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# ------------------------------------
# Copyright (c) Microsoft Corporation.
# Licensed under the MIT License.
# ------------------------------------
"""Base class for credentials using MSAL for interactive user authentication"""
import abc
import base64
import json
import logging
import time
from typing import Any, Optional, Iterable, Dict
from urllib.parse import urlparse
from azure.core.credentials import AccessToken, AccessTokenInfo, TokenRequestOptions
from azure.core.exceptions import ClientAuthenticationError
from .msal_credentials import MsalCredential
from .._auth_record import AuthenticationRecord
from .._constants import KnownAuthorities
from .._exceptions import AuthenticationRequiredError, CredentialUnavailableError
from .._internal import wrap_exceptions
ABC = abc.ABC
_LOGGER = logging.getLogger(__name__)
_DEFAULT_AUTHENTICATE_SCOPES = {
"https://" + KnownAuthorities.AZURE_CHINA: ("https://management.core.chinacloudapi.cn//.default",),
"https://" + KnownAuthorities.AZURE_GOVERNMENT: ("https://management.core.usgovcloudapi.net//.default",),
"https://" + KnownAuthorities.AZURE_PUBLIC_CLOUD: ("https://management.core.windows.net//.default",),
}
def _decode_client_info(raw) -> str:
"""Decode client info. Taken from msal.oauth2cli.oidc.
:param str raw: base64-encoded client info
:return: decoded client info
:rtype: str
"""
raw += "=" * (-len(raw) % 4)
raw = str(raw) # On Python 2.7, argument of urlsafe_b64decode must be str, not unicode.
return base64.urlsafe_b64decode(raw).decode("utf-8")
def _build_auth_record(response):
"""Build an AuthenticationRecord from the result of an MSAL ClientApplication token request.
:param response: The result of a token request
:type response: dict[str, typing.Any]
:return: An AuthenticationRecord
:rtype: ~azure.identity.AuthenticationRecord
:raises ~azure.core.exceptions.ClientAuthenticationError: If the response doesn't contain expected data
"""
try:
id_token = response["id_token_claims"]
if "client_info" in response:
client_info = json.loads(_decode_client_info(response["client_info"]))
home_account_id = "{uid}.{utid}".format(**client_info)
else:
# MSAL uses the subject claim as home_account_id when the STS doesn't provide client_info
home_account_id = id_token["sub"]
# "iss" is the URL of the issuing tenant e.g. https://authority/tenant
issuer = urlparse(id_token["iss"])
# tenant which issued the token, not necessarily user's home tenant
tenant_id = id_token.get("tid") or issuer.path.strip("/")
# Microsoft Entra ID returns "preferred_username", ADFS returns "upn"
username = id_token.get("preferred_username") or id_token["upn"]
return AuthenticationRecord(
authority=issuer.netloc,
client_id=id_token["aud"],
home_account_id=home_account_id,
tenant_id=tenant_id,
username=username,
)
except (KeyError, ValueError) as ex:
auth_error = ClientAuthenticationError(
message="Failed to build AuthenticationRecord from unexpected identity token"
)
raise auth_error from ex
class InteractiveCredential(MsalCredential, ABC):
def __init__(
self,
*,
authentication_record: Optional[AuthenticationRecord] = None,
disable_automatic_authentication: bool = False,
**kwargs: Any,
) -> None:
self._disable_automatic_authentication = disable_automatic_authentication
self._auth_record = authentication_record
if self._auth_record:
kwargs.pop("client_id", None) # authentication_record overrides client_id argument
tenant_id = kwargs.pop("tenant_id", None) or self._auth_record.tenant_id
super(InteractiveCredential, self).__init__(
client_id=self._auth_record.client_id,
authority=self._auth_record.authority,
tenant_id=tenant_id,
**kwargs,
)
else:
super(InteractiveCredential, self).__init__(**kwargs)
def get_token(
self,
*scopes: str,
claims: Optional[str] = None,
tenant_id: Optional[str] = None,
enable_cae: bool = False,
**kwargs: Any,
) -> AccessToken:
"""Request an access token for `scopes`.
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.
For more information about scopes, see
https://learn.microsoft.com/entra/identity-platform/scopes-oidc.
:keyword str claims: additional claims required in the token, such as those returned in a resource provider's
claims challenge following an authorization failure
:keyword str tenant_id: optional tenant to include in the token request.
:keyword bool enable_cae: indicates whether to enable Continuous Access Evaluation (CAE) for the requested
token. Defaults to False.
:return: An access token with the desired scopes.
:rtype: ~azure.core.credentials.AccessToken
:raises CredentialUnavailableError: the credential is unable to attempt authentication because it lacks
required data, state, or platform support
:raises ~azure.core.exceptions.ClientAuthenticationError: authentication failed. The error's ``message``
attribute gives a reason.
:raises AuthenticationRequiredError: user interaction is necessary to acquire a token, and the credential is
configured not to begin this automatically. Call :func:`authenticate` to begin interactive authentication.
"""
options: TokenRequestOptions = {}
if claims:
options["claims"] = claims
if tenant_id:
options["tenant_id"] = tenant_id
options["enable_cae"] = enable_cae
token_info = self._get_token_base(*scopes, options=options, base_method_name="get_token", **kwargs)
return AccessToken(token_info.token, token_info.expires_on)
def get_token_info(self, *scopes: str, options: Optional[TokenRequestOptions] = None) -> AccessTokenInfo:
"""Request an access token for `scopes`.
This is an alternative to `get_token` to enable certain scenarios that require additional properties
on the 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.
For more information about scopes, see https://learn.microsoft.com/entra/identity-platform/scopes-oidc.
