text: # Copyright (c) 2014-2015, Erica Ehrhardt
  # Copyright (c) 2016, Patrick Uiterwijk <patrick@puiterwijk.org>
  # All rights reserved.
  #
  # Redistribution and use in source and binary forms, with or without
  # modification, are permitted provided that the following conditions are met:
  #
  # * Redistributions of source code must retain the above copyright notice, this
  #   list of conditions and the following disclaimer.
  #
  # * Redistributions in binary form must reproduce the above copyright notice,
  #   this list of conditions and the following disclaimer in the documentation
  #   and/or other materials provided with the distribution.
  #
  # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  # DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  # FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  # DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  # SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  # OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  from functools import wraps
  import os
  import json
  from base64 import b64encode, b64decode, urlsafe_b64encode, urlsafe_b64decode
  import time
  from copy import copy
  import logging
  from warnings import warn
  import calendar
  
  from six.moves.urllib.parse import urlencode
  from flask import request, session, redirect, url_for, g, current_app, abort
  from oauth2client.client import flow_from_clientsecrets, OAuth2WebServerFlow,\
      AccessTokenRefreshError, OAuth2Credentials
  import httplib2
  from itsdangerous import JSONWebSignatureSerializer, BadSignature
  
  __all__ = ['OpenIDConnect', 'MemoryCredentials']
  
  logger = logging.getLogger(__name__)
  
  
  def _json_loads(content):
      if not isinstance(content, str):
          content = content.decode('utf-8')
      return json.loads(content)
  
  class MemoryCredentials(dict):
      """
      Non-persistent local credentials store.
      Use this if you only have one app server, and don't mind making everyone
      log in again after a restart.
      """
      pass
  
  
  class DummySecretsCache(object):
      """
      oauth2client secrets cache
      """
      def __init__(self, client_secrets):
          self.client_secrets = client_secrets
  
      def get(self, filename, namespace):
          return self.client_secrets
  
  
  class ErrStr(str):
      """
      This is a class to work around the time I made a terrible API decision.
  
      Basically, the validate_token() function returns a boolean True if all went
      right, but a string with an error message if something went wrong.
  
      The problem here is that this means that "if validate_token(...)" will
      always be True, even with an invalid token, and users had to do
      "if validate_token(...) is True:".
  
      This is counter-intuitive, so let's "fix" this by returning instances of
      this ErrStr class, which are basic strings except for their bool() results:
      they return False.
      """
      def __nonzero__(self):
          """The py2 method for bool()."""
          return False
  
      def __bool__(self):
          """The py3 method for bool()."""
          return False
  
  
  GOOGLE_ISSUERS = ['accounts.google.com', 'https://accounts.google.com']
  
  
  class OpenIDConnect(object):
      """
      The core OpenID Connect client object.
      """
      def __init__(self, app=None, credentials_store=None, http=None, time=None,
                   urandom=None):
          self.credentials_store = credentials_store\
              if credentials_store is not None\
              else MemoryCredentials()
  
          if http is not None:
              warn('HTTP argument is deprecated and unused', DeprecationWarning)
          if time is not None:
              warn('time argument is deprecated and unused', DeprecationWarning)
          if urandom is not None:
              warn('urandom argument is deprecated and unused',
                   DeprecationWarning)
  
          # By default, we do not have a custom callback
          self._custom_callback = None
  
          # get stuff from the app's config, which may override stuff set above
          if app is not None:
              self.init_app(app)
  
      def init_app(self, app):
          """
          Do setup that requires a Flask app.
  
