import json
import logging
import flask
from flask import current_app, redirect, request, url_for
from oauthlib.common import generate_token
from oauthlib.oauth2 import MissingCodeError
from werkzeug.utils import cached_property
from werkzeug.wrappers import Response
from .base import (
BaseOAuthConsumerBlueprint,
oauth_authorized,
oauth_before_login,
oauth_error,
)
from .requests import OAuth2Session
log = logging.getLogger(__name__)
[docs]
class OAuth2ConsumerBlueprint(BaseOAuthConsumerBlueprint):
"""
A subclass of :class:`flask.Blueprint` that sets up OAuth 2 authentication.
"""
[docs]
def __init__(
self,
name,
import_name,
client_id=None,
client_secret=None,
*,
client=None,
auto_refresh_url=None,
auto_refresh_kwargs=None,
scope=None,
state=None,
static_folder=None,
static_url_path=None,
template_folder=None,
url_prefix=None,
subdomain=None,
url_defaults=None,
root_path=None,
login_url=None,
authorized_url=None,
base_url=None,
authorization_url=None,
authorization_url_params=None,
token_url=None,
token_url_params=None,
redirect_url=None,
redirect_to=None,
session_class=None,
storage=None,
rule_kwargs=None,
use_pkce=False,
code_challenge_method="S256",
**kwargs,
):
"""
Most of the constructor arguments are forwarded either to the
:class:`flask.Blueprint` constructor or the
:class:`requests_oauthlib.OAuth2Session` constructor, including
``**kwargs`` (which is forwarded to
:class:`~requests_oauthlib.OAuth2Session`).
Only the arguments that are relevant to Flask-Dance are documented here.
Args:
base_url: The base URL of the OAuth provider.
If specified, all URLs passed to this instance will be
resolved relative to this URL.
authorization_url: The URL specified by the OAuth provider for
obtaining an
`authorization grant <https://datatracker.ietf.org/doc/html/rfc6749#section-1.3>`__.
This can be an fully-qualified URL, or a path that is
resolved relative to the ``base_url``.
authorization_url_params (dict): A dict of extra
key-value pairs to include in the query string of the
``authorization_url``, beyond those necessary for a standard
OAuth 2 authorization grant request.
token_url: The URL specified by the OAuth provider for
obtaining an
`access token <https://datatracker.ietf.org/doc/html/rfc6749#section-1.4>`__.
This can be an fully-qualified URL, or a path that is
resolved relative to the ``base_url``.
token_url_params (dict): A dict of extra
key-value pairs to include in the query string of the
``token_url``, beyond those necessary for a standard
OAuth 2 access token request.
login_url: The URL route for the ``login`` view that kicks off
the OAuth dance. This string will be
:ref:`formatted <python:formatstrings>`
with the instance so that attributes can be interpolated.
Defaults to ``/{bp.name}``, so that the URL is based on the name
of the blueprint.
authorized_url: The URL route for the ``authorized`` view that
completes the OAuth dance. This string will be
:ref:`formatted <python:formatstrings>`
with the instance so that attributes can be interpolated.
Defaults to ``/{bp.name}/authorized``, so that the URL is
based on the name of the blueprint.
redirect_url: When the OAuth dance is complete,
redirect the user to this URL.
redirect_to: When the OAuth dance is complete,
redirect the user to the URL obtained by calling
:func:`~flask.url_for` with this argument. If you do not specify
either ``redirect_url`` or ``redirect_to``, the user will be
redirected to the root path (``/``).
session_class: The class to use for creating a Requests session
between the consumer (your website) and the provider (e.g.
Google). Defaults to
:class:`~flask_dance.consumer.requests.OAuth2Session`.
storage: A token storage class, or an instance of a token storage
class, to use for this blueprint. Defaults to
:class:`~flask_dance.consumer.storage.session.SessionStorage`.
rule_kwargs (dict, optional): Additional arguments that should be passed when adding
the login and authorized routes. Defaults to ``None``.
use_pkce: If true then the authorization flow will follow the PKCE (Proof Key for Code Exchange).
For more details please refer to `RFC7636 <https://www.rfc-editor.org/rfc/rfc7636#section-4.1>`__
code_challenge_method: Code challenge method to be used in authorization code flow with PKCE
instead of client secret. It will be used only if ``use_pkce`` is set to True.
Defaults to ``S256``.
