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# Copyright (C) 2007-2008 AG Projects. See LICENSE for details.
#
"""GNUTLS Twisted interface"""
__all__ = ['X509Credentials', 'connectTLS', 'listenTLS']
import socket
from time import time
from errno import EWOULDBLOCK, EINTR
from twisted.python import failure
from twisted.internet import main, base, interfaces, address, tcp, error
from twisted.internet.protocol import BaseProtocol
from zope.interface import implements, implementsOnly, implementedBy
from gnutls.connection import ClientSession, ServerSession, ServerSessionFactory
from gnutls.connection import X509Credentials as _X509Credentials
from gnutls.constants import SHUT_RDWR, SHUT_WR
from gnutls.errors import *
class KeepRunning:
"""Return this class from a recurrent function to indicate that it should keep running"""
pass
class RecurrentCall(object):
"""Execute a function repeatedly at the given interval, until signaled to stop"""
def __init__(self, period, func, *args, **kwargs):
from twisted.internet import reactor
self.func = func
self.args = args
self.kwargs = kwargs
self.period = period
self.now = None
self.next = None
self.callid = reactor.callLater(period, self)
def __call__(self):
from twisted.internet import reactor
self.callid = None
if self.now is None:
self.now = time()
self.next = self.now + self.period
else:
self.now, self.next = self.next, self.next + self.period
result = self.func(*self.args, **self.kwargs)
if result is KeepRunning:
delay = max(self.next-time(), 0)
self.callid = reactor.callLater(delay, self)
def cancel(self):
if self.callid is not None:
try:
self.callid.cancel()
except ValueError:
pass
self.callid = None
class CertificateOK: pass
class X509Credentials(_X509Credentials):
"""A Twisted enhanced X509Credentials"""
verify_peer = False
verify_period = None
def verify_callback(self, peer_cert, preverify_status=None):
"""Verifies the peer certificate and raises an exception if it cannot be accepted"""
if isinstance(preverify_status, Exception):
raise preverify_status
self.check_certificate(peer_cert, cert_name='peer certificate')
class TLSMixin:
"""TLS specific functionality common to both clients and servers"""
def getPeerCertificate(self):
return self.socket.peer_certificate
def doRead(self):
try:
return tcp.Connection.doRead(self)
except (OperationWouldBlock, OperationInterrupted):
return
except GNUTLSError, e:
return e
def writeSomeData(self, data):
try:
return tcp.Connection.writeSomeData(self, data)
except OperationInterrupted:
return self.writeSomeData(data)
except OperationWouldBlock:
return 0
except GNUTLSError, e:
return e
def _sendCloseReason(self, reason):
try:
self.socket.send_alert(reason)
except OperationInterrupted:
self._sendCloseReason(reason)
def _sendCloseAlert(self, how=SHUT_RDWR):
try:
self.socket.bye(how)
except OperationInterrupted:
self._sendCloseAlert(how)
def closeTLSSession(self, reason):
try:
self._sendCloseReason(reason)
self._sendCloseAlert(SHUT_RDWR)
except Exception, e:
pass
def _postLoseConnection(self):
self.closeTLSSession(self._close_reason)
return self._close_reason
def endTLSWrite(self):
self.stopWriting()
try:
self._sendCloseAlert(SHUT_WR)
except OperationWouldBlock, e:
if self.socket.interrupted_while_writing:
self.startWriting()
return
except Exception, e:
return e
del self.doWrite
def _closeWriteConnection(self):
self.doWrite = self.endTLSWrite
result = self.endTLSWrite()
if isinstance(result, Exception):
return result
return tcp.Connection._closeWriteConnection(self)
class TLSClient(TLSMixin, tcp.Client):
"""Add TLS capabilities to a TCP client"""
implementsOnly(interfaces.ISSLTransport, *[i for i in implementedBy(tcp.Client) if i != interfaces.ITLSTransport])
def __init__(self, host, port, bindAddress, credentials, connector, reactor=None, server_name=None):
self.credentials = credentials
self.server_name = server_name
self.__watchdog = None
tcp.Client.__init__(self, host, port, bindAddress, connector, reactor)
def createInternetSocket(self):
sock = tcp.Client.createInternetSocket(self)
return ClientSession(sock, self.credentials, self.server_name)
def _recurrentVerify(self):
if not self.connected or self.disconnecting:
return
try:
self.credentials.verify_callback(self.socket.peer_certificate)
except Exception, e:
self.loseConnection(e)
return
else:
return KeepRunning
def _verifyPeer(self):
session = self.socket
credentials = self.credentials
if not credentials.verify_peer:
return
try:
session.verify_peer()
except Exception, e:
preverify_status = e
else:
preverify_status = CertificateOK
credentials.verify_callback(session.peer_certificate, preverify_status)
if credentials.verify_period > 0:
self.__watchdog = RecurrentCall(credentials.verify_period, self._recurrentVerify)
def doHandshake(self):
self.stopWriting()
try:
self.socket.handshake()
except (OperationWouldBlock, OperationInterrupted):
if self.socket.interrupted_while_writing:
self.startWriting()
return
except GNUTLSError, e:
del self.doRead