          :param app: The application to initialize.
          :type app: Flask
          """
          secrets = self.load_secrets(app)
          self.client_secrets = list(secrets.values())[0]
          secrets_cache = DummySecretsCache(secrets)
  
          # Set some default configuration options
          app.config.setdefault('OIDC_SCOPES', ['openid', 'email'])
          app.config.setdefault('OIDC_GOOGLE_APPS_DOMAIN', None)
          app.config.setdefault('OIDC_ID_TOKEN_COOKIE_NAME', 'oidc_id_token')
          app.config.setdefault('OIDC_ID_TOKEN_COOKIE_PATH', '/')
          app.config.setdefault('OIDC_ID_TOKEN_COOKIE_TTL', 7 * 86400)  # 7 days
          # should ONLY be turned off for local debugging
          app.config.setdefault('OIDC_COOKIE_SECURE', True)
          app.config.setdefault('OIDC_VALID_ISSUERS',
                                (self.client_secrets.get('issuer') or
                                 GOOGLE_ISSUERS))
          app.config.setdefault('OIDC_CLOCK_SKEW', 60)  # 1 minute
          app.config.setdefault('OIDC_REQUIRE_VERIFIED_EMAIL', False)
          app.config.setdefault('OIDC_OPENID_REALM', None)
          app.config.setdefault('OIDC_USER_INFO_ENABLED', True)
          app.config.setdefault('OIDC_CALLBACK_ROUTE', '/oidc_callback')
          app.config.setdefault('OVERWRITE_REDIRECT_URI', False)
          app.config.setdefault("OIDC_EXTRA_REQUEST_AUTH_PARAMS", {})
          # Configuration for resource servers
          app.config.setdefault('OIDC_RESOURCE_SERVER_ONLY', False)
          app.config.setdefault('OIDC_RESOURCE_CHECK_AUD', False)
  
          # We use client_secret_post, because that's what the Google
          # oauth2client library defaults to
          app.config.setdefault('OIDC_INTROSPECTION_AUTH_METHOD', 'client_secret_post')
          app.config.setdefault('OIDC_TOKEN_TYPE_HINT', 'access_token')
  
          if not 'openid' in app.config['OIDC_SCOPES']:
              raise ValueError('The value "openid" must be in the OIDC_SCOPES')
  
          # register callback route and cookie-setting decorator
          if not app.config['OIDC_RESOURCE_SERVER_ONLY']:
              app.route(app.config['OIDC_CALLBACK_ROUTE'])(self._oidc_callback)
              app.before_request(self._before_request)
              app.after_request(self._after_request)
  
          # Initialize oauth2client
          self.flow = flow_from_clientsecrets(
              app.config['OIDC_CLIENT_SECRETS'],
              scope=app.config['OIDC_SCOPES'],
              cache=secrets_cache)
          assert isinstance(self.flow, OAuth2WebServerFlow)
  
          # create signers using the Flask secret key
          self.extra_data_serializer = JSONWebSignatureSerializer(
              app.config['SECRET_KEY'], salt='flask-oidc-extra-data')
          self.cookie_serializer = JSONWebSignatureSerializer(
              app.config['SECRET_KEY'], salt='flask-oidc-cookie')
  
          try:
              self.credentials_store = app.config['OIDC_CREDENTIALS_STORE']
          except KeyError:
              pass
  
      def load_secrets(self, app):
          # Load client_secrets.json to pre-initialize some configuration
          content = app.config['OIDC_CLIENT_SECRETS']
          if isinstance(content, dict):
              return content
          else:
              return _json_loads(open(content, 'r').read())
  
      @property
      def user_loggedin(self):
          """
          Represents whether the user is currently logged in.
  
          Returns:
              bool: Whether the user is logged in with Flask-OIDC.
  
          .. versionadded:: 1.0
          """
          return g.oidc_id_token is not None
  
      def user_getfield(self, field, access_token=None):
          """
          Request a single field of information about the user.
  
          :param field: The name of the field requested.
          :type field: str
          :returns: The value of the field. Depending on the type, this may be
              a string, list, dict, or something else.
          :rtype: object
  
          .. versionadded:: 1.0
          """
          info = self.user_getinfo([field], access_token)
          return info.get(field)
  
      def user_getinfo(self, fields, access_token=None):
          """
          Request multiple fields of information about the user.
  
