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https://github.com/GNS3/gns3-server.git
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Docker cleanup and improvements
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Julien Duponchelle
227
gns3server/utils/asyncio/telnet_server.py
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227
gns3server/utils/asyncio/telnet_server.py
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# -*- coding: utf-8 -*-
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#
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# Copyright (C) 2014 GNS3 Technologies Inc.
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (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, see <http://www.gnu.org/licenses/>.
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import asyncio
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import asyncio.subprocess
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import logging
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log = logging.getLogger(__name__)
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# Mostly from https://code.google.com/p/miniboa/source/browse/trunk/miniboa/telnet.py
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# Telnet Commands
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SE = 240 # End of sub-negotiation parameters
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NOP = 241 # No operation
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DATMK = 242 # Data stream portion of a sync.
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BREAK = 243 # NVT Character BRK
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IP = 244 # Interrupt Process
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AO = 245 # Abort Output
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AYT = 246 # Are you there
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EC = 247 # Erase Character
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EL = 248 # Erase Line
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GA = 249 # The Go Ahead Signal
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SB = 250 # Sub-option to follow
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WILL = 251 # Will; request or confirm option begin
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WONT = 252 # Wont; deny option request
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DO = 253 # Do = Request or confirm remote option
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DONT = 254 # Don't = Demand or confirm option halt
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IAC = 255 # Interpret as Command
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SEND = 1 # Sub-process negotiation SEND command
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IS = 0 # Sub-process negotiation IS command
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# Telnet Options
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BINARY = 0 # Transmit Binary
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ECHO = 1 # Echo characters back to sender
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RECON = 2 # Reconnection
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SGA = 3 # Suppress Go-Ahead
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TMARK = 6 # Timing Mark
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TTYPE = 24 # Terminal Type
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NAWS = 31 # Negotiate About Window Size
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LINEMO = 34 # Line Mode
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READ_SIZE = 1024
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class AsyncioTelnetServer:
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def __init__(self, reader=None, writer=None):
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self._reader = reader
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self._writer = writer
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self._clients = set()
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self._lock = asyncio.Lock()
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self._reader_process = None
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self._current_read = None
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@asyncio.coroutine
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def run(self, network_reader, network_writer):
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# Keep track of connected clients
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self._clients.add(network_writer)
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try:
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# Send initial telnet session opening
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network_writer.write(bytes([IAC, WILL, ECHO,
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IAC, WILL, SGA,
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IAC, WILL, BINARY,
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IAC, DO, BINARY]))
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yield from network_writer.drain()
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yield from self._process(network_reader, network_writer)
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except ConnectionResetError:
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with (yield from self._lock):
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if self._reader_process == network_reader:
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self._reader_process = None
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# Cancel current read from this reader
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self._current_read.cancel()
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self._clients.remove(network_writer)
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@asyncio.coroutine
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def _get_reader(self, network_reader):
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"""
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Get a reader or None if another reader is already reading.
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"""
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with (yield from self._lock):
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if self._reader_process is None:
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self._reader_process = network_reader
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if self._reader_process == network_reader:
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self._current_read = asyncio.async(self._reader.read(READ_SIZE))
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return self._current_read
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return None
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@asyncio.coroutine
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def _process(self, network_reader, network_writer):
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network_read = asyncio.async(network_reader.read(READ_SIZE))
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reader_read = yield from self._get_reader(network_reader)
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while True:
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if reader_read is None:
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reader_read = yield from self._get_reader(network_reader)
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if reader_read is None:
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done, pending = yield from asyncio.wait(
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[
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network_read,
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],
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timeout=1,
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return_when=asyncio.FIRST_COMPLETED)
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else:
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done, pending = yield from asyncio.wait(
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[
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network_read,
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reader_read
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],
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return_when=asyncio.FIRST_COMPLETED)
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for coro in done:
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data = coro.result()
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if coro == network_read:
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network_read = asyncio.async(network_reader.read(READ_SIZE))
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if IAC in data:
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data = yield from self._IAC_parser(data, network_reader, network_writer)
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if self._writer:
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self._writer.write(data)
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yield from self._writer.drain()
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elif coro == reader_read:
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reader_read = yield from self._get_reader(network_reader)
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# Replicate the output on all clients
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for writer in self._clients:
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writer.write(data)
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yield from writer.drain()
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def _IAC_parser(self, buf, network_reader, network_writer):
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"""
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Processes and removes any Telnet commands from the buffer.
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:param buf: buffer
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:returns: buffer minus Telnet commands
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"""
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skip_to = 0
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while True:
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# Locate an IAC to process
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iac_loc = buf.find(IAC, skip_to)
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if iac_loc < 0:
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break
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# Get the TELNET command
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iac_cmd = bytearray([IAC])
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try:
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iac_cmd.append(buf[iac_loc + 1])
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except IndexError:
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d = yield from network_reader.read(1)
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buf.extend(d)
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iac_cmd.append(buf[iac_loc + 1])
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# Is this just a 2-byte TELNET command?
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if iac_cmd[1] not in [WILL, WONT, DO, DONT]:
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if iac_cmd[1] == AYT:
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log.debug("Telnet server received Are-You-There (AYT)")
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network_writer.write(b'\r\nYour Are-You-There received. I am here.\r\n')
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elif iac_cmd[1] == IAC:
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# It's data, not an IAC
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iac_cmd.pop()
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# This prevents the 0xff from being
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# interrupted as yet another IAC
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skip_to = iac_loc + 1
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log.debug("Received IAC IAC")
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elif iac_cmd[1] == NOP:
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pass
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else:
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log.debug("Unhandled telnet command: "
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"{0:#x} {1:#x}".format(*iac_cmd))
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# This must be a 3-byte TELNET command
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else:
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try:
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iac_cmd.append(buf[iac_loc + 2])
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except IndexError:
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d = yield from network_reader.read(1)
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buf.extend(d)
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iac_cmd.append(buf[iac_loc + 2])
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# We do ECHO, SGA, and BINARY. Period.
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if iac_cmd[1] == DO and iac_cmd[2] not in [ECHO, SGA, BINARY]:
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network_writer.write(bytes([IAC, WONT, iac_cmd[2]]))
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log.debug("Telnet WON'T {:#x}".format(iac_cmd[2]))
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else:
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log.debug("Unhandled telnet command: "
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"{0:#x} {1:#x} {2:#x}".format(*iac_cmd))
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# Remove the entire TELNET command from the buffer
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buf = buf.replace(iac_cmd, b'', 1)
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yield from