Upgrade 3rd packages

third_party/oauth2client/client.py

-# Copyright (C) 2010 Google Inc.
+# Copyright 2014 Google Inc. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #      http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
 """An OAuth 2.0 client.
 
 Tools for interacting with OAuth 2.0 protected resources.
 """
 
 __author__ = 'jcgregorio@google.com (Joe Gregorio)'
 
 import base64
-import clientsecrets
+import collections
 import copy
 import datetime
+import json
+import logging
+import os
+import socket
+import sys
+import tempfile
+import time
+import shutil
+
 from .. import httplib2
-import logging
-import sys
-import time
-import urllib
-import urlparse
-
+from . import clientsecrets
 from . import GOOGLE_AUTH_URI
+from . import GOOGLE_DEVICE_URI
 from . import GOOGLE_REVOKE_URI
 from . import GOOGLE_TOKEN_URI
 from . import util
-from .anyjson import simplejson
+from third_party import six
+from third_party.six.moves import urllib
 
 HAS_OPENSSL = False
 HAS_CRYPTO = False
 try:
-  from . import crypt
+  from oauth2client import crypt

[Adrian Kuegel, 2015/04/16 11:36:28]

From the error message I gather that this was the reason for the breakage.

   HAS_CRYPTO = True
   if crypt.OpenSSLVerifier is not None:
     HAS_OPENSSL = True
 except ImportError:
   pass
 
-try:
-  from urlparse import parse_qsl
-except ImportError:
-  from cgi import parse_qsl
-
 logger = logging.getLogger(__name__)
 
 # Expiry is stored in RFC3339 UTC format
 EXPIRY_FORMAT = '%Y-%m-%dT%H:%M:%SZ'
 
 # Which certs to use to validate id_tokens received.
-ID_TOKEN_VERIFICATON_CERTS = 'https://www.googleapis.com/oauth2/v1/certs'
+ID_TOKEN_VERIFICATION_CERTS = 'https://www.googleapis.com/oauth2/v1/certs'
+# This symbol previously had a typo in the name; we keep the old name
+# around for now, but will remove it in the future.
+ID_TOKEN_VERIFICATON_CERTS = ID_TOKEN_VERIFICATION_CERTS
 
 # Constant to use for the out of band OAuth 2.0 flow.
 OOB_CALLBACK_URN = 'urn:ietf:wg:oauth:2.0:oob'
 
 # Google Data client libraries may need to set this to [401, 403].
 REFRESH_STATUS_CODES = [401]
 
+# The value representing user credentials.
+AUTHORIZED_USER = 'authorized_user'
+
+# The value representing service account credentials.
+SERVICE_ACCOUNT = 'service_account'
+
+# The environment variable pointing the file with local
+# Application Default Credentials.
+GOOGLE_APPLICATION_CREDENTIALS = 'GOOGLE_APPLICATION_CREDENTIALS'
+# The ~/.config subdirectory containing gcloud credentials. Intended
+# to be swapped out in tests.
+_CLOUDSDK_CONFIG_DIRECTORY = 'gcloud'
+
+# The error message we show users when we can't find the Application
+# Default Credentials.
+ADC_HELP_MSG = (
+    'The Application Default Credentials are not available. They are available '
+    'if running in Google Compute Engine. Otherwise, the environment variable '
+    + GOOGLE_APPLICATION_CREDENTIALS +
+    ' must be defined pointing to a file defining the credentials. See '
+    'https://developers.google.com/accounts/docs/application-default-credentials'  # pylint:disable=line-too-long
+    ' for more information.')
+
+# The access token along with the seconds in which it expires.
+AccessTokenInfo = collections.namedtuple(
+    'AccessTokenInfo', ['access_token', 'expires_in'])
+
+DEFAULT_ENV_NAME = 'UNKNOWN'
+
+# If set to True _get_environment avoid GCE check (_detect_gce_environment)
+NO_GCE_CHECK = os.environ.setdefault('NO_GCE_CHECK', 'False')
+
+class SETTINGS(object):
+  """Settings namespace for globally defined values."""
+  env_name = None
+
 
 class Error(Exception):
   """Base error for this module."""
 
 
 class FlowExchangeError(Error):
   """Error trying to exchange an authorization grant for an access token."""
 
 
 class AccessTokenRefreshError(Error):
   """Error trying to refresh an expired access token."""
 
 
 class TokenRevokeError(Error):
   """Error trying to revoke a token."""
 
 
 class UnknownClientSecretsFlowError(Error):
   """The client secrets file called for an unknown type of OAuth 2.0 flow. """
 
 
 class AccessTokenCredentialsError(Error):
   """Having only the access_token means no refresh is possible."""
 
 
 class VerifyJwtTokenError(Error):
-  """Could on retrieve certificates for validation."""
+  """Could not retrieve certificates for validation."""
 
 
 class NonAsciiHeaderError(Error):
   """Header names and values must be ASCII strings."""
 
 
+class ApplicationDefaultCredentialsError(Error):
+  """Error retrieving the Application Default Credentials."""
+
+
+class OAuth2DeviceCodeError(Error):
+  """Error trying to retrieve a device code."""
+
+
+class CryptoUnavailableError(Error, NotImplementedError):
+  """Raised when a crypto library is required, but none is available."""
+
+
 def _abstract():
   raise NotImplementedError('You need to override this function')
 
 
 class MemoryCache(object):
   """httplib2 Cache implementation which only caches locally."""
 
   def __init__(self):
     self.cache = {}
 
   def get(self, key):
     return self.cache.get(key)
 
   def set(self, key, value):
     self.cache[key] = value
 
   def delete(self, key):
     self.cache.pop(key, None)
 
 
 class Credentials(object):
   """Base class for all Credentials objects.
 
   Subclasses must define an authorize() method that applies the credentials to
   an HTTP transport.
 
   Subclasses must also specify a classmethod named 'from_json' that takes a JSON
-  string as input and returns an instaniated Credentials object.
+  string as input and returns an instantiated Credentials object.
   """
 
   NON_SERIALIZED_MEMBERS = ['store']
 
+
   def authorize(self, http):
     """Take an httplib2.Http instance (or equivalent) and authorizes it.
 
     Authorizes it for the set of credentials, usually by replacing
     http.request() with a method that adds in the appropriate headers and then
     delegates to the original Http.request() method.
 
     Args:
       http: httplib2.Http, an http object to be used to make the refresh
         request.
     """
     _abstract()
 
+
   def refresh(self, http):
     """Forces a refresh of the access_token.
 
     Args:
       http: httplib2.Http, an http object to be used to make the refresh
         request.
     """
     _abstract()
 
+
   def revoke(self, http):
     """Revokes a refresh_token and makes the credentials void.
 
     Args:
       http: httplib2.Http, an http object to be used to make the revoke
         request.
     """
     _abstract()
 
+
   def apply(self, headers):
     """Add the authorization to the headers.
 
     Args:
       headers: dict, the headers to add the Authorization header to.
     """
     _abstract()
 
   def _to_json(self, strip):
     """Utility function that creates JSON repr. of a Credentials object.
 
     Args:
       strip: array, An array of names of members to not include in the JSON.
 
     Returns:
        string, a JSON representation of this instance, suitable to pass to
        from_json().
     """
     t = type(self)
     d = copy.copy(self.__dict__)
     for member in strip:
       if member in d:
         del d[member]
-    if 'token_expiry' in d and isinstance(d['token_expiry'], datetime.datetime):
+    if (d.get('token_expiry') and
+        isinstance(d['token_expiry'], datetime.datetime)):
       d['token_expiry'] = d['token_expiry'].strftime(EXPIRY_FORMAT)
     # Add in information we will need later to reconsistitue this instance.
     d['_class'] = t.__name__
     d['_module'] = t.__module__
-    return simplejson.dumps(d)
+    for key, val in d.items():
+      if isinstance(val, bytes):
+        d[key] = val.decode('utf-8')
+    return json.dumps(d)
 
   def to_json(self):
     """Creating a JSON representation of an instance of Credentials.
 
     Returns:
        string, a JSON representation of this instance, suitable to pass to
        from_json().
     """
     return self._to_json(Credentials.NON_SERIALIZED_MEMBERS)
 
   @classmethod
   def new_from_json(cls, s):
     """Utility class method to instantiate a Credentials subclass from a JSON
     representation produced by to_json().
 
     Args:
       s: string, JSON from to_json().
 