          :param fields: The names of the fields requested.
          :type fields: list
          :returns: The values of the current user for the fields requested.
              The keys are the field names, values are the values of the
              fields as indicated by the OpenID Provider. Note that fields
              that were not provided by the Provider are absent.
          :rtype: dict
          :raises Exception: If the user was not authenticated. Check this with
              user_loggedin.
  
          .. versionadded:: 1.0
          """
          if g.oidc_id_token is None and access_token is None:
              raise Exception('User was not authenticated')
          info = {}
          all_info = None
          for field in fields:
              if access_token is None and field in g.oidc_id_token:
                  info[field] = g.oidc_id_token[field]
              elif current_app.config['OIDC_USER_INFO_ENABLED']:
                  # This was not in the id_token. Let's get user information
                  if all_info is None:
                      all_info = self._retrieve_userinfo(access_token)
                      if all_info is None:
                          # To make sure we don't retry for every field
                          all_info = {}
                  if field in all_info:
                      info[field] = all_info[field]
                  else:
                      # We didn't get this information
                      pass
          return info
  
      def get_access_token(self):
          """Method to return the current requests' access_token.
  
          :returns: Access token or None
          :rtype: str
  
          .. versionadded:: 1.2
          """
          try:
              credentials = OAuth2Credentials.from_json(
                  self.credentials_store[g.oidc_id_token['sub']])
              return credentials.access_token
          except KeyError:
              logger.debug("Expired ID token, credentials missing",
                           exc_info=True)
              return None
  
      def get_refresh_token(self):
          """Method to return the current requests' refresh_token.
  
          :returns: Access token or None
          :rtype: str
  
          .. versionadded:: 1.2
          """
          try:
              credentials = OAuth2Credentials.from_json(
                  self.credentials_store[g.oidc_id_token['sub']])
              return credentials.refresh_token
          except KeyError:
              logger.debug("Expired ID token, credentials missing",
                           exc_info=True)
              return None
  
      def _retrieve_userinfo(self, access_token=None):
          """
          Requests extra user information from the Provider's UserInfo and
          returns the result.
  
          :returns: The contents of the UserInfo endpoint.
          :rtype: dict
          """
          if 'userinfo_uri' not in self.client_secrets:
              logger.debug('Userinfo uri not specified')
              raise AssertionError('UserInfo URI not specified')
  
          # Cache the info from this request
          if '_oidc_userinfo' in g:
              return g._oidc_userinfo
  
          http = httplib2.Http()
          if access_token is None:
              try:
                  credentials = OAuth2Credentials.from_json(
                      self.credentials_store[g.oidc_id_token['sub']])
              except KeyError:
                  logger.debug("Expired ID token, credentials missing",
                               exc_info=True)
                  return None
              credentials.authorize(http)
              resp, content = http.request(self.client_secrets['userinfo_uri'])
          else:
              # We have been manually overriden with an access token
              resp, content = http.request(
                  self.client_secrets['userinfo_uri'],
                  "POST",
                  body=urlencode({"access_token": access_token}),
                  headers={'Content-Type': 'application/x-www-form-urlencoded'})
  
          logger.debug('Retrieved user info: %s' % content)
          info = _json_loads(content)
  
          g._oidc_userinfo = info
  
          return info
  
  
      def get_cookie_id_token(self):
          """
          .. deprecated:: 1.0
             Use :func:`user_getinfo` instead.
          """
          warn('You are using a deprecated function (get_cookie_id_token). '
               'Please reconsider using this', DeprecationWarning)
          return self._get_cookie_id_token()
  
      def _get_cookie_id_token(self):
          try:
              id_token_cookie = request.cookies.get(current_app.config[
                  'OIDC_ID_TOKEN_COOKIE_NAME'])
              if not id_token_cookie:
                  # Do not error if we were unable to get the cookie.
                  # The user can debug this themselves.
                  return None
              return self.cookie_serializer.loads(id_token_cookie)
          except SignatureExpired:
              logger.debug("Invalid ID token cookie", exc_info=True)
              return None
          except BadSignature:
              logger.info("Signature invalid for ID token cookie", exc_info=True)
              return None
  
