authentik/passbook/oauth_client/clients.py

"""OAuth Clients"""

import json
from urllib.parse import parse_qs, urlencode

from django.conf import settings
from django.utils.crypto import constant_time_compare, get_random_string
from django.utils.encoding import force_text
from requests import Session
from requests.exceptions import RequestException
from requests_oauthlib import OAuth1
from structlog import get_logger

LOGGER = get_logger(__name__)


class BaseOAuthClient:
    """Base OAuth Client"""

    _session = None

    def __init__(self, source, token=''): # nosec
        self.source = source
        self.token = token
        self._session = Session()
        self._session.headers.update({'User-Agent': 'web:passbook:%s' % settings.VERSION})

    def get_access_token(self, request, callback=None):
        "Fetch access token from callback request."
        raise NotImplementedError('Defined in a sub-class')  # pragma: no cover

    def get_profile_info(self, raw_token):
        "Fetch user profile information."
        try:
            response = self.request('get', self.source.profile_url, token=raw_token)
            response.raise_for_status()
        except RequestException as exc:
            LOGGER.warning('Unable to fetch user profile: %s', exc)
            return None
        else:
            return response.json() or response.text

    def get_redirect_args(self, request, callback):
        "Get request parameters for redirect url."
        raise NotImplementedError('Defined in a sub-class')  # pragma: no cover

    def get_redirect_url(self, request, callback, parameters=None):
        "Build authentication redirect url."
        args = self.get_redirect_args(request, callback=callback)
        additional = parameters or {}
        args.update(additional)
        params = urlencode(args)
        LOGGER.info("Redirect args: %s", args)
        return '{0}?{1}'.format(self.source.authorization_url, params)

    def parse_raw_token(self, raw_token):
        "Parse token and secret from raw token response."
        raise NotImplementedError('Defined in a sub-class')  # pragma: no cover

    def request(self, method, url, **kwargs):
        "Build remote url request."
        return self._session.request(method, url, **kwargs)

    @property
    def session_key(self):
        """
        Return Session Key
        """
        raise NotImplementedError('Defined in a sub-class')  # pragma: no cover


class OAuthClient(BaseOAuthClient):
    """OAuth1 Client"""

    def get_access_token(self, request, callback=None):
        "Fetch access token from callback request."
        raw_token = request.session.get(self.session_key, None)
        verifier = request.GET.get('oauth_verifier', None)
        if raw_token is not None and verifier is not None:
            data = {'oauth_verifier': verifier}
            callback = request.build_absolute_uri(callback or request.path)
            callback = force_text(callback)
            try:
                response = self.request('post', self.source.access_token_url,
                                        token=raw_token, data=data, oauth_callback=callback)
                response.raise_for_status()
            except RequestException as exc:
                LOGGER.warning('Unable to fetch access token: %s', exc)
                return None
            else:
                return response.text
        return None

    def get_request_token(self, request, callback):
        "Fetch the OAuth request token. Only required for OAuth 1.0."
        callback = force_text(request.build_absolute_uri(callback))
        try:
            response = self.request(
                'post', self.source.request_token_url, oauth_callback=callback)
            response.raise_for_status()
        except RequestException as exc:
            LOGGER.warning('Unable to fetch request token: %s', exc)
            return None
        else:
            return response.text

    def get_redirect_args(self, request, callback):
        "Get request parameters for redirect url."
        callback = force_text(request.build_absolute_uri(callback))
        raw_token = self.get_request_token(request, callback)
        token, secret = self.parse_raw_token(raw_token)
        if token is not None and secret is not None:
            request.session[self.session_key] = raw_token
        return {
            'oauth_token': token,
            'oauth_callback': callback,
        }

    def parse_raw_token(self, raw_token):
        "Parse token and secret from raw token response."
        if raw_token is None:
            return (None, None)
        query_string = parse_qs(raw_token)
        token = query_string.get('oauth_token', [None])[0]
        secret = query_string.get('oauth_token_secret', [None])[0]
        return (token, secret)

    def request(self, method, url, **kwargs):
        "Build remote url request. Constructs necessary auth."
        user_token = kwargs.pop('token', self.token)
        token, secret = self.parse_raw_token(user_token)
        callback = kwargs.pop('oauth_callback', None)
        verifier = kwargs.get('data', {}).pop('oauth_verifier', None)
        oauth = OAuth1(
            resource_owner_key=token,
            resource_owner_secret=secret,
            client_key=self.source.consumer_key,
            client_secret=self.source.consumer_secret,
            verifier=verifier,
            callback_uri=callback,
        )
        kwargs['auth'] = oauth
        return super(OAuthClient, self).request(method, url, **kwargs)

    @property
    def session_key(self):
        return 'oauth-client-{0}-request-token'.format(self.source.name)


class OAuth2Client(BaseOAuthClient):
    """OAuth2 Client"""

    def check_application_state(self, request, callback):
        "Check optional state parameter."
        stored = request.session.get(self.session_key, None)
        returned = request.GET.get('state', None)
        check = False
        if stored is not None:
            if returned is not None:
                check = constant_time_compare(stored, returned)
            else:
                LOGGER.warning('No state parameter returned by the source.')
        else:
            LOGGER.warning('No state stored in the sesssion.')
        return check

    def get_access_token(self, request, callback=None, **request_kwargs):
        "Fetch access token from callback request."
        callback = request.build_absolute_uri(callback or request.path)
        if not self.check_application_state(request, callback):
            LOGGER.warning('Application state check failed.')
            return None
        if 'code' in request.GET:
            args = {
                'client_id': self.source.consumer_key,
                'redirect_uri': callback,
                'client_secret': self.source.consumer_secret,
                'code': request.GET['code'],
                'grant_type': 'authorization_code',
            }
        else:
            LOGGER.warning('No code returned by the source')
            return None
        try:
            response = self.request('post', self.source.access_token_url,
                                    data=args, **request_kwargs)
            response.raise_for_status()
        except RequestException as exc:
            LOGGER.warning('Unable to fetch access token: %s', exc)
            return None
        else:
            return response.text

    def get_application_state(self, request, callback):
        "Generate state optional parameter."
        return get_random_string(32)

    def get_redirect_args(self, request, callback):
        "Get request parameters for redirect url."
        callback = request.build_absolute_uri(callback)
        args = {
            'client_id': self.source.consumer_key,
            'redirect_uri': callback,
            'response_type': 'code',
        }
        state = self.get_application_state(request, callback)
        if state is not None:
            args['state'] = state
            request.session[self.session_key] = state
        return args

    def parse_raw_token(self, raw_token):
        "Parse token and secret from raw token response."
        if raw_token is None:
            return (None, None)
        # Load as json first then parse as query string
        try:
            token_data = json.loads(raw_token)
        except ValueError:
            token = parse_qs(raw_token).get('access_token', [None])[0]
        else:
            token = token_data.get('access_token', None)
        return (token, None)

    def request(self, method, url, **kwargs):
        "Build remote url request. Constructs necessary auth."
        user_token = kwargs.pop('token', self.token)
        token, _ = self.parse_raw_token(user_token)
        if token is not None:
            params = kwargs.get('params', {})
            params['access_token'] = token
            kwargs['params'] = params
        return super(OAuth2Client, self).request(method, url, **kwargs)

    @property
    def session_key(self):
        return 'oauth-client-{0}-request-state'.format(self.source.name)


def get_client(source, token=''): # nosec
    "Return the API client for the given source."
    cls = OAuth2Client
    if source.request_token_url:
        cls = OAuthClient
    return cls(source, token)