forked from s434596/CatOrNot
323 lines
11 KiB
Python
323 lines
11 KiB
Python
# Copyright 2016 Google Inc.
|
|
#
|
|
# 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.
|
|
|
|
|
|
"""Interfaces for credentials."""
|
|
|
|
import abc
|
|
|
|
import six
|
|
|
|
from google.auth import _helpers
|
|
|
|
|
|
@six.add_metaclass(abc.ABCMeta)
|
|
class Credentials(object):
|
|
"""Base class for all credentials.
|
|
|
|
All credentials have a :attr:`token` that is used for authentication and
|
|
may also optionally set an :attr:`expiry` to indicate when the token will
|
|
no longer be valid.
|
|
|
|
Most credentials will be :attr:`invalid` until :meth:`refresh` is called.
|
|
Credentials can do this automatically before the first HTTP request in
|
|
:meth:`before_request`.
|
|
|
|
Although the token and expiration will change as the credentials are
|
|
:meth:`refreshed <refresh>` and used, credentials should be considered
|
|
immutable. Various credentials will accept configuration such as private
|
|
keys, scopes, and other options. These options are not changeable after
|
|
construction. Some classes will provide mechanisms to copy the credentials
|
|
with modifications such as :meth:`ScopedCredentials.with_scopes`.
|
|
"""
|
|
def __init__(self):
|
|
self.token = None
|
|
"""str: The bearer token that can be used in HTTP headers to make
|
|
authenticated requests."""
|
|
self.expiry = None
|
|
"""Optional[datetime]: When the token expires and is no longer valid.
|
|
If this is None, the token is assumed to never expire."""
|
|
|
|
@property
|
|
def expired(self):
|
|
"""Checks if the credentials are expired.
|
|
|
|
Note that credentials can be invalid but not expired because
|
|
Credentials with :attr:`expiry` set to None is considered to never
|
|
expire.
|
|
"""
|
|
if not self.expiry:
|
|
return False
|
|
|
|
# Remove 5 minutes from expiry to err on the side of reporting
|
|
# expiration early so that we avoid the 401-refresh-retry loop.
|
|
skewed_expiry = self.expiry - _helpers.CLOCK_SKEW
|
|
return _helpers.utcnow() >= skewed_expiry
|
|
|
|
@property
|
|
def valid(self):
|
|
"""Checks the validity of the credentials.
|
|
|
|
This is True if the credentials have a :attr:`token` and the token
|
|
is not :attr:`expired`.
|
|
"""
|
|
return self.token is not None and not self.expired
|
|
|
|
@abc.abstractmethod
|
|
def refresh(self, request):
|
|
"""Refreshes the access token.
|
|
|
|
Args:
|
|
request (google.auth.transport.Request): The object used to make
|
|
HTTP requests.
|
|
|
|
Raises:
|
|
google.auth.exceptions.RefreshError: If the credentials could
|
|
not be refreshed.
|
|
"""
|
|
# pylint: disable=missing-raises-doc
|
|
# (pylint doesn't recognize that this is abstract)
|
|
raise NotImplementedError('Refresh must be implemented')
|
|
|
|
def apply(self, headers, token=None):
|
|
"""Apply the token to the authentication header.
|
|
|
|
Args:
|
|
headers (Mapping): The HTTP request headers.
|
|
token (Optional[str]): If specified, overrides the current access
|
|
token.
|
|
"""
|
|
headers['authorization'] = 'Bearer {}'.format(
|
|
_helpers.from_bytes(token or self.token))
|
|
|
|
def before_request(self, request, method, url, headers):
|
|
"""Performs credential-specific before request logic.
|
|
|
|
Refreshes the credentials if necessary, then calls :meth:`apply` to
|
|
apply the token to the authentication header.
|
|
|
|
Args:
|
|
request (google.auth.transport.Request): The object used to make
|
|
HTTP requests.
|
|
method (str): The request's HTTP method or the RPC method being
|
|
invoked.
|
|
url (str): The request's URI or the RPC service's URI.
|
|
headers (Mapping): The request's headers.
