forked from s434596/CatOrNot
758 lines
26 KiB
Python
758 lines
26 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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"""JSON Web Tokens
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Provides support for creating (encoding) and verifying (decoding) JWTs,
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especially JWTs generated and consumed by Google infrastructure.
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See `rfc7519`_ for more details on JWTs.
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To encode a JWT use :func:`encode`::
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from google.auth import crypt
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from google.auth import jwt
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signer = crypt.Signer(private_key)
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payload = {'some': 'payload'}
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encoded = jwt.encode(signer, payload)
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To decode a JWT and verify claims use :func:`decode`::
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claims = jwt.decode(encoded, certs=public_certs)
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You can also skip verification::
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claims = jwt.decode(encoded, verify=False)
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.. _rfc7519: https://tools.ietf.org/html/rfc7519
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"""
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import base64
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import collections
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import copy
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import datetime
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import json
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import cachetools
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import six
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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 _service_account_info
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from google.auth import crypt
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from google.auth import exceptions
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import google.auth.credentials
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_DEFAULT_TOKEN_LIFETIME_SECS = 3600 # 1 hour in seconds
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_DEFAULT_MAX_CACHE_SIZE = 10
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def encode(signer, payload, header=None, key_id=None):
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"""Make a signed JWT.
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Args:
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signer (google.auth.crypt.Signer): The signer used to sign the JWT.
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payload (Mapping[str, str]): The JWT payload.
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header (Mapping[str, str]): Additional JWT header payload.
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key_id (str): The key id to add to the JWT header. If the
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signer has a key id it will be used as the default. If this is
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specified it will override the signer's key id.
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Returns:
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bytes: The encoded JWT.
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"""
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if header is None:
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header = {}
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if key_id is None:
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key_id = signer.key_id
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header.update({'typ': 'JWT', 'alg': 'RS256'})
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if key_id is not None:
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header['kid'] = key_id
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segments = [
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base64.urlsafe_b64encode(json.dumps(header).encode('utf-8')),
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base64.urlsafe_b64encode(json.dumps(payload).encode('utf-8')),
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]
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signing_input = b'.'.join(segments)
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signature = signer.sign(signing_input)
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segments.append(base64.urlsafe_b64encode(signature))
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return b'.'.join(segments)
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def _decode_jwt_segment(encoded_section):
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"""Decodes a single JWT segment."""
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section_bytes = _helpers.padded_urlsafe_b64decode(encoded_section)
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try:
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return json.loads(section_bytes.decode('utf-8'))
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except ValueError as caught_exc:
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new_exc = ValueError('Can\'t parse segment: {0}'.format(section_bytes))
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six.raise_from(new_exc, caught_exc)
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def _unverified_decode(token):
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"""Decodes a token and does no verification.
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Args:
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token (Union[str, bytes]): The encoded JWT.
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Returns:
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Tuple[str, str, str, str]: header, payload, signed_section, and
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signature.
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Raises:
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ValueError: if there are an incorrect amount of segments in the token.
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"""
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token = _helpers.to_bytes(token)
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if token.count(b'.') != 2:
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raise ValueError(
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'Wrong number of segments in token: {0}'.format(token))
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encoded_header, encoded_payload, signature = token.split(b'.')
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signed_section = encoded_header + b'.' + encoded_payload
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signature = _helpers.padded_urlsafe_b64decode(signature)
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# Parse segments
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header = _decode_jwt_segment(encoded_header)
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payload = _decode_jwt_segment(encoded_payload)
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return header, payload, signed_section, signature
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def decode_header(token):
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"""Return the decoded header of a token.
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No verification is done. This is useful to extract the key id from
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the header in order to acquire the appropriate certificate to verify
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the token.
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Args:
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token (Union[str, bytes]): the encoded JWT.
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Returns:
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Mapping: The decoded JWT header.
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"""
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header, _, _, _ = _unverified_decode(token)
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return header
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def _verify_iat_and_exp(payload):
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"""Verifies the ``iat`` (Issued At) and ``exp`` (Expires) claims in a token
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payload.
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Args:
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payload (Mapping[str, str]): The JWT payload.
