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# Copyright (c) 2018 The Johns Hopkins University/Applied Physics Laboratory
# All Rights Reserved.
#
# 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.
from cryptography import x509
from cryptography.hazmat import backends
from kmip.core import exceptions
def get_certificate_from_connection(connection):
"""
Extract an X.509 certificate from a socket connection.
"""
certificate = connection.getpeercert(binary_form=True)
if certificate:
return x509.load_der_x509_certificate(
certificate,
backends.default_backend()
)
return None
def get_extended_key_usage_from_certificate(certificate):
"""
Given an X.509 certificate, extract and return the extendedKeyUsage
extension.
"""
try:
return certificate.extensions.get_extension_for_oid(
x509.oid.ExtensionOID.EXTENDED_KEY_USAGE
).value
except x509.ExtensionNotFound:
return None
def get_common_names_from_certificate(certificate):
"""
Given an X.509 certificate, extract and return all common names.
"""
common_names = certificate.subject.get_attributes_for_oid(
x509.oid.NameOID.COMMON_NAME
)
return [common_name.value for common_name in common_names]
def get_client_identity_from_certificate(certificate):
"""
Given an X.509 certificate, extract and return the client identity.
"""
client_ids = get_common_names_from_certificate(certificate)
if len(client_ids) > 0:
if len(client_ids) > 1:
raise exceptions.PermissionDenied(
"Multiple client identities found."
)
return client_ids[0]
else:
raise exceptions.PermissionDenied(
"The certificate does not define any subject common names. "
"Client identity unavailable."
)
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