Fix infinite redirect during token verification if login page is acce…

…ssed

src/simple_openid_connect/integrations/django/middleware.py

@@ -20,20 +20,29 @@ def __init__(self, get_response: Callable[[HttpRequest], HttpResponse]) -> None:
 
     def __call__(self, request: HttpRequest) -> HttpResponse:
         response = self.get_response(request)
+
+        # if we are already trying to log in, no redirect should happen
+        if request.path == resolve_url(settings.LOGIN_URL):
+            return response
+
+        # if the user is not logged in, also no redirect should happen
         openid_session_id = request.session.get("openid_session")
         if not openid_session_id:
             return response
 
+        # the refresh token has a long validity, the access token expires quickly
         openid_session = OpenidSession.objects.get(id=openid_session_id)
         refresh_token = openid_session.refresh_token
         session_valid_until = openid_session.access_token_expiry
         access_token_valid = (
             session_valid_until is not None
             and session_valid_until > datetime.now(timezone.utc)
         )
+        # if the access token is valid, everything is fine
         if access_token_valid:
             return response
 
+        # try to refresh the access token with the refresh token
         logger.debug("access token expired, trying to refresh")
         client = OpenidAppConfig.get_instance().get_client(request)
         exchange_response = client.exchange_refresh_token(refresh_token)
@@ -42,4 +51,5 @@ def __call__(self, request: HttpRequest) -> HttpResponse:
             openid_session.save()
             return response
         else:
+            # the refresh token is also expired, redirect to login
             return HttpResponseRedirect(resolve_url(settings.LOGIN_URL))