Protocol.send_task: handle missing url or protocol param

protocol.py

@@ -1531,8 +1531,12 @@ def send_task():
     logger.info(f'Params: {list(form.items())}')
 
     # prepare
-    url = form['url']
-    protocol = form['protocol']
+    url = form.get('url')
+    protocol = form.get('protocol')
+    if not url or not protocol:
+        logger.warning(f'Missing protocol or url; got {protocol} {url}')
+        return '', 204
+
     target = Target(uri=url, protocol=protocol)
 
     obj = ndb.Key(urlsafe=form['obj']).get()

tests/test_protocol.py

@@ -2363,3 +2363,13 @@ class ProtocolReceiveTest(TestCase):
             'user': self.user.key.urlsafe(),
         }, headers={CLOUD_TASKS_QUEUE_HEADER: ''})
         self.assertEqual(200, resp.status_code)
+
+    def test_send_task_missing_url(self):
+        obj = self.store_object(id='fake:post')
+        resp = self.client.post('/queue/send', data={
+            'protocol': 'fake',
+            'obj': obj.key.urlsafe(),
+            'url': None,
+            'user': self.user.key.urlsafe(),
+        }, headers={CLOUD_TASKS_QUEUE_HEADER: ''})
+        self.assertEqual(204, resp.status_code)