      def set_cookie_id_token(self, id_token):
          """
          .. deprecated:: 1.0
          """
          warn('You are using a deprecated function (set_cookie_id_token). '
               'Please reconsider using this', DeprecationWarning)
          return self._set_cookie_id_token(id_token)
  
      def _set_cookie_id_token(self, id_token):
          """
          Cooperates with @after_request to set a new ID token cookie.
          """
          g.oidc_id_token = id_token
          g.oidc_id_token_dirty = True
  
      def _after_request(self, response):
          """
          Set a new ID token cookie if the ID token has changed.
          """
          # This means that if either the new or the old are False, we set
          # insecure cookies.
          # We don't define OIDC_ID_TOKEN_COOKIE_SECURE in init_app, because we
          # don't want people to find it easily.
          cookie_secure = (current_app.config['OIDC_COOKIE_SECURE'] and
                           current_app.config.get('OIDC_ID_TOKEN_COOKIE_SECURE',
                                                  True))
  
          if getattr(g, 'oidc_id_token_dirty', False):
              if g.oidc_id_token:
                  signed_id_token = self.cookie_serializer.dumps(g.oidc_id_token)
                  response.set_cookie(
                      current_app.config['OIDC_ID_TOKEN_COOKIE_NAME'],
                      signed_id_token,
                      secure=cookie_secure,
                      httponly=True,
                      max_age=current_app.config['OIDC_ID_TOKEN_COOKIE_TTL'])
              else:
                  # This was a log out
                  response.set_cookie(
                      current_app.config['OIDC_ID_TOKEN_COOKIE_NAME'],
                      '',
                      path=current_app.config['OIDC_ID_TOKEN_COOKIE_PATH'],
                      secure=cookie_secure,
                      httponly=True,
                      expires=0)
          return response
  
      def _before_request(self):
          g.oidc_id_token = None
          self.authenticate_or_redirect()
  
      def authenticate_or_redirect(self):
          """
          Helper function suitable for @app.before_request and @check.
          Sets g.oidc_id_token to the ID token if the user has successfully
          authenticated, else returns a redirect object so they can go try
          to authenticate.
  
          :returns: A redirect object, or None if the user is logged in.
          :rtype: Redirect
  
          .. deprecated:: 1.0
             Use :func:`require_login` instead.
          """
          # the auth callback and error pages don't need user to be authenticated
          if request.endpoint in frozenset(['_oidc_callback', '_oidc_error']):
              return None
  
          # retrieve signed ID token cookie
          id_token = self._get_cookie_id_token()
          if id_token is None:
              return self.redirect_to_auth_server(request.url)
  
          # ID token expired
          # when Google is the IdP, this happens after one hour
          if time.time() >= id_token['exp']:
              # get credentials from store
              try:
                  credentials = OAuth2Credentials.from_json(
                      self.credentials_store[id_token['sub']])
              except KeyError:
                  logger.debug("Expired ID token, credentials missing",
                               exc_info=True)
                  return self.redirect_to_auth_server(request.url)
              except ValueError:
                  logger.debug("Credentials missing",
                               exc_info=True)
                  return self.redirect_to_auth_server(request.url)
  
