"""
Make Twisted use M2Crypto for SSL
Copyright (c) 2004-2007 Open Source Applications Foundation.
All rights reserved.
FIXME THIS HAS NOT BEEN FINISHED. NEITHER PEP484 NOR PORT PYTHON3 HAS
BEEN FINISHED. THE FURTHER WORK WILL BE DONE WHEN THE STATUS OF TWISTED
IN THE PYTHON 3 (AND ASYNCIO) WORLD WILL BE CLEAR.
"""
__all__ = ['connectSSL', 'connectTCP', 'listenSSL', 'listenTCP',
'TLSProtocolWrapper']
import logging
from functools import partial
import twisted.internet.reactor
import twisted.protocols.policies as policies
from M2Crypto import BIO, X509, m2, util
from M2Crypto.SSL.Checker import Checker, SSLVerificationError
from twisted.internet.interfaces import ITLSTransport
from twisted.protocols.policies import ProtocolWrapper
from typing import AnyStr, Callable, Iterable, Optional # noqa
from zope.interface import implementer
log = logging.getLogger(__name__)
def _alwaysSucceedsPostConnectionCheck(peerX509, expectedHost):
return 1
[docs]
def connectSSL(host, port, factory, contextFactory, timeout=30,
bindAddress=None,
reactor=twisted.internet.reactor,
postConnectionCheck=Checker()):
# type: (str, int, object, object, int, Optional[str], twisted.internet.reactor, Checker) -> reactor.connectTCP
"""
A convenience function to start an SSL/TLS connection using Twisted.
See IReactorSSL interface in Twisted.
"""
wrappingFactory = policies.WrappingFactory(factory)
wrappingFactory.protocol = lambda factory, wrappedProtocol: \
TLSProtocolWrapper(factory,
wrappedProtocol,
startPassThrough=0,
client=1,
contextFactory=contextFactory,
postConnectionCheck=postConnectionCheck)
return reactor.connectTCP(host, port, wrappingFactory, timeout, bindAddress)
[docs]
def connectTCP(host, port, factory, timeout=30, bindAddress=None,
reactor=twisted.internet.reactor,
postConnectionCheck=Checker()):
# type: (str, int, object, int, Optional[util.AddrType], object, Callable) -> object
"""
A convenience function to start a TCP connection using Twisted.
NOTE: You must call startTLS(ctx) to go into SSL/TLS mode.
See IReactorTCP interface in Twisted.
"""
wrappingFactory = policies.WrappingFactory(factory)
wrappingFactory.protocol = lambda factory, wrappedProtocol: \
TLSProtocolWrapper(factory,
wrappedProtocol,
startPassThrough=1,
client=1,
contextFactory=None,
postConnectionCheck=postConnectionCheck)
return reactor.connectTCP(host, port, wrappingFactory, timeout, bindAddress)
[docs]
def listenSSL(port, factory, contextFactory, backlog=5, interface='',
reactor=twisted.internet.reactor,
postConnectionCheck=_alwaysSucceedsPostConnectionCheck):
"""
A convenience function to listen for SSL/TLS connections using Twisted.
See IReactorSSL interface in Twisted.
"""
wrappingFactory = policies.WrappingFactory(factory)
wrappingFactory.protocol = lambda factory, wrappedProtocol: \
TLSProtocolWrapper(factory,
wrappedProtocol,
startPassThrough=0,
client=0,
contextFactory=contextFactory,
postConnectionCheck=postConnectionCheck)
return reactor.listenTCP(port, wrappingFactory, backlog, interface)
[docs]
def listenTCP(port, factory, backlog=5, interface='',
reactor=twisted.internet.reactor,
postConnectionCheck=None):
"""
A convenience function to listen for TCP connections using Twisted.
NOTE: You must call startTLS(ctx) to go into SSL/TLS mode.
See IReactorTCP interface in Twisted.