|
|
"""
|
|
# pylint: disable=unused-argument
|
|
# (Subclasses may use these arguments to ascertain information about
|
|
# the http request.)
|
|
if not self.valid:
|
|
self.refresh(request)
|
|
self.apply(headers)
|
|
|
|
|
|
class AnonymousCredentials(Credentials):
|
|
"""Credentials that do not provide any authentication information.
|
|
|
|
These are useful in the case of services that support anonymous access or
|
|
local service emulators that do not use credentials.
|
|
"""
|
|
|
|
@property
|
|
def expired(self):
|
|
"""Returns `False`, anonymous credentials never expire."""
|
|
return False
|
|
|
|
@property
|
|
def valid(self):
|
|
"""Returns `True`, anonymous credentials are always valid."""
|
|
return True
|
|
|
|
def refresh(self, request):
|
|
"""Raises :class:`ValueError``, anonymous credentials cannot be
|
|
refreshed."""
|
|
raise ValueError("Anonymous credentials cannot be refreshed.")
|
|
|
|
def apply(self, headers, token=None):
|
|
"""Anonymous credentials do nothing to the request.
|
|
|
|
The optional ``token`` argument is not supported.
|
|
|
|
Raises:
|
|
ValueError: If a token was specified.
|
|
"""
|
|
if token is not None:
|
|
raise ValueError("Anonymous credentials don't support tokens.")
|
|
|
|
def before_request(self, request, method, url, headers):
|
|
"""Anonymous credentials do nothing to the request."""
|
|
|
|
|
|
@six.add_metaclass(abc.ABCMeta)
|
|
class ReadOnlyScoped(object):
|
|
"""Interface for credentials whose scopes can be queried.
|
|
|
|
OAuth 2.0-based credentials allow limiting access using scopes as described
|
|
in `RFC6749 Section 3.3`_.
|
|
If a credential class implements this interface then the credentials either
|
|
use scopes in their implementation.
|
|
|
|
Some credentials require scopes in order to obtain a token. You can check
|
|
if scoping is necessary with :attr:`requires_scopes`::
|
|
|
|
if credentials.requires_scopes:
|
|
# Scoping is required.
|
|
credentials = credentials.with_scopes(scopes=['one', 'two'])
|
|
|
|
Credentials that require scopes must either be constructed with scopes::
|
|
|
|
credentials = SomeScopedCredentials(scopes=['one', 'two'])
|
|
|
|
Or must copy an existing instance using :meth:`with_scopes`::
|
|
|
|
scoped_credentials = credentials.with_scopes(scopes=['one', 'two'])
|
|
|
|
Some credentials have scopes but do not allow or require scopes to be set,
|
|
these credentials can be used as-is.
|
|
|
|
.. _RFC6749 Section 3.3: https://tools.ietf.org/html/rfc6749#section-3.3
|
|
"""
|
|
def __init__(self):
|
|
super(ReadOnlyScoped, self).__init__()
|
|
self._scopes = None
|
|
|
|
@property
|
|
def scopes(self):
|
|
"""Sequence[str]: the credentials' current set of scopes."""
|
|
return self._scopes
|
|
|
|
@abc.abstractproperty
|
|
def requires_scopes(self):
|
|
"""True if these credentials require scopes to obtain an access token.
|
|
"""
|
|
return False
|
|
|
|
def has_scopes(self, scopes):
|
|
"""Checks if the credentials have the given scopes.
|
|
|
|
.. warning: This method is not guaranteed to be accurate if the
|
|
credentials are :attr:`~Credentials.invalid`.
|
|
|
|
Args:
|
|
scopes (Sequence[str]): The list of scopes to check.
|
|
|
|
Returns:
|
|
bool: True if the credentials have the given scopes.
|
|
"""
|
|
return set(scopes).issubset(set(self._scopes or []))
|
|
|
|
|
|
class Scoped(ReadOnlyScoped):
|
|
"""Interface for credentials whose scopes can be replaced while copying.
|
|
|
|
OAuth 2.0-based credentials allow limiting access using scopes as described
|
|
in `RFC6749 Section 3.3`_.
|
|
If a credential class implements this interface then the credentials either
|
|
use scopes in their implementation.
|
|
|
|
Some credentials require scopes in order to obtain a token. You can check
|
|
if scoping is necessary with :attr:`requires_scopes`::
|
|
|
|
if credentials.requires_scopes:
|
|
# Scoping is required.
|
|
credentials = credentials.create_scoped(['one', 'two'])
|
|
|
|
Credentials that require scopes must either be constructed with scopes::
|
|
|
|
credentials = SomeScopedCredentials(scopes=['one', 'two'])
|
|
|
|
Or must copy an existing instance using :meth:`with_scopes`::
|
|
|
|
scoped_credentials = credentials.with_scopes(scopes=['one', 'two'])
|
|
|
|
Some credentials have scopes but do not allow or require scopes to be set,
|
|
these credentials can be used as-is.
|
|
|
|
.. _RFC6749 Section 3.3: https://tools.ietf.org/html/rfc6749#section-3.3
|
|
"""
|
|
@abc.abstractmethod
|
|
def with_scopes(self, scopes):
|
|
"""Create a copy of these credentials with the specified scopes.
|
|
|
|
Args:
|
|
scopes (Sequence[str]): The list of scopes to attach to the
|
|
current credentials.
|
|
|
|
Raises:
|
|
NotImplementedError: If the credentials' scopes can not be changed.
|
|
This can be avoided by checking :attr:`requires_scopes` before
|
|
calling this method.
|
|
"""
|
|
raise NotImplementedError('This class does not require scoping.')
|
|
|
|
|
|
def with_scopes_if_required(credentials, scopes):
|
|
"""Creates a copy of the credentials with scopes if scoping is required.
|
|
|
|
This helper function is useful when you do not know (or care to know) the
|
|
specific type of credentials you are using (such as when you use
|
|
:func:`google.auth.default`). This function will call
|
|
:meth:`Scoped.with_scopes` if the credentials are scoped credentials and if
|
|
the credentials require scoping. Otherwise, it will return the credentials
|
|
as-is.
|
|
|
|
Args:
|
|
credentials (google.auth.credentials.Credentials): The credentials to
|
|
scope if necessary.
|
|
scopes (Sequence[str]): The list of scopes to use.
|
|
|
|
Returns:
|
|
google.auth.credentials.Credentials: Either a new set of scoped
|
|
credentials, or the passed in credentials instance if no scoping
|
|
was required.
|
|
"""
|
|
if isinstance(credentials, Scoped) and credentials.requires_scopes:
|
|
return credentials.with_scopes(scopes)
|
|
else:
|
|
return credentials
|
|
|
|
|
|
@six.add_metaclass(abc.ABCMeta)
|
|
class Signing(object):
|
|
"""Interface for credentials that can cryptographically sign messages."""
|
|
|
|
@abc.abstractmethod
|
|
def sign_bytes(self, message):
|
|
"""Signs the given message.
|
|
|
|
Args:
|
|
message (bytes): The message to sign.
|
|
|
|
Returns:
|
|
bytes: The message's cryptographic signature.
|
|
"""
|
|
# pylint: disable=missing-raises-doc,redundant-returns-doc
|
|
# (pylint doesn't recognize that this is abstract)
|
|
raise NotImplementedError('Sign bytes must be implemented.')
|
|
|
|
@abc.abstractproperty
|
|
def signer_email(self):
|
|
"""Optional[str]: An email address that identifies the signer."""
|
|
# pylint: disable=missing-raises-doc
|
|
# (pylint doesn't recognize that this is abstract)
|
|
raise NotImplementedError('Signer email must be implemented.')
|
|
|
|
@abc.abstractproperty
|
|
def signer(self):
|
|
"""google.auth.crypt.Signer: The signer used to sign bytes."""
|
|
# pylint: disable=missing-raises-doc
|
|
# (pylint doesn't recognize that this is abstract)
|
|
raise NotImplementedError('Signer must be implemented.')
|