              # refresh and store credentials
              try:
                  credentials.refresh(httplib2.Http())
                  if credentials.id_token:
                      id_token = credentials.id_token
                  else:
                      # It is not guaranteed that we will get a new ID Token on
                      # refresh, so if we do not, let's just update the id token
                      # expiry field and reuse the existing ID Token.
                      if credentials.token_expiry is None:
                          logger.debug('Expired ID token, no new expiry. Falling'
                                       ' back to assuming 1 hour')
                          id_token['exp'] = time.time() + 3600
                      else:
                          id_token['exp'] = calendar.timegm(
                              credentials.token_expiry.timetuple())
                  self.credentials_store[id_token['sub']] = credentials.to_json()
                  self._set_cookie_id_token(id_token)
              except AccessTokenRefreshError:
                  # Can't refresh. Wipe credentials and redirect user to IdP
                  # for re-authentication.
                  logger.debug("Expired ID token, can't refresh credentials",
                               exc_info=True)
                  del self.credentials_store[id_token['sub']]
                  return self.redirect_to_auth_server(request.url)
  
          # make ID token available to views
          g.oidc_id_token = id_token
  
          return None
  
      def require_login(self, view_func):
          """
          Use this to decorate view functions that require a user to be logged
          in. If the user is not already logged in, they will be sent to the
          Provider to log in, after which they will be returned.
  
          .. versionadded:: 1.0
             This was :func:`check` before.
          """
          @wraps(view_func)
          def decorated(*args, **kwargs):
              if g.oidc_id_token is None:
                  return self.redirect_to_auth_server(request.url)
              return view_func(*args, **kwargs)
          return decorated
      # Backwards compatibility
      check = require_login
      """
      .. deprecated:: 1.0
         Use :func:`require_login` instead.
      """
  
      def require_keycloak_role(self, client, role):
          """
          Function to check for a KeyCloak client role in JWT access token.
  
          This is intended to be replaced with a more generic 'require this value
          in token or claims' system, at which point backwards compatibility will
          be added.
  
          .. versionadded:: 1.5.0
          """
          def wrapper(view_func):
              @wraps(view_func)
              def decorated(*args, **kwargs):
                  pre, tkn, post = self.get_access_token().split('.')
                  access_token = json.loads(b64decode(tkn))
                  if role in access_token['resource_access'][client]['roles']:
                      return view_func(*args, **kwargs)
                  else:
                      return abort(403)
              return decorated
          return wrapper
  
      def flow_for_request(self):
          """
          .. deprecated:: 1.0
             Use :func:`require_login` instead.
          """
          warn('You are using a deprecated function (flow_for_request). '
               'Please reconsider using this', DeprecationWarning)
          return self._flow_for_request()
  
      def _flow_for_request(self):
          """
          Build a flow with the correct absolute callback URL for this request.
          :return:
          """
          flow = copy(self.flow)
          redirect_uri = current_app.config['OVERWRITE_REDIRECT_URI']
          if not redirect_uri:
              flow.redirect_uri = url_for('_oidc_callback', _external=True)
          else:
              flow.redirect_uri = redirect_uri
          return flow
  
      def redirect_to_auth_server(self, destination=None, customstate=None):
          """
          Set a CSRF token in the session, and redirect to the IdP.
  
          :param destination: The page that the user was going to,
              before we noticed they weren't logged in.
          :type destination: Url to return the client to if a custom handler is
              not used. Not available with custom callback.
          :param customstate: The custom data passed via the ODIC state.
              Note that this only works with a custom_callback, and this will
              ignore destination.
          :type customstate: Anything that can be serialized
          :returns: A redirect response to start the login process.
          :rtype: Flask Response
  
          .. deprecated:: 1.0
             Use :func:`require_login` instead.
          """
          if not self._custom_callback and customstate:
              raise ValueError('Custom State is only avilable with a custom '
                               'handler')
          if 'oidc_csrf_token' not in session:
              csrf_token = urlsafe_b64encode(os.urandom(24)).decode('utf-8')
              session['oidc_csrf_token'] = csrf_token
          state = {
              'csrf_token': session['oidc_csrf_token'],
          }
          statefield = 'destination'
          statevalue = destination
          if customstate is not None:
              statefield = 'custom'
              statevalue = customstate
          state[statefield] = self.extra_data_serializer.dumps(
              statevalue).decode('utf-8')
  
