# ------------------------------------
# Copyright (c) Microsoft Corporation.
# Licensed under the MIT License.
# ------------------------------------
import os
import time
from msal.application import PublicClientApplication
from azure.core.credentials import AccessToken
from azure.core.exceptions import ClientAuthenticationError
from .. import CredentialUnavailableError
from .._constants import DEVELOPER_SIGN_ON_CLIENT_ID
from .._internal import AadClient, validate_tenant_id
from .._internal.decorators import log_get_token, wrap_exceptions
from .._internal.msal_client import MsalClient
from .._internal.shared_token_cache import NO_TOKEN, SharedTokenCacheBase
try:
from typing import TYPE_CHECKING
except ImportError:
TYPE_CHECKING = False
if TYPE_CHECKING:
# pylint:disable=unused-import,ungrouped-imports
from typing import Any, Optional
from .. import AuthenticationRecord
from .._internal import AadClientBase
[docs]class SharedTokenCacheCredential(SharedTokenCacheBase):
"""Authenticates using tokens in the local cache shared between Microsoft applications.
:param str username:
Username (typically an email address) of the user to authenticate as. This is used when the local cache
contains tokens for multiple identities.
:keyword str authority: Authority of an Azure Active Directory endpoint, for example 'login.microsoftonline.com',
the authority for Azure Public Cloud (which is the default). :class:`~azure.identity.AzureAuthorityHosts`
defines authorities for other clouds.
:keyword str tenant_id: an Azure Active Directory tenant ID. Used to select an account when the cache contains
tokens for multiple identities.
:keyword AuthenticationRecord authentication_record: an authentication record returned by a user credential such as
:class:`DeviceCodeCredential` or :class:`InteractiveBrowserCredential`
:keyword cache_persistence_options: configuration for persistent token caching. If not provided, the credential
will use the persistent cache shared by Microsoft development applications
:paramtype cache_persistence_options: ~azure.identity.TokenCachePersistenceOptions
"""
def __init__(self, username=None, **kwargs):
# type: (Optional[str], **Any) -> None
self._auth_record = kwargs.pop("authentication_record", None) # type: Optional[AuthenticationRecord]
if self._auth_record:
# authenticate in the tenant that produced the record unless "tenant_id" specifies another
self._tenant_id = kwargs.pop("tenant_id", None) or self._auth_record.tenant_id
validate_tenant_id(self._tenant_id)
self._cache = kwargs.pop("_cache", None)
self._app = None
self._client_kwargs = kwargs
self._initialized = False
else:
super(SharedTokenCacheCredential, self).__init__(username=username, **kwargs)
[docs] @log_get_token("SharedTokenCacheCredential")
def get_token(self, *scopes, **kwargs): # pylint:disable=unused-argument
# type (*str, **Any) -> AccessToken
"""Get an access token for `scopes` from the shared cache.
If no access token is cached, attempt to acquire one using a cached refresh token.
This method is called automatically by Azure SDK clients.
:param str scopes: desired scopes for the access token. This method requires at least one scope.
:keyword str claims: additional claims required in the token, such as those returned in a resource provider's
claims challenge following an authorization failure
:rtype: :class:`azure.core.credentials.AccessToken`
:raises ~azure.identity.CredentialUnavailableError: the cache is unavailable or contains insufficient user
information
:raises ~azure.core.exceptions.ClientAuthenticationError: authentication failed. The error's ``message``
attribute gives a reason.
"""
if not scopes:
raise ValueError("'get_token' requires at least one scope")
if not self._initialized:
self._initialize()
if not self._cache:
raise CredentialUnavailableError(message="Shared token cache unavailable")
if self._auth_record:
return self._acquire_token_silent(*scopes, **kwargs)
account = self._get_account(self._username, self._tenant_id)
token = self._get_cached_access_token(scopes, account)
if token:
return token
# try each refresh token, returning the first access token acquired
for refresh_token in self._get_refresh_tokens(account):
token = self._client.obtain_token_by_refresh_token(scopes, refresh_token)
return token
raise CredentialUnavailableError(message=NO_TOKEN.format(account.get("username")))
def _get_auth_client(self, **kwargs):
# type: (**Any) -> AadClientBase
return AadClient(client_id=DEVELOPER_SIGN_ON_CLIENT_ID, **kwargs)
def _initialize(self):
if self._initialized:
return
if not self._auth_record:
super(SharedTokenCacheCredential, self)._initialize()
return
self._load_cache()
if self._cache:
if "AZURE_IDENTITY_DISABLE_CP1" in os.environ:
capabilities = None
else:
capabilities = ["CP1"] # able to handle CAE claims challenges
self._app = PublicClientApplication(
client_id=self._auth_record.client_id,
authority="https://{}/{}".format(self._auth_record.authority, self._tenant_id),
token_cache=self._cache,
http_client=MsalClient(**self._client_kwargs),
client_capabilities=capabilities
)
self._initialized = True
@wrap_exceptions
def _acquire_token_silent(self, *scopes, **kwargs):
# type: (*str, **Any) -> AccessToken
"""Silently acquire a token from MSAL. Requires an AuthenticationRecord."""
# self._auth_record and ._app will not be None when this method is called by get_token
# but should either be None anyway (and to satisfy mypy) we raise
if self._app is None or self._auth_record is None:
raise CredentialUnavailableError("Initialization failed")
result = None
accounts_for_user = self._app.get_accounts(username=self._auth_record.username)
if not accounts_for_user:
raise CredentialUnavailableError("The cache contains no account matching the given AuthenticationRecord.")
for account in accounts_for_user:
if account.get("home_account_id") != self._auth_record.home_account_id:
continue
now = int(time.time())
result = self._app.acquire_token_silent_with_error(
list(scopes), account=account, claims_challenge=kwargs.get("claims")
)
if result and "access_token" in result and "expires_in" in result:
return AccessToken(result["access_token"], now + int(result["expires_in"]))
# if we get this far, the cache contained a matching account but MSAL failed to authenticate it silently
if result:
# cache contains a matching refresh token but STS returned an error response when MSAL tried to use it
message = "Token acquisition failed"
details = result.get("error_description") or result.get("error")
if details:
message += ": {}".format(details)
raise ClientAuthenticationError(message=message)
# cache doesn't contain a matching refresh (or access) token
raise CredentialUnavailableError(message=NO_TOKEN.format(self._auth_record.username))