"""
wrappingFactory = policies.WrappingFactory(factory)
wrappingFactory.protocol = lambda factory, wrappedProtocol: \
TLSProtocolWrapper(factory,
wrappedProtocol,
startPassThrough=1,
client=0,
contextFactory=None,
postConnectionCheck=postConnectionCheck)
return reactor.listenTCP(port, wrappingFactory, backlog, interface)
class _BioProxy(object):
"""
The purpose of this class is to eliminate the __del__ method from
TLSProtocolWrapper, and thus letting it be garbage collected.
"""
m2_bio_free_all = m2.bio_free_all
def __init__(self, bio):
self.bio = bio
def _ptr(self):
return self.bio
def __del__(self):
if self.bio is not None:
self.m2_bio_free_all(self.bio)
class _SSLProxy(object):
"""
The purpose of this class is to eliminate the __del__ method from
TLSProtocolWrapper, and thus letting it be garbage collected.
"""
m2_ssl_free = m2.ssl_free
def __init__(self, ssl):
self.ssl = ssl
def _ptr(self):
return self.ssl
def __del__(self):
if self.ssl is not None:
self.m2_ssl_free(self.ssl)
[docs]
@implementer(ITLSTransport)
class TLSProtocolWrapper(ProtocolWrapper):
"""
A SSL/TLS protocol wrapper to be used with Twisted. Typically
you would not use this class directly. Use connectTCP,
connectSSL, listenTCP, listenSSL functions defined above,
which will hook in this class.
"""
def __init__(self, factory, wrappedProtocol, startPassThrough, client,
contextFactory, postConnectionCheck):
# type: (policies.WrappingFactory, object, int, int, object, Checker) -> None
"""
:param factory:
:param wrappedProtocol:
:param startPassThrough: If true we won't encrypt at all. Need to
call startTLS() later to switch to SSL/TLS.
:param client: True if this should be a client protocol.
:param contextFactory: Factory that creates SSL.Context objects.
The called function is getContext().
:param postConnectionCheck: The post connection check callback that
will be called just after connection has
been established but before any real data
has been exchanged. The first argument to
this function is an X509 object, the second
is the expected host name string.
"""
# ProtocolWrapper.__init__(self, factory, wrappedProtocol)
# XXX: Twisted 2.0 has a new addition where the wrappingFactory is
# set as the factory of the wrappedProtocol. This is an issue
# as the wrap should be transparent. What we want is
# the factory of the wrappedProtocol to be the wrappedFactory and
# not the outer wrappingFactory. This is how it was implemented in
# Twisted 1.3
self.factory = factory
self.wrappedProtocol = wrappedProtocol
# wrappedProtocol == client/server instance
# factory.wrappedFactory == client/server factory
self.data = b'' # Clear text to encrypt and send
self.encrypted = b'' # Encrypted data we need to decrypt and pass on
self.tlsStarted = 0 # SSL/TLS mode or pass through
self.checked = 0 # Post connection check done or not
self.isClient = client
self.helloDone = 0 # True when hello has been sent
if postConnectionCheck is None:
self.postConnectionCheck = _alwaysSucceedsPostConnectionCheck
else:
self.postConnectionCheck = postConnectionCheck
if not startPassThrough:
self.startTLS(contextFactory.getContext())
[docs]
def clear(self):
"""
Clear this instance, after which it is ready for reuse.
"""
if getattr(self, 'tlsStarted', 0):
self.sslBio = None
self.ssl = None
self.internalBio = None
self.networkBio = None
self.data = b''
self.encrypted = b''
self.tlsStarted = 0
self.checked = 0
self.isClient = 1
self.helloDone = 0
# We can reuse self.ctx and it will be deleted automatically
# when this instance dies
[docs]
def startTLS(self, ctx):
"""
Start SSL/TLS. If this is not called, this instance just passes data
through untouched.
