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# Copyright 2012 OpenStack LLC
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

"""Main entry point into the S3 Credentials service.

TODO-DOCS
"""

import base64
import hmac

from hashlib import sha1

from keystone import config
from keystone.common import utils
from keystone.common import wsgi
from keystone.contrib import ec2

CONF = config.CONF


class S3Extension(wsgi.ExtensionRouter):
    def add_routes(self, mapper):
        controller = S3Controller()
        # validation
        mapper.connect('/s3tokens',
                       controller=controller,
                       action='authenticate',
                       conditions=dict(method=['POST']))


class S3Controller(ec2.Ec2Controller):
    def check_signature(self, creds_ref, credentials):
        msg = base64.urlsafe_b64decode(str(credentials['token']))
        key = str(creds_ref['secret'])
        signed = base64.encodestring(hmac.new(key, msg, sha1).digest()).strip()

        if not utils.auth_str_equal(credentials['signature'], signed):
            raise Exception('Not Authorized')
