Synnefo

# Copyright 2013 GRNET S.A. All rights reserved.

#

# Redistribution and use in source and binary forms, with or

# without modification, are permitted provided that the following

# conditions are met:

#

#   1. Redistributions of source code must retain the above

#      copyright notice, this list of conditions and the following

#      disclaimer.

#

#   2. Redistributions in binary form must reproduce the above

#      copyright notice, this list of conditions and the following

#      disclaimer in the documentation and/or other materials

#      provided with the distribution.

#

# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR

# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

# POSSIBILITY OF SUCH DAMAGE.

#

# The views and conclusions contained in the software and

# documentation are those of the authors and should not be

# interpreted as representing official policies, either expressed

# or implied, of GRNET S.A.

import urllib

import urlparse

import uuid

import datetime

import json

from base64 import b64encode, b64decode

from hashlib import sha512

import logging

logger = logging.getLogger(__name__)

def handles_oa2_requests(func):

    def wrapper(self, *args, **kwargs):

        if not self._errors_to_http:

            return func(self, *args, **kwargs)

        try:

            return func(self, *args, **kwargs)

        except OA2Error, e:

            return self.build_response_from_error(e)

    return wrapper

class OA2Error(Exception):

    error = None

class InvalidClientID(OA2Error):

    pass

class NotAuthenticatedError(OA2Error):

    pass

class InvalidClientRedirectUrl(OA2Error):

    pass

class InvalidAuthorizationRequest(OA2Error):

    pass

class Response(object):

    def __init__(self, status, body='', headers=None,

                 content_type='plain/text'):

        if not body:

            body = ''

        if not headers:

            headers = {}

        self.status = status

        self.body = body

        self.headers = headers

        self.content_type = content_type

    def __repr__(self):

        return "%d RESPONSE (BODY: %r, HEADERS: %r)" % (self.status,

                                                        self.body,

                                                        self.headers)

class Request(object):

    def __init__(self, method, path, GET=None, POST=None, META=None,

                 secure=False, user=None):

        self.method = method

        self.path = path

        if not GET:

            GET = {}

        if not POST:

            POST = {}

        if not META:

            META = {}

        self.secure = secure

        self.GET = GET

        self.POST = POST

        self.META = META

        self.user = user

    def __repr__(self):

        prepend = ""

        if self.secure:

            prepend = "SECURE "

        return "%s%s REQUEST (POST: %r, GET:%r, HEADERS:%r, " % (prepend,

                                                                 self.method,

                                                                 self.POST,

                                                                 self.GET,

                                                                 self.META)

class ORMAbstractBase(type):

    def __new__(cls, name, bases, attrs):

        attrs['ENTRIES'] = {}

        return super(ORMAbstractBase, cls).__new__(cls, name, bases, attrs)

class ORMAbstract(object):

    ENTRIES = {}

    __metaclass__ = ORMAbstractBase

    def __init__(self, **kwargs):

        for key, value in kwargs.iteritems():

            setattr(self, key, value)

    @classmethod

    def create(cls, id, **params):

        params = cls.clean_params(params)

        params['id'] = id

        cls.ENTRIES[id] = cls(**params)

        return cls.get(id)

    @classmethod

    def get(cls, pk):

        return cls.ENTRIES.get(pk)

    @classmethod

    def clean_params(cls, params):

        return params

class Client(ORMAbstract):

    def get_id(self):

        return self.id

    def get_redirect_uris(self):

        return self.uris

    def get_default_redirect_uri(self):

        return self.uris[0]

    def redirect_uri_is_valid(self, redirect_uri):

        split = urlparse.urlsplit(redirect_uri)

        if split.scheme not in urlparse.uses_query:

            raise OA2Error("Invalid redirect url scheme")

        uris = self.get_redirect_uris()

        return redirect_uri in uris

    def requires_auth(self):

        if self.client_type == 'confidential':

            return True

        return 'secret' in dir(self)