:keyword options: A dictionary of options for the token request. Unknown options will be ignored. Optional.
:paramtype options: ~azure.core.credentials.TokenRequestOptions
:rtype: AccessTokenInfo
:return: An AccessTokenInfo instance containing information about the token.
:raises CredentialUnavailableError: the credential is unable to attempt authentication because it lacks
required data, state, or platform support
:raises ~azure.core.exceptions.ClientAuthenticationError: authentication failed. The error's ``message``
attribute gives a reason.
:raises AuthenticationRequiredError: user interaction is necessary to acquire a token, and the credential is
configured not to begin this automatically. Call :func:`authenticate` to begin interactive authentication.
"""
return self._get_token_base(*scopes, options=options, base_method_name="get_token_info")
def _get_token_base(
self,
*scopes: str,
options: Optional[TokenRequestOptions] = None,
base_method_name: str = "get_token_info",
**kwargs: Any,
) -> AccessTokenInfo:
if not scopes:
message = f"'{base_method_name}' requires at least one scope"
_LOGGER.warning("%s.%s failed: %s", self.__class__.__name__, base_method_name, message)
raise ValueError(message)
allow_prompt = kwargs.pop("_allow_prompt", not self._disable_automatic_authentication)
options = options or {}
claims = options.get("claims")
tenant_id = options.get("tenant_id")
enable_cae = options.get("enable_cae", False)
# Check for arbitrary additional options to enable intermediary support for PoP tokens.
for key in options:
if key not in TokenRequestOptions.__annotations__: # pylint:disable=no-member
kwargs.setdefault(key, options[key]) # type: ignore
try:
token = self._acquire_token_silent(
*scopes, claims=claims, tenant_id=tenant_id, enable_cae=enable_cae, **kwargs
)
_LOGGER.info("%s.%s succeeded", self.__class__.__name__, base_method_name)
return token
except Exception as ex: # pylint:disable=broad-except
if not (isinstance(ex, AuthenticationRequiredError) and allow_prompt):
_LOGGER.warning(
"%s.%s failed: %s",
self.__class__.__name__,
base_method_name,
ex,
exc_info=_LOGGER.isEnabledFor(logging.DEBUG),
)
raise
# silent authentication failed -> authenticate interactively
now = int(time.time())
try:
result = self._request_token(*scopes, claims=claims, tenant_id=tenant_id, enable_cae=enable_cae, **kwargs)
if "access_token" not in result:
message = "Authentication failed: {}".format(result.get("error_description") or result.get("error"))
response = self._client.get_error_response(result)
raise ClientAuthenticationError(message=message, response=response)
# this may be the first authentication, or the user may have authenticated a different identity
self._auth_record = _build_auth_record(result)
except Exception as ex: # pylint:disable=broad-except
_LOGGER.warning(
"%s.%s failed: %s",
self.__class__.__name__,
base_method_name,
ex,
exc_info=_LOGGER.isEnabledFor(logging.DEBUG),
)
raise
_LOGGER.info("%s.%s succeeded", self.__class__.__name__, base_method_name)
refresh_on = int(result["refresh_on"]) if "refresh_on" in result else None
return AccessTokenInfo(
result["access_token"],
now + int(result["expires_in"]),
token_type=result.get("token_type", "Bearer"),
refresh_on=refresh_on,
)
def authenticate(
self, *, scopes: Optional[Iterable[str]] = None, claims: Optional[str] = None, **kwargs: Any
) -> AuthenticationRecord:
"""Interactively authenticate a user. This method will always generate a challenge to the user.
:keyword Iterable[str] scopes: scopes to request during authentication, such as those provided by
:func:`AuthenticationRequiredError.scopes`. If provided, successful authentication will cache an access token
for these scopes.
:keyword str claims: additional claims required in the token, such as those provided by
:func:`AuthenticationRequiredError.claims`
:rtype: ~azure.identity.AuthenticationRecord
:raises ~azure.core.exceptions.ClientAuthenticationError: authentication failed. The error's ``message``
attribute gives a reason.
"""
if not scopes:
if self._authority not in _DEFAULT_AUTHENTICATE_SCOPES:
# the credential is configured to use a cloud whose ARM scope we can't determine
raise CredentialUnavailableError(
message="Authenticating in this environment requires a value for the 'scopes' keyword argument."
)
scopes = _DEFAULT_AUTHENTICATE_SCOPES[self._authority]
_ = self.get_token(*scopes, _allow_prompt=True, claims=claims, **kwargs)
return self._auth_record # type: ignore
@wrap_exceptions
def _acquire_token_silent(self, *scopes: str, **kwargs: Any) -> AccessTokenInfo:
result = None
claims = kwargs.get("claims")
if self._auth_record:
app = self._get_app(**kwargs)
for account in app.get_accounts(username=self._auth_record.username):
if account.get("home_account_id") != self._auth_record.home_account_id:
continue
now = int(time.time())
result = app.acquire_token_silent_with_error(list(scopes), account=account, claims_challenge=claims)
if result and "access_token" in result and "expires_in" in result:
refresh_on = int(result["refresh_on"]) if "refresh_on" in result else None
return AccessTokenInfo(
result["access_token"],
now + int(result["expires_in"]),
token_type=result.get("token_type", "Bearer"),
refresh_on=refresh_on,
)
# if we get this far, result is either None or the content of a Microsoft Entra ID error response
if result:
response = self._client.get_error_response(result)
raise AuthenticationRequiredError(scopes, claims=claims, response=response)
raise AuthenticationRequiredError(scopes, claims=claims)
@abc.abstractmethod
def _request_token(self, *scopes, **kwargs) -> Dict:
pass
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