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90 lines
3.0 KiB
Python

# Copyright (C) 2021-2022 Intel Corporation
#
# SPDX-License-Identifier: MIT
from django.core import signing
from rest_framework import exceptions
from rest_framework.authentication import BaseAuthentication
from rest_framework.authentication import TokenAuthentication
from django.contrib.auth import login
from django.contrib.auth import get_user_model
from furl import furl
import hashlib
# Got implementation ideas in https://github.com/marcgibbons/drf_signed_auth
class Signer:
QUERY_PARAM = 'sign'
MAX_AGE = 30
@classmethod
def get_salt(cls, url):
normalized_url = furl(url).remove(cls.QUERY_PARAM).url.encode('utf-8')
salt = hashlib.sha256(normalized_url).hexdigest()
return salt
def sign(self, user, url):
"""
Create a signature for a user object.
"""
data = {
'user_id': user.pk,
'username': user.get_username()
}
return signing.dumps(data, salt=self.get_salt(url))
def unsign(self, signature, url):
"""
Return a user object for a valid signature.
"""
User = get_user_model()
data = signing.loads(signature, salt=self.get_salt(url),
max_age=self.MAX_AGE)
if not isinstance(data, dict):
raise signing.BadSignature()
try:
return User.objects.get(**{
'pk': data.get('user_id'),
User.USERNAME_FIELD: data.get('username')
})
except User.DoesNotExist:
raise signing.BadSignature()
# Even with token authorization it is very important to have a valid session id
# in cookies because in some cases we cannot use token authorization (e.g. when
# we redirect to the server in UI using just URL). To overkill that we override
# the class to call `login` method which restores the session id in cookies.
class TokenAuthenticationEx(TokenAuthentication):
def authenticate(self, request):
auth = super().authenticate(request)
session = getattr(request, 'session')
if auth is not None and (session.session_key is None or (not session.modified and not session.load())):
login(request, auth[0], 'django.contrib.auth.backends.ModelBackend')
return auth
class SignatureAuthentication(BaseAuthentication):
"""
Authentication backend for signed URLs.
"""
def authenticate(self, request):
"""
Returns authenticated user if URL signature is valid.
"""
signer = Signer()
sign = request.query_params.get(Signer.QUERY_PARAM)
if not sign:
return
try:
user = signer.unsign(sign, request.build_absolute_uri())
except signing.SignatureExpired:
raise exceptions.AuthenticationFailed('This URL has expired.')
except signing.BadSignature:
raise exceptions.AuthenticationFailed('Invalid signature.')
if not user.is_active:
raise exceptions.AuthenticationFailed('User inactive or deleted.')
return (user, None)