244 lines
9.3 KiB
Python
244 lines
9.3 KiB
Python
"""
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SSL/TLS negotiation.
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"""
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import logging
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import os
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import socket
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import ssl
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import sys
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import network.asyncore_pollchoose as asyncore
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import paths
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from network.advanceddispatcher import AdvancedDispatcher
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from queues import receiveDataQueue
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logger = logging.getLogger('default')
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_DISCONNECTED_SSL = frozenset((ssl.SSL_ERROR_EOF,))
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# sslProtocolVersion
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if sys.version_info >= (2, 7, 13):
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# this means TLSv1 or higher
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# in the future change to
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# ssl.PROTOCOL_TLS1.2
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sslProtocolVersion = ssl.PROTOCOL_TLS # pylint: disable=no-member
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elif sys.version_info >= (2, 7, 9):
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# this means any SSL/TLS.
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# SSLv2 and 3 are excluded with an option after context is created
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sslProtocolVersion = ssl.PROTOCOL_SSLv23
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else:
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# this means TLSv1, there is no way to set "TLSv1 or higher" or
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# "TLSv1.2" in < 2.7.9
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sslProtocolVersion = ssl.PROTOCOL_TLSv1
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# ciphers
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if ssl.OPENSSL_VERSION_NUMBER >= 0x10100000 and not \
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ssl.OPENSSL_VERSION.startswith("LibreSSL"):
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sslProtocolCiphers = "AECDH-AES256-SHA@SECLEVEL=0"
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else:
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sslProtocolCiphers = "AECDH-AES256-SHA"
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class TLSDispatcher(AdvancedDispatcher):
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"""TLS functionality for classes derived from AdvancedDispatcher"""
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# pylint: disable=too-many-instance-attributes, too-many-arguments
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# pylint: disable=super-init-not-called
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def __init__(self, _=None, sock=None, certfile=None, keyfile=None,
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server_side=False, ciphers=sslProtocolCiphers):
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self.want_read = self.want_write = True
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if certfile is None:
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self.certfile = os.path.join(
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paths.codePath(), 'sslkeys', 'cert.pem')
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else:
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self.certfile = certfile
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if keyfile is None:
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self.keyfile = os.path.join(
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paths.codePath(), 'sslkeys', 'key.pem')
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else:
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self.keyfile = keyfile
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self.server_side = server_side
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self.ciphers = ciphers
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self.tlsStarted = False
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self.tlsDone = False
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self.tlsVersion = "N/A"
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self.isSSL = False
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def state_tls_init(self):
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"""Prepare sockets for TLS handshake"""
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# pylint: disable=attribute-defined-outside-init
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self.isSSL = True
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self.tlsStarted = True
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# Once the connection has been established,
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# it's safe to wrap the socket.
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if sys.version_info >= (2, 7, 9):
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context = ssl.create_default_context(
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purpose=ssl.Purpose.SERVER_AUTH
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if self.server_side else ssl.Purpose.CLIENT_AUTH)
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context.set_ciphers(self.ciphers)
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context.set_ecdh_curve("secp256k1")
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context.check_hostname = False
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context.verify_mode = ssl.CERT_NONE
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# also exclude TLSv1 and TLSv1.1 in the future
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context.options = ssl.OP_ALL | ssl.OP_NO_SSLv2 |\
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ssl.OP_NO_SSLv3 | ssl.OP_SINGLE_ECDH_USE |\
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ssl.OP_CIPHER_SERVER_PREFERENCE
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self.sslSocket = context.wrap_socket(
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self.socket, server_side=self.server_side,
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do_handshake_on_connect=False)
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else:
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self.sslSocket = ssl.wrap_socket(
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self.socket, server_side=self.server_side,
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ssl_version=sslProtocolVersion,
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certfile=self.certfile, keyfile=self.keyfile,
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ciphers=self.ciphers, do_handshake_on_connect=False)
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self.sslSocket.setblocking(0)
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self.want_read = self.want_write = True
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self.set_state("tls_handshake")
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return False
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# if hasattr(self.socket, "context"):
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# self.socket.context.set_ecdh_curve("secp256k1")
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@staticmethod
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def state_tls_handshake():
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"""
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Do nothing while TLS handshake is pending, as during this phase
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we need to react to callbacks instead
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"""
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return False
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def writable(self):
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"""Handle writable checks for TLS-enabled sockets"""
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try:
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if self.tlsStarted and not self.tlsDone and not self.write_buf:
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return self.want_write
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return AdvancedDispatcher.writable(self)
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except AttributeError:
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return AdvancedDispatcher.writable(self)
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def readable(self):
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"""Handle readable check for TLS-enabled sockets"""
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try:
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# during TLS handshake, and after flushing write buffer,
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# return status of last handshake attempt
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if self.tlsStarted and not self.tlsDone and not self.write_buf:
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# print "tls readable, %r" % (self.want_read)
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return self.want_read
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# prior to TLS handshake,
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# receiveDataThread should emulate synchronous behaviour
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elif not self.fullyEstablished and (
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self.expectBytes == 0 or not self.write_buf_empty()):
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return False
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return AdvancedDispatcher.readable(self)
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except AttributeError:
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return AdvancedDispatcher.readable(self)
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def handle_read(self): # pylint: disable=inconsistent-return-statements
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"""
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Handle reads for sockets during TLS handshake. Requires special
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treatment as during the handshake, buffers must remain empty
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and normal reads must be ignored.
