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#!/usr/bin/env python

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# -*- coding: utf-8 -*-

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# This file is part of Beremiz, a Integrated Development Environment for

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# programming IEC 61131-3 automates supporting plcopen standard and CanFestival.

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#

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# Copyright (C) 2019: Edouard TISSERANT

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#

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# See COPYING file for copyrights details.

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#

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# This program is free software; you can redistribute it and/or

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# modify it under the terms of the GNU General Public License

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# as published by the Free Software Foundation; either version 2

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# of the License, or (at your option) any later version.

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#

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# This program is distributed in the hope that it will be useful,

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# but WITHOUT ANY WARRANTY; without even the implied warranty of

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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

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# GNU General Public License for more details.

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#

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# You should have received a copy of the GNU General Public License

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# along with this program; if not, write to the Free Software

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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

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"""

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The TLS-PSK adapter that handles SSL connections instead of regular sockets,

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but using Pre Shared Keys instead of Certificates

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"""

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from __future__ import absolute_import

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from __future__ import print_function

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import socket

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import re

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import ssl

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import Pyro

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from Pyro.core import PyroURI

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from Pyro.protocol import _connect_socket, TCPConnection, PYROAdapter

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from Pyro.errors import ConnectionDeniedError, ProtocolError

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from Pyro.util import Log

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try:

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    import sslpsk

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except ImportError as e:

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    print(str(e))

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    sslpsk = None

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class PYROPSKAdapter(PYROAdapter):

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    """

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    This is essentialy the same as in Pyro/protocol.py

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    only raw_sock wrapping into sock through sslpsk.wrap_socket was added

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    Pyro unfortunately doesn't allow cleaner customization

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    """

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    def bindToURI(self, URI):

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        with self.lock:   # only 1 thread at a time can bind the URI

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            try:

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                self.URI = URI

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                # This are the statements that differ from Pyro/protocol.py

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                raw_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

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                _connect_socket(raw_sock, URI.address, URI.port, self.timeout)

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                sock = sslpsk.wrap_socket(

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                    raw_sock, psk=Pyro.config.PYROPSK, server_side=False,

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                    ciphers="PSK-AES256-CBC-SHA",  # available in openssl 1.0.2

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                    ssl_version=ssl.PROTOCOL_TLSv1)

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                # all the rest is the same as in Pyro/protocol.py

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                conn = TCPConnection(sock, sock.getpeername())

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                # receive the authentication challenge string, and use that to build the actual identification string.

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                try:

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                    authChallenge = self.recvAuthChallenge(conn)

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                except ProtocolError as x:

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                    # check if we were denied

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                    if hasattr(x, "partialMsg") and x.partialMsg[:len(self.denyMSG)] == self.denyMSG:

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                        raise ConnectionDeniedError(Pyro.constants.deniedReasons[int(x.partialMsg[-1])])

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                    else:

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                        raise

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                # reply with our ident token, generated from the ident passphrase and the challenge

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                msg = self._sendConnect(sock, self.newConnValidator.createAuthToken(self.ident, authChallenge, conn.addr, self.URI, None))

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                if msg == self.acceptMSG:

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                    self.conn = conn

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                    self.conn.connected = 1

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                    Log.msg('PYROAdapter', 'connected to', str(URI))

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                    if URI.protocol == 'PYROLOCPSK':

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                        self.resolvePYROLOC_URI("PYROPSK")  # updates self.URI

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                elif msg[:len(self.denyMSG)] == self.denyMSG:

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                    try:

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                        raise ConnectionDeniedError(Pyro.constants.deniedReasons[int(msg[-1])])

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                    except (KeyError, ValueError):

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                        raise ConnectionDeniedError('invalid response')

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            except socket.error:

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                Log.msg('PYROAdapter', 'connection failed to URI', str(URI))

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                raise ProtocolError('connection failed')

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_getProtocolAdapter = Pyro.protocol.getProtocolAdapter

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def getProtocolAdapter(protocol):

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    if protocol in ('PYROPSK', 'PYROLOCPSK'):

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        return PYROPSKAdapter()

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    return _getProtocolAdapter(protocol)

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_processStringURI = Pyro.core.processStringURI

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def processStringURI(URI):

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    x = re.match(r'(?P<protocol>PYROLOCPSK)://(?P<hostname>[^\s:]+):?(?P<port>\d+)?/(?P<name>\S*)', URI)

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    if x:

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        protocol = x.group('protocol')

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        hostname = x.group('hostname')

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        port = x.group('port')

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        if port:

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            port = int(port)

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        else:

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            port = 0

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        name = x.group('name')

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        return PyroURI(hostname, name, port, protocol)

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    return _processStringURI(URI)

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def setupPSKAdapter():

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    """

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    Add PyroAdapter to the list of available in

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    Pyro adapters and handle new supported protocols

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    This function should be called after

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    reimport of Pyro module to enable PYROS:// again.

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    """

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    if sslpsk is not None:

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        Pyro.protocol.getProtocolAdapter = getProtocolAdapter

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        Pyro.core.processStringURI = processStringURI

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    else:

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        raise Exception("sslpsk python module unavailable")