# -------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See LICENSE.txt in the project root for
# license information.
# -------------------------------------------------------------------------
import time
import base64
from typing import TYPE_CHECKING, Optional, TypeVar, MutableMapping, Any, Union, cast
from azure.core.credentials import (
TokenCredential,
SupportsTokenInfo,
TokenRequestOptions,
TokenProvider,
)
from azure.core.exceptions import HttpResponseError
from azure.core.pipeline import PipelineRequest, PipelineResponse
from azure.core.pipeline.transport import (
HttpResponse as LegacyHttpResponse,
HttpRequest as LegacyHttpRequest,
)
from azure.core.rest import HttpResponse, HttpRequest
from . import HTTPPolicy, SansIOHTTPPolicy
from ...exceptions import ServiceRequestError
from ._utils import get_challenge_parameter
if TYPE_CHECKING:
from azure.core.credentials import (
AccessToken,
AccessTokenInfo,
AzureKeyCredential,
AzureSasCredential,
)
HTTPResponseType = TypeVar("HTTPResponseType", HttpResponse, LegacyHttpResponse)
HTTPRequestType = TypeVar("HTTPRequestType", HttpRequest, LegacyHttpRequest)
# pylint:disable=too-few-public-methods
class _BearerTokenCredentialPolicyBase:
"""Base class for a Bearer Token Credential Policy.
:param credential: The credential.
:type credential: ~azure.core.credentials.TokenProvider
:param str scopes: Lets you specify the type of access needed.
:keyword bool enable_cae: Indicates whether to enable Continuous Access Evaluation (CAE) on all requested
tokens. Defaults to False.
"""
def __init__(self, credential: TokenProvider, *scopes: str, **kwargs: Any) -> None:
super(_BearerTokenCredentialPolicyBase, self).__init__()
self._scopes = scopes
self._credential = credential
self._token: Optional[Union["AccessToken", "AccessTokenInfo"]] = None
self._enable_cae: bool = kwargs.get("enable_cae", False)
@staticmethod
def _enforce_https(request: PipelineRequest[HTTPRequestType]) -> None:
# move 'enforce_https' from options to context so it persists
# across retries but isn't passed to a transport implementation
option = request.context.options.pop("enforce_https", None)
# True is the default setting; we needn't preserve an explicit opt in to the default behavior
if option is False:
request.context["enforce_https"] = option
enforce_https = request.context.get("enforce_https", True)
if enforce_https and not request.http_request.url.lower().startswith("https"):
raise ServiceRequestError(
"Bearer token authentication is not permitted for non-TLS protected (non-https) URLs."
)
@staticmethod
def _update_headers(headers: MutableMapping[str, str], token: str) -> None:
"""Updates the Authorization header with the bearer token.
:param MutableMapping[str, str] headers: The HTTP Request headers
:param str token: The OAuth token.
"""
headers["Authorization"] = "Bearer {}".format(token)
@property
def _need_new_token(self) -> bool:
now = time.time()
refresh_on = getattr(self._token, "refresh_on", None)
return not self._token or (refresh_on and refresh_on <= now) or self._token.expires_on - now < 300
def _get_token(self, *scopes: str, **kwargs: Any) -> Union["AccessToken", "AccessTokenInfo"]:
if self._enable_cae:
kwargs.setdefault("enable_cae", self._enable_cae)
if hasattr(self._credential, "get_token_info"):
options: TokenRequestOptions = {}
# Loop through all the keyword arguments and check if they are part of the TokenRequestOptions.
for key in list(kwargs.keys()):
if key in TokenRequestOptions.__annotations__: # pylint: disable=no-member
options[key] = kwargs.pop(key) # type: ignore[literal-required]
return cast(SupportsTokenInfo, self._credential).get_token_info(*scopes, options=options)
return cast(TokenCredential, self._credential).get_token(*scopes, **kwargs)
def _request_token(self, *scopes: str, **kwargs: Any) -> None:
"""Request a new token from the credential.
This will call the credential's appropriate method to get a token and store it in the policy.
:param str scopes: The type of access needed.
"""
self._token = self._get_token(*scopes, **kwargs)
[docs]
class BearerTokenCredentialPolicy(_BearerTokenCredentialPolicyBase, HTTPPolicy[HTTPRequestType, HTTPResponseType]):
"""Adds a bearer token Authorization header to requests.
:param credential: The credential.
:type credential: ~azure.core.TokenCredential
:param str scopes: Lets you specify the type of access needed.
:keyword bool enable_cae: Indicates whether to enable Continuous Access Evaluation (CAE) on all requested
tokens. Defaults to False.
:raises ~azure.core.exceptions.ServiceRequestError: If the request fails.
"""
[docs]
def on_request(self, request: PipelineRequest[HTTPRequestType]) -> None:
"""Called before the policy sends a request.
The base implementation authorizes the request with a bearer token.
:param ~azure.core.pipeline.PipelineRequest request: the request
"""
self._enforce_https(request)
if self._token is None or self._need_new_token:
self._request_token(*self._scopes)
bearer_token = cast(Union["AccessToken", "AccessTokenInfo"], self._token).token
self._update_headers(request.http_request.headers, bearer_token)
[docs]
def authorize_request(self, request: PipelineRequest[HTTPRequestType], *scopes: str, **kwargs: Any) -> None:
"""Acquire a token from the credential and authorize the request with it.
Keyword arguments are passed to the credential's get_token method. The token will be cached and used to
authorize future requests.