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Raises:
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ValueError: if any checks failed.
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"""
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now = _helpers.datetime_to_secs(_helpers.utcnow())
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# Make sure the iat and exp claims are present.
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for key in ('iat', 'exp'):
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if key not in payload:
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raise ValueError(
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'Token does not contain required claim {}'.format(key))
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# Make sure the token wasn't issued in the future.
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iat = payload['iat']
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# Err on the side of accepting a token that is slightly early to account
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# for clock skew.
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earliest = iat - _helpers.CLOCK_SKEW_SECS
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if now < earliest:
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raise ValueError('Token used too early, {} < {}'.format(now, iat))
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# Make sure the token wasn't issued in the past.
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exp = payload['exp']
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# Err on the side of accepting a token that is slightly out of date
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# to account for clow skew.
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latest = exp + _helpers.CLOCK_SKEW_SECS
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if latest < now:
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raise ValueError('Token expired, {} < {}'.format(latest, now))
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def decode(token, certs=None, verify=True, audience=None):
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"""Decode and verify a JWT.
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Args:
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token (str): The encoded JWT.
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certs (Union[str, bytes, Mapping[str, Union[str, bytes]]]): The
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certificate used to validate the JWT signatyre. If bytes or string,
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it must the the public key certificate in PEM format. If a mapping,
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it must be a mapping of key IDs to public key certificates in PEM
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format. The mapping must contain the same key ID that's specified
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in the token's header.
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verify (bool): Whether to perform signature and claim validation.
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Verification is done by default.
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audience (str): The audience claim, 'aud', that this JWT should
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contain. If None then the JWT's 'aud' parameter is not verified.
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Returns:
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Mapping[str, str]: The deserialized JSON payload in the JWT.
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Raises:
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ValueError: if any verification checks failed.
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"""
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header, payload, signed_section, signature = _unverified_decode(token)
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if not verify:
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return payload
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# If certs is specified as a dictionary of key IDs to certificates, then
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# use the certificate identified by the key ID in the token header.
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if isinstance(certs, collections.Mapping):
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key_id = header.get('kid')
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if key_id:
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if key_id not in certs:
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raise ValueError(
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'Certificate for key id {} not found.'.format(key_id))
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certs_to_check = [certs[key_id]]
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# If there's no key id in the header, check against all of the certs.
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else:
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certs_to_check = certs.values()
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else:
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certs_to_check = certs
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# Verify that the signature matches the message.
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if not crypt.verify_signature(signed_section, signature, certs_to_check):
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raise ValueError('Could not verify token signature.')
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# Verify the issued at and created times in the payload.
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_verify_iat_and_exp(payload)
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# Check audience.
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if audience is not None:
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claim_audience = payload.get('aud')
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if audience != claim_audience:
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raise ValueError(
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'Token has wrong audience {}, expected {}'.format(
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claim_audience, audience))
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return payload
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class Credentials(google.auth.credentials.Signing,
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google.auth.credentials.Credentials):
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"""Credentials that use a JWT as the bearer token.
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These credentials require an "audience" claim. This claim identifies the
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intended recipient of the bearer token.
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The constructor arguments determine the claims for the JWT that is
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sent with requests. Usually, you'll construct these credentials with
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one of the helper constructors as shown in the next section.
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To create JWT credentials using a Google service account private key
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JSON file::
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audience = 'https://pubsub.googleapis.com/google.pubsub.v1.Publisher'
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credentials = jwt.Credentials.from_service_account_file(
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'service-account.json',
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audience=audience)
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If you already have the service account file loaded and parsed::
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service_account_info = json.load(open('service_account.json'))
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credentials = jwt.Credentials.from_service_account_info(
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service_account_info,
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audience=audience)
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Both helper methods pass on arguments to the constructor, so you can
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specify the JWT claims::
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credentials = jwt.Credentials.from_service_account_file(
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'service-account.json',
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audience=audience,
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additional_claims={'meta': 'data'})
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You can also construct the credentials directly if you have a
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:class:`~google.auth.crypt.Signer` instance::
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credentials = jwt.Credentials(
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signer,
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issuer='your-issuer',
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subject='your-subject',
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audience=audience)
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The claims are considered immutable. If you want to modify the claims,
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you can easily create another instance using :meth:`with_claims`::
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new_audience = (
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'https://pubsub.googleapis.com/google.pubsub.v1.Subscriber')
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new_credentials = credentials.with_claims(audience=new_audience)
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"""
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def __init__(self, signer, issuer, subject, audience,
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additional_claims=None,
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token_lifetime=_DEFAULT_TOKEN_LIFETIME_SECS):
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"""
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Args:
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signer (google.auth.crypt.Signer): The signer used to sign JWTs.
