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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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import socket

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import ssl

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try:

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    import sslpsk

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except ImportError as e:

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    sslpsk = None

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from erpc.transport import TCPTransport

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class SSLPSKClientTransport(TCPTransport):

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    def __init__(self, host, port, psk):

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        """ overrides TCPTransport's __init__ to wrap socket in SSl wrapper """

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        super(TCPTransport, self).__init__()

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        self._host = host

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        self._port = port

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        self._isServer = isServer

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        self._sock = None

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        if sslpsk is None:

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             raise ImportError("sslpsk module is not available")

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

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        raw_sock.setsockopt(socket.SOL_TCP, socket.TCP_NODELAY, 1)

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        raw_sock.connect((self._host, self._port))

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        self._sock = sslpsk.wrap_socket(

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                raw_sock, psk=psk, 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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