     Returns:
       An instance of the subclass of Credentials that was serialized with
       to_json().
     """
-    data = simplejson.loads(s)
+    if six.PY3 and isinstance(s, bytes):
+      s = s.decode('utf-8')
+    data = json.loads(s)
     # Find and call the right classmethod from_json() to restore the object.
     module = data['_module']
     try:
       m = __import__(module)
     except ImportError:
       # In case there's an object from the old package structure, update it
-      module = module.replace('.apiclient', '')
+      module = module.replace('.googleapiclient', '')
       m = __import__(module)
 
     m = __import__(module, fromlist=module.split('.')[:-1])
     kls = getattr(m, data['_class'])
     from_json = getattr(kls, 'from_json')
     return from_json(s)
 
   @classmethod
-  def from_json(cls, s):
+  def from_json(cls, unused_data):
     """Instantiate a Credentials object from a JSON description of it.
 
     The JSON should have been produced by calling .to_json() on the object.
 
     Args:
-      data: dict, A deserialized JSON object.
+      unused_data: dict, A deserialized JSON object.
 
     Returns:
       An instance of a Credentials subclass.
     """
     return Credentials()
 
 
 class Flow(object):
   """Base class for all Flow objects."""
   pass
@@ skipping 101 matching lines @@
   contatenate to a binary request body may result in a unicode decode error.
 
   Args:
     headers: dict, A dictionary of headers.
 
   Returns:
     The same dictionary but with all the keys converted to strings.
   """
   clean = {}
   try:
-    for k, v in headers.iteritems():
-      clean[str(k)] = str(v)
+    for k, v in six.iteritems(headers):
+      clean_k = k if isinstance(k, bytes) else str(k).encode('ascii')
+      clean_v = v if isinstance(v, bytes) else str(v).encode('ascii')
+      clean[clean_k] = clean_v
   except UnicodeEncodeError:
     raise NonAsciiHeaderError(k + ': ' + v)
   return clean
 
 
 def _update_query_params(uri, params):
   """Updates a URI with new query parameters.
 
   Args:
     uri: string, A valid URI, with potential existing query parameters.
     params: dict, A dictionary of query parameters.
 
   Returns:
     The same URI but with the new query parameters added.
   """
-  parts = list(urlparse.urlparse(uri))
-  query_params = dict(parse_qsl(parts[4])) # 4 is the index of the query part
+  parts = urllib.parse.urlparse(uri)
+  query_params = dict(urllib.parse.parse_qsl(parts.query))
   query_params.update(params)
-  parts[4] = urllib.urlencode(query_params)
-  return urlparse.urlunparse(parts)
+  new_parts = parts._replace(query=urllib.parse.urlencode(query_params))
+  return urllib.parse.urlunparse(new_parts)
 
 
 class OAuth2Credentials(Credentials):
   """Credentials object for OAuth 2.0.
 
   Credentials can be applied to an httplib2.Http object using the authorize()
   method, which then adds the OAuth 2.0 access token to each request.
 
   OAuth2Credentials objects may be safely pickled and unpickled.
   """
@@ skipping 47 matching lines @@
   def authorize(self, http):
     """Authorize an httplib2.Http instance with these credentials.
 
     The modified http.request method will add authentication headers to each
     request and will refresh access_tokens when a 401 is received on a
     request. In addition the http.request method has a credentials property,
     http.request.credentials, which is the Credentials object that authorized
     it.
 
     Args:
-       http: An instance of httplib2.Http
-         or something that acts like it.
+       http: An instance of ``httplib2.Http`` or something that acts
+         like it.
 
     Returns:
        A modified instance of http that was passed in.
 
-    Example:
+    Example::
 
       h = httplib2.Http()
       h = credentials.authorize(h)
 
-    You can't create a new OAuth subclass of httplib2.Authenication
+    You can't create a new OAuth subclass of httplib2.Authentication
     because it never gets passed the absolute URI, which is needed for
     signing. So instead we have to overload 'request' with a closure
     that adds in the Authorization header and then calls the original
     version of 'request()'.
+
     """
     request_orig = http.request
 
     # The closure that will replace 'httplib2.Http.request'.
     @util.positional(1)
     def new_request(uri, method='GET', body=None, headers=None,
                     redirections=httplib2.DEFAULT_MAX_REDIRECTS,
                     connection_type=None):
       if not self.access_token:
         logger.info('Attempting refresh to obtain initial access_token')
         self._refresh(request_orig)
 
-      # Modify the request headers to add the appropriate
+      # Clone and modify the request headers to add the appropriate
       # Authorization header.
       if headers is None:
         headers = {}
+      else:
+        headers = dict(headers)
       self.apply(headers)
 
       if self.user_agent is not None:
         if 'user-agent' in headers:
           headers['user-agent'] = self.user_agent + ' ' + headers['user-agent']
         else:
           headers['user-agent'] = self.user_agent
 
       resp, content = request_orig(uri, method, body, clean_headers(headers),
                                    redirections, connection_type)
 
       if resp.status in REFRESH_STATUS_CODES:
-        logger.info('Refreshing due to a %s' % str(resp.status))
+        logger.info('Refreshing due to a %s', resp.status)
         self._refresh(request_orig)
         self.apply(headers)
         return request_orig(uri, method, body, clean_headers(headers),
                             redirections, connection_type)
       else:
         return (resp, content)
 
     # Replace the request method with our own closure.
     http.request = new_request
 
@@ skipping 35 matching lines @@
   def from_json(cls, s):
     """Instantiate a Credentials object from a JSON description of it. The JSON
     should have been produced by calling .to_json() on the object.
 
     Args:
       data: dict, A deserialized JSON object.
 
     Returns:
       An instance of a Credentials subclass.
     """
-    data = simplejson.loads(s)
-    if 'token_expiry' in data and not isinstance(data['token_expiry'],
-        datetime.datetime):
+    if six.PY3 and isinstance(s, bytes):
+      s = s.decode('utf-8')
+    data = json.loads(s)
+    if (data.get('token_expiry') and
+        not isinstance(data['token_expiry'], datetime.datetime)):
       try:
         data['token_expiry'] = datetime.datetime.strptime(
             data['token_expiry'], EXPIRY_FORMAT)
-      except:
+      except ValueError:
         data['token_expiry'] = None
     retval = cls(
         data['access_token'],
         data['client_id'],
         data['client_secret'],
         data['refresh_token'],
         data['token_expiry'],
         data['token_uri'],
         data['user_agent'],
         revoke_uri=data.get('revoke_uri', None),
@@ skipping 14 matching lines @@
     if not self.token_expiry:
       return False
 
     now = datetime.datetime.utcnow()
     if now >= self.token_expiry:
       logger.info('access_token is expired. Now: %s, token_expiry: %s',
                   now, self.token_expiry)
       return True
     return False
 
+  def get_access_token(self, http=None):
+    """Return the access token and its expiration information.
+
+    If the token does not exist, get one.
+    If the token expired, refresh it.
+    """
+    if not self.access_token or self.access_token_expired:
+      if not http:
+        http = httplib2.Http()
+      self.refresh(http)
+    return AccessTokenInfo(access_token=self.access_token,
+                           expires_in=self._expires_in())
+
   def set_store(self, store):
     """Set the Storage for the credential.
 
     Args:
-      store: Storage, an implementation of Stroage object.
+      store: Storage, an implementation of Storage object.
         This is needed to store the latest access_token if it
         has expired and been refreshed. This implementation uses
         locking to check for updates before updating the
         access_token.
     """
     self.store = store
 
+  def _expires_in(self):
+    """Return the number of seconds until this token expires.
+
+    If token_expiry is in the past, this method will return 0, meaning the
+    token has already expired.
+    If token_expiry is None, this method will return None. Note that returning
+    0 in such a case would not be fair: the token may still be valid;
+    we just don't know anything about it.
+    """
+    if self.token_expiry:
+      now = datetime.datetime.utcnow()
+      if self.token_expiry > now:
+        time_delta = self.token_expiry - now
+        # TODO(orestica): return time_delta.total_seconds()
+        # once dropping support for Python 2.6
+        return time_delta.days * 86400 + time_delta.seconds
+      else:
+        return 0
+
   def _updateFromCredential(self, other):
     """Update this Credential from another instance."""
     self.__dict__.update(other.__getstate__())
 
   def __getstate__(self):
     """Trim the state down to something that can be pickled."""
     d = copy.copy(self.__dict__)
     del d['store']
     return d
 
   def __setstate__(self, state):
     """Reconstitute the state of the object from being pickled."""
     self.__dict__.update(state)
     self.store = None
 
   def _generate_refresh_request_body(self):
     """Generate the body that will be used in the refresh request."""
-    body = urllib.urlencode({
+    body = urllib.parse.urlencode({
         'grant_type': 'refresh_token',
         'client_id': self.client_id,
         'client_secret': self.client_secret,
         'refresh_token': self.refresh_token,
         })
     return body
 
   def _generate_refresh_request_headers(self):
     """Generate the headers that will be used in the refresh request."""
     headers = {
@@ skipping 43 matching lines @@
 
