properly respect REFRESH_TOKEN_EXPIRE_SECONDS when generating new tokens

see: https://github.com/ansible/awx/issues/6630
see: https://github.com/jazzband/django-oauth-toolkit/issues/746

awx/api/urls/oauth2_root.py

@@ -1,11 +1,15 @@
 # Copyright (c) 2017 Ansible, Inc.
 # All Rights Reserved.
+from datetime import timedelta
 
+from django.utils.timezone import now
+from django.conf import settings
 from django.conf.urls import url
 
 from oauthlib import oauth2
 from oauth2_provider import views
 
+from awx.main.models import RefreshToken
 from awx.api.views import (
     ApiOAuthAuthorizationRootView,
 )
@@ -14,6 +18,21 @@ from awx.api.views import (
 class TokenView(views.TokenView):
 
     def create_token_response(self, request):
+        # Django OAuth2 Toolkit has a bug whereby refresh tokens are *never*
+        # properly expired (ugh):
+        #
+        # https://github.com/jazzband/django-oauth-toolkit/issues/746
+        #
+        # This code detects and auto-expires them on refresh grant
+        # requests.
+        if request.POST.get('grant_type') == 'refresh_token' and 'refresh_token' in request.POST:
+            refresh_token = RefreshToken.objects.filter(
+                token=request.POST['refresh_token']
+            ).first()
+            if refresh_token:
+                expire_seconds = settings.OAUTH2_PROVIDER.get('REFRESH_TOKEN_EXPIRE_SECONDS', 0)
+                if refresh_token.created + timedelta(seconds=expire_seconds) < now():
+                    return request.build_absolute_uri(), {}, 'The refresh token has expired.', '403'
         try:
             return super(TokenView, self).create_token_response(request)
         except oauth2.AccessDeniedError as e: