[Findit] Use PubSub built-in authentication for push endpoint.

appengine/findit/handlers/crash/fracas_crash.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import base64
 import json
 import logging
 
 from common import constants
 from common.base_handler import BaseHandler
 from common.base_handler import Permission
 from crash import fracas_crash_pipeline
-from model.crash.crash_config import CrashConfig
-
-
-FRACAS_ANALYSIS_QUEUE = 'fracas-crash-queue'
 
 
 class FracasCrash(BaseHandler):
-  PERMISSION_LEVEL = Permission.ANYONE
+  PERMISSION_LEVEL = Permission.ADMIN
 
   def HandlePost(self):
     """Handles push delivery from Pub/Sub for crash data.
 
     The crash data should be in the following json format:
     {
       'channel': 'canary',
       'platform': 'win',
       'signature': 'namesapce1:namespace2:class_name:func_name',
       'stack_trace': 'frame1\nframe2\nframe3',
       'chrome_version': '50.0.2500.0',
       'versions_to_cpm': {
         '50.0.2500.0': 1.2,
         '50.0.2499.0': 1.0,
       },
     }
     """
-    token = self.request.get('token', '').strip()
-    crash_config = CrashConfig.Get()
-    if token != crash_config.fracas.get('crash_data_push_token'):
-      logging.warning('Unauthorized access.')
-      return self.CreateError(
-          'Unauthorized access: invalid token "%s"' % token, 403)
-
     received_message = json.loads(self.request.body)
     pubsub_message = received_message['message']
     crash_data = json.loads(base64.b64decode(pubsub_message['data']))
 
     logging.info('Processing message %s from subscription %s.',
                  pubsub_message['message_id'], received_message['subscription'])
 
-    fracas_crash_pipeline.ScheduleNewAnalysisForCrash(
-        crash_data['channel'], crash_data['platform'], crash_data['signature'],
-        crash_data['stack_trace'], crash_data['chrome_version'],
-        crash_data['versions_to_cpm'],
-        queue_name=constants.CRASH_ANALYSIS_FRACAS_QUEUE)
+    try:
+      fracas_crash_pipeline.ScheduleNewAnalysisForCrash(
+          crash_data['channel'], crash_data['platform'],
+          crash_data['signature'], crash_data['stack_trace'],
+          crash_data['chrome_version'], crash_data['versions_to_cpm'],
+          queue_name=constants.CRASH_ANALYSIS_FRACAS_QUEUE)
+    except KeyError:  # pragma: no cover.
+      # TODO: save exception in datastore and create a page to show them.
+      logging.exception('Failed to process fracas message')