"""
BaseOAuthConsumerBlueprint.__init__(
self,
name,
import_name,
static_folder=static_folder,
static_url_path=static_url_path,
template_folder=template_folder,
url_prefix=url_prefix,
subdomain=subdomain,
url_defaults=url_defaults,
root_path=root_path,
login_url=login_url,
authorized_url=authorized_url,
storage=storage,
rule_kwargs=rule_kwargs,
)
self.base_url = base_url
self.session_class = session_class or OAuth2Session
# passed to OAuth2Session()
self._client_id = client_id
self.client = client
self.auto_refresh_url = auto_refresh_url
self.auto_refresh_kwargs = auto_refresh_kwargs
self.scope = scope
self.state = state
self.kwargs = kwargs
self.client_secret = client_secret
# used by view functions
self.authorization_url = authorization_url
self.authorization_url_params = authorization_url_params or {}
self.token_url = token_url
self.token_url_params = token_url_params or {}
self.redirect_url = redirect_url
self.redirect_to = redirect_to
self.code_challenge_method = code_challenge_method
self.use_pkce = use_pkce
self.teardown_app_request(self.teardown_session)
@property
def client_id(self):
return self.session.client_id
@client_id.setter
def client_id(self, value):
self.session.client_id = value
# due to a bug in requests-oauthlib, we need to set this manually
self.session._client.client_id = value
[docs]
@cached_property
def session(self):
"""
This is a session between the consumer (your website) and the provider
(e.g. Google). It is *not* a session between a user of your website
and your website.
:return:
"""
ret = self.session_class(
client_id=self._client_id,
client=self.client,
auto_refresh_url=self.auto_refresh_url,
auto_refresh_kwargs=self.auto_refresh_kwargs,
scope=self.scope,
state=self.state,
blueprint=self,
base_url=self.base_url,
**self.kwargs,
)
def token_updater(token):
self.token = token
ret.token_updater = token_updater
return self.session_created(ret)
def session_created(self, session):
return session
def teardown_session(self, exception=None):
try:
del self.session
except KeyError:
pass
def login(self):
log.debug("client_id = %s", self.client_id)
self.session.redirect_uri = url_for(".authorized", _external=True)
if self.use_pkce:
code_verifier = generate_token(length=48)
code_challenge = self.session._client.create_code_challenge(
code_verifier=code_verifier,
code_challenge_method=self.code_challenge_method,
)
self.authorization_url_params.update(
{
"code_challenge_method": self.code_challenge_method,
"code_challenge": code_challenge,
}
)
code_verifier_key = f"{self.name}_oauth_code_verifier"
flask.session[code_verifier_key] = code_verifier
log.debug("code_verifier = %s", code_verifier)
url, state = self.session.authorization_url(
self.authorization_url, state=self.state, **self.authorization_url_params
)
state_key = f"{self.name}_oauth_state"
flask.session[state_key] = state
log.debug("state = %s", state)
log.debug("redirect URL = %s", url)
oauth_before_login.send(self, url=url)
return redirect(url)
def authorized(self):
"""
This is the route/function that the user will be redirected to by
the provider (e.g. Google) after the user has logged into the
provider's website and authorized your app to access their account.
"""
if self.redirect_url:
next_url = self.redirect_url
elif self.redirect_to:
next_url = url_for(self.redirect_to)
else:
next_url = "/"
log.debug("next_url = %s", next_url)
# check for error in request args
error = request.args.get("error")
if error:
error_desc = request.args.get("error_description")
error_uri = request.args.get("error_uri")
log.warning(
"OAuth 2 authorization error: %s description: %s uri: %s",
error,
error_desc,
error_uri,
)
results = oauth_error.send(
self, error=error, error_description=error_desc, error_uri=error_uri
)
if results:
for _, ret in results:
if isinstance(ret, (Response, current_app.response_class)):
return ret
return redirect(next_url)
state_key = f"{self.name}_oauth_state"
if state_key not in flask.session:
# can't validate state, so redirect back to login view
log.info("state not found, redirecting user to login")
return redirect(url_for(".login"))
state = flask.session[state_key]
log.debug("state = %s", state)
self.session._state = state
del flask.session[state_key]
if self.use_pkce:
code_verifier_key = f"{self.name}_oauth_code_verifier"
if code_verifier_key not in flask.session:
# can't find code_verifier, so redirect back to login view
log.info("code_verifier not found, redirecting user to login")
return redirect(url_for(".login"))
code_verifier = flask.session[code_verifier_key]
log.debug("code_verifier = %s", code_verifier)
del flask.session[code_verifier_key]
self.token_url_params["code_verifier"] = code_verifier
self.session.redirect_uri = url_for(".authorized", _external=True)
log.debug("client_id = %s", self.client_id)
log.debug("client_secret = %s", self.client_secret)
try:
token = self.session.fetch_token(
self.token_url,
authorization_response=request.url,
client_secret=self.client_secret,
**self.token_url_params,
)
except MissingCodeError as e:
e.args = (
e.args[0],
"The redirect request did not contain the expected parameters. Instead I got: {}".format(
json.dumps(request.args)
),
)
raise
results = oauth_authorized.send(self, token=token) or []
set_token = True
for func, ret in results:
if isinstance(ret, (Response, current_app.response_class)):
return ret
if ret == False:
set_token = False
if set_token:
try:
self.token = token
except ValueError as error:
log.warning("OAuth 2 authorization error: %s", str(error))
oauth_error.send(self, error=error)
return redirect(next_url)