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"""
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try:
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# wait for write buffer flush
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if self.tlsStarted and not self.tlsDone and not self.write_buf:
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# logger.debug(
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# "%s:%i TLS handshaking (read)", self.destination.host,
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# self.destination.port)
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self.tls_handshake()
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else:
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# logger.debug(
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# "%s:%i Not TLS handshaking (read)", self.destination.host,
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# self.destination.port)
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return AdvancedDispatcher.handle_read(self)
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except AttributeError:
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return AdvancedDispatcher.handle_read(self)
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except ssl.SSLError as err:
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if err.errno == ssl.SSL_ERROR_WANT_READ:
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return
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elif err.errno in _DISCONNECTED_SSL:
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self.handle_close()
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return
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logger.info("SSL Error: %s", str(err))
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self.handle_close()
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return
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def handle_write(self): # pylint: disable=inconsistent-return-statements
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"""
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Handle writes for sockets during TLS handshake. Requires special
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treatment as during the handshake, buffers must remain empty
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and normal writes must be ignored.
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"""
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try:
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# wait for write buffer flush
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if self.tlsStarted and not self.tlsDone and not self.write_buf:
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# logger.debug(
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# "%s:%i TLS handshaking (write)", self.destination.host,
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# self.destination.port)
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self.tls_handshake()
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else:
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# logger.debug(
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# "%s:%i Not TLS handshaking (write)", self.destination.host,
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# self.destination.port)
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return AdvancedDispatcher.handle_write(self)
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except AttributeError:
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return AdvancedDispatcher.handle_write(self)
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except ssl.SSLError as err:
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if err.errno == ssl.SSL_ERROR_WANT_WRITE:
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return 0
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elif err.errno in _DISCONNECTED_SSL:
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self.handle_close()
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return 0
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logger.info("SSL Error: %s", str(err))
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self.handle_close()
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return
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def tls_handshake(self):
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"""Perform TLS handshake and handle its stages"""
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# wait for flush
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if self.write_buf:
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return False
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# Perform the handshake.
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try:
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# print "handshaking (internal)"
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self.sslSocket.do_handshake()
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except ssl.SSLError as err:
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# print "%s:%i: handshake fail" % (
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# self.destination.host, self.destination.port)
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self.want_read = self.want_write = False
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if err.args[0] == ssl.SSL_ERROR_WANT_READ:
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# print "want read"
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self.want_read = True
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if err.args[0] == ssl.SSL_ERROR_WANT_WRITE:
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# print "want write"
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self.want_write = True
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if not (self.want_write or self.want_read):
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raise
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except socket.error as err:
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# pylint: disable=protected-access
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if err.errno in asyncore._DISCONNECTED:
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self.handle_close()
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else:
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raise
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else:
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if sys.version_info >= (2, 7, 9):
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self.tlsVersion = self.sslSocket.version()
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logger.debug(
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'%s:%i: TLS handshake success, TLS protocol version: %s',
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self.destination.host, self.destination.port,
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self.tlsVersion)
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else:
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self.tlsVersion = "TLSv1"
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logger.debug(
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'%s:%i: TLS handshake success',
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self.destination.host, self.destination.port)
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# The handshake has completed, so remove this channel and...
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self.del_channel()
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self.set_socket(self.sslSocket)
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self.tlsDone = True
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self.bm_proto_reset()
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self.set_state("connection_fully_established")
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receiveDataQueue.put(self.destination)
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return False
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