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# Copyright 2016 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.
import logging
import httplib2
import six
from six.moves import http_client
from oauth2client._helpers import _to_bytes
_LOGGER = logging.getLogger(__name__)
# Properties present in file-like streams / buffers.
_STREAM_PROPERTIES = ('read', 'seek', 'tell')
# Google Data client libraries may need to set this to [401, 403].
REFRESH_STATUS_CODES = (http_client.UNAUTHORIZED,)
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)
def get_cached_http():
"""Return an HTTP object which caches results returned.
This is intended to be used in methods like
oauth2client.client.verify_id_token(), which calls to the same URI
to retrieve certs.
Returns:
httplib2.Http, an HTTP object with a MemoryCache
"""
return _CACHED_HTTP
def get_http_object():
"""Return a new HTTP object.
Returns:
httplib2.Http, an HTTP object.
"""
return httplib2.Http()
def _initialize_headers(headers):
"""Creates a copy of the headers.
Args:
headers: dict, request headers to copy.
Returns:
dict, the copied headers or a new dictionary if the headers
were None.
"""
return {} if headers is None else dict(headers)
def _apply_user_agent(headers, user_agent):
"""Adds a user-agent to the headers.
Args:
headers: dict, request headers to add / modify user
agent within.
user_agent: str, the user agent to add.
Returns:
dict, the original headers passed in, but modified if the
user agent is not None.
"""
if user_agent is not None:
if 'user-agent' in headers:
headers['user-agent'] = (user_agent + ' ' + headers['user-agent'])
else:
headers['user-agent'] = user_agent
return headers
def clean_headers(headers):
"""Forces header keys and values to be strings, i.e not unicode.
The httplib module just concats the header keys and values in a way that
may make the message header a unicode string, which, if it then tries to
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 six.iteritems(headers):
if not isinstance(k, six.binary_type):
k = str(k)
if not isinstance(v, six.binary_type):
v = str(v)
clean[_to_bytes(k)] = _to_bytes(v)
except UnicodeEncodeError:
from oauth2client.client import NonAsciiHeaderError
raise NonAsciiHeaderError(k, ': ', v)
return clean
def wrap_http_for_auth(credentials, http):
"""Prepares an HTTP object's request method for auth.
Wraps HTTP requests with logic to catch auth failures (typically
identified via a 401 status code). In the event of failure, tries
to refresh the token used and then retry the original request.
Args:
credentials: Credentials, the credentials used to identify
the authenticated user.
http: httplib2.Http, an http object to be used to make
auth requests.
"""
orig_request_method = http.request
# The closure that will replace 'httplib2.Http.request'.
def new_request(uri, method='GET', body=None, headers=None,
redirections=httplib2.DEFAULT_MAX_REDIRECTS,
connection_type=None):
if not credentials.access_token:
_LOGGER.info('Attempting refresh to obtain '
'initial access_token')
credentials._refresh(orig_request_method)
# Clone and modify the request headers to add the appropriate
# Authorization header.
headers = _initialize_headers(headers)
credentials.apply(headers)
_apply_user_agent(headers, credentials.user_agent)
body_stream_position = None
# Check if the body is a file-like stream.
if all(getattr(body, stream_prop, None) for stream_prop in
_STREAM_PROPERTIES):
body_stream_position = body.tell()
resp, content = orig_request_method(uri, method, body,
clean_headers(headers),
redirections, connection_type)
# 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.
max_refresh_attempts = 2
for refresh_attempt in range(max_refresh_attempts):
if resp.status not in REFRESH_STATUS_CODES:
break
_LOGGER.info('Refreshing due to a %s (attempt %s/%s)',
resp.status, refresh_attempt + 1,
max_refresh_attempts)
credentials._refresh(orig_request_method)
credentials.apply(headers)
if body_stream_position is not None:
body.seek(body_stream_position)
resp, content = orig_request_method(uri, method, body,
clean_headers(headers),
redirections, connection_type)
return resp, content
# Replace the request method with our own closure.
http.request = new_request
# Set credentials as a property of the request method.
setattr(http.request, 'credentials', credentials)
def wrap_http_for_jwt_access(credentials, http):
"""Prepares an HTTP object's request method for JWT access.
Wraps HTTP requests with logic to catch auth failures (typically
identified via a 401 status code). In the event of failure, tries
to refresh the token used and then retry the original request.
Args:
credentials: _JWTAccessCredentials, the credentials used to identify
a service account that uses JWT access tokens.
http: httplib2.Http, an http object to be used to make
auth requests.
"""
orig_request_method = http.request
wrap_http_for_auth(credentials, http)
# The new value of ``http.request`` set by ``wrap_http_for_auth``.
authenticated_request_method = http.request
# The closure that will replace 'httplib2.Http.request'.
def new_request(uri, method='GET', body=None, headers=None,
redirections=httplib2.DEFAULT_MAX_REDIRECTS,
connection_type=None):
if 'aud' in credentials._kwargs:
# Preemptively refresh token, this is not done for OAuth2
if (credentials.access_token is None or
credentials.access_token_expired):
credentials.refresh(None)
return authenticated_request_method(uri, method, body,
headers, redirections,
connection_type)
else:
# If we don't have an 'aud' (audience) claim,
# create a 1-time token with the uri root as the audience
headers = _initialize_headers(headers)
_apply_user_agent(headers, credentials.user_agent)
uri_root = uri.split('?', 1)[0]
token, unused_expiry = credentials._create_token({'aud': uri_root})
headers['Authorization'] = 'Bearer ' + token
return orig_request_method(uri, method, body,
clean_headers(headers),
redirections, connection_type)
# Replace the request method with our own closure.
http.request = new_request
_CACHED_HTTP = httplib2.Http(MemoryCache())
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