     Raises:
       AccessTokenRefreshError: When the refresh fails.
     """
     body = self._generate_refresh_request_body()
     headers = self._generate_refresh_request_headers()
 
     logger.info('Refreshing access_token')
     resp, content = http_request(
         self.token_uri, method='POST', body=body, headers=headers)
+    if six.PY3 and isinstance(content, bytes):
+      content = content.decode('utf-8')
     if resp.status == 200:
-      # TODO(jcgregorio) Raise an error if loads fails?
-      d = simplejson.loads(content)
+      d = json.loads(content)
       self.token_response = d
       self.access_token = d['access_token']
       self.refresh_token = d.get('refresh_token', self.refresh_token)
       if 'expires_in' in d:
         self.token_expiry = datetime.timedelta(
             seconds=int(d['expires_in'])) + datetime.datetime.utcnow()
       else:
         self.token_expiry = None
+      # On temporary refresh errors, the user does not actually have to
+      # re-authorize, so we unflag here.
+      self.invalid = False
       if self.store:
         self.store.locked_put(self)
     else:
       # An {'error':...} response body means the token is expired or revoked,
       # so we flag the credentials as such.
-      logger.info('Failed to retrieve access token: %s' % content)
+      logger.info('Failed to retrieve access token: %s', content)
       error_msg = 'Invalid response %s.' % resp['status']
       try:
-        d = simplejson.loads(content)
+        d = json.loads(content)
         if 'error' in d:
           error_msg = d['error']
+          if 'error_description' in d:
+            error_msg += ': ' + d['error_description']
           self.invalid = True
           if self.store:
             self.store.locked_put(self)
-      except StandardError:
+      except (TypeError, ValueError):
         pass
       raise AccessTokenRefreshError(error_msg)
 
   def _revoke(self, http_request):
-    """Revokes the refresh_token and deletes the store if available.
+    """Revokes this credential and deletes the stored copy (if it exists).
 
     Args:
       http_request: callable, a callable that matches the method signature of
         httplib2.Http.request, used to make the revoke request.
     """
-    self._do_revoke(http_request, self.refresh_token)
+    self._do_revoke(http_request, self.refresh_token or self.access_token)
 
   def _do_revoke(self, http_request, token):
-    """Revokes the credentials and deletes the store if available.
+    """Revokes this credential and deletes the stored copy (if it exists).
 
     Args:
       http_request: callable, a callable that matches the method signature of
         httplib2.Http.request, used to make the refresh request.
       token: A string used as the token to be revoked. Can be either an
         access_token or refresh_token.
 
     Raises:
       TokenRevokeError: If the revoke request does not return with a 200 OK.
     """
     logger.info('Revoking token')
     query_params = {'token': token}
     token_revoke_uri = _update_query_params(self.revoke_uri, query_params)
     resp, content = http_request(token_revoke_uri)
     if resp.status == 200:
       self.invalid = True
     else:
       error_msg = 'Invalid response %s.' % resp.status
       try:
-        d = simplejson.loads(content)
+        d = json.loads(content)
         if 'error' in d:
           error_msg = d['error']
-      except StandardError:
+      except (TypeError, ValueError):
         pass
       raise TokenRevokeError(error_msg)
 
     if self.store:
       self.store.delete()
 
 
 class AccessTokenCredentials(OAuth2Credentials):
   """Credentials object for OAuth 2.0.
 
   Credentials can be applied to an httplib2.Http object using the
   authorize() method, which then signs each request from that object
   with the OAuth 2.0 access token. This set of credentials is for the
   use case where you have acquired an OAuth 2.0 access_token from
   another place such as a JavaScript client or another web
   application, and wish to use it from Python. Because only the
   access_token is present it can not be refreshed and will in time
   expire.
 
   AccessTokenCredentials objects may be safely pickled and unpickled.
 
-  Usage:
+  Usage::
+
     credentials = AccessTokenCredentials('<an access token>',
       'my-user-agent/1.0')
     http = httplib2.Http()
     http = credentials.authorize(http)
 
   Exceptions:
     AccessTokenCredentialsExpired: raised when the access_token expires or is
       revoked.
   """
 
@@ skipping 15 matching lines @@
         None,
         None,
         None,
         None,
         user_agent,
         revoke_uri=revoke_uri)
 
 
   @classmethod
   def from_json(cls, s):
-    data = simplejson.loads(s)
+    if six.PY3 and isinstance(s, bytes):
+      s = s.decode('utf-8')
+    data = json.loads(s)
     retval = AccessTokenCredentials(
-        data['access_token'],
-        data['user_agent'])
+      data['access_token'],
+      data['user_agent'])
     return retval
 
   def _refresh(self, http_request):
     raise AccessTokenCredentialsError(
         'The access_token is expired or invalid and can\'t be refreshed.')
 
   def _revoke(self, http_request):
     """Revokes the access_token and deletes the store if available.
 
     Args:
       http_request: callable, a callable that matches the method signature of
         httplib2.Http.request, used to make the revoke request.
     """
     self._do_revoke(http_request, self.access_token)
 
