blob: a2cb6d568c44c6952d2eef08528494352d257bb8 [file] [log] [blame]
# Copyright 2016 The Chromium Authors. All rights reserved.
# Use of this source code is govered by a BSD-style
# license that can be found in the LICENSE file or at
# https://developers.google.com/open-source/licenses/bsd
"""This file defines a subclass of Servlet for JSON feeds.
A "feed" is a servlet that is accessed by another part of our system and that
responds with a JSON value rather than HTML to display in a browser.
"""
import httplib
import json
import logging
from google.appengine.api import app_identity
import settings
from framework import framework_constants
from framework import permissions
from framework import servlet
from framework import xsrf
# This causes a JS error for a hacker trying to do a cross-site inclusion.
XSSI_PREFIX = ")]}'\n"
class JsonFeed(servlet.Servlet):
"""A convenient base class for JSON feeds."""
# By default, JSON output is compact. Subclasses can set this to
# an integer, like 4, for pretty-printed output.
JSON_INDENT = None
# Some JSON handlers can only be accessed from our own app.
CHECK_SAME_APP = False
def HandleRequest(self, _mr):
"""Override this method to implement handling of the request.
Args:
mr: common information parsed from the HTTP request.
Returns:
A dictionary of json data.
"""
raise servlet.MethodNotSupportedError()
def _DoRequestHandling(self, request, mr):
"""Do permission checking, page processing, and response formatting."""
try:
if self.CHECK_SECURITY_TOKEN and mr.auth.user_id:
# Validate the XSRF token with the specific request path for this
# servlet. But, not every XHR request has a distinct token, so just
# use 'xhr' for ones that don't.
# TODO(jrobbins): make specific tokens for:
# user and project stars, issue options, check names.
try:
logging.info('request in jsonfeed is %r', request)
xsrf.ValidateToken(mr.token, mr.auth.user_id, request.path)
except xsrf.TokenIncorrect:
logging.info('using token path "xhr"')
xsrf.ValidateToken(mr.token, mr.auth.user_id, xsrf.XHR_SERVLET_PATH)
if self.CHECK_SAME_APP and not settings.dev_mode:
calling_app_id = request.headers.get('X-Appengine-Inbound-Appid')
if calling_app_id != app_identity.get_application_id():
self.response.status = httplib.FORBIDDEN
return
self._CheckForMovedProject(mr, request)
self.AssertBasePermission(mr)
json_data = self.HandleRequest(mr)
self._RenderJsonResponse(json_data)
raise servlet.AlreadySentResponseException()
except permissions.PermissionException as e:
logging.info('Trapped PermissionException %s', e)
self.response.status = httplib.FORBIDDEN
# pylint: disable=unused-argument
# pylint: disable=arguments-differ
def get(self, project_name=None, viewed_username=None):
"""Collect page-specific and generic info, then render the page.
Args:
project_name: string project name parsed from the URL by webapp2,
but we also parse it out in our code.
viewed_username: string user email parsed from the URL by webapp2,
but we also parse it out in our code.
"""
self._DoRequestHandling(self.mr.request, self.mr)
# pylint: disable=unused-argument
# pylint: disable=arguments-differ
def post(self, project_name=None, viewed_username=None):
"""Parse the request, check base perms, and call form-specific code."""
self._DoRequestHandling(self.mr.request, self.mr)
def _RenderJsonResponse(self, json_data):
"""Serialize the data as JSON so that it can be sent to the browser."""
json_str = json.dumps(json_data, indent=self.JSON_INDENT)
logging.debug(
'Sending JSON response: %r length: %r',
json_str[:framework_constants.LOGGING_MAX_LENGTH], len(json_str))
self.response.content_type = framework_constants.CONTENT_TYPE_JSON
self.response.write(XSSI_PREFIX)
self.response.write(json_str)
class InternalTask(JsonFeed):
"""Internal tasks are JSON feeds that can only be reached by our own code."""
CHECK_SECURITY_TOKEN = False