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issuer (str): The `iss` claim.
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subject (str): The `sub` claim.
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audience (str): the `aud` claim. The intended audience for the
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credentials.
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additional_claims (Mapping[str, str]): Any additional claims for
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the JWT payload.
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token_lifetime (int): The amount of time in seconds for
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which the token is valid. Defaults to 1 hour.
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"""
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super(Credentials, self).__init__()
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self._signer = signer
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self._issuer = issuer
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self._subject = subject
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self._audience = audience
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self._token_lifetime = token_lifetime
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if additional_claims is None:
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additional_claims = {}
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self._additional_claims = additional_claims
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@classmethod
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def _from_signer_and_info(cls, signer, info, **kwargs):
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"""Creates a Credentials instance from a signer and service account
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info.
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Args:
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signer (google.auth.crypt.Signer): The signer used to sign JWTs.
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info (Mapping[str, str]): The service account info.
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kwargs: Additional arguments to pass to the constructor.
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Returns:
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google.auth.jwt.Credentials: The constructed credentials.
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Raises:
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ValueError: If the info is not in the expected format.
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"""
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kwargs.setdefault('subject', info['client_email'])
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kwargs.setdefault('issuer', info['client_email'])
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return cls(signer, **kwargs)
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@classmethod
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def from_service_account_info(cls, info, **kwargs):
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"""Creates an Credentials instance from a dictionary.
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Args:
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info (Mapping[str, str]): The service account info in Google
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format.
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kwargs: Additional arguments to pass to the constructor.
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Returns:
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google.auth.jwt.Credentials: The constructed credentials.
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Raises:
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ValueError: If the info is not in the expected format.
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"""
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signer = _service_account_info.from_dict(
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info, require=['client_email'])
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return cls._from_signer_and_info(signer, info, **kwargs)
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@classmethod
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def from_service_account_file(cls, filename, **kwargs):
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"""Creates a Credentials instance from a service account .json file
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in Google format.
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Args:
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filename (str): The path to the service account .json file.
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kwargs: Additional arguments to pass to the constructor.
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Returns:
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google.auth.jwt.Credentials: The constructed credentials.
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"""
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info, signer = _service_account_info.from_filename(
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filename, require=['client_email'])
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return cls._from_signer_and_info(signer, info, **kwargs)
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@classmethod
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def from_signing_credentials(cls, credentials, audience, **kwargs):
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"""Creates a new :class:`google.auth.jwt.Credentials` instance from an
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existing :class:`google.auth.credentials.Signing` instance.
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The new instance will use the same signer as the existing instance and
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will use the existing instance's signer email as the issuer and
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subject by default.
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Example::
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svc_creds = service_account.Credentials.from_service_account_file(
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'service_account.json')
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audience = (
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'https://pubsub.googleapis.com/google.pubsub.v1.Publisher')
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jwt_creds = jwt.Credentials.from_signing_credentials(
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svc_creds, audience=audience)
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Args:
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credentials (google.auth.credentials.Signing): The credentials to
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use to construct the new credentials.
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audience (str): the `aud` claim. The intended audience for the
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credentials.
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kwargs: Additional arguments to pass to the constructor.
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Returns:
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google.auth.jwt.Credentials: A new Credentials instance.
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"""
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kwargs.setdefault('issuer', credentials.signer_email)
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kwargs.setdefault('subject', credentials.signer_email)
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return cls(
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credentials.signer,
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audience=audience,
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**kwargs)
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def with_claims(self, issuer=None, subject=None, audience=None,
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additional_claims=None):
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"""Returns a copy of these credentials with modified claims.