          extra_params = {
              'state': urlsafe_b64encode(json.dumps(state).encode('utf-8')),
          }
          extra_params.update(current_app.config['OIDC_EXTRA_REQUEST_AUTH_PARAMS'])
          if current_app.config['OIDC_GOOGLE_APPS_DOMAIN']:
              extra_params['hd'] = current_app.config['OIDC_GOOGLE_APPS_DOMAIN']
          if current_app.config['OIDC_OPENID_REALM']:
              extra_params['openid.realm'] = current_app.config[
                  'OIDC_OPENID_REALM']
  
          flow = self._flow_for_request()
          auth_url = '{url}&{extra_params}'.format(
              url=flow.step1_get_authorize_url(),
              extra_params=urlencode(extra_params))
          # if the user has an ID token, it's invalid, or we wouldn't be here
          self._set_cookie_id_token(None)
          return redirect(auth_url)
  
      def _is_id_token_valid(self, id_token):
          """
          Check if `id_token` is a current ID token for this application,
          was issued by the Apps domain we expected,
          and that the email address has been verified.
  
          @see: http://openid.net/specs/openid-connect-core-1_0.html#IDTokenValidation
          """
          if not id_token:
              return False
  
          # step 2: check issuer
          if id_token['iss'] not in current_app.config['OIDC_VALID_ISSUERS']:
              logger.error('id_token issued by non-trusted issuer: %s'
                           % id_token['iss'])
              return False
  
          if isinstance(id_token['aud'], list):
              # step 3 for audience list
              if self.flow.client_id not in id_token['aud']:
                  logger.error('We are not a valid audience')
                  return False
              # step 4
              if 'azp' not in id_token and len(id_token['aud']) > 1:
                  logger.error('Multiple audiences and not authorized party')
                  return False
          else:
              # step 3 for single audience
              if id_token['aud'] != self.flow.client_id:
                  logger.error('We are not the audience')
                  return False
  
          # step 5
          if 'azp' in id_token and id_token['azp'] != self.flow.client_id:
              logger.error('Authorized Party is not us')
              return False
  
          # step 6-8: TLS checked
  
          # step 9: check exp
          if int(time.time()) >= int(id_token['exp']):
              logger.error('Token has expired')
              return False
  
          # step 10: check iat
          if id_token['iat'] < (time.time() -
                                current_app.config['OIDC_CLOCK_SKEW']):
              logger.error('Token issued in the past')
              return False
  
          # (not required if using HTTPS?) step 11: check nonce
  
          # step 12-13: not requested acr or auth_time, so not needed to test
  
          # additional steps specific to our usage
          if current_app.config['OIDC_GOOGLE_APPS_DOMAIN'] and \
                  id_token.get('hd') != current_app.config[
                      'OIDC_GOOGLE_APPS_DOMAIN']:
              logger.error('Invalid google apps domain')
              return False
  
          if not id_token.get('email_verified', False) and \
                  current_app.config['OIDC_REQUIRE_VERIFIED_EMAIL']:
              logger.error('Email not verified')
              return False
  
          return True
  
      WRONG_GOOGLE_APPS_DOMAIN = 'WRONG_GOOGLE_APPS_DOMAIN'
  
      def custom_callback(self, view_func):
          """
          Wrapper function to use a custom callback.
          The custom OIDC callback will get the custom state field passed in with
          redirect_to_auth_server.
          """
          @wraps(view_func)
          def decorated(*args, **kwargs):
              plainreturn, data = self._process_callback('custom')
              if plainreturn:
                  return data
              else:
                  return view_func(data, *args, **kwargs)
          self._custom_callback = decorated
          return decorated
  
      def _oidc_callback(self):
          plainreturn, data = self._process_callback('destination')
          if plainreturn:
              return data
          else:
              return redirect(data)
  
      def _process_callback(self, statefield):
          """
          Exchange the auth code for actual credentials,
          then redirect to the originally requested page.
          """
          # retrieve session and callback variables
          try:
              session_csrf_token = session.get('oidc_csrf_token')
  
              state = _json_loads(urlsafe_b64decode(request.args['state'].encode('utf-8')))
              csrf_token = state['csrf_token']
  
              code = request.args['code']
          except (KeyError, ValueError):
              logger.debug("Can't retrieve CSRF token, state, or code",
                           exc_info=True)
              return True, self._oidc_error()
  