    def check_credentials(self, username, secret):

        return username == self.id and secret == self.secret

class Token(ORMAbstract):

    def to_dict(self):

        params = {

            'access_token': self.token,

            'token_type': self.token_type,

            'expires_in': self.expires,

        }

        if self.refresh_token:

            params['refresh_token'] = self.refresh_token

        return params

class AuthorizationCode(ORMAbstract):

    pass

class User(ORMAbstract):

    pass

class BackendBase(type):

    def __new__(cls, name, bases, attrs):

        super_new = super(BackendBase, cls).__new__

        #parents = [b for b in bases if isinstance(b, BackendBase)]

        #meta = attrs.pop('Meta', None)

        return super_new(cls, name, bases, attrs)

    @classmethod

    def get_orm_options(cls, attrs):

        meta = attrs.pop('ORM', None)

        orm = {}

        if meta:

            for attr in dir(meta):

                orm[attr] = getattr(meta, attr)

        return orm

class SimpleBackend(object):

    __metaclass__ = BackendBase

    base_url = ''

    endpoints_prefix = 'oauth2/'

    token_endpoint = 'token/'

    token_length = 30

    token_expires = 20

    authorization_endpoint = 'auth/'

    authorization_code_length = 60

    authorization_response_types = ['code', 'token']

    grant_types = ['authorization_code']

    response_cls = Response

    request_cls = Request

    client_model = Client

    token_model = Token

    code_model = AuthorizationCode

    user_model = User

    def __init__(self, base_url='', endpoints_prefix='oauth2/', id='oauth2',

                 token_endpoint='token/', token_length=30,

                 token_expires=20, authorization_endpoint='auth/',

                 authorization_code_length=60,

                 redirect_uri_limit=5000, **kwargs):

        self.base_url = base_url

        self.endpoints_prefix = endpoints_prefix

        self.token_endpoint = token_endpoint

        self.token_length = token_length

        self.token_expires = token_expires

        self.authorization_endpoint = authorization_endpoint

        self.authorization_code_length = authorization_code_length

        self.id = id

        self._errors_to_http = kwargs.get('errors_to_http', True)

        self.redirect_uri_limit = redirect_uri_limit

    # Request/response builders

    def build_request(self, method, get, post, meta):

        return self.request_cls(method=method, GET=get, POST=post, META=meta)

    def build_response(self, status, headers=None, body=''):

        return self.response_cls(status=status, headers=headers, body=body)

    # ORM Methods

    def create_authorization_code(self, user, client, code, redirect_uri,

                                  scope, state, **kwargs):

        code_params = {

            'code': code,

            'redirect_uri': redirect_uri,

            'client': client,

            'scope': scope,

            'state': state,

            'user': user

        }

        code_params.update(kwargs)

        code_instance = self.code_model.create(**code_params)

        logger.info(u'%r created' % code_instance)

        return code_instance

    def _token_params(self, value, token_type, authorization, scope):

        created_at = datetime.datetime.now()

        expires = self.token_expires

        expires_at = created_at + datetime.timedelta(seconds=expires)

        token_params = {

            'code': value,

            'token_type': token_type,

            'created_at': created_at,

            'expires_at': expires_at,

            'user': authorization.user,

            'redirect_uri': authorization.redirect_uri,

            'client': authorization.client,

            'scope': authorization.scope,

        }

        return token_params

    def create_token(self, value, token_type, authorization, scope,

                     refresh=False):

        params = self._token_params(value, token_type, authorization, scope)

        if refresh:

            refresh_token = self.generate_token()

            params['refresh_token'] = refresh_token

            # TODO: refresh token expires ???

        token = self.token_model.create(**params)

        logger.info(u'%r created' % token)

        return token

#    def delete_authorization_code(self, code):

#        del self.code_model.ENTRIES[code]

    def get_client_by_id(self, client_id):

        return self.client_model.get(client_id)

    def get_client_by_credentials(self, username, password):