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Args:
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issuer (str): The `iss` claim. If unspecified the current issuer
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claim will be used.
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subject (str): The `sub` claim. If unspecified the current subject
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claim will be used.
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audience (str): the `aud` claim. If unspecified the current
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audience claim will be used.
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additional_claims (Mapping[str, str]): Any additional claims for
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the JWT payload. This will be merged with the current
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additional claims.
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Returns:
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google.auth.jwt.Credentials: A new credentials instance.
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"""
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new_additional_claims = copy.deepcopy(self._additional_claims)
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new_additional_claims.update(additional_claims or {})
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return self.__class__(
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self._signer,
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issuer=issuer if issuer is not None else self._issuer,
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subject=subject if subject is not None else self._subject,
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audience=audience if audience is not None else self._audience,
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additional_claims=new_additional_claims)
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def _make_jwt(self):
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"""Make a signed JWT.
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Returns:
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Tuple[bytes, datetime]: The encoded JWT and the expiration.
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"""
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now = _helpers.utcnow()
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lifetime = datetime.timedelta(seconds=self._token_lifetime)
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expiry = now + lifetime
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payload = {
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'iss': self._issuer,
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'sub': self._subject,
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'iat': _helpers.datetime_to_secs(now),
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'exp': _helpers.datetime_to_secs(expiry),
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'aud': self._audience,
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}
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payload.update(self._additional_claims)
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jwt = encode(self._signer, payload)
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return jwt, expiry
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def refresh(self, request):
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"""Refreshes the access token.
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Args:
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request (Any): Unused.
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"""
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# pylint: disable=unused-argument
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# (pylint doesn't correctly recognize overridden methods.)
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self.token, self.expiry = self._make_jwt()
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@_helpers.copy_docstring(google.auth.credentials.Signing)
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def sign_bytes(self, message):
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return self._signer.sign(message)
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@property
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@_helpers.copy_docstring(google.auth.credentials.Signing)
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def signer_email(self):
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return self._issuer
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@property
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@_helpers.copy_docstring(google.auth.credentials.Signing)
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def signer(self):
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return self._signer
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class OnDemandCredentials(
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google.auth.credentials.Signing,
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google.auth.credentials.Credentials):
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"""On-demand JWT credentials.
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Like :class:`Credentials`, this class uses a JWT as the bearer token for
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authentication. However, this class does not require the audience at
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construction time. Instead, it will generate a new token on-demand for
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each request using the request URI as the audience. It caches tokens
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so that multiple requests to the same URI do not incur the overhead
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of generating a new token every time.
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This behavior is especially useful for `gRPC`_ clients. A gRPC service may
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have multiple audience and gRPC clients may not know all of the audiences
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required for accessing a particular service. With these credentials,
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no knowledge of the audiences is required ahead of time.
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.. _grpc: http://www.grpc.io/
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"""
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def __init__(self, signer, issuer, subject,
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additional_claims=None,
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token_lifetime=_DEFAULT_TOKEN_LIFETIME_SECS,
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max_cache_size=_DEFAULT_MAX_CACHE_SIZE):
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"""
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Args:
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signer (google.auth.crypt.Signer): The signer used to sign JWTs.
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issuer (str): The `iss` claim.
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subject (str): The `sub` claim.
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additional_claims (Mapping[str, str]): Any additional claims for
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the JWT payload.
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token_lifetime (int): The amount of time in seconds for
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which the token is valid. Defaults to 1 hour.
|
|
max_cache_size (int): The maximum number of JWT tokens to keep in
|
|
cache. Tokens are cached using :class:`cachetools.LRUCache`.
|
|
"""
|
|
super(OnDemandCredentials, self).__init__()
|
|
self._signer = signer
|
|
self._issuer = issuer
|
|
self._subject = subject
|
|
self._token_lifetime = token_lifetime
|
|
|
|
if additional_claims is None:
|
|
additional_claims = {}
|
|
|
|
self._additional_claims = additional_claims
|
|
self._cache = cachetools.LRUCache(maxsize=max_cache_size)
|
|
|
|
@classmethod
|
|
def _from_signer_and_info(cls, signer, info, **kwargs):
|
|
"""Creates an OnDemandCredentials instance from a signer and service
|
|
account info.