          # check callback CSRF token passed to IdP
          # against session CSRF token held by user
          if csrf_token != session_csrf_token:
              logger.debug("CSRF token mismatch")
              return True, self._oidc_error()
  
          # make a request to IdP to exchange the auth code for OAuth credentials
          flow = self._flow_for_request()
          credentials = flow.step2_exchange(code)
          id_token = credentials.id_token
          if not self._is_id_token_valid(id_token):
              logger.debug("Invalid ID token")
              if id_token.get('hd') != current_app.config[
                      'OIDC_GOOGLE_APPS_DOMAIN']:
                  return True, self._oidc_error(
                      "You must log in with an account from the {0} domain."
                      .format(current_app.config['OIDC_GOOGLE_APPS_DOMAIN']),
                      self.WRONG_GOOGLE_APPS_DOMAIN)
              return True, self._oidc_error()
  
          # store credentials by subject
          # when Google is the IdP, the subject is their G+ account number
          self.credentials_store[id_token['sub']] = credentials.to_json()
  
          # Retrieve the extra statefield data
          try:
              response = self.extra_data_serializer.loads(state[statefield])
          except BadSignature:
              logger.error('State field was invalid')
              return True, self._oidc_error()
  
          # set a persistent signed cookie containing the ID token
          # and redirect to the final destination
          self._set_cookie_id_token(id_token)
          return False, response
  
      def _oidc_error(self, message='Not Authorized', code=None):
          return (message, 401, {
              'Content-Type': 'text/plain',
          })
  
      def logout(self):
          """
          Request the browser to please forget the cookie we set, to clear the
          current session.
  
          Note that as described in [1], this will not log out in the case of a
          browser that doesn't clear cookies when requested to, and the user
          could be automatically logged in when they hit any authenticated
          endpoint.
  
          [1]: https://github.com/puiterwijk/flask-oidc/issues/5#issuecomment-86187023
  
          .. versionadded:: 1.0
          """
          # TODO: Add single logout
          self._set_cookie_id_token(None)
  
      # Below here is for resource servers to validate tokens
      def validate_token(self, token, scopes_required=None):
          """
          This function can be used to validate tokens.
  
          Note that this only works if a token introspection url is configured,
          as that URL will be queried for the validity and scopes of a token.
  
          :param scopes_required: List of scopes that are required to be
              granted by the token before returning True.
          :type scopes_required: list
  
          :returns: True if the token was valid and contained the required
              scopes. An ErrStr (subclass of string for which bool() is False) if
              an error occured.
          :rtype: Boolean or String
  
          .. versionadded:: 1.1
          """
          valid = self._validate_token(token, scopes_required)
          if valid is True:
              return True
          else:
              return ErrStr(valid)
  
      def _validate_token(self, token, scopes_required=None):
          """The actual implementation of validate_token."""
          if scopes_required is None:
              scopes_required = []
          scopes_required = set(scopes_required)
  
          token_info = None
          valid_token = False
          has_required_scopes = False
          if token:
              try:
                  token_info = self._get_token_info(token)
              except Exception as ex:
                  token_info = {'active': False}
                  logger.error('ERROR: Unable to get token info')
                  logger.error(str(ex))
  
              valid_token = token_info.get('active', False)
  
              if 'aud' in token_info and \
                      current_app.config['OIDC_RESOURCE_CHECK_AUD']:
                  valid_audience = False
                  aud = token_info['aud']
                  clid = self.client_secrets['client_id']
                  if isinstance(aud, list):
                      valid_audience = clid in aud
                  else:
                      valid_audience = clid == aud
  