self.failIfNotConnected(err = e)
return
## reset any references to the old doRead
del self.doRead
self.stopReading()
try:
self._verifyPeer()
except GNUTLSError, e:
self.closeTLSSession(e)
self.failIfNotConnected(err = e)
return
except Exception, e:
self.closeTLSSession(e)
self.failIfNotConnected(err = error.getConnectError(str(e)))
return
## TLS handshake (including certificate verification) finished succesfully
tcp.Client._connectDone(self)
def startTLS(self):
self.doRead = self.doHandshake
self.startReading()
self.doHandshake()
def _connectDone(self):
self.startTLS()
def loseConnection(self, reason=failure.Failure(main.CONNECTION_DONE)):
reason = failure.Failure(reason) # accept python exceptions too
self._close_reason = reason.value
tcp.Client.loseConnection(self, reason)
def connectionLost(self, reason):
if self.__watchdog is not None:
self.__watchdog.cancel()
self.__watchdog = None
tcp.Client.connectionLost(self, reason)
class TLSConnector(base.BaseConnector):
def __init__(self, host, port, factory, credentials, timeout, bindAddress, reactor=None, server_name=None):
self.host = host
self.port = port
self.bindAddress = bindAddress
self.credentials = credentials
self.server_name = server_name
base.BaseConnector.__init__(self, factory, timeout, reactor)
def _makeTransport(self):
return TLSClient(self.host, self.port, self.bindAddress, self.credentials, self, self.reactor, self.server_name)
class TLSServer(TLSMixin, tcp.Server):
"""Add TLS capabilities to a TCP server"""
#implements(interfaces.ISSLTransport)
implementsOnly(interfaces.ISSLTransport, *[i for i in implementedBy(tcp.Server) if i != interfaces.ITLSTransport])
def __init__(self, sock, protocol, client, server, sessionno, *args, **kw):
self.__watchdog = None
self.credentials = server.credentials
tcp.Server.__init__(self, sock, protocol, client, server, sessionno, *args, **kw)
def _recurrentVerify(self):
if not self.connected or self.disconnecting:
return
try:
self.credentials.verify_callback(self.socket.peer_certificate)
except Exception, e:
self.loseConnection(e)
return
else:
return KeepRunning
def _verifyPeer(self):
session = self.socket
credentials = self.credentials
if not credentials.verify_peer:
return
try:
session.verify_peer()
except Exception, e:
preverify_status = e
else:
preverify_status = CertificateOK
credentials.verify_callback(session.peer_certificate, preverify_status)
if credentials.verify_period > 0:
self.__watchdog = RecurrentCall(credentials.verify_period, self._recurrentVerify)
def doHandshake(self):
self.stopWriting()
try:
self.socket.handshake()
except (OperationWouldBlock, OperationInterrupted):
if self.socket.interrupted_while_writing:
self.startWriting()
return
except GNUTLSError, e:
del self.doRead
return e
## reset any references to the old doRead
del self.doRead
self.stopReading()
self.startReading()
try:
self._verifyPeer()
except Exception, e:
self.loseConnection(e)
return
## TLS handshake (including certificate verification) finished succesfully
del self.protocol.makeConnection
self.protocol.makeConnection(self)
def startTLS(self):
self.doRead = self.doHandshake
self.startReading()
def loseConnection(self, reason=failure.Failure(main.CONNECTION_DONE)):
reason = failure.Failure(reason) # accept python exceptions too
self._close_reason = reason.value
tcp.Server.loseConnection(self, reason)
def connectionLost(self, reason):
if self.__watchdog is not None:
self.__watchdog.cancel()
self.__watchdog = None
tcp.Server.connectionLost(self, reason)
class TLSPort(tcp.Port):
"""Add TLS capabilities to a TCP port"""
transport = TLSServer
def __init__(self, port, factory, credentials, backlog=50, interface='', reactor=None):
tcp.Port.__init__(self, port, factory, backlog, interface, reactor)
self.credentials = credentials
def createInternetSocket(self):
sock = tcp.Port.createInternetSocket(self)
return ServerSessionFactory(sock, self.credentials, ServerSession)
def _preMakeConnection(self, transport):
transport.protocol.makeConnection = lambda *args: None
transport.protocol.transport = transport ## because we may call connectionLost without connectionMade
transport.startTLS()
return tcp.Port._preMakeConnection(self, transport)
def connectTLS(reactor, host, port, factory, credentials, timeout=30, bindAddress=None, server_name=None):
c = TLSConnector(host, port, factory, credentials, timeout, bindAddress, reactor, server_name)
c.connect()
return c
def listenTLS(reactor, port, factory, credentials, backlog=50, interface=''):
p = TLSPort(port, factory, credentials, backlog, interface, reactor)
p.startListening()
return p
## Add the connectTLS and listenTLS methods to the reactor
import new
from twisted.internet.posixbase import PosixReactorBase
method = new.instancemethod(connectTLS, None, PosixReactorBase)
setattr(PosixReactorBase, 'connectTLS', method)
method = new.instancemethod(listenTLS, None, PosixReactorBase)
setattr(PosixReactorBase, 'listenTLS', method)
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