 
-class AssertionCredentials(OAuth2Credentials):
+def _detect_gce_environment(urlopen=None):
+  """Determine if the current environment is Compute Engine.
+
+  Args:
+      urlopen: Optional argument. Function used to open a connection to a URL.
+
+  Returns:
+      Boolean indicating whether or not the current environment is Google
+          Compute Engine.
+  """
+  urlopen = urlopen or urllib.request.urlopen
+  # Note: the explicit `timeout` below is a workaround. The underlying
+  # issue is that resolving an unknown host on some networks will take
+  # 20-30 seconds; making this timeout short fixes the issue, but
+  # could lead to false negatives in the event that we are on GCE, but
+  # the metadata resolution was particularly slow. The latter case is
+  # "unlikely".
+  try:
+    response = urlopen('http://169.254.169.254/', timeout=1)
+    return response.info().get('Metadata-Flavor', '') == 'Google'
+  except socket.timeout:
+    logger.info('Timeout attempting to reach GCE metadata service.')
+    return False
+  except urllib.error.URLError as e:
+    if isinstance(getattr(e, 'reason', None), socket.timeout):
+      logger.info('Timeout attempting to reach GCE metadata service.')
+    return False
+
+
+def _get_environment(urlopen=None):
+  """Detect the environment the code is being run on.
+
+  Args:
+      urlopen: Optional argument. Function used to open a connection to a URL.
+
+  Returns:
+      The value of SETTINGS.env_name after being set. If already
+          set, simply returns the value.
+  """
+  if SETTINGS.env_name is not None:
+    return SETTINGS.env_name
+
+  # None is an unset value, not the default.
+  SETTINGS.env_name = DEFAULT_ENV_NAME
+
+  server_software = os.environ.get('SERVER_SOFTWARE', '')
+  if server_software.startswith('Google App Engine/'):
+    SETTINGS.env_name = 'GAE_PRODUCTION'
+  elif server_software.startswith('Development/'):
+    SETTINGS.env_name = 'GAE_LOCAL'
+  elif NO_GCE_CHECK != 'True' and _detect_gce_environment(urlopen=urlopen):
+    SETTINGS.env_name = 'GCE_PRODUCTION'
+
+  return SETTINGS.env_name
+
+
+class GoogleCredentials(OAuth2Credentials):
+  """Application Default Credentials for use in calling Google APIs.
+
+  The Application Default Credentials are being constructed as a function of
+  the environment where the code is being run.
+  More details can be found on this page:
+  https://developers.google.com/accounts/docs/application-default-credentials
+
+  Here is an example of how to use the Application Default Credentials for a
+  service that requires authentication:
+
+      from googleapiclient.discovery import build
+      from oauth2client.client import GoogleCredentials
+
+      credentials = GoogleCredentials.get_application_default()
+      service = build('compute', 'v1', credentials=credentials)
+
+      PROJECT = 'bamboo-machine-422'
+      ZONE = 'us-central1-a'
+      request = service.instances().list(project=PROJECT, zone=ZONE)
+      response = request.execute()
+
+      print(response)
+ """
+
+  def __init__(self, access_token, client_id, client_secret, refresh_token,
+               token_expiry, token_uri, user_agent,
+               revoke_uri=GOOGLE_REVOKE_URI):
+    """Create an instance of GoogleCredentials.
+
+    This constructor is not usually called by the user, instead
+    GoogleCredentials objects are instantiated by
+    GoogleCredentials.from_stream() or
+    GoogleCredentials.get_application_default().
+
+    Args:
+      access_token: string, access token.
+      client_id: string, client identifier.
+      client_secret: string, client secret.
+      refresh_token: string, refresh token.
+      token_expiry: datetime, when the access_token expires.
+      token_uri: string, URI of token endpoint.
+      user_agent: string, The HTTP User-Agent to provide for this application.
+      revoke_uri: string, URI for revoke endpoint.
+        Defaults to GOOGLE_REVOKE_URI; a token can't be revoked if this is None.
+    """
+    super(GoogleCredentials, self).__init__(
+        access_token, client_id, client_secret, refresh_token, token_expiry,
+        token_uri, user_agent, revoke_uri=revoke_uri)
+
+  def create_scoped_required(self):
+    """Whether this Credentials object is scopeless.
+
+    create_scoped(scopes) method needs to be called in order to create
+    a Credentials object for API calls.
+    """
+    return False
+
+  def create_scoped(self, scopes):
+    """Create a Credentials object for the given scopes.
+
+    The Credentials type is preserved.
+    """
+    return self
+
+  @property
+  def serialization_data(self):
+    """Get the fields and their values identifying the current credentials."""
+    return {
+        'type': 'authorized_user',
+        'client_id': self.client_id,
+        'client_secret': self.client_secret,
+        'refresh_token': self.refresh_token
+    }
+
+  @staticmethod
+  def _implicit_credentials_from_gae(env_name=None):
+    """Attempts to get implicit credentials in Google App Engine env.
+
+    If the current environment is not detected as App Engine, returns None,
+    indicating no Google App Engine credentials can be detected from the
+    current environment.
+
+    Args:
+        env_name: String, indicating current environment.
+
+    Returns:
+        None, if not in GAE, else an appengine.AppAssertionCredentials object.
+    """
+    env_name = env_name or _get_environment()
+    if env_name not in ('GAE_PRODUCTION', 'GAE_LOCAL'):
+      return None
+
+    return _get_application_default_credential_GAE()
+
+  @staticmethod
+  def _implicit_credentials_from_gce(env_name=None):
+    """Attempts to get implicit credentials in Google Compute Engine env.
+
+    If the current environment is not detected as Compute Engine, returns None,
+    indicating no Google Compute Engine credentials can be detected from the
+    current environment.
+
+    Args:
+        env_name: String, indicating current environment.
+
+    Returns:
+        None, if not in GCE, else a gce.AppAssertionCredentials object.
+    """
+    env_name = env_name or _get_environment()
+    if env_name != 'GCE_PRODUCTION':
+      return None
+
+    return _get_application_default_credential_GCE()
+
+  @staticmethod
+  def _implicit_credentials_from_files(env_name=None):
+    """Attempts to get implicit credentials from local credential files.
+
+    First checks if the environment variable GOOGLE_APPLICATION_CREDENTIALS
+    is set with a filename and then falls back to a configuration file (the
+    "well known" file) associated with the 'gcloud' command line tool.
+
+    Args:
+        env_name: Unused argument.
+
+    Returns:
+        Credentials object associated with the GOOGLE_APPLICATION_CREDENTIALS
+            file or the "well known" file if either exist. If neither file is
+            define, returns None, indicating no credentials from a file can
+            detected from the current environment.
+    """
+    credentials_filename = _get_environment_variable_file()
+    if not credentials_filename:
+      credentials_filename = _get_well_known_file()
+      if os.path.isfile(credentials_filename):
+        extra_help = (' (produced automatically when running'
+                      ' "gcloud auth login" command)')
+      else:
+        credentials_filename = None
+    else:
+      extra_help = (' (pointed to by ' + GOOGLE_APPLICATION_CREDENTIALS +
+                    ' environment variable)')
+
+    if not credentials_filename:
+      return
+
+    try:
+      return _get_application_default_credential_from_file(credentials_filename)
+    except (ApplicationDefaultCredentialsError, ValueError) as error:
+      _raise_exception_for_reading_json(credentials_filename, extra_help, error)
+
+  @classmethod
+  def _get_implicit_credentials(cls):
+    """Gets credentials implicitly from the environment.
+
+    Checks environment in order of precedence:
+    - Google App Engine (production and testing)
+    - Environment variable GOOGLE_APPLICATION_CREDENTIALS pointing to
+      a file with stored credentials information.
+    - Stored "well known" file associated with `gcloud` command line tool.
+    - Google Compute Engine production environment.
+
+    Exceptions:
+      ApplicationDefaultCredentialsError: raised when the credentials fail
+          to be retrieved.
+    """
+    env_name = _get_environment()
+
+    # Environ checks (in order). Assumes each checker takes `env_name`
+    # as a kwarg.
+    environ_checkers = [
+      cls._implicit_credentials_from_gae,
+      cls._implicit_credentials_from_files,
+      cls._implicit_credentials_from_gce,
+    ]
+
+    for checker in environ_checkers:
+      credentials = checker(env_name=env_name)
+      if credentials is not None:
+        return credentials
+
+    # If no credentials, fail.
+    raise ApplicationDefaultCredentialsError(ADC_HELP_MSG)
+
+  @staticmethod
+  def get_application_default():
+    """Get the Application Default Credentials for the current environment.
+
+    Exceptions:
+      ApplicationDefaultCredentialsError: raised when the credentials fail
+                                          to be retrieved.
+    """
+    return GoogleCredentials._get_implicit_credentials()
+
+  @staticmethod
+  def from_stream(credential_filename):
+    """Create a Credentials object by reading the information from a given file.
+
+    It returns an object of type GoogleCredentials.
+
+    Args:
+      credential_filename: the path to the file from where the credentials
+        are to be read
+
+    Exceptions:
+      ApplicationDefaultCredentialsError: raised when the credentials fail
+                                          to be retrieved.
+    """
+
+    if credential_filename and os.path.isfile(credential_filename):
+      try:
+        return _get_application_default_credential_from_file(
+            credential_filename)
+      except (ApplicationDefaultCredentialsError, ValueError) as error:
+        extra_help = ' (provided as parameter to the from_stream() method)'
+        _raise_exception_for_reading_json(credential_filename,
+                                          extra_help,
+                                          error)
+    else:
+      raise ApplicationDefaultCredentialsError(
+          'The parameter passed to the from_stream() '
+          'method should point to a file.')
+
+
+def _save_private_file(filename, json_contents):
+  """Saves a file with read-write permissions on for the owner.
+
+  Args:
+    filename: String. Absolute path to file.
+    json_contents: JSON serializable object to be saved.
+  """
+  temp_filename = tempfile.mktemp()
+  file_desc = os.open(temp_filename, os.O_WRONLY | os.O_CREAT, 0o600)
+  with os.fdopen(file_desc, 'w') as file_handle:
+    json.dump(json_contents, file_handle, sort_keys=True,
+              indent=2, separators=(',', ': '))
+  shutil.move(temp_filename, filename)
+
+
+def save_to_well_known_file(credentials, well_known_file=None):
+  """Save the provided GoogleCredentials to the well known file.
+
+  Args:
+    credentials:
+      the credentials to be saved to the well known file;
+      it should be an instance of GoogleCredentials
+    well_known_file:
+      the name of the file where the credentials are to be saved;
+      this parameter is supposed to be used for testing only
+  """
+  # TODO(orestica): move this method to tools.py
+  # once the argparse import gets fixed (it is not present in Python 2.6)
+
+  if well_known_file is None:
+    well_known_file = _get_well_known_file()
+
+  credentials_data = credentials.serialization_data
+  _save_private_file(well_known_file, credentials_data)
+
+
+def _get_environment_variable_file():
+  application_default_credential_filename = (
+      os.environ.get(GOOGLE_APPLICATION_CREDENTIALS,
+                     None))
+
+  if application_default_credential_filename:
+    if os.path.isfile(application_default_credential_filename):
+      return application_default_credential_filename
+    else:
+      raise ApplicationDefaultCredentialsError(
+          'File ' + application_default_credential_filename + ' (pointed by ' +
+          GOOGLE_APPLICATION_CREDENTIALS +
+          ' environment variable) does not exist!')
+
+
+def _get_well_known_file():
+  """Get the well known file produced by command 'gcloud auth login'."""
+  # TODO(orestica): Revisit this method once gcloud provides a better way
+  # of pinpointing the exact location of the file.
+
+  WELL_KNOWN_CREDENTIALS_FILE = 'application_default_credentials.json'
+
+  if os.name == 'nt':
+    try:
+      default_config_path = os.path.join(os.environ['APPDATA'],
+                                         _CLOUDSDK_CONFIG_DIRECTORY)
+    except KeyError:
+      # This should never happen unless someone is really messing with things.
+      drive = os.environ.get('SystemDrive', 'C:')
+      default_config_path = os.path.join(drive, '\\',
+                                         _CLOUDSDK_CONFIG_DIRECTORY)
+  else:
+    default_config_path = os.path.join(os.path.expanduser('~'),
+                                       '.config',
+                                       _CLOUDSDK_CONFIG_DIRECTORY)
+
+  default_config_path = os.path.join(default_config_path,
+                                     WELL_KNOWN_CREDENTIALS_FILE)
+
+  return default_config_path
+
+
+def _get_application_default_credential_from_file(filename):
+  """Build the Application Default Credentials from file."""
+
+  from oauth2client import service_account
+
+  # read the credentials from the file
+  with open(filename) as file_obj:
+    client_credentials = json.load(file_obj)
+
+  credentials_type = client_credentials.get('type')
+  if credentials_type == AUTHORIZED_USER:
+    required_fields = set(['client_id', 'client_secret', 'refresh_token'])
+  elif credentials_type == SERVICE_ACCOUNT:
+    required_fields = set(['client_id', 'client_email', 'private_key_id',
+                           'private_key'])
+  else:
+    raise ApplicationDefaultCredentialsError(
+        "'type' field should be defined (and have one of the '" +
+        AUTHORIZED_USER + "' or '" + SERVICE_ACCOUNT + "' values)")
+
+  missing_fields = required_fields.difference(client_credentials.keys())
+
+  if missing_fields:
+    _raise_exception_for_missing_fields(missing_fields)
+
+  if client_credentials['type'] == AUTHORIZED_USER:
+    return GoogleCredentials(
+        access_token=None,
+        client_id=client_credentials['client_id'],
+        client_secret=client_credentials['client_secret'],
+        refresh_token=client_credentials['refresh_token'],
+        token_expiry=None,
+        token_uri=GOOGLE_TOKEN_URI,
+        user_agent='Python client library')
+  else:  # client_credentials['type'] == SERVICE_ACCOUNT
+    return service_account._ServiceAccountCredentials(
+        service_account_id=client_credentials['client_id'],
+        service_account_email=client_credentials['client_email'],
+        private_key_id=client_credentials['private_key_id'],
+        private_key_pkcs8_text=client_credentials['private_key'],
+        scopes=[])
+
+
+def _raise_exception_for_missing_fields(missing_fields):
+  raise ApplicationDefaultCredentialsError(
+      'The following field(s) must be defined: ' + ', '.join(missing_fields))
+
+
+def _raise_exception_for_reading_json(credential_file,
+                                      extra_help,
+                                      error):
+  raise ApplicationDefaultCredentialsError(
+      'An error was encountered while reading json file: '+
+      credential_file + extra_help + ': ' + str(error))
+
+
+def _get_application_default_credential_GAE():
+  from oauth2client.appengine import AppAssertionCredentials
+
+  return AppAssertionCredentials([])
+
+
+def _get_application_default_credential_GCE():
+  from oauth2client.gce import AppAssertionCredentials
+
+  return AppAssertionCredentials([])
+
+
+class AssertionCredentials(GoogleCredentials):
   """Abstract Credentials object used for OAuth 2.0 assertion grants.
 
