# Copyright 2016 Google LLC
#
# 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.
"""Transport adapter for Requests."""
from __future__ import absolute_import
import functools
import logging
import numbers
import time
try:
import requests
except ImportError as caught_exc: # pragma: NO COVER
import six
six.raise_from(
ImportError(
"The requests library is not installed, please install the "
"requests package to use the requests transport."
),
caught_exc,
)
import requests.adapters # pylint: disable=ungrouped-imports
import requests.exceptions # pylint: disable=ungrouped-imports
from requests.packages.urllib3.util.ssl_ import (
create_urllib3_context,
) # pylint: disable=ungrouped-imports
import six # pylint: disable=ungrouped-imports
from google.auth import exceptions
from google.auth import transport
import google.auth.transport._mtls_helper
_LOGGER = logging.getLogger(__name__)
_DEFAULT_TIMEOUT = 120 # in seconds
class _Response(transport.Response):
"""Requests transport response adapter.
Args:
response (requests.Response): The raw Requests response.
"""
def __init__(self, response):
self._response = response
@property
def status(self):
return self._response.status_code
@property
def headers(self):
return self._response.headers
@property
def data(self):
return self._response.content
[docs]class TimeoutGuard(object):
"""A context manager raising an error if the suite execution took too long.
Args:
timeout ([Union[None, float, Tuple[float, float]]]):
The maximum number of seconds a suite can run without the context
manager raising a timeout exception on exit. If passed as a tuple,
the smaller of the values is taken as a timeout. If ``None``, a
timeout error is never raised.
timeout_error_type (Optional[Exception]):
The type of the error to raise on timeout. Defaults to
:class:`requests.exceptions.Timeout`.
"""
def __init__(self, timeout, timeout_error_type=requests.exceptions.Timeout):
self._timeout = timeout
self.remaining_timeout = timeout
self._timeout_error_type = timeout_error_type
def __enter__(self):
self._start = time.time()
return self
def __exit__(self, exc_type, exc_value, traceback):
if exc_value:
return # let the error bubble up automatically
if self._timeout is None:
return # nothing to do, the timeout was not specified
elapsed = time.time() - self._start
deadline_hit = False
if isinstance(self._timeout, numbers.Number):
self.remaining_timeout = self._timeout - elapsed
deadline_hit = self.remaining_timeout <= 0
else:
self.remaining_timeout = tuple(x - elapsed for x in self._timeout)
deadline_hit = min(self.remaining_timeout) <= 0
if deadline_hit:
raise self._timeout_error_type()
[docs]class Request(transport.Request):
"""Requests request adapter.
This class is used internally for making requests using various transports
in a consistent way. If you use :class:`AuthorizedSession` you do not need
to construct or use this class directly.
This class can be useful if you want to manually refresh a
:class:`~google.auth.credentials.Credentials` instance::
import google.auth.transport.requests
import requests
request = google.auth.transport.requests.Request()
credentials.refresh(request)
Args:
session (requests.Session): An instance :class:`requests.Session` used
to make HTTP requests. If not specified, a session will be created.
.. automethod:: __call__
"""
def __init__(self, session=None):
if not session:
session = requests.Session()
self.session = session
[docs] def __call__(
self,
url,
method="GET",
body=None,
headers=None,
timeout=_DEFAULT_TIMEOUT,
**kwargs
):
"""Make an HTTP request using requests.
Args:
url (str): The URI to be requested.
method (str): The HTTP method to use for the request. Defaults
to 'GET'.
body (bytes): The payload / body in HTTP request.
headers (Mapping[str, str]): Request headers.
timeout (Optional[int]): The number of seconds to wait for a
response from the server. If not specified or if None, the
requests default timeout will be used.
kwargs: Additional arguments passed through to the underlying
requests :meth:`~requests.Session.request` method.
Returns:
google.auth.transport.Response: The HTTP response.
Raises:
google.auth.exceptions.TransportError: If any exception occurred.
"""
try:
_LOGGER.debug("Making request: %s %s", method, url)
response = self.session.request(
method, url, data=body, headers=headers, timeout=timeout, **kwargs
)
return _Response(response)
except requests.exceptions.RequestException as caught_exc:
new_exc = exceptions.TransportError(caught_exc)
six.raise_from(new_exc, caught_exc)
class _MutualTlsAdapter(requests.adapters.HTTPAdapter):
"""
A TransportAdapter that enables mutual TLS.
