250 lines
7.8 KiB
Python
250 lines
7.8 KiB
Python
# Copyright 2016 Google Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""OAuth 2.0 client.
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This is a client for interacting with an OAuth 2.0 authorization server's
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token endpoint.
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For more information about the token endpoint, see
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`Section 3.1 of rfc6749`_
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.. _Section 3.1 of rfc6749: https://tools.ietf.org/html/rfc6749#section-3.2
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"""
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import datetime
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import json
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import six
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from six.moves import http_client
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from six.moves import urllib
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from google.auth import _helpers
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from google.auth import exceptions
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from google.auth import jwt
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_URLENCODED_CONTENT_TYPE = 'application/x-www-form-urlencoded'
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_JWT_GRANT_TYPE = 'urn:ietf:params:oauth:grant-type:jwt-bearer'
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_REFRESH_GRANT_TYPE = 'refresh_token'
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def _handle_error_response(response_body):
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""""Translates an error response into an exception.
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Args:
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response_body (str): The decoded response data.
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Raises:
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google.auth.exceptions.RefreshError
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"""
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try:
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error_data = json.loads(response_body)
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error_details = '{}: {}'.format(
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error_data['error'],
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error_data.get('error_description'))
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# If no details could be extracted, use the response data.
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except (KeyError, ValueError):
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error_details = response_body
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raise exceptions.RefreshError(
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error_details, response_body)
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def _parse_expiry(response_data):
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"""Parses the expiry field from a response into a datetime.
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Args:
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response_data (Mapping): The JSON-parsed response data.
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Returns:
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Optional[datetime]: The expiration or ``None`` if no expiration was
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specified.
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"""
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expires_in = response_data.get('expires_in', None)
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if expires_in is not None:
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return _helpers.utcnow() + datetime.timedelta(
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seconds=expires_in)
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else:
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return None
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def _token_endpoint_request(request, token_uri, body):
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"""Makes a request to the OAuth 2.0 authorization server's token endpoint.
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Args:
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request (google.auth.transport.Request): A callable used to make
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HTTP requests.
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token_uri (str): The OAuth 2.0 authorizations server's token endpoint
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URI.
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body (Mapping[str, str]): The parameters to send in the request body.
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Returns:
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Mapping[str, str]: The JSON-decoded response data.
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Raises:
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google.auth.exceptions.RefreshError: If the token endpoint returned
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an error.
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"""
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body = urllib.parse.urlencode(body)
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headers = {
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'content-type': _URLENCODED_CONTENT_TYPE,
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}
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response = request(
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method='POST', url=token_uri, headers=headers, body=body)
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response_body = response.data.decode('utf-8')
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if response.status != http_client.OK:
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_handle_error_response(response_body)
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response_data = json.loads(response_body)
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return response_data
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def jwt_grant(request, token_uri, assertion):
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"""Implements the JWT Profile for OAuth 2.0 Authorization Grants.
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For more details, see `rfc7523 section 4`_.
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Args:
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request (google.auth.transport.Request): A callable used to make
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HTTP requests.
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token_uri (str): The OAuth 2.0 authorizations server's token endpoint
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URI.
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assertion (str): The OAuth 2.0 assertion.
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Returns:
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Tuple[str, Optional[datetime], Mapping[str, str]]: The access token,
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expiration, and additional data returned by the token endpoint.
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Raises:
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google.auth.exceptions.RefreshError: If the token endpoint returned
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an error.
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.. _rfc7523 section 4: https://tools.ietf.org/html/rfc7523#section-4
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"""
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body = {
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'assertion': assertion,
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'grant_type': _JWT_GRANT_TYPE,
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}
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response_data = _token_endpoint_request(request, token_uri, body)
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try:
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access_token = response_data['access_token']
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except KeyError as caught_exc:
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new_exc = exceptions.RefreshError(
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'No access token in response.', response_data)
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six.raise_from(new_exc, caught_exc)
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expiry = _parse_expiry(response_data)
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return access_token, expiry, response_data
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def id_token_jwt_grant(request, token_uri, assertion):
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"""Implements the JWT Profile for OAuth 2.0 Authorization Grants, but
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requests an OpenID Connect ID Token instead of an access token.
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This is a variant on the standard JWT Profile that is currently unique
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to Google. This was added for the benefit of authenticating to services
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that require ID Tokens instead of access tokens or JWT bearer tokens.
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Args:
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request (google.auth.transport.Request): A callable used to make
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HTTP requests.
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token_uri (str): The OAuth 2.0 authorization server's token endpoint
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URI.
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assertion (str): JWT token signed by a service account. The token's
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payload must include a ``target_audience`` claim.
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Returns:
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Tuple[str, Optional[datetime], Mapping[str, str]]:
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The (encoded) Open ID Connect ID Token, expiration, and additional
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data returned by the endpoint.
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Raises:
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google.auth.exceptions.RefreshError: If the token endpoint returned
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an error.
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"""
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body = {
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'assertion': assertion,
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'grant_type': _JWT_GRANT_TYPE,
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}
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response_data = _token_endpoint_request(request, token_uri, body)
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try:
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id_token = response_data['id_token']
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except KeyError as caught_exc:
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new_exc = exceptions.RefreshError(
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'No ID token in response.', response_data)
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six.raise_from(new_exc, caught_exc)
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payload = jwt.decode(id_token, verify=False)
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expiry = datetime.datetime.utcfromtimestamp(payload['exp'])
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return id_token, expiry, response_data
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def refresh_grant(request, token_uri, refresh_token, client_id, client_secret):
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"""Implements the OAuth 2.0 refresh token grant.
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For more details, see `rfc678 section 6`_.
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Args:
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request (google.auth.transport.Request): A callable used to make
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HTTP requests.
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token_uri (str): The OAuth 2.0 authorizations server's token endpoint
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URI.
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refresh_token (str): The refresh token to use to get a new access
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token.
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client_id (str): The OAuth 2.0 application's client ID.
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client_secret (str): The Oauth 2.0 appliaction's client secret.
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Returns:
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Tuple[str, Optional[str], Optional[datetime], Mapping[str, str]]: The
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access token, new refresh token, expiration, and additional data
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returned by the token endpoint.
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Raises:
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google.auth.exceptions.RefreshError: If the token endpoint returned
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an error.
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.. _rfc6748 section 6: https://tools.ietf.org/html/rfc6749#section-6
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"""
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body = {
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'grant_type': _REFRESH_GRANT_TYPE,
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'client_id': client_id,
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'client_secret': client_secret,
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'refresh_token': refresh_token,
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}
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response_data = _token_endpoint_request(request, token_uri, body)
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try:
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access_token = response_data['access_token']
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except KeyError as caught_exc:
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new_exc = exceptions.RefreshError(
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'No access token in response.', response_data)
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six.raise_from(new_exc, caught_exc)
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refresh_token = response_data.get('refresh_token', refresh_token)
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expiry = _parse_expiry(response_data)
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return access_token, refresh_token, expiry, response_data
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