   This credential does not require a flow to instantiate because it
   represents a two legged flow, and therefore has all of the required
   information to generate and refresh its own access tokens. It must
   be subclassed to generate the appropriate assertion string.
 
   AssertionCredentials objects may be safely pickled and unpickled.
   """
 
@@ skipping 19 matching lines @@
         None,
         None,
         token_uri,
         user_agent,
         revoke_uri=revoke_uri)
     self.assertion_type = assertion_type
 
   def _generate_refresh_request_body(self):
     assertion = self._generate_assertion()
 
-    body = urllib.urlencode({
+    body = urllib.parse.urlencode({
         'assertion': assertion,
         'grant_type': 'urn:ietf:params:oauth:grant-type:jwt-bearer',
         })
 
     return body
 
   def _generate_assertion(self):
     """Generate the assertion string that will be used in the access token
     request.
     """
     _abstract()
 
   def _revoke(self, http_request):
     """Revokes the access_token and deletes the store if available.
 
     Args:
       http_request: callable, a callable that matches the method signature of
         httplib2.Http.request, used to make the revoke request.
     """
     self._do_revoke(http_request, self.access_token)
 
 
-if HAS_CRYPTO:
-  # PyOpenSSL and PyCrypto are not prerequisites for oauth2client, so if it is
-  # missing then don't create the SignedJwtAssertionCredentials or the
-  # verify_id_token() method.
+def _RequireCryptoOrDie():
+  """Ensure we have a crypto library, or throw CryptoUnavailableError.
 
-  class SignedJwtAssertionCredentials(AssertionCredentials):
-    """Credentials object used for OAuth 2.0 Signed JWT assertion grants.
+  The oauth2client.crypt module requires either PyCrypto or PyOpenSSL
+  to be available in order to function, but these are optional
+  dependencies.
+  """
+  if not HAS_CRYPTO:
+    raise CryptoUnavailableError('No crypto library available')
 
-    This credential does not require a flow to instantiate because it represents
-    a two legged flow, and therefore has all of the required information to
-    generate and refresh its own access tokens.
 
-    SignedJwtAssertionCredentials requires either PyOpenSSL, or PyCrypto 2.6 or
-    later. For App Engine you may also consider using AppAssertionCredentials.
-    """
+class SignedJwtAssertionCredentials(AssertionCredentials):
+  """Credentials object used for OAuth 2.0 Signed JWT assertion grants.
 
-    MAX_TOKEN_LIFETIME_SECS = 3600 # 1 hour in seconds
+  This credential does not require a flow to instantiate because it
+  represents a two legged flow, and therefore has all of the required
+  information to generate and refresh its own access tokens.
 
-    @util.positional(4)
-    def __init__(self,
-        service_account_name,
-        private_key,
-        scope,
-        private_key_password='notasecret',
-        user_agent=None,
-        token_uri=GOOGLE_TOKEN_URI,
-        revoke_uri=GOOGLE_REVOKE_URI,
-        **kwargs):
-      """Constructor for SignedJwtAssertionCredentials.
+  SignedJwtAssertionCredentials requires either PyOpenSSL, or PyCrypto
+  2.6 or later. For App Engine you may also consider using
+  AppAssertionCredentials.
+  """
 
-      Args:
-        service_account_name: string, id for account, usually an email address.
-        private_key: string, private key in PKCS12 or PEM format.
-        scope: string or iterable of strings, scope(s) of the credentials being
-          requested.
-        private_key_password: string, password for private_key, unused if
-          private_key is in PEM format.
-        user_agent: string, HTTP User-Agent to provide for this application.
-        token_uri: string, URI for token endpoint. For convenience
-          defaults to Google's endpoints but any OAuth 2.0 provider can be used.
-        revoke_uri: string, URI for revoke endpoint.
-        kwargs: kwargs, Additional parameters to add to the JWT token, for
-          example sub=joe@xample.org."""
+  MAX_TOKEN_LIFETIME_SECS = 3600  # 1 hour in seconds
 