|
|
|
|
Args:
|
|
signer (google.auth.crypt.Signer): The signer used to sign JWTs.
|
|
info (Mapping[str, str]): The service account info.
|
|
kwargs: Additional arguments to pass to the constructor.
|
|
|
|
Returns:
|
|
google.auth.jwt.OnDemandCredentials: The constructed credentials.
|
|
|
|
Raises:
|
|
ValueError: If the info is not in the expected format.
|
|
"""
|
|
kwargs.setdefault('subject', info['client_email'])
|
|
kwargs.setdefault('issuer', info['client_email'])
|
|
return cls(signer, **kwargs)
|
|
|
|
@classmethod
|
|
def from_service_account_info(cls, info, **kwargs):
|
|
"""Creates an OnDemandCredentials instance from a dictionary.
|
|
|
|
Args:
|
|
info (Mapping[str, str]): The service account info in Google
|
|
format.
|
|
kwargs: Additional arguments to pass to the constructor.
|
|
|
|
Returns:
|
|
google.auth.jwt.OnDemandCredentials: The constructed credentials.
|
|
|
|
Raises:
|
|
ValueError: If the info is not in the expected format.
|
|
"""
|
|
signer = _service_account_info.from_dict(
|
|
info, require=['client_email'])
|
|
return cls._from_signer_and_info(signer, info, **kwargs)
|
|
|
|
@classmethod
|
|
def from_service_account_file(cls, filename, **kwargs):
|
|
"""Creates an OnDemandCredentials instance from a service account .json
|
|
file in Google format.
|
|
|
|
Args:
|
|
filename (str): The path to the service account .json file.
|
|
kwargs: Additional arguments to pass to the constructor.
|
|
|
|
Returns:
|
|
google.auth.jwt.OnDemandCredentials: The constructed credentials.
|
|
"""
|
|
info, signer = _service_account_info.from_filename(
|
|
filename, require=['client_email'])
|
|
return cls._from_signer_and_info(signer, info, **kwargs)
|
|
|
|
@classmethod
|
|
def from_signing_credentials(cls, credentials, **kwargs):
|
|
"""Creates a new :class:`google.auth.jwt.OnDemandCredentials` instance
|
|
from an existing :class:`google.auth.credentials.Signing` instance.
|
|
|
|
The new instance will use the same signer as the existing instance and
|
|
will use the existing instance's signer email as the issuer and
|
|
subject by default.
|
|
|
|
Example::
|
|
|
|
svc_creds = service_account.Credentials.from_service_account_file(
|
|
'service_account.json')
|
|
jwt_creds = jwt.OnDemandCredentials.from_signing_credentials(
|
|
svc_creds)
|
|
|
|
Args:
|
|
credentials (google.auth.credentials.Signing): The credentials to
|
|
use to construct the new credentials.
|
|
kwargs: Additional arguments to pass to the constructor.
|
|
|
|
Returns:
|
|
google.auth.jwt.Credentials: A new Credentials instance.
|
|
"""
|
|
kwargs.setdefault('issuer', credentials.signer_email)
|
|
kwargs.setdefault('subject', credentials.signer_email)
|
|
return cls(credentials.signer, **kwargs)
|
|
|
|
def with_claims(self, issuer=None, subject=None, additional_claims=None):
|
|
"""Returns a copy of these credentials with modified claims.
|
|
|
|
Args:
|
|
issuer (str): The `iss` claim. If unspecified the current issuer
|
|
claim will be used.
|
|
subject (str): The `sub` claim. If unspecified the current subject
|
|
claim will be used.
|
|
additional_claims (Mapping[str, str]): Any additional claims for
|
|
the JWT payload. This will be merged with the current
|
|
additional claims.
|
|
|
|
Returns:
|
|
google.auth.jwt.OnDemandCredentials: A new credentials instance.
