auth: Expect name in request params in Apple auth.

The name used to be included in the id_token, but this seems to have
been changed by Apple and now it's sent in the `user` request param.

https://github.com/python-social-auth/social-core/pull/483 is the
upstream PR for this - but upstream is currently unmaintained, so we
have to monkey patch.

We also alter the tests to reflect this situation. Tests no longer put
the name in the id_token, but rather in the `user` request param in the
browser flow, just like it happens in reality.

An adaptation has to be made in the native flow - since the name won't
be included by Apple in the id_token anymore, the app, when POSTing
to the /complete/apple/ endpoint,
can (and should for better user experience)
add the `user` param formatted as json of
{"email": "hamlet@zulip.com", "name": {"firstName": "Full", "lastName": "Name"}}
dict. This is also reflected by the change in the
native flow tests.

zerver/tests/test_auth_backends.py

@@ -2064,7 +2064,7 @@ class AppleAuthMixin:
     CONFIG_ERROR_URL = "/config-error/apple"
 
     def generate_id_token(self, account_data_dict: Dict[str, str], audience: Optional[str]=None) -> str:
-        payload = account_data_dict
+        payload = dict(email=account_data_dict['email'])
 
         # This setup is important because python-social-auth decodes `id_token`
         # with `SOCIAL_AUTH_APPLE_CLIENT` as the `audience`
@@ -2107,9 +2107,10 @@ class AppleIdAuthBackendTest(AppleAuthMixin, SocialAuthBase):
                                 **extra_data: Any) -> HttpResponse:
         parsed_url = urllib.parse.urlparse(result.url)
         state = urllib.parse.parse_qs(parsed_url.query)['state']
+        user_param = json.dumps(account_data_dict)
         self.client.session.flush()
         result = self.client_post(self.AUTH_FINISH_URL,
-                                  dict(state=state), **headers)
+                                  dict(state=state, user=user_param), **headers)
         return result
 
     def register_extra_endpoints(self, requests_mock: responses.RequestsMock,
@@ -2205,6 +2206,7 @@ class AppleAuthBackendNativeFlowTest(AppleAuthMixin, SocialAuthBase):
         multiuse_object_key: str='',
         alternative_start_url: Optional[str]=None,
         id_token: Optional[str]=None,
+        account_data_dict: Dict[str, str]={},
         *,
         user_agent: Optional[str]=None,
     ) -> Tuple[str, Dict[str, Any]]:
@@ -2225,6 +2227,8 @@ class AppleAuthBackendNativeFlowTest(AppleAuthMixin, SocialAuthBase):
         if subdomain:
             params['subdomain'] = subdomain
 
+        params['user'] = json.dumps(account_data_dict)
+
         url += f"&{urllib.parse.urlencode(params)}"
         return url, headers
 
@@ -2259,7 +2263,7 @@ class AppleAuthBackendNativeFlowTest(AppleAuthMixin, SocialAuthBase):
         url, headers = self.prepare_login_url_and_headers(
             subdomain, mobile_flow_otp, desktop_flow_otp, is_signup, next,
             multiuse_object_key, alternative_start_url=self.AUTH_FINISH_URL,
-            user_agent=user_agent, id_token=id_token,
+            user_agent=user_agent, id_token=id_token, account_data_dict=account_data_dict,
         )
 
         with self.apple_jwk_url_mock():
@@ -2291,11 +2295,13 @@ class AppleAuthBackendNativeFlowTest(AppleAuthMixin, SocialAuthBase):
 
     def test_social_auth_session_fields_cleared_correctly(self) -> None:
         mobile_flow_otp = '1234abcd' * 8
+        account_data_dict = self.get_account_data_dict(email=self.email, name=self.name)
 
         def initiate_auth(mobile_flow_otp: Optional[str]=None) -> None:
             url, headers = self.prepare_login_url_and_headers(subdomain='zulip',
                                                               id_token='invalid',
-                                                              mobile_flow_otp=mobile_flow_otp)
+                                                              mobile_flow_otp=mobile_flow_otp,
+                                                              account_data_dict=account_data_dict)
             result = self.client_get(url, **headers)
             self.assertEqual(result.status_code, 302)
 
@@ -2324,6 +2330,7 @@ class AppleAuthBackendNativeFlowTest(AppleAuthMixin, SocialAuthBase):
         url, headers = self.prepare_login_url_and_headers(
             subdomain='zulip', alternative_start_url=self.AUTH_FINISH_URL,
             id_token=self.generate_id_token(account_data_dict, audience='com.different.app'),
+            account_data_dict=account_data_dict,
         )
 
         with self.apple_jwk_url_mock(),  self.assertLogs(self.logger_string, level='INFO') as m:

zproject/backends.py

@@ -1643,6 +1643,33 @@ class AppleAuthBackend(SocialAuthMixin, AppleIdAuth):
                 self.strategy.session_set(param, value)
         return request_state
 
+    def get_user_details(self, response: Dict[str, Any]) -> Dict[str, Any]:
+        """
+        Overriden to correctly grab the user's name from the request params,
+        as current upstream code expects it in the id_token and Apple changed
+        the API.
+        Taken from https://github.com/python-social-auth/social-core/pull/483
+        TODO: Remove this when the PR is merged.
+        """
+        name = response.get('name') or {}
+        name = json.loads(self.data.get('user', '{}')).get('name', {})
+        fullname, first_name, last_name = self.get_user_names(
+            fullname='',
+            first_name=name.get('firstName', ''),
+            last_name=name.get('lastName', '')
+        )
+        email = response.get('email', '')
+        # prevent updating User with empty strings
+        user_details = {
+            'fullname': fullname or None,
+            'first_name': first_name or None,
+            'last_name': last_name or None,
+            'email': email,
+        }
+        user_details['username'] = email
+
+        return user_details
+
     def auth_complete(self, *args: Any, **kwargs: Any) -> Optional[HttpResponse]:
         if not self.is_native_flow():
             # The default implementation in python-social-auth is the browser flow.