-      super(SignedJwtAssertionCredentials, self).__init__(
-          None,
-          user_agent=user_agent,
-          token_uri=token_uri,
-          revoke_uri=revoke_uri,
-          )
-
-      self.scope = util.scopes_to_string(scope)
-
-      # Keep base64 encoded so it can be stored in JSON.
-      self.private_key = base64.b64encode(private_key)
-
-      self.private_key_password = private_key_password
-      self.service_account_name = service_account_name
-      self.kwargs = kwargs
-
-    @classmethod
-    def from_json(cls, s):
-      data = simplejson.loads(s)
-      retval = SignedJwtAssertionCredentials(
-          data['service_account_name'],
-          base64.b64decode(data['private_key']),
-          data['scope'],
-          private_key_password=data['private_key_password'],
-          user_agent=data['user_agent'],
-          token_uri=data['token_uri'],
-          **data['kwargs']
-          )
-      retval.invalid = data['invalid']
-      retval.access_token = data['access_token']
-      return retval
-
-    def _generate_assertion(self):
-      """Generate the assertion that will be used in the request."""
-      now = long(time.time())
-      payload = {
-          'aud': self.token_uri,
-          'scope': self.scope,
-          'iat': now,
-          'exp': now + SignedJwtAssertionCredentials.MAX_TOKEN_LIFETIME_SECS,
-          'iss': self.service_account_name
-      }
-      payload.update(self.kwargs)
-      logger.debug(str(payload))
-
-      private_key = base64.b64decode(self.private_key)
-      return crypt.make_signed_jwt(crypt.Signer.from_string(
-          private_key, self.private_key_password), payload)
-
-  # Only used in verify_id_token(), which is always calling to the same URI
-  # for the certs.
-  _cached_http = httplib2.Http(MemoryCache())
-
-  @util.positional(2)
-  def verify_id_token(id_token, audience, http=None,
-      cert_uri=ID_TOKEN_VERIFICATON_CERTS):
-    """Verifies a signed JWT id_token.
-
-    This function requires PyOpenSSL and because of that it does not work on
-    App Engine.
+  @util.positional(4)
+  def __init__(self,
+               service_account_name,
+               private_key,
+               scope,
+               private_key_password='notasecret',
+               user_agent=None,
+               token_uri=GOOGLE_TOKEN_URI,
+               revoke_uri=GOOGLE_REVOKE_URI,
+               **kwargs):
+    """Constructor for SignedJwtAssertionCredentials.
 
     Args:
-      id_token: string, A Signed JWT.
-      audience: string, The audience 'aud' that the token should be for.
-      http: httplib2.Http, instance to use to make the HTTP request. Callers
-        should supply an instance that has caching enabled.
-      cert_uri: string, URI of the certificates in JSON format to
-        verify the JWT against.
-
-    Returns:
-      The deserialized JSON in the JWT.
+      service_account_name: string, id for account, usually an email address.
+      private_key: string, private key in PKCS12 or PEM format.
+      scope: string or iterable of strings, scope(s) of the credentials being
+        requested.
+      private_key_password: string, password for private_key, unused if
+        private_key is in PEM format.
+      user_agent: string, HTTP User-Agent to provide for this application.
+      token_uri: string, URI for token endpoint. For convenience
+        defaults to Google's endpoints but any OAuth 2.0 provider can be used.
+      revoke_uri: string, URI for revoke endpoint.
+      kwargs: kwargs, Additional parameters to add to the JWT token, for
+        example sub=joe@xample.org.
 
     Raises:
-      oauth2client.crypt.AppIdentityError if the JWT fails to verify.
+      CryptoUnavailableError if no crypto library is available.
     """
-    if http is None:
-      http = _cached_http
+    _RequireCryptoOrDie()
+    super(SignedJwtAssertionCredentials, self).__init__(
+        None,
+        user_agent=user_agent,
+        token_uri=token_uri,
+        revoke_uri=revoke_uri,
+        )
 
-    resp, content = http.request(cert_uri)
+    self.scope = util.scopes_to_string(scope)
 
-    if resp.status == 200:
-      certs = simplejson.loads(content)
-      return crypt.verify_signed_jwt_with_certs(id_token, certs, audience)
-    else:
-      raise VerifyJwtTokenError('Status code: %d' % resp.status)
+    # Keep base64 encoded so it can be stored in JSON.
+    self.private_key = base64.b64encode(private_key)
+    if isinstance(self.private_key, six.text_type):
+      self.private_key = self.private_key.encode('utf-8')
+
+    self.private_key_password = private_key_password
+    self.service_account_name = service_account_name
+    self.kwargs = kwargs
+
+  @classmethod
+  def from_json(cls, s):
+    data = json.loads(s)
+    retval = SignedJwtAssertionCredentials(
+        data['service_account_name'],
+        base64.b64decode(data['private_key']),
+        data['scope'],
+        private_key_password=data['private_key_password'],
+        user_agent=data['user_agent'],
+        token_uri=data['token_uri'],
+        **data['kwargs']
+        )
+    retval.invalid = data['invalid']
+    retval.access_token = data['access_token']
+    return retval
+
+  def _generate_assertion(self):
+    """Generate the assertion that will be used in the request."""
+    now = int(time.time())
+    payload = {
+        'aud': self.token_uri,
+        'scope': self.scope,
+        'iat': now,
+        'exp': now + SignedJwtAssertionCredentials.MAX_TOKEN_LIFETIME_SECS,
+        'iss': self.service_account_name
+    }
+    payload.update(self.kwargs)
+    logger.debug(str(payload))
+
+    private_key = base64.b64decode(self.private_key)
+    return crypt.make_signed_jwt(crypt.Signer.from_string(
+        private_key, self.private_key_password), payload)
+
+# Only used in verify_id_token(), which is always calling to the same URI
+# for the certs.
+_cached_http = httplib2.Http(MemoryCache())
+
+@util.positional(2)
+def verify_id_token(id_token, audience, http=None,
+                    cert_uri=ID_TOKEN_VERIFICATION_CERTS):
+  """Verifies a signed JWT id_token.
+
+  This function requires PyOpenSSL and because of that it does not work on
+  App Engine.
+
+  Args:
+    id_token: string, A Signed JWT.
+    audience: string, The audience 'aud' that the token should be for.
+    http: httplib2.Http, instance to use to make the HTTP request. Callers
+      should supply an instance that has caching enabled.
+    cert_uri: string, URI of the certificates in JSON format to
+      verify the JWT against.
+
+  Returns:
+    The deserialized JSON in the JWT.
+
+  Raises:
+    oauth2client.crypt.AppIdentityError: if the JWT fails to verify.
+    CryptoUnavailableError: if no crypto library is available.
+  """
+  _RequireCryptoOrDie()
+  if http is None:
+    http = _cached_http
+
+  resp, content = http.request(cert_uri)
+
+  if resp.status == 200:
+    certs = json.loads(content.decode('utf-8'))
+    return crypt.verify_signed_jwt_with_certs(id_token, certs, audience)
+  else:
+    raise VerifyJwtTokenError('Status code: %d' % resp.status)
 
 
 def _urlsafe_b64decode(b64string):
   # Guard against unicode strings, which base64 can't handle.
-  b64string = b64string.encode('ascii')
-  padded = b64string + '=' * (4 - len(b64string) % 4)
+  if isinstance(b64string, six.text_type):
+    b64string = b64string.encode('ascii')
+  padded = b64string + b'=' * (4 - len(b64string) % 4)
   return base64.urlsafe_b64decode(padded)
 
 
 def _extract_id_token(id_token):
   """Extract the JSON payload from a JWT.
 
   Does the extraction w/o checking the signature.
 
   Args:
-    id_token: string, OAuth 2.0 id_token.
+    id_token: string or bytestring, OAuth 2.0 id_token.
 
   Returns:
     object, The deserialized JSON payload.
   """
-  segments = id_token.split('.')
+  if type(id_token) == bytes:
+    segments = id_token.split(b'.')
+  else:
+    segments = id_token.split(u'.')
 
-  if (len(segments) != 3):
+  if len(segments) != 3:
     raise VerifyJwtTokenError(
-      'Wrong number of segments in token: %s' % id_token)
+        'Wrong number of segments in token: %s' % id_token)
 
-  return simplejson.loads(_urlsafe_b64decode(segments[1]))
+  return json.loads(_urlsafe_b64decode(segments[1]).decode('utf-8'))
 
 
 def _parse_exchange_token_response(content):
   """Parses response of an exchange token request.
 
   Most providers return JSON but some (e.g. Facebook) return a
   url-encoded string.
 
   Args:
     content: The body of a response
 
   Returns:
     Content as a dictionary object. Note that the dict could be empty,
     i.e. {}. That basically indicates a failure.
   """
   resp = {}
   try:
-    resp = simplejson.loads(content)
-  except StandardError:
+    resp = json.loads(content.decode('utf-8'))
+  except Exception:
     # different JSON libs raise different exceptions,
     # so we just do a catch-all here
-    resp = dict(parse_qsl(content))
+    content = content.decode('utf-8')
+    resp = dict(urllib.parse.parse_qsl(content))
 
   # some providers respond with 'expires', others with 'expires_in'
   if resp and 'expires' in resp:
     resp['expires_in'] = resp.pop('expires')
 
   return resp
 
 
 @util.positional(4)
 def credentials_from_code(client_id, client_secret, scope, code,
                           redirect_uri='postmessage', http=None,
                           user_agent=None, token_uri=GOOGLE_TOKEN_URI,
                           auth_uri=GOOGLE_AUTH_URI,
-                          revoke_uri=GOOGLE_REVOKE_URI):
+                          revoke_uri=GOOGLE_REVOKE_URI,
+                          device_uri=GOOGLE_DEVICE_URI):
   """Exchanges an authorization code for an OAuth2Credentials object.
 
