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import logging
from ..rfc6749 import BaseGrant
from ..rfc6749 import TokenEndpointMixin
from ..rfc6749.errors import AccessDeniedError
from ..rfc6749.errors import InvalidRequestError
from ..rfc6749.errors import UnauthorizedClientError
from ..rfc6749.hooks import hooked
from .errors import AuthorizationPendingError
from .errors import ExpiredTokenError
from .errors import SlowDownError
log = logging.getLogger(__name__)
DEVICE_CODE_GRANT_TYPE = "urn:ietf:params:oauth:grant-type:device_code"
class DeviceCodeGrant(BaseGrant, TokenEndpointMixin):
"""This OAuth 2.0 [RFC6749] protocol extension enables OAuth clients to
request user authorization from applications on devices that have
limited input capabilities or lack a suitable browser. Such devices
include smart TVs, media consoles, picture frames, and printers,
which lack an easy input method or a suitable browser required for
traditional OAuth interactions. Here is the authorization flow::
+----------+ +----------------+
| |>---(A)-- Client Identifier --->| |
| | | |
| |<---(B)-- Device Code, ---<| |
| | User Code, | |
| Device | & Verification URI | |
| Client | | |
| | [polling] | |
| |>---(E)-- Device Code --->| |
| | & Client Identifier | |
| | | Authorization |
| |<---(F)-- Access Token ---<| Server |
+----------+ (& Optional Refresh Token) | |
v | |
: | |
(C) User Code & Verification URI | |
: | |
v | |
+----------+ | |
| End User | | |
| at |<---(D)-- End user reviews --->| |
| Browser | authorization request | |
+----------+ +----------------+
This DeviceCodeGrant is the implementation of step (E) and (F).
(E) While the end user reviews the client's request (step D), the
client repeatedly polls the authorization server to find out if
the user completed the user authorization step. The client
includes the device code and its client identifier.
(F) The authorization server validates the device code provided by
the client and responds with the access token if the client is
granted access, an error if they are denied access, or an
indication that the client should continue to poll.
"""
GRANT_TYPE = DEVICE_CODE_GRANT_TYPE
TOKEN_ENDPOINT_AUTH_METHODS = ["client_secret_basic", "client_secret_post", "none"]
def validate_token_request(self):
"""After displaying instructions to the user, the client creates an
access token request and sends it to the token endpoint with the
following parameters:
grant_type
REQUIRED. Value MUST be set to
"urn:ietf:params:oauth:grant-type:device_code".
device_code
REQUIRED. The device verification code, "device_code" from the
device authorization response.
client_id
REQUIRED if the client is not authenticating with the
authorization server as described in Section 3.2.1. of [RFC6749].
The client identifier as described in Section 2.2 of [RFC6749].
For example, the client makes the following HTTPS request::
POST /token HTTP/1.1
Host: server.example.com
Content-Type: application/x-www-form-urlencoded
grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Adevice_code
&device_code=GmRhmhcxhwAzkoEqiMEg_DnyEysNkuNhszIySk9eS
&client_id=1406020730
"""
device_code = self.request.payload.data.get("device_code")
if not device_code:
raise InvalidRequestError("Missing 'device_code' in payload")
client = self.authenticate_token_endpoint_client()
if not client.check_grant_type(self.GRANT_TYPE):
raise UnauthorizedClientError(
f"The client is not authorized to use 'response_type={self.GRANT_TYPE}'",
)
credential = self.query_device_credential(device_code)
if not credential:
raise InvalidRequestError("Invalid 'device_code' in payload")
if credential.get_client_id() != client.get_client_id():
raise UnauthorizedClientError()
user = self.validate_device_credential(credential)
self.request.user = user
self.request.client = client
self.request.credential = credential
@hooked
def create_token_response(self):
"""If the access token request is valid and authorized, the
authorization server issues an access token and optional refresh
token.
"""
client = self.request.client
scope = self.request.credential.get_scope()
token = self.generate_token(
user=self.request.user,
scope=scope,
include_refresh_token=client.check_grant_type("refresh_token"),
)
log.debug("Issue token %r to %r", token, client)
self.save_token(token)
return 200, token, self.TOKEN_RESPONSE_HEADER
def validate_device_credential(self, credential):
if credential.is_expired():
raise ExpiredTokenError()
user_code = credential.get_user_code()
user_grant = self.query_user_grant(user_code)
if user_grant is not None:
user, approved = user_grant
if not approved:
raise AccessDeniedError()
return user
if self.should_slow_down(credential):
raise SlowDownError()
raise AuthorizationPendingError()
def query_device_credential(self, device_code):
"""Get device credential from previously savings via ``DeviceAuthorizationEndpoint``.
Developers MUST implement it in subclass::
def query_device_credential(self, device_code):
return DeviceCredential.get(device_code)
:param device_code: a string represent the code.
:return: DeviceCredential instance
"""
raise NotImplementedError()
def query_user_grant(self, user_code):
"""Get user and grant via the given user code. Developers MUST
implement it in subclass::
def query_user_grant(self, user_code):
# e.g. we saved user grant info in redis
data = redis.get("oauth_user_grant:" + user_code)
if not data:
return None
user_id, allowed = data.split()
user = User.get(user_id)
return user, bool(allowed)
Note, user grant information is saved by verification endpoint.
"""
raise NotImplementedError()
def should_slow_down(self, credential):
"""The authorization request is still pending and polling should
continue, but the interval MUST be increased by 5 seconds for this
and all subsequent requests.
"""
raise NotImplementedError()
|
