (JSONWebTokenAuthentication, authentication.SessionAuthentication) #认证类
    def get_serializer_class(self):
        if self.action == "retrieve":
            return UserDetailSerializer
        elif self.action == "create":
            return UserRegSerializer

        return UserDetailSerializer

    def get_permissions(self):
        if self.action == "retrieve":
            return [permissions.IsAuthenticated()]
        elif self.action == "create":
            return []

        return []

    def create(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        user = self.perform_create(serializer)
        re_dict = serializer.data
        payload = jwt_payload_handler(user)
        re_dict["token"] = jwt_encode_handler(payload)
        re_dict["name"] = user.name if user.name else user.username

        headers = self.get_success_headers(serializer.data)
        return Response(re_dict, status=status.HTTP_201_CREATED, headers=headers)

    def get_object(self):
        return self.request.user

    def perform_create(self, serializer):
        return serializer.save()

认证类JSONWebTokenAuthentication代码：

class JSONWebTokenAuthentication(BaseJSONWebTokenAuthentication):
    """
    Clients should authenticate by passing the token key in the "Authorization"
    HTTP header, prepended with the string specified in the setting
    `JWT_AUTH_HEADER_PREFIX`. For example:

        Authorization: JWT eyJhbGciOiAiSFMyNTYiLCAidHlwIj
    """
    www_authenticate_realm = 'api'

    def get_jwt_value(self, request):
        auth = get_authorization_header(request).split() #获取请求里面的token
        auth_header_prefix = api_settings.JWT_AUTH_HEADER_PREFIX.lower() #获取认证方式

        if not auth:  #如果没有token就获取其cookie
            if api_settings.JWT_AUTH_COOKIE:
                return request.COOKIES.get(api_settings.JWT_AUTH_COOKIE)
            return None

        if smart_text(auth[0].lower()) != auth_header_prefix: #看看是不是jwt认证
            return None

        if len(auth) == 1: #认证的字符必须是由空格隔开的字符
            msg = _('Invalid Authorization header. No credentials provided.')
            raise exceptions.AuthenticationFailed(msg)
        elif len(auth) > 2:
            msg = _('Invalid Authorization header. Credentials string '
                    'should not contain spaces.')
            raise exceptions.AuthenticationFailed(msg)

        return auth[1]

    def authenticate_header(self, request):
        """
        Return a string to be used as the value of the `WWW-Authenticate`
        header in a `401 Unauthenticated` response, or `None` if the
        authentication scheme should return `403 Permission Denied` responses.
        """
        return '{0} realm="{1}"'.format(api_settings.JWT_AUTH_HEADER_PREFIX, self.www_authenticate_realm) #返回响应

在父类BaseJSONWebTokenAuthentication中做认证判断：

class BaseJSONWebTokenAuthentication(BaseAuthentication):
    """
    Token based authentication using the JSON Web Token standard.
    """

    def authenticate(self, request):  #开始认证
        """
        Returns a two-tuple of `User` and token if a valid signature has been
        supplied using JWT-based authentication.  Otherwise returns `None`.
        """
        jwt_value = self.get_jwt_value(request) #获取token
        if jwt_value is None:
            return None

        try:
            payload = jwt_decode_handler(jwt_value) #获取用户的token的实体
        except jwt.ExpiredSignature:
            msg = _('Signature has expired.')
            raise exceptions.AuthenticationFailed(msg)
        except jwt.DecodeError:
            msg = _('Error decoding signature.')
            raise exceptions.AuthenticationFailed(msg)
        except jwt.InvalidTokenError:
            raise exceptions.AuthenticationFailed()

        user = self.authenticate_credentials(payload) #获取用户

        return (user, jwt_value)

    def authenticate_credentials(self, payload):
        """
        Returns an active user that matches the payload's user id and email.
        """
        User = get_user_model()
        username = jwt_get_username_from_payload(payload) #获取用户名

        if not username:
            msg = _('Invalid payload.')
            raise exceptions.AuthenticationFailed(msg)

        try:
            user = User.objects.get_by_natural_key(username) #获取用户
        except User.DoesNotExist:
            msg = _('Invalid signature.')
            raise exceptions.AuthenticationFailed(msg)

        if not user.is_active:
            msg = _('User account is disabled.')
            raise exceptions.AuthenticationFailed(msg)

        return user

用户请求进来以后，首先进入dispatch函数：

    def dispatch(self, request, *args, **kwargs):
        """
        `.dispatch()` is pretty much the same as Django's regular dispatch,
        but with extra hooks for startup, finalize, and exception handling.
        """
        self.args = args
        self.kwargs = kwargs
        request = self.initialize_request(request, *args, **kwargs) #加载添加的认证类
        self.request = request
        self.headers = self.default_response_headers  # deprecate?

        try:
            self.initial(request, *args, **kwargs)  #初始化request

            # Get the appropriate handler method
            if request.method.lower() in self.http_method_names:
                handler = getattr(self, request.method.lower(),
                                  self.http_method_not_allowed)
            else:
                handler = self.http_method_not_allowed

            response = handler(request, *args, **kwargs)

        except Exception as exc:
            response = self.handle_exception(exc)

        self.response = self.finalize_response(request, response, *args, **kwargs)
        return self.response

加载initialize_request：

    def initialize_request(self, request, *args, **kwargs):
        """
        Returns the initial request object.
        """
        parser_context = self.get_parser_context(request)

        return Request(
            request,
            parsers=self.get_parsers(),
            authenticators=self.get_authenticators(),加载添加的认证类
            negotiator=self.get_content_negotiator(),
            parser_context=parser_context
        )

初始化initial：

    def initial(self, request, *args, **kwargs):
        """
        Runs anything that needs to occur prior to calling the method handler.
        """
        self.format_kwarg = self.get_format_suffix(**kwargs)

        # Perform content negotiation and store the accepted info on the request
        neg = self.perform_content_negotiation(request)
        request.accepted_renderer, request.accepted_media_type = neg

        # Determine the API version, if versioning is in use.
        version, scheme = self.determine_version(request, *args, **kwargs)
        request.version, request.versioning_scheme = version, scheme

        # Ensure that the incoming request is permitted
        self.perform_authentication(request) 开始认证
        self.check_permissions(request)
        self.check_throttles(request)

在request中做认证：

    def _authenticate(self):
        """
        Attempt to authenticate the request using each authentication instance
        in turn.
        """
        for authenticator in self.authenticators:
            try:
                user_auth_tuple = authenticator.authenticate(self)
            except exceptions.APIException:
                self._not_authenticated()
                raise

            if user_auth_tuple is not None:
                self._authenticator = authenticator
                self.user, self.auth = user_auth_tuple
                return

        self._not_authenticated()