   Args:
     client_id: string, client identifier.
     client_secret: string, client secret.
     scope: string or iterable of strings, scope(s) to request.
-    code: string, An authroization code, most likely passed down from
+    code: string, An authorization code, most likely passed down from
       the client
     redirect_uri: string, this is generally set to 'postmessage' to match the
       redirect_uri that the client specified
     http: httplib2.Http, optional http instance to use to do the fetch
     token_uri: string, URI for token endpoint. For convenience
       defaults to Google's endpoints but any OAuth 2.0 provider can be used.
     auth_uri: string, URI for authorization endpoint. For convenience
       defaults to Google's endpoints but any OAuth 2.0 provider can be used.
     revoke_uri: string, URI for revoke endpoint. For convenience
       defaults to Google's endpoints but any OAuth 2.0 provider can be used.
+    device_uri: string, URI for device authorization endpoint. For convenience
+      defaults to Google's endpoints but any OAuth 2.0 provider can be used.
 
   Returns:
     An OAuth2Credentials object.
 
   Raises:
     FlowExchangeError if the authorization code cannot be exchanged for an
      access token
   """
   flow = OAuth2WebServerFlow(client_id, client_secret, scope,
                              redirect_uri=redirect_uri, user_agent=user_agent,
                              auth_uri=auth_uri, token_uri=token_uri,
-                             revoke_uri=revoke_uri)
+                             revoke_uri=revoke_uri, device_uri=device_uri)
 
   credentials = flow.step2_exchange(code, http=http)
   return credentials
 
 
 @util.positional(3)
 def credentials_from_clientsecrets_and_code(filename, scope, code,
                                             message = None,
                                             redirect_uri='postmessage',
                                             http=None,
-                                            cache=None):
+                                            cache=None,
+                                            device_uri=None):
   """Returns OAuth2Credentials from a clientsecrets file and an auth code.
 
   Will create the right kind of Flow based on the contents of the clientsecrets
   file or will raise InvalidClientSecretsError for unknown types of Flows.
 
   Args:
     filename: string, File name of clientsecrets.
     scope: string or iterable of strings, scope(s) to request.
     code: string, An authorization code, most likely passed down from
       the client
     message: string, A friendly string to display to the user if the
       clientsecrets file is missing or invalid. If message is provided then
       sys.exit will be called in the case of an error. If message in not
       provided then clientsecrets.InvalidClientSecretsError will be raised.
     redirect_uri: string, this is generally set to 'postmessage' to match the
       redirect_uri that the client specified
     http: httplib2.Http, optional http instance to use to do the fetch
     cache: An optional cache service client that implements get() and set()
       methods. See clientsecrets.loadfile() for details.
+    device_uri: string, OAuth 2.0 device authorization endpoint
 
   Returns:
     An OAuth2Credentials object.
 
   Raises:
     FlowExchangeError if the authorization code cannot be exchanged for an
      access token
     UnknownClientSecretsFlowError if the file describes an unknown kind of Flow.
     clientsecrets.InvalidClientSecretsError if the clientsecrets file is
       invalid.
   """
   flow = flow_from_clientsecrets(filename, scope, message=message, cache=cache,
-                                 redirect_uri=redirect_uri)
+                                 redirect_uri=redirect_uri,
+                                 device_uri=device_uri)
   credentials = flow.step2_exchange(code, http=http)
   return credentials
 
 
+class DeviceFlowInfo(collections.namedtuple('DeviceFlowInfo', (
+    'device_code', 'user_code', 'interval', 'verification_url',
+    'user_code_expiry'))):
+  """Intermediate information the OAuth2 for devices flow."""
+
+  @classmethod
+  def FromResponse(cls, response):
+    """Create a DeviceFlowInfo from a server response.
+
+    The response should be a dict containing entries as described here:
+
+      http://tools.ietf.org/html/draft-ietf-oauth-v2-05#section-3.7.1
+    """
+    # device_code, user_code, and verification_url are required.
+    kwargs = {
+        'device_code': response['device_code'],
+        'user_code': response['user_code'],
+    }
+    # The response may list the verification address as either
+    # verification_url or verification_uri, so we check for both.
+    verification_url = response.get(
+        'verification_url', response.get('verification_uri'))
+    if verification_url is None:
+      raise OAuth2DeviceCodeError(
+          'No verification_url provided in server response')
+    kwargs['verification_url'] = verification_url
+    # expires_in and interval are optional.
+    kwargs.update({
+        'interval': response.get('interval'),
+        'user_code_expiry': None,
+    })
+    if 'expires_in' in response:
+      kwargs['user_code_expiry'] = datetime.datetime.now() + datetime.timedelta(
+          seconds=int(response['expires_in']))
+
+    return cls(**kwargs)
+
 class OAuth2WebServerFlow(Flow):
   """Does the Web Server Flow for OAuth 2.0.
 
   OAuth2WebServerFlow objects may be safely pickled and unpickled.
   """
 
   @util.positional(4)
   def __init__(self, client_id, client_secret, scope,
                redirect_uri=None,
                user_agent=None,
                auth_uri=GOOGLE_AUTH_URI,
                token_uri=GOOGLE_TOKEN_URI,
                revoke_uri=GOOGLE_REVOKE_URI,
+               login_hint=None,
+               device_uri=GOOGLE_DEVICE_URI,
                **kwargs):
     """Constructor for OAuth2WebServerFlow.
 
     The kwargs argument is used to set extra query parameters on the
     auth_uri. For example, the access_type and approval_prompt
     query parameters can be set via kwargs.
 
     Args:
       client_id: string, client identifier.
       client_secret: string client secret.
       scope: string or iterable of strings, scope(s) of the credentials being
         requested.
       redirect_uri: string, Either the string 'urn:ietf:wg:oauth:2.0:oob' for
         a non-web-based application, or a URI that handles the callback from
         the authorization server.
       user_agent: string, HTTP User-Agent to provide for this application.
       auth_uri: string, URI for authorization endpoint. For convenience
         defaults to Google's endpoints but any OAuth 2.0 provider can be used.
       token_uri: string, URI for token endpoint. For convenience
         defaults to Google's endpoints but any OAuth 2.0 provider can be used.
       revoke_uri: string, URI for revoke endpoint. For convenience
         defaults to Google's endpoints but any OAuth 2.0 provider can be used.
+      login_hint: string, Either an email address or domain. Passing this hint
+        will either pre-fill the email box on the sign-in form or select the
+        proper multi-login session, thereby simplifying the login flow.
+      device_uri: string, URI for device authorization endpoint. For convenience
+        defaults to Google's endpoints but any OAuth 2.0 provider can be used.
       **kwargs: dict, The keyword arguments are all optional and required
                         parameters for the OAuth calls.
     """
     self.client_id = client_id
     self.client_secret = client_secret
     self.scope = util.scopes_to_string(scope)
     self.redirect_uri = redirect_uri
+    self.login_hint = login_hint
     self.user_agent = user_agent
     self.auth_uri = auth_uri
     self.token_uri = token_uri
     self.revoke_uri = revoke_uri
+    self.device_uri = device_uri
     self.params = {
         'access_type': 'offline',
         'response_type': 'code',
     }
     self.params.update(kwargs)
 
   @util.positional(1)
   def step1_get_authorize_url(self, redirect_uri=None):
     """Returns a URI to redirect to the provider.
 
     Args:
       redirect_uri: string, Either the string 'urn:ietf:wg:oauth:2.0:oob' for
         a non-web-based application, or a URI that handles the callback from
         the authorization server. This parameter is deprecated, please move to
         passing the redirect_uri in via the constructor.
 