        return None

    def get_authorization_code(self, code):

        return self.code_model.get(code)

    def get_client_authorization_code(self, client, code):

        code_instance = self.get_authorization_code(code)

        if not code_instance:

            raise OA2Error("Invalid code")

        if client.get_id() != code_instance.client.get_id():

            raise OA2Error("Mismatching client with code client")

        return code_instance

    def client_id_exists(self, client_id):

        return bool(self.get_client_by_id(client_id))

    def build_site_url(self, prefix='', **params):

        params = urllib.urlencode(params)

        return "%s%s%s%s" % (self.base_url, self.endpoints_prefix, prefix,

                             params)

    def _get_uri_base(self, uri):

        split = urlparse.urlsplit(uri)

        return "%s://%s%s" % (split.scheme, split.netloc, split.path)

    def build_client_redirect_uri(self, client, uri, **params):

        if not client.redirect_uri_is_valid(uri):

            raise OA2Error("Invalid redirect uri")

        params = urllib.urlencode(params)

        uri = self._get_uri_base(uri)

        return "%s?%s" % (uri, params)

    def generate_authorization_code(self):

        dg64 = b64encode(sha512(str(uuid.uuid4())).hexdigest())

        return dg64[:self.authorization_code_length]

    def generate_token(self, *args, **kwargs):

        dg64 = b64encode(sha512(str(uuid.uuid4())).hexdigest())

        return dg64[:self.token_length]

    def add_authorization_code(self, user, client, redirect_uri, scope, state,

                               **kwargs):

        code = self.generate_authorization_code()

        self.create_authorization_code(user, client, code, redirect_uri, scope,

                                       state, **kwargs)

        return code

    def add_token_for_client(self, token_type, authorization, refresh=False):

        token = self.generate_token()

        self.create_token(token, token_type, authorization, refresh)

        return token

    #

    # Response helpers

    #

    def grant_accept_response(self, client, redirect_uri, scope, state):

        context = {'client': client.get_id(), 'redirect_uri': redirect_uri,

                   'scope': scope, 'state': state,

                   #'url': url,

                   }

        json_content = json.dumps(context)

        return self.response_cls(status=200, body=json_content)

    def grant_token_response(self, token, token_type):

        context = {'access_token': token, 'token_type': token_type,

                   'expires_in': self.token_expires}

        json_content = json.dumps(context)

        return self.response_cls(status=200, body=json_content)

    def redirect_to_login_response(self, request, params):

        parts = list(urlparse.urlsplit(request.path))

        parts[3] = urllib.urlencode(params)

        query = {'next': urlparse.urlunsplit(parts)}

        return Response(302,

                        headers={'Location': '%s?%s' %

                                 (self.get_login_uri(),

                                  urllib.urlencode(query))})

    def redirect_to_uri(self, redirect_uri, code, state=None):

        parts = list(urlparse.urlsplit(redirect_uri))

        params = dict(urlparse.parse_qsl(parts[3], keep_blank_values=True))

        params['code'] = code

        if state is not None:

            params['state'] = state

        parts[3] = urllib.urlencode(params)

        return Response(302,

                        headers={'Location': '%s' %

                                 urlparse.urlunsplit(parts)})

    def build_response_from_error(self, exception):

        response = Response(400)

        logger.exception(exception)

        error = 'generic_error'

        if exception.error:

            error = exception.error

        body = {

            'error': error,

            'exception': exception.message,

        }

        response.body = json.dumps(body)

        response.content_type = "application/json"

        return response

    #

    # Processor methods

    #

    def process_code_request(self, user, client, uri, scope, state):

        code = self.add_authorization_code(user, client, uri, scope, state)

        return self.redirect_to_uri(uri, code, state)

    #

    # Helpers

    #

    def grant_authorization_code(self, client, code_instance, redirect_uri,

                                 scope=None, token_type="Bearer"):

        if scope and code_instance.scope != scope:

            raise OA2Error("Invalid scope")

        if redirect_uri != code_instance.redirect_uri:

            raise OA2Error("The redirect uri does not match "

