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##
# Copyright (c) 2005-2016 Apple Inc. 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.
##
"""
Extensions to twisted.internet.ssl.
"""
__all__ = [
"ChainingOpenSSLContextFactory",
"simpleClientContextFactory",
]
import OpenSSL
from OpenSSL.SSL import Context as SSLContext, SSLv23_METHOD, OP_NO_SSLv2, \
OP_CIPHER_SERVER_PREFERENCE, OP_NO_SSLv3, VERIFY_NONE, VERIFY_PEER, \
VERIFY_FAIL_IF_NO_PEER_CERT, VERIFY_CLIENT_ONCE
from twisted.internet.ssl import DefaultOpenSSLContextFactory
from twisted.internet._sslverify import Certificate, _tolerateErrors, VerificationError, verifyHostname
from twisted.python.failure import Failure
import uuid
_OP_NO_COMPRESSION = getattr(OpenSSL.SSL, 'OP_NO_COMPRESSION', 0x00020000)
SSL_CB_HANDSHAKE_DONE = 0x20
class ChainingOpenSSLContextFactory (DefaultOpenSSLContextFactory):
def __init__(
self, privateKeyFileName, certificateFileName,
sslmethod=SSLv23_METHOD,
certificateChainFile=None, keychainIdentity=None,
passwdCallback=None, ciphers=None,
verifyClient=False, requireClientCertificate=False,
verifyClientOnce=True, verifyClientDepth=9,
clientCACertFileNames=[], sendCAsToClient=True,
peerName=None
):
self.certificateChainFile = certificateChainFile
self.keychainIdentity = keychainIdentity
self.passwdCallback = passwdCallback
self.ciphers = ciphers
self.peerName = peerName
self.verifyClient = verifyClient
self.requireClientCertificate = requireClientCertificate
self.verifyClientOnce = verifyClientOnce
self.verifyClientDepth = verifyClientDepth
self.clientCACertFileNames = clientCACertFileNames
self.sendCAsToClient = sendCAsToClient
DefaultOpenSSLContextFactory.__init__(
self,
privateKeyFileName,
certificateFileName,
sslmethod=sslmethod
)
def cacheContext(self):
# Unfortunate code duplication.
ctx = SSLContext(self.sslmethod)
# Always disable SSLv2/SSLv3/Compression
ctx.set_options(OP_NO_SSLv2)
ctx.set_options(OP_NO_SSLv3)
ctx.set_options(_OP_NO_COMPRESSION)
if self.ciphers is not None:
ctx.set_cipher_list(self.ciphers)
ctx.set_options(OP_CIPHER_SERVER_PREFERENCE)
if self.passwdCallback is not None:
ctx.set_passwd_cb(self.passwdCallback)
if self.keychainIdentity and hasattr(ctx, "use_keychain_identity"):
ctx.use_keychain_identity(self.keychainIdentity)
else:
if self.certificateFileName:
ctx.use_certificate_file(self.certificateFileName)
if self.privateKeyFileName:
ctx.use_privatekey_file(self.privateKeyFileName)
if self.certificateChainFile:
ctx.use_certificate_chain_file(self.certificateChainFile)
verifyFlags = VERIFY_NONE
if self.verifyClient:
verifyFlags = VERIFY_PEER
if self.requireClientCertificate:
verifyFlags |= VERIFY_FAIL_IF_NO_PEER_CERT
if self.verifyClientOnce:
verifyFlags |= VERIFY_CLIENT_ONCE
if self.clientCACertFileNames:
store = ctx.get_cert_store()
for cert in self.clientCACertFileNames:
with open(cert) as f:
certpem = f.read()
cert = Certificate.loadPEM(certpem)
store.add_cert(cert.original)
if self.sendCAsToClient:
ctx.add_client_ca(cert.original)
# When a client certificate is used we also need to set a session context id
# to avoid openssl SSL_F_SSL_GET_PREV_SESSION,SSL_R_SESSION_ID_CONTEXT_UNINITIALIZED
# errors
ctx.set_session_id(str(uuid.uuid4()).replace("-", ""))
# It'd be nice if pyOpenSSL let us pass None here for this behavior (as
# the underlying OpenSSL API call allows NULL to be passed). It
# doesn't, so we'll supply a function which does the same thing.
def _verifyCallback(conn, cert, errno, depth, preverify_ok):
return preverify_ok
ctx.set_verify(verifyFlags, _verifyCallback)
if self.verifyClientDepth is not None:
ctx.set_verify_depth(self.verifyClientDepth)
if self.peerName:
if hasattr(ctx, "set_peer_name"):
ctx.set_peer_name(self.peerName)
elif hasattr(ctx, "set_info_callback"):
ctx.set_info_callback(
_tolerateErrors(self._identityVerifyingInfoCallback)
)
else:
raise ValueError("No suitable SSL API for verifying the peer host name")
self._context = ctx
def _identityVerifyingInfoCallback(self, connection, where, ret):
"""
U{info_callback
<http://pythonhosted.org/pyOpenSSL/api/ssl.html#OpenSSL.SSL.Context.set_info_callback>
} for pyOpenSSL that verifies the hostname in the presented certificate
matches the one passed to this L{ClientTLSOptions}.
@param connection: the connection which is handshaking.
@type connection: L{OpenSSL.SSL.Connection}
@param where: flags indicating progress through a TLS handshake.
@type where: L{int}
@param ret: ignored
@type ret: ignored
"""
if where & SSL_CB_HANDSHAKE_DONE:
try:
hostname = self.peerName.decode("utf-8") if isinstance(self.peerName, str) else self.peerName
verifyHostname(connection, hostname)
except VerificationError:
f = Failure()
transport = connection.get_app_data()
transport.failVerification(f)
def simpleClientContextFactory(hostname):
"""
Get a client context factory.
"""
return ChainingOpenSSLContextFactory(
"", "",
certificateChainFile="",
keychainIdentity="",
peerName=hostname,
)
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