     Returns:
       A URI as a string to redirect the user to begin the authorization flow.
     """
     if redirect_uri is not None:
-      logger.warning(('The redirect_uri parameter for'
-          'OAuth2WebServerFlow.step1_get_authorize_url is deprecated. Please'
+      logger.warning((
+          'The redirect_uri parameter for '
+          'OAuth2WebServerFlow.step1_get_authorize_url is deprecated. Please '
           'move to passing the redirect_uri in via the constructor.'))
       self.redirect_uri = redirect_uri
 
     if self.redirect_uri is None:
       raise ValueError('The value of redirect_uri must not be None.')
 
     query_params = {
         'client_id': self.client_id,
         'redirect_uri': self.redirect_uri,
         'scope': self.scope,
     }
+    if self.login_hint is not None:
+      query_params['login_hint'] = self.login_hint
     query_params.update(self.params)
     return _update_query_params(self.auth_uri, query_params)
 
+  @util.positional(1)
+  def step1_get_device_and_user_codes(self, http=None):
+    """Returns a user code and the verification URL where to enter it
+
+    Returns:
+      A user code as a string for the user to authorize the application
+      An URL as a string where the user has to enter the code
+    """
+    if self.device_uri is None:
+      raise ValueError('The value of device_uri must not be None.')
+
+    body = urllib.parse.urlencode({
+        'client_id': self.client_id,
+        'scope': self.scope,
+    })
+    headers = {
+        'content-type': 'application/x-www-form-urlencoded',
+    }
+
+    if self.user_agent is not None:
+      headers['user-agent'] = self.user_agent
+
+    if http is None:
+      http = httplib2.Http()
+
+    resp, content = http.request(self.device_uri, method='POST', body=body,
+                                 headers=headers)
+    if resp.status == 200:
+      try:
+        flow_info = json.loads(content)
+      except ValueError as e:
+        raise OAuth2DeviceCodeError(
+            'Could not parse server response as JSON: "%s", error: "%s"' % (
+                content, e))
+      return DeviceFlowInfo.FromResponse(flow_info)
+    else:
+      error_msg = 'Invalid response %s.' % resp.status
+      try:
+        d = json.loads(content)
+        if 'error' in d:
+          error_msg += ' Error: %s' % d['error']
+      except ValueError:
+        # Couldn't decode a JSON response, stick with the default message.
+        pass
+      raise OAuth2DeviceCodeError(error_msg)
+
   @util.positional(2)
-  def step2_exchange(self, code, http=None):
-    """Exhanges a code for OAuth2Credentials.
+  def step2_exchange(self, code=None, http=None, device_flow_info=None):
+    """Exchanges a code for OAuth2Credentials.
 
     Args:
-      code: string or dict, either the code as a string, or a dictionary
-        of the query parameters to the redirect_uri, which contains
-        the code.
-      http: httplib2.Http, optional http instance to use to do the fetch
+
+      code: string, a dict-like object, or None. For a non-device
+          flow, this is either the response code as a string, or a
+          dictionary of query parameters to the redirect_uri. For a
+          device flow, this should be None.
+      http: httplib2.Http, optional http instance to use when fetching
+          credentials.
+      device_flow_info: DeviceFlowInfo, return value from step1 in the
+          case of a device flow.
 
     Returns:
       An OAuth2Credentials object that can be used to authorize requests.
 
     Raises:
-      FlowExchangeError if a problem occured exchanging the code for a
-      refresh_token.
+      FlowExchangeError: if a problem occurred exchanging the code for a
+          refresh_token.
+      ValueError: if code and device_flow_info are both provided or both
+          missing.
+
     """
+    if code is None and device_flow_info is None:
+      raise ValueError('No code or device_flow_info provided.')
+    if code is not None and device_flow_info is not None:
+      raise ValueError('Cannot provide both code and device_flow_info.')
 
-    if not (isinstance(code, str) or isinstance(code, unicode)):
+    if code is None:
+      code = device_flow_info.device_code
+    elif not isinstance(code, six.string_types):
       if 'code' not in code:
-        if 'error' in code:
-          error_msg = code['error']
-        else:
-          error_msg = 'No code was supplied in the query parameters.'
-        raise FlowExchangeError(error_msg)
-      else:
-        code = code['code']
+        raise FlowExchangeError(code.get(
+            'error', 'No code was supplied in the query parameters.'))
+      code = code['code']
 
-    body = urllib.urlencode({
-        'grant_type': 'authorization_code',
+    post_data = {
         'client_id': self.client_id,
         'client_secret': self.client_secret,
         'code': code,
-        'redirect_uri': self.redirect_uri,
         'scope': self.scope,
-        })
+    }
+    if device_flow_info is not None:
+      post_data['grant_type'] = 'http://oauth.net/grant_type/device/1.0'
+    else:
+      post_data['grant_type'] = 'authorization_code'
+      post_data['redirect_uri'] = self.redirect_uri
+    body = urllib.parse.urlencode(post_data)
     headers = {
         'content-type': 'application/x-www-form-urlencoded',
     }
 
     if self.user_agent is not None:
       headers['user-agent'] = self.user_agent
 
     if http is None:
       http = httplib2.Http()
 
     resp, content = http.request(self.token_uri, method='POST', body=body,
                                  headers=headers)
     d = _parse_exchange_token_response(content)
     if resp.status == 200 and 'access_token' in d:
       access_token = d['access_token']
       refresh_token = d.get('refresh_token', None)
+      if not refresh_token:
+        logger.info(
+            'Received token response with no refresh_token. Consider '
+            "reauthenticating with approval_prompt='force'.")
       token_expiry = None
       if 'expires_in' in d:
         token_expiry = datetime.datetime.utcnow() + datetime.timedelta(
             seconds=int(d['expires_in']))
 
+      extracted_id_token = None
       if 'id_token' in d:
-        d['id_token'] = _extract_id_token(d['id_token'])
+        extracted_id_token = _extract_id_token(d['id_token'])
 
       logger.info('Successfully retrieved access token')
       return OAuth2Credentials(access_token, self.client_id,
                                self.client_secret, refresh_token, token_expiry,
                                self.token_uri, self.user_agent,
                                revoke_uri=self.revoke_uri,
-                               id_token=d.get('id_token', None),
+                               id_token=extracted_id_token,
                                token_response=d)
     else:
-      logger.info('Failed to retrieve access token: %s' % content)
+      logger.info('Failed to retrieve access token: %s', content)
       if 'error' in d:
         # you never know what those providers got to say
-        error_msg = unicode(d['error'])
+        error_msg = str(d['error']) + str(d.get('error_description', ''))
       else:
         error_msg = 'Invalid response: %s.' % str(resp.status)
       raise FlowExchangeError(error_msg)
 
 
 @util.positional(2)
 def flow_from_clientsecrets(filename, scope, redirect_uri=None,
-                            message=None, cache=None):
+                            message=None, cache=None, login_hint=None,
+                            device_uri=None):
   """Create a Flow from a clientsecrets file.
 
   Will create the right kind of Flow based on the contents of the clientsecrets
   file or will raise InvalidClientSecretsError for unknown types of Flows.
 
   Args:
     filename: string, File name of client secrets.
     scope: string or iterable of strings, scope(s) to request.
     redirect_uri: string, Either the string 'urn:ietf:wg:oauth:2.0:oob' for
       a non-web-based application, or a URI that handles the callback from
       the authorization server.
     message: string, A friendly string to display to the user if the
       clientsecrets file is missing or invalid. If message is provided then
       sys.exit will be called in the case of an error. If message in not
       provided then clientsecrets.InvalidClientSecretsError will be raised.
     cache: An optional cache service client that implements get() and set()
       methods. See clientsecrets.loadfile() for details.
+    login_hint: string, Either an email address or domain. Passing this hint
+      will either pre-fill the email box on the sign-in form or select the
+      proper multi-login session, thereby simplifying the login flow.
+    device_uri: string, URI for device authorization endpoint. For convenience
+      defaults to Google's endpoints but any OAuth 2.0 provider can be used.
 
   Returns:
     A Flow object.
 
   Raises:
     UnknownClientSecretsFlowError if the file describes an unknown kind of Flow.
     clientsecrets.InvalidClientSecretsError if the clientsecrets file is
       invalid.
   """
   try:
     client_type, client_info = clientsecrets.loadfile(filename, cache=cache)
     if client_type in (clientsecrets.TYPE_WEB, clientsecrets.TYPE_INSTALLED):
       constructor_kwargs = {
           'redirect_uri': redirect_uri,
           'auth_uri': client_info['auth_uri'],
           'token_uri': client_info['token_uri'],
+          'login_hint': login_hint,
       }
       revoke_uri = client_info.get('revoke_uri')
       if revoke_uri is not None:
         constructor_kwargs['revoke_uri'] = revoke_uri
+      if device_uri is not None:
+        constructor_kwargs['device_uri'] = device_uri
       return OAuth2WebServerFlow(
           client_info['client_id'], client_info['client_secret'],
           scope, **constructor_kwargs)
 
   except clientsecrets.InvalidClientSecretsError:
     if message:
       sys.exit(message)
     else:
       raise
   else:
     raise UnknownClientSecretsFlowError(
-        'This OAuth 2.0 flow is unsupported: %r' % client_type)
+        'This OAuth 2.0 flow is unsupported: %r' % client_type)