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util.py
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util.py
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###############################################################################
#
# The MIT License (MIT)
#
# Copyright (c) Crossbar.io Technologies GmbH
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
###############################################################################
import hashlib
from typing import Optional
from twisted.internet.defer import Deferred
from twisted.internet.address import IPv4Address, UNIXAddress
try:
from twisted.internet.stdio import PipeAddress
except ImportError:
# stdio.PipeAddress is only avail on Twisted 13.0+
PipeAddress = type(None)
try:
from twisted.internet.address import IPv6Address
_HAS_IPV6 = True
except ImportError:
_HAS_IPV6 = False
__all = (
'sleep',
'peer2str',
'transport_channel_id'
)
def sleep(delay, reactor=None):
"""
Inline sleep for use in co-routines (Twisted ``inlineCallback`` decorated functions).
.. seealso::
* `twisted.internet.defer.inlineCallbacks <http://twistedmatrix.com/documents/current/api/twisted.internet.defer.html#inlineCallbacks>`__
* `twisted.internet.interfaces.IReactorTime <http://twistedmatrix.com/documents/current/api/twisted.internet.interfaces.IReactorTime.html>`__
:param delay: Time to sleep in seconds.
:type delay: float
:param reactor: The Twisted reactor to use.
:type reactor: None or provider of ``IReactorTime``.
"""
if not reactor:
from twisted.internet import reactor
d = Deferred()
reactor.callLater(delay, d.callback, None)
return d
def peer2str(addr):
"""
Convert a Twisted address as returned from ``self.transport.getPeer()`` to a string.
:returns: Returns a string representation of the peer on a Twisted transport.
:rtype: unicode
"""
if isinstance(addr, IPv4Address):
res = "tcp4:{0}:{1}".format(addr.host, addr.port)
elif _HAS_IPV6 and isinstance(addr, IPv6Address):
res = "tcp6:{0}:{1}".format(addr.host, addr.port)
elif isinstance(addr, UNIXAddress):
res = "unix:{0}".format(addr.name)
elif isinstance(addr, PipeAddress):
res = "<pipe>"
else:
# gracefully fallback if we can't map the peer's address
res = "?:{0}".format(addr)
return res
try:
from twisted.protocols.tls import TLSMemoryBIOProtocol
except ImportError:
def transport_channel_id(transport: object, is_server: bool, channel_id_type: Optional[str] = None) -> bytes:
if channel_id_type is None:
return b'\x00' * 32
else:
def transport_channel_id(transport: TLSMemoryBIOProtocol, is_server: bool, channel_id_type: Optional[str] = None) -> bytes:
"""
Application-layer user authentication protocols are vulnerable to generic
credential forwarding attacks, where an authentication credential sent by
a client C to a server M may then be used by M to impersonate C at another
server S. To prevent such credential forwarding attacks, modern authentication
protocols rely on channel bindings. For example, WAMP-cryptosign can use
the tls-unique channel identifier provided by the TLS layer to strongly bind
authentication credentials to the underlying channel, so that a credential
received on one TLS channel cannot be forwarded on another.
:param transport: The Twisted TLS transport to extract the TLS channel ID from.
:param is_server: Flag indicating the transport is for a server.
:param channel_id_type: TLS channel ID type, currently only "tls-unique" is supported.
:returns: The TLS channel id (32 bytes).
"""
if channel_id_type is None:
return b'\x00' * 32
if channel_id_type not in ['tls-unique']:
raise Exception("invalid channel ID type {}".format(channel_id_type))
# transport: instance of :class:`twisted.protocols.tls.TLSMemoryBIOProtocol`
# transport._tlsConnection: instance of :class:`OpenSSL.SSL.Connection`
if not hasattr(transport, '_tlsConnection'):
print("TLS transport channel_id for tls-unique requested, but _tlsConnection not found on transport {}".format(dir(transport)))
return b'\x00' * 32
# Obtain latest TLS Finished message that we expected from peer, or None if handshake is not completed.
# http://www.pyopenssl.org/en/stable/api/ssl.html#OpenSSL.SSL.Connection.get_peer_finished
is_not_resumed = True
if channel_id_type == 'tls-unique':
# see also: https://bugs.python.org/file22646/tls_channel_binding.patch
if is_server != is_not_resumed:
# for routers (=servers) XOR new sessions, the channel ID is based on the TLS Finished message we
# expected to receive from the client
tls_finished_msg = transport._tlsConnection.get_peer_finished()
else:
# for clients XOR resumed sessions, the channel ID is based on the TLS Finished message we sent
# to the router (=server)
tls_finished_msg = transport._tlsConnection.get_finished()
if tls_finished_msg is None:
# this can occur if we made a successful connection (in a
# TCP sense) but something failed with the TLS handshake
# (e.g. invalid certificate)
return b'\x00' * 32
else:
m = hashlib.sha256()
m.update(tls_finished_msg)
return m.digest()
else:
assert False, 'should not arrive here'