                           "the one used during authorization")

        token = self.add_token_for_client(token_type, code_instance)

        self.delete_authorization_code(code_instance)  # use only once

        return token, token_type

    def consume_token(self, token):

        token_instance = self.get_token(token)

        if datetime.datetime.now() > token_instance.expires_at:

            self.delete_token(token_instance)  # delete expired token

            raise OA2Error("Token has expired")

        # TODO: delete token?

        return token_instance

    def _get_credentials(self, params, headers):

        if 'HTTP_AUTHORIZATION' in headers:

            scheme, b64credentials = headers.get(

                'HTTP_AUTHORIZATION').split(" ")

            if scheme != 'Basic':

                # TODO: raise 401 + WWW-Authenticate

                raise OA2Error("Unsupported authorization scheme")

            credentials = b64decode(b64credentials).split(":")

            return scheme, credentials

        else:

            return None, None

        pass

    def _get_authorization(self, params, headers):

        scheme, client_credentials = self._get_credentials(params, headers)

        no_authorization = scheme is None and client_credentials is None

        if no_authorization:

            raise OA2Error("Missing authorization header")

        return client_credentials

    def get_redirect_uri_from_params(self, client, params, default=True):

        """

        Accepts a client instance and request parameters.

        """

        redirect_uri = params.get('redirect_uri', None)

        if not redirect_uri and default:

            redirect_uri = client.get_default_redirect_uri()

        else:

            # TODO: sanitize redirect_uri (self.clean_redirect_uri ???)

            # clean and validate

            if not client.redirect_uri_is_valid(redirect_uri):

                raise OA2Error("Invalid client redirect uri")

        return redirect_uri

    #

    # Request identifiers

    #

    def identify_authorize_request(self, params, headers):

        return params.get('response_type'), params

    def identify_token_request(self, headers, params):

        content_type = headers.get('CONTENT_TYPE')

        if content_type != 'application/x-www-form-urlencoded':

            raise OA2Error("Invalid Content-Type header")

        return params.get('grant_type')

    #

    # Parameters validation methods

    #

    def validate_client(self, params, meta, requires_auth=True,

                        client_id_required=True):

        client_id = params.get('client_id')

        if client_id is None and client_id_required:

            raise OA2Error("Client identification is required")

        client_credentials = None

        try:  # check authorization header

            client_credentials = self._get_authorization(params, meta)

            if client_credentials is not None:

                _client_id = client_credentials[0]

                if client_id is not None and client_id != _client_id:

                    raise OA2Error("Client identification conflicts "

                                   "with client authorization")

                client_id = _client_id

        except:

            pass

        if client_id is None:

            raise OA2Error("Missing client identification")

        client = self.get_client_by_id(client_id)

        if requires_auth and client.requires_auth():

            if client_credentials is None:

                raise OA2Error("Client authentication is required")

        if client_credentials is not None:

            self.check_credentials(client, *client_credentials)

        return client

    def validate_redirect_uri(self, client, params, headers,

                              allow_default=True, is_required=False,

                              expected_value=None):

        redirect_uri = params.get('redirect_uri')

        if is_required and redirect_uri is None:

            raise OA2Error("Missing redirect uri")

        if redirect_uri is not None:

            if not bool(urlparse.urlparse(redirect_uri).scheme):

                raise OA2Error("Redirect uri should be an absolute URI")

            if len(redirect_uri) > self.redirect_uri_limit:

                raise OA2Error("Redirect uri length limit exceeded")

            if not client.redirect_uri_is_valid(redirect_uri):

                raise OA2Error("Mismatching redirect uri")

            if expected_value is not None and redirect_uri != expected_value:

                raise OA2Error("Invalid redirect uri")

        else:

            try:

                redirect_uri = client.redirecturl_set.values_list('url',

                                                                  flat=True)[0]

            except IndexError:

                raise OA2Error("Unable to fallback to client redirect URI")

        return redirect_uri

    def validate_state(self, client, params, headers):

        return params.get('state')

        raise OA2Error("Invalid state")

    def validate_scope(self, client, params, headers):

        scope = params.get('scope')

        if scope is not None:

            scope = scope.split(' ')[0]  # keep only the first

        # TODO: check for invalid characters

        return scope

    def validate_code(self, client, params, headers):

        code = params.get('code')

        if code is None:

            raise OA2Error("Missing authorization code")

        return self.get_client_authorization_code(client, code)