"""
# NOTE: This method signature must match the startTLS() method Twisted
# expects transports to have. This will be called automatically
# by Twisted in STARTTLS situations, for example with SMTP.
if self.tlsStarted:
raise Exception('TLS already started')
self.ctx = ctx
self.internalBio = m2.bio_new(m2.bio_s_bio())
m2.bio_set_write_buf_size(self.internalBio, 0)
self.networkBio = _BioProxy(m2.bio_new(m2.bio_s_bio()))
m2.bio_set_write_buf_size(self.networkBio._ptr(), 0)
m2.bio_make_bio_pair(self.internalBio, self.networkBio._ptr())
self.sslBio = _BioProxy(m2.bio_new(m2.bio_f_ssl()))
self.ssl = _SSLProxy(m2.ssl_new(self.ctx.ctx))
if self.isClient:
m2.ssl_set_connect_state(self.ssl._ptr())
else:
m2.ssl_set_accept_state(self.ssl._ptr())
m2.ssl_set_bio(self.ssl._ptr(), self.internalBio, self.internalBio)
m2.bio_set_ssl(self.sslBio._ptr(), self.ssl._ptr(), m2.bio_noclose)
# Need this for writes that are larger than BIO pair buffers
mode = m2.ssl_get_mode(self.ssl._ptr())
m2.ssl_set_mode(self.ssl._ptr(),
mode |
m2.SSL_MODE_ENABLE_PARTIAL_WRITE |
m2.SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER)
self.tlsStarted = 1
[docs]
def write(self, data):
# type: (bytes) -> None
if not self.tlsStarted:
ProtocolWrapper.write(self, data)
return
try:
encryptedData = self._encrypt(data)
ProtocolWrapper.write(self, encryptedData)
self.helloDone = 1
except BIO.BIOError as e:
# See http://www.openssl.org/docs/apps/verify.html#DIAGNOSTICS
# for the error codes returned by SSL_get_verify_result.
e.args = (m2.ssl_get_verify_result(self.ssl._ptr()), e.args[0])
raise e
[docs]
def writeSequence(self, data):
# type: (Iterable[bytes]) -> None
if not self.tlsStarted:
ProtocolWrapper.writeSequence(self, b''.join(data))
return
self.write(b''.join(data))
[docs]
def loseConnection(self):
# XXX Do we need to do m2.ssl_shutdown(self.ssl._ptr())?
ProtocolWrapper.loseConnection(self)
[docs]
def connectionMade(self):
ProtocolWrapper.connectionMade(self)
if self.tlsStarted and self.isClient and not self.helloDone:
self._clientHello()
[docs]
def dataReceived(self, data):
# type: (bytes) -> None
if not self.tlsStarted:
ProtocolWrapper.dataReceived(self, data)
return
self.encrypted += data
try:
while 1:
decryptedData = self._decrypt()
self._check()
encryptedData = self._encrypt()
ProtocolWrapper.write(self, encryptedData)
ProtocolWrapper.dataReceived(self, decryptedData)
if decryptedData == b'' and encryptedData == b'':
break
except BIO.BIOError as e:
# See http://www.openssl.org/docs/apps/verify.html#DIAGNOSTICS
# for the error codes returned by SSL_get_verify_result.
e.args = (m2.ssl_get_verify_result(self.ssl._ptr()), e.args[0])
raise e
[docs]
def connectionLost(self, reason):
# type: (AnyStr) -> None
self.clear()
ProtocolWrapper.connectionLost(self, reason)
def _check(self):
if not self.checked and m2.ssl_is_init_finished(self.ssl._ptr()):
x509 = m2.ssl_get_peer_cert(self.ssl._ptr())
if x509 is not None:
x509 = X509.X509(x509, 1)
if self.isClient:
host = self.transport.addr[0]
else:
host = self.transport.getPeer().host
if not self.postConnectionCheck(x509, host):
raise SSLVerificationError('post connection check')
self.checked = 1
def _clientHello(self):
try:
# We rely on OpenSSL implicitly starting with client hello
# when we haven't yet established an SSL connection
encryptedData = self._encrypt(clientHello=1)
ProtocolWrapper.write(self, encryptedData)
self.helloDone = 1
except BIO.BIOError as e:
# See http://www.openssl.org/docs/apps/verify.html#DIAGNOSTICS
# for the error codes returned by SSL_get_verify_result.
e.args = (m2.ssl_get_verify_result(self.ssl._ptr()), e.args[0])
raise e
# Optimizations to reduce attribute accesses
@property
def _get_wr_guar_ssl(self):
# type: () -> Callable[[], int]
"""Return max. length of data can be written to the BIO.
