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from typing import Optional, TypeVar
from django.contrib.auth import get_user_model
from django.contrib.auth.models import AbstractBaseUser
from django.utils.translation import gettext_lazy as _
from rest_framework import HTTP_HEADER_ENCODING, authentication
from rest_framework.request import Request
from .exceptions import AuthenticationFailed, InvalidToken, TokenError
from .models import TokenUser
from .settings import api_settings
from .tokens import Token
from .utils import get_md5_hash_password
AUTH_HEADER_TYPES = api_settings.AUTH_HEADER_TYPES
if not isinstance(api_settings.AUTH_HEADER_TYPES, (list, tuple)):
AUTH_HEADER_TYPES = (AUTH_HEADER_TYPES,)
AUTH_HEADER_TYPE_BYTES: set[bytes] = {
h.encode(HTTP_HEADER_ENCODING) for h in AUTH_HEADER_TYPES
}
AuthUser = TypeVar("AuthUser", AbstractBaseUser, TokenUser)
class JWTAuthentication(authentication.BaseAuthentication):
"""
An authentication plugin that authenticates requests through a JSON web
token provided in a request header.
"""
www_authenticate_realm = "api"
media_type = "application/json"
def __init__(self, *args, **kwargs) -> None:
super().__init__(*args, **kwargs)
self.user_model = get_user_model()
def authenticate(self, request: Request) -> Optional[tuple[AuthUser, Token]]:
header = self.get_header(request)
if header is None:
return None
raw_token = self.get_raw_token(header)
if raw_token is None:
return None
validated_token = self.get_validated_token(raw_token)
return self.get_user(validated_token), validated_token
def authenticate_header(self, request: Request) -> str:
return '{} realm="{}"'.format(
AUTH_HEADER_TYPES[0],
self.www_authenticate_realm,
)
def get_header(self, request: Request) -> bytes:
"""
Extracts the header containing the JSON web token from the given
request.
"""
header = request.META.get(api_settings.AUTH_HEADER_NAME)
if isinstance(header, str):
# Work around django test client oddness
header = header.encode(HTTP_HEADER_ENCODING)
return header
def get_raw_token(self, header: bytes) -> Optional[bytes]:
"""
Extracts an unvalidated JSON web token from the given "Authorization"
header value.
"""
parts = header.split()
if len(parts) == 0:
# Empty AUTHORIZATION header sent
return None
if parts[0] not in AUTH_HEADER_TYPE_BYTES:
# Assume the header does not contain a JSON web token
return None
if len(parts) != 2:
raise AuthenticationFailed(
_("Authorization header must contain two space-delimited values"),
code="bad_authorization_header",
)
return parts[1]
def get_validated_token(self, raw_token: bytes) -> Token:
"""
Validates an encoded JSON web token and returns a validated token
wrapper object.
"""
messages = []
for AuthToken in api_settings.AUTH_TOKEN_CLASSES:
try:
return AuthToken(raw_token)
except TokenError as e:
messages.append(
{
"token_class": AuthToken.__name__,
"token_type": AuthToken.token_type,
"message": e.args[0],
}
)
raise InvalidToken(
{
"detail": _("Given token not valid for any token type"),
"messages": messages,
}
)
def get_user(self, validated_token: Token) -> AuthUser:
"""
Attempts to find and return a user using the given validated token.
"""
try:
user_id = validated_token[api_settings.USER_ID_CLAIM]
except KeyError as e:
raise InvalidToken(
_("Token contained no recognizable user identification")
) from e
try:
user = self.user_model.objects.get(**{api_settings.USER_ID_FIELD: user_id})
except self.user_model.DoesNotExist as e:
raise AuthenticationFailed(
_("User not found"), code="user_not_found"
) from e
if api_settings.CHECK_USER_IS_ACTIVE and not user.is_active:
raise AuthenticationFailed(_("User is inactive"), code="user_inactive")
if api_settings.CHECK_REVOKE_TOKEN:
if validated_token.get(
api_settings.REVOKE_TOKEN_CLAIM
) != get_md5_hash_password(user.password):
raise AuthenticationFailed(
_("The user's password has been changed."), code="password_changed"
)
return user
class JWTStatelessUserAuthentication(JWTAuthentication):
"""
An authentication plugin that authenticates requests through a JSON web
token provided in a request header without performing a database lookup to obtain a user instance.
"""
def get_user(self, validated_token: Token) -> AuthUser:
"""
Returns a stateless user object which is backed by the given validated
token.
"""
if api_settings.USER_ID_CLAIM not in validated_token:
# The TokenUser class assumes tokens will have a recognizable user
# identifier claim.
raise InvalidToken(_("Token contained no recognizable user identification"))
return api_settings.TOKEN_USER_CLASS(validated_token)
JWTTokenUserAuthentication = JWTStatelessUserAuthentication
def default_user_authentication_rule(user: AuthUser) -> bool:
# Prior to Django 1.10, inactive users could be authenticated with the
# default `ModelBackend`. As of Django 1.10, the `ModelBackend`
# prevents inactive users from authenticating. App designers can still
# allow inactive users to authenticate by opting for the new
# `AllowAllUsersModelBackend`. However, we explicitly prevent inactive
# users from authenticating to enforce a reasonable policy and provide
# sensible backwards compatibility with older Django versions.
return user is not None and (
not api_settings.CHECK_USER_IS_ACTIVE or user.is_active
)
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