Open Source Monorail

appengine/monorail/framework/captcha.py

+# 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
+
+"""A simple python interface to ReCAPTCHA."""
+
+import json
+import logging
+import urllib
+import urllib2
+
+from services import secrets_svc
+
+def Verify(remote_ip, response):
+  """Check the user's guess at a captcha solution.
+
+  Args:
+    remote_ip: user's IP address.
+    challenge: The captcha challenge presented to the user.
+    guess: The user's response to the captcha.
+
+  Returns:
+    A pair (correct, error_msg) where error_msg will indicate
+    why a response was deemed incorrect. It is logged so that
+    you can see, e.g., if you have the wrong private key.
+  """
+  # If the use did not enter anything, that is always incorrect
+  if not response:
+    logging.info('response was blank')
+    return False, 'incorrect-captcha-sol'
+
+  resp = _AskRecaptcha(remote_ip, response)
+  if not resp['success']:
+    if 'error-codes' in resp:
+      return False, resp['error-codes']
+    else:
+      return False, 'incorrect-captcha-sol'
+
+  return True, ''
+
+def _AskRecaptcha(remote_ip, response):
+  """Ask the ReCAPTCHA backend to verify the user's guess."""
+  recaptcha_server_request = urllib2.Request(
+      url='https://www.google.com/recaptcha/api/siteverify',
+      data=urllib.urlencode({
+          'secret': secrets_svc.GetRecaptchaPrivateKey(),
+          'remoteip': remote_ip,
+          'response': response}),
+      headers={
+          'Content-type': 'application/x-www-form-urlencoded',
+          'User-agent': 'reCAPTCHA Python'})
+  recaptcha_server_response = urllib2.urlopen(recaptcha_server_request)
+  resp = json.loads(recaptcha_server_response.read())
+  recaptcha_server_response.close()
+
+  return resp
+