:param ~azure.core.pipeline.PipelineRequest request: the request
:param str scopes: required scopes of authentication
"""
self._request_token(*scopes, **kwargs)
bearer_token = cast(Union["AccessToken", "AccessTokenInfo"], self._token).token
self._update_headers(request.http_request.headers, bearer_token)
[docs]
def send(self, request: PipelineRequest[HTTPRequestType]) -> PipelineResponse[HTTPRequestType, HTTPResponseType]:
"""Authorize request with a bearer token and send it to the next policy
:param request: The pipeline request object
:type request: ~azure.core.pipeline.PipelineRequest
:return: The pipeline response object
:rtype: ~azure.core.pipeline.PipelineResponse
"""
self.on_request(request)
try:
response = self.next.send(request)
except Exception:
self.on_exception(request)
raise
self.on_response(request, response)
if response.http_response.status_code == 401:
self._token = None # any cached token is invalid
if "WWW-Authenticate" in response.http_response.headers:
try:
request_authorized = self.on_challenge(request, response)
except Exception as ex:
# If the response is streamed, read it so the error message is immediately available to the user.
# Otherwise, a generic error message will be given and the user will have to read the response
# body to see the actual error.
if response.context.options.get("stream"):
try:
response.http_response.read() # type: ignore
except Exception: # pylint:disable=broad-except
pass
# Raise the exception from the token request with the original 401 response
raise ex from HttpResponseError(response=response.http_response)
if request_authorized:
# if we receive a challenge response, we retrieve a new token
# which matches the new target. In this case, we don't want to remove
# token from the request so clear the 'insecure_domain_change' tag
request.context.options.pop("insecure_domain_change", False)
try:
response = self.next.send(request)
self.on_response(request, response)
except Exception:
self.on_exception(request)
raise
return response
[docs]
def on_challenge(
self,
request: PipelineRequest[HTTPRequestType],
response: PipelineResponse[HTTPRequestType, HTTPResponseType],
) -> bool:
"""Authorize request according to an authentication challenge
This method is called when the resource provider responds 401 with a WWW-Authenticate header.
:param ~azure.core.pipeline.PipelineRequest request: the request which elicited an authentication challenge
:param ~azure.core.pipeline.PipelineResponse response: the resource provider's response
:returns: a bool indicating whether the policy should send the request
:rtype: bool
"""
headers = response.http_response.headers
error = get_challenge_parameter(headers, "Bearer", "error")
if error == "insufficient_claims":
encoded_claims = get_challenge_parameter(headers, "Bearer", "claims")
if not encoded_claims:
return False
padding_needed = -len(encoded_claims) % 4
claims = base64.urlsafe_b64decode(encoded_claims + "=" * padding_needed).decode("utf-8")
if claims:
self.authorize_request(request, *self._scopes, claims=claims)
return True
return False
[docs]
def on_response(
self,
request: PipelineRequest[HTTPRequestType],
response: PipelineResponse[HTTPRequestType, HTTPResponseType],
) -> None:
"""Executed after the request comes back from the next policy.
:param request: Request to be modified after returning from the policy.
:type request: ~azure.core.pipeline.PipelineRequest
:param response: Pipeline response object
:type response: ~azure.core.pipeline.PipelineResponse
"""
[docs]
def on_exception(self, request: PipelineRequest[HTTPRequestType]) -> None:
"""Executed when an exception is raised while executing the next policy.
This method is executed inside the exception handler.
:param request: The Pipeline request object
:type request: ~azure.core.pipeline.PipelineRequest
"""
# pylint: disable=unused-argument
return
[docs]
class AzureKeyCredentialPolicy(SansIOHTTPPolicy[HTTPRequestType, HTTPResponseType]):
"""Adds a key header for the provided credential.
:param credential: The credential used to authenticate requests.
:type credential: ~azure.core.credentials.AzureKeyCredential
:param str name: The name of the key header used for the credential.
:keyword str prefix: The name of the prefix for the header value if any.
:raises ValueError: if name is None or empty.
:raises TypeError: if name is not a string or if credential is not an instance of AzureKeyCredential.
"""
def __init__( # pylint: disable=unused-argument
self,
credential: "AzureKeyCredential",
name: str,
*,
prefix: Optional[str] = None,
**kwargs: Any,
) -> None:
super().__init__()
if not hasattr(credential, "key"):
raise TypeError("String is not a supported credential input type. Use an instance of AzureKeyCredential.")
if not name:
raise ValueError("name can not be None or empty")
if not isinstance(name, str):
raise TypeError("name must be a string.")
self._credential = credential
self._name = name
self._prefix = prefix + " " if prefix else ""
[docs]
def on_request(self, request: PipelineRequest[HTTPRequestType]) -> None:
"""Called before the policy sends a request.
:param request: The request to be modified before sending.
:type request: ~azure.core.pipeline.PipelineRequest
"""
request.http_request.headers[self._name] = f"{self._prefix}{self._credential.key}"
[docs]
class AzureSasCredentialPolicy(SansIOHTTPPolicy[HTTPRequestType, HTTPResponseType]):
"""Adds a shared access signature to query for the provided credential.
:param credential: The credential used to authenticate requests.
:type credential: ~azure.core.credentials.AzureSasCredential
:raises ValueError: if credential is None.
"""
def __init__(
self, # pylint: disable=unused-argument
credential: "AzureSasCredential",
**kwargs: Any,
) -> None:
super(AzureSasCredentialPolicy, self).__init__()
if not credential:
raise ValueError("credential can not be None")
self._credential = credential
[docs]
def on_request(self, request: PipelineRequest[HTTPRequestType]) -> None:
"""Called before the policy sends a request.
:param request: The request to be modified before sending.
:type request: ~azure.core.pipeline.PipelineRequest
"""
url = request.http_request.url
query = request.http_request.query
signature = self._credential.signature
if signature.startswith("?"):
signature = signature[1:]
if query:
if signature not in url:
url = url + "&" + signature
else:
if url.endswith("?"):
url = url + signature
else:
url = url + "?" + signature
request.http_request.url = url