                  if not valid_audience:
                      logger.error('Refused token because of invalid '
                                   'audience')
                      valid_token = False
  
              if valid_token:
                  token_scopes = token_info.get('scope', '').split(' ')
              else:
                  token_scopes = []
              has_required_scopes = scopes_required.issubset(
                  set(token_scopes))
  
              if not has_required_scopes:
                  logger.debug('Token missed required scopes')
  
          if (valid_token and has_required_scopes):
              g.oidc_token_info = token_info
              return True
  
          if not valid_token:
              return 'Token required but invalid'
          elif not has_required_scopes:
              return 'Token does not have required scopes'
          else:
              return 'Something went wrong checking your token'
  
      def accept_token(self, require_token=False, scopes_required=None,
                             render_errors=True):
          """
          Use this to decorate view functions that should accept OAuth2 tokens,
          this will most likely apply to API functions.
  
          Tokens are accepted as part of the query URL (access_token value) or
          a POST form value (access_token).
  
          Note that this only works if a token introspection url is configured,
          as that URL will be queried for the validity and scopes of a token.
  
          :param require_token: Whether a token is required for the current
              function. If this is True, we will abort the request if there
              was no token provided.
          :type require_token: bool
          :param scopes_required: List of scopes that are required to be
              granted by the token before being allowed to call the protected
              function.
          :type scopes_required: list
          :param render_errors: Whether or not to eagerly render error objects
              as JSON API responses. Set to False to pass the error object back
              unmodified for later rendering.
          :type render_errors: callback(obj) or None
  
          .. versionadded:: 1.0
          """
  
          def wrapper(view_func):
              @wraps(view_func)
              def decorated(*args, **kwargs):
                  token = None
                  if 'Authorization' in request.headers and request.headers['Authorization'].startswith('Bearer '):
                      token = request.headers['Authorization'].split(None,1)[1].strip()
                  if 'access_token' in request.form:
                      token = request.form['access_token']
                  elif 'access_token' in request.args:
                      token = request.args['access_token']
  
                  validity = self.validate_token(token, scopes_required)
                  if (validity is True) or (not require_token):
                      return view_func(*args, **kwargs)
                  else:
                      response_body = {'error': 'invalid_token',
                                       'error_description': validity}
                      if render_errors:
                          response_body = json.dumps(response_body)
                      return response_body, 401, {'WWW-Authenticate': 'Bearer'}
  
              return decorated
          return wrapper
  
      def _get_token_info(self, token):
          # We hardcode to use client_secret_post, because that's what the Google
          # oauth2client library defaults to
          request = {'token': token}
          headers = {'Content-type': 'application/x-www-form-urlencoded'}
  
          hint = current_app.config['OIDC_TOKEN_TYPE_HINT']
          if hint != 'none':
              request['token_type_hint'] = hint
  
          auth_method = current_app.config['OIDC_INTROSPECTION_AUTH_METHOD'] 
          if (auth_method == 'client_secret_basic'):
              basic_auth_string = '%s:%s' % (self.client_secrets['client_id'], self.client_secrets['client_secret'])
              basic_auth_bytes = bytearray(basic_auth_string, 'utf-8')
              headers['Authorization'] = 'Basic %s' % b64encode(basic_auth_bytes).decode('utf-8')
          elif (auth_method == 'bearer'):
              headers['Authorization'] = 'Bearer %s' % token
          elif (auth_method == 'client_secret_post'):
              request['client_id'] = self.client_secrets['client_id']
              if self.client_secrets['client_secret'] is not None:
                  request['client_secret'] = self.client_secrets['client_secret']
  
          resp, content = httplib2.Http().request(
              self.client_secrets['token_introspection_uri'], 'POST',
              urlencode(request), headers=headers)
          # TODO: Cache this reply
          return _json_loads(content)
  