Args:
cert (bytes): client certificate in PEM format
key (bytes): client private key in PEM format
Raises:
ImportError: if certifi or pyOpenSSL is not installed
OpenSSL.crypto.Error: if client cert or key is invalid
"""
def __init__(self, cert, key):
import certifi
from OpenSSL import crypto
import urllib3.contrib.pyopenssl
urllib3.contrib.pyopenssl.inject_into_urllib3()
pkey = crypto.load_privatekey(crypto.FILETYPE_PEM, key)
x509 = crypto.load_certificate(crypto.FILETYPE_PEM, cert)
ctx_poolmanager = create_urllib3_context()
ctx_poolmanager.load_verify_locations(cafile=certifi.where())
ctx_poolmanager._ctx.use_certificate(x509)
ctx_poolmanager._ctx.use_privatekey(pkey)
self._ctx_poolmanager = ctx_poolmanager
ctx_proxymanager = create_urllib3_context()
ctx_proxymanager.load_verify_locations(cafile=certifi.where())
ctx_proxymanager._ctx.use_certificate(x509)
ctx_proxymanager._ctx.use_privatekey(pkey)
self._ctx_proxymanager = ctx_proxymanager
super(_MutualTlsAdapter, self).__init__()
def init_poolmanager(self, *args, **kwargs):
kwargs["ssl_context"] = self._ctx_poolmanager
super(_MutualTlsAdapter, self).init_poolmanager(*args, **kwargs)
def proxy_manager_for(self, *args, **kwargs):
kwargs["ssl_context"] = self._ctx_proxymanager
return super(_MutualTlsAdapter, self).proxy_manager_for(*args, **kwargs)
[docs]class AuthorizedSession(requests.Session):
"""A Requests Session class with credentials.
This class is used to perform requests to API endpoints that require
authorization::
from google.auth.transport.requests import AuthorizedSession
authed_session = AuthorizedSession(credentials)
response = authed_session.request(
'GET', 'https://www.googleapis.com/storage/v1/b')
The underlying :meth:`request` implementation handles adding the
credentials' headers to the request and refreshing credentials as needed.
This class also supports mutual TLS via :meth:`configure_mtls_channel`
method. If client_cert_callback is provided, client certificate and private
key are loaded using the callback; if client_cert_callback is None,
application default SSL credentials will be used. Exceptions are raised if
there are problems with the certificate, private key, or the loading process,
so it should be called within a try/except block.
First we create an :class:`AuthorizedSession` instance and specify the endpoints::
regular_endpoint = 'https://pubsub.googleapis.com/v1/projects/{my_project_id}/topics'
mtls_endpoint = 'https://pubsub.mtls.googleapis.com/v1/projects/{my_project_id}/topics'
authed_session = AuthorizedSession(credentials)
Now we can pass a callback to :meth:`configure_mtls_channel`::
def my_cert_callback():
# some code to load client cert bytes and private key bytes, both in
# PEM format.
some_code_to_load_client_cert_and_key()
if loaded:
return cert, key
raise MyClientCertFailureException()
# Always call configure_mtls_channel within a try/except block.
try:
authed_session.configure_mtls_channel(my_cert_callback)
except:
# handle exceptions.
if authed_session.is_mtls:
response = authed_session.request('GET', mtls_endpoint)
else:
response = authed_session.request('GET', regular_endpoint)
You can alternatively use application default SSL credentials like this::
try:
authed_session.configure_mtls_channel()
except:
# handle exceptions.
Args:
credentials (google.auth.credentials.Credentials): The credentials to
add to the request.
refresh_status_codes (Sequence[int]): Which HTTP status codes indicate
that credentials should be refreshed and the request should be
retried.
max_refresh_attempts (int): The maximum number of times to attempt to
refresh the credentials and retry the request.
refresh_timeout (Optional[int]): The timeout value in seconds for
credential refresh HTTP requests.
auth_request (google.auth.transport.requests.Request):
(Optional) An instance of
:class:`~google.auth.transport.requests.Request` used when
refreshing credentials. If not passed,
an instance of :class:`~google.auth.transport.requests.Request`
is created.