    #

    # Requests validation methods

    #

    def validate_code_request(self, params, headers):

        client = self.validate_client(params, headers, requires_auth=False)

        redirect_uri = self.validate_redirect_uri(client, params, headers)

        scope = self.validate_scope(client, params, headers)

        scope = scope or redirect_uri  # set default

        state = self.validate_state(client, params, headers)

        return client, redirect_uri, scope, state

    def validate_token_request(self, params, headers, requires_auth=False):

        client = self.validate_client(params, headers)

        redirect_uri = self.validate_redirect_uri(client, params, headers)

        scope = self.validate_scope(client, params, headers)

        scope = scope or redirect_uri  # set default

        state = self.validate_state(client, params, headers)

        return client, redirect_uri, scope, state

    def validate_code_grant(self, params, headers):

        client = self.validate_client(params, headers,

                                      client_id_required=False)

        code_instance = self.validate_code(client, params, headers)

        redirect_uri = self.validate_redirect_uri(

            client, params, headers,

            expected_value=code_instance.redirect_uri)

        return client, redirect_uri, code_instance

    #

    # Endpoint methods

    #

    @handles_oa2_requests

    def authorize(self, request, **extra):

        """

        Used in the following cases

        """

        if not request.secure:

            raise OA2Error("Secure request required")

        # identify

        request_params = request.GET

        if request.method == "POST":

            request_params = request.POST

        auth_type, params = self.identify_authorize_request(request_params,

                                                            request.META)

        if auth_type is None:

            raise OA2Error("Missing authorization type")

        if auth_type == 'code':

            client, uri, scope, state = \

                self.validate_code_request(params, request.META)

        elif auth_type == 'token':

            raise OA2Error("Unsupported authorization type")

#            client, uri, scope, state = \

#                self.validate_token_request(params, request.META)

        else:

            #TODO: handle custom type

            raise OA2Error("Invalid authorization type")

        user = getattr(request, 'user', None)

        if not user:

            return self.redirect_to_login_response(request, params)

        if request.method == 'POST':

            if auth_type == 'code':

                return self.process_code_request(user, client, uri, scope,

                                                 state)

            elif auth_type == 'token':

                raise OA2Error("Unsupported response type")

#                return self.process_token_request(user, client, uri, scope,

#                                                 state)

            else:

                #TODO: handle custom type

                raise OA2Error("Invalid authorization type")

        else:

            if client.is_trusted:

                return self.process_code_request(user, client, uri, scope,

                                                 state)

            else:

                return self.grant_accept_response(client, uri, scope, state)

    @handles_oa2_requests

    def grant_token(self, request, **extra):

        """

        Used in the following cases

        """

        if not request.secure:

            raise OA2Error("Secure request required")

        grant_type = self.identify_token_request(request.META, request.POST)

        if grant_type is None:

            raise OA2Error("Missing grant type")

        elif grant_type == 'authorization_code':

            client, redirect_uri, code = \

                self.validate_code_grant(request.POST, request.META)

            token, token_type = \

                self.grant_authorization_code(client, code, redirect_uri)

            return self.grant_token_response(token, token_type)

        elif (grant_type in ['client_credentials', 'token'] or

              self.is_uri(grant_type)):

            raise OA2Error("Unsupported grant type")

        else:

            #TODO: handle custom type

            raise OA2Error("Invalid grant type")