Writes larger than this value will return a value from
BIO_write() less than the amount requested or if the buffer is
full request a retry.
"""
return partial(m2.bio_ctrl_get_write_guarantee,
self.sslBio._ptr())
@property
def _get_wr_guar_net(self):
# type: () -> Callable[[], int]
return partial(m2.bio_ctrl_get_write_guarantee,
self.networkBio._ptr())
@property
def _shoud_retry_ssl(self):
# type: () -> Callable[[], int]
# BIO_should_retry() is true if the call that produced this
# condition should then be retried at a later time.
return partial(m2.bio_should_retry, self.sslBio._ptr())
@property
def _shoud_retry_net(self):
# type: () -> Callable[[], int]
return partial(m2.bio_should_retry, self.networkBio._ptr())
@property
def _ctrl_pend_ssl(self):
# type: () -> Callable[[], int]
# size_t BIO_ctrl_pending(BIO *b);
# BIO_ctrl_pending() return the number of pending characters in
# the BIOs read and write buffers.
return partial(m2.bio_ctrl_pending, self.sslBio._ptr())
@property
def _ctrl_pend_net(self):
# type: () -> Callable[[], int]
return partial(m2.bio_ctrl_pending, self.networkBio._ptr())
@property
def _write_ssl(self):
# type: () -> Callable[[bytes], int]
# All these functions return either the amount of data
# successfully read or written (if the return value is
# positive) or that no data was successfully read or written
# if the result is 0 or -1. If the return value is -2 then
# the operation is not implemented in the specific BIO type.
return partial(m2.bio_write, self.sslBio._ptr())
@property
def _write_net(self):
# type: () -> Callable[[bytes], int]
return partial(m2.bio_write, self.networkBio._ptr())
@property
def _read_ssl(self):
# type: () -> Callable[[int], Optional[bytes]]
return partial(m2.bio_read, self.sslBio._ptr())
@property
def _read_net(self):
# type: () -> Callable[[int], Optional[bytes]]
return partial(m2.bio_read, self.networkBio._ptr())
def _encrypt(self, data=b'', clientHello=0):
# type: (bytes, int) -> bytes
"""
:param data:
:param clientHello:
:return:
"""
encryptedData = b''
self.data += data
while 1:
if (self._get_wr_guar_ssl() > 0 and self.data != b'') or clientHello:
r = self._write_ssl(self.data)
if r <= 0:
if not self._shoud_retry_ssl():
raise IOError(
('Data left to be written to {}, ' +
'but cannot retry SSL connection!').format(self.sslBio))
else:
assert self.checked
self.data = self.data[r:]
pending = self._ctrl_pend_net()
if pending:
d = self._read_net(pending)
if d is not None: # This is strange, but d can be None
encryptedData += d
else:
assert(self._shoud_retry_net())
else:
break
return encryptedData
def _decrypt(self, data=b''):
# type: (bytes) -> bytes
self.encrypted += data
decryptedData = b''
while 1:
if self._get_wr_guar_ssl() > 0 and self.encrypted != b'':
r = self._write_net(self.encrypted)
if r <= 0:
if not self._shoud_retry_net():
raise IOError(
('Data left to be written to {}, ' +
'but cannot retry SSL connection!').format(self.networkBio))
else:
self.encrypted = self.encrypted[r:]
pending = self._ctrl_pend_ssl()
if pending:
d = self._read_ssl(pending)
if d is not None: # This is strange, but d can be None
decryptedData += d
else:
assert(self._shoud_retry_ssl())
else:
break
return decryptedData