|
|
"""
|
|
new_additional_claims = copy.deepcopy(self._additional_claims)
|
|
new_additional_claims.update(additional_claims or {})
|
|
|
|
return self.__class__(
|
|
self._signer,
|
|
issuer=issuer if issuer is not None else self._issuer,
|
|
subject=subject if subject is not None else self._subject,
|
|
additional_claims=new_additional_claims,
|
|
max_cache_size=self._cache.maxsize)
|
|
|
|
@property
|
|
def valid(self):
|
|
"""Checks the validity of the credentials.
|
|
|
|
These credentials are always valid because it generates tokens on
|
|
demand.
|
|
"""
|
|
return True
|
|
|
|
def _make_jwt_for_audience(self, audience):
|
|
"""Make a new JWT for the given audience.
|
|
|
|
Args:
|
|
audience (str): The intended audience.
|
|
|
|
Returns:
|
|
Tuple[bytes, datetime]: The encoded JWT and the expiration.
|
|
"""
|
|
now = _helpers.utcnow()
|
|
lifetime = datetime.timedelta(seconds=self._token_lifetime)
|
|
expiry = now + lifetime
|
|
|
|
payload = {
|
|
'iss': self._issuer,
|
|
'sub': self._subject,
|
|
'iat': _helpers.datetime_to_secs(now),
|
|
'exp': _helpers.datetime_to_secs(expiry),
|
|
'aud': audience,
|
|
}
|
|
|
|
payload.update(self._additional_claims)
|
|
|
|
jwt = encode(self._signer, payload)
|
|
|
|
return jwt, expiry
|
|
|
|
def _get_jwt_for_audience(self, audience):
|
|
"""Get a JWT For a given audience.
|
|
|
|
If there is already an existing, non-expired token in the cache for
|
|
the audience, that token is used. Otherwise, a new token will be
|
|
created.
|
|
|
|
Args:
|
|
audience (str): The intended audience.
|
|
|
|
Returns:
|
|
bytes: The encoded JWT.
|
|
"""
|
|
token, expiry = self._cache.get(audience, (None, None))
|
|
|
|
if token is None or expiry < _helpers.utcnow():
|
|
token, expiry = self._make_jwt_for_audience(audience)
|
|
self._cache[audience] = token, expiry
|
|
|
|
return token
|
|
|
|
def refresh(self, request):
|
|
"""Raises an exception, these credentials can not be directly
|
|
refreshed.
|
|
|
|
Args:
|
|
request (Any): Unused.
|
|
|
|
Raises:
|
|
google.auth.RefreshError
|
|
"""
|
|
# pylint: disable=unused-argument
|
|
# (pylint doesn't correctly recognize overridden methods.)
|
|
raise exceptions.RefreshError(
|
|
'OnDemandCredentials can not be directly refreshed.')
|
|
|
|
def before_request(self, request, method, url, headers):
|
|
"""Performs credential-specific before request logic.
|
|
|
|
Args:
|
|
request (Any): Unused. JWT credentials do not need to make an
|
|
HTTP request to refresh.
|
|
method (str): The request's HTTP method.
|
|
url (str): The request's URI. This is used as the audience claim
|
|
when generating the JWT.
|
|
headers (Mapping): The request's headers.
|
|
"""
|
|
# pylint: disable=unused-argument
|
|
# (pylint doesn't correctly recognize overridden methods.)
|
|
parts = urllib.parse.urlsplit(url)
|
|
# Strip query string and fragment
|
|
audience = urllib.parse.urlunsplit(
|
|
(parts.scheme, parts.netloc, parts.path, "", ""))
|
|
token = self._get_jwt_for_audience(audience)
|
|
self.apply(headers, token=token)
|
|
|
|
@_helpers.copy_docstring(google.auth.credentials.Signing)
|
|
def sign_bytes(self, message):
|
|
return self._signer.sign(message)
|
|
|
|
@property
|
|
@_helpers.copy_docstring(google.auth.credentials.Signing)
|
|
def signer_email(self):
|
|
return self._issuer
|
|
|
|
@property
|
|
@_helpers.copy_docstring(google.auth.credentials.Signing)
|
|
def signer(self):
|
|
return self._signer
|