"""
def __init__(
self,
credentials,
refresh_status_codes=transport.DEFAULT_REFRESH_STATUS_CODES,
max_refresh_attempts=transport.DEFAULT_MAX_REFRESH_ATTEMPTS,
refresh_timeout=None,
auth_request=None,
):
super(AuthorizedSession, self).__init__()
self.credentials = credentials
self._refresh_status_codes = refresh_status_codes
self._max_refresh_attempts = max_refresh_attempts
self._refresh_timeout = refresh_timeout
self._is_mtls = False
if auth_request is None:
auth_request_session = requests.Session()
# Using an adapter to make HTTP requests robust to network errors.
# This adapter retrys HTTP requests when network errors occur
# and the requests seems safely retryable.
retry_adapter = requests.adapters.HTTPAdapter(max_retries=3)
auth_request_session.mount("https://", retry_adapter)
# Do not pass `self` as the session here, as it can lead to
# infinite recursion.
auth_request = Request(auth_request_session)
# Request instance used by internal methods (for example,
# credentials.refresh).
self._auth_request = auth_request
[docs] def request(
self,
method,
url,
data=None,
headers=None,
max_allowed_time=None,
timeout=_DEFAULT_TIMEOUT,
**kwargs
):
"""Implementation of Requests' request.
Args:
timeout (Optional[Union[float, Tuple[float, float]]]):
The amount of time in seconds to wait for the server response
with each individual request.
Can also be passed as a tuple (connect_timeout, read_timeout).
See :meth:`requests.Session.request` documentation for details.
max_allowed_time (Optional[float]):
If the method runs longer than this, a ``Timeout`` exception is
automatically raised. Unlike the ``timeout` parameter, this
value applies to the total method execution time, even if
multiple requests are made under the hood.
Mind that it is not guaranteed that the timeout error is raised
at ``max_allowed_time`. It might take longer, for example, if
an underlying request takes a lot of time, but the request
itself does not timeout, e.g. if a large file is being
transmitted. The timout error will be raised after such
request completes.
"""
# pylint: disable=arguments-differ
# Requests has a ton of arguments to request, but only two
# (method, url) are required. We pass through all of the other
# arguments to super, so no need to exhaustively list them here.
# Use a kwarg for this instead of an attribute to maintain
# thread-safety.
_credential_refresh_attempt = kwargs.pop("_credential_refresh_attempt", 0)
# Make a copy of the headers. They will be modified by the credentials
# and we want to pass the original headers if we recurse.
request_headers = headers.copy() if headers is not None else {}
# Do not apply the timeout unconditionally in order to not override the
# _auth_request's default timeout.
auth_request = (
self._auth_request
if timeout is None
else functools.partial(self._auth_request, timeout=timeout)
)
remaining_time = max_allowed_time
with TimeoutGuard(remaining_time) as guard:
self.credentials.before_request(auth_request, method, url, request_headers)
remaining_time = guard.remaining_timeout
with TimeoutGuard(remaining_time) as guard:
response = super(AuthorizedSession, self).request(
method,
url,
data=data,
headers=request_headers,
timeout=timeout,
**kwargs
)
remaining_time = guard.remaining_timeout
# If the response indicated that the credentials needed to be
# refreshed, then refresh the credentials and re-attempt the
# request.
# A stored token may expire between the time it is retrieved and
# the time the request is made, so we may need to try twice.
if (
response.status_code in self._refresh_status_codes
and _credential_refresh_attempt < self._max_refresh_attempts
):
_LOGGER.info(
"Refreshing credentials due to a %s response. Attempt %s/%s.",
response.status_code,
_credential_refresh_attempt + 1,
self._max_refresh_attempts,
)
# Do not apply the timeout unconditionally in order to not override the
# _auth_request's default timeout.
auth_request = (
self._auth_request
if timeout is None
else functools.partial(self._auth_request, timeout=timeout)
)
with TimeoutGuard(remaining_time) as guard:
self.credentials.refresh(auth_request)
remaining_time = guard.remaining_timeout
# Recurse. Pass in the original headers, not our modified set, but
# do pass the adjusted max allowed time (i.e. the remaining total time).
return self.request(
method,
url,
data=data,
headers=headers,
max_allowed_time=remaining_time,
timeout=timeout,
_credential_refresh_attempt=_credential_refresh_attempt + 1,
**kwargs
)
return response
@property
def is_mtls(self):
"""Indicates if the created SSL channel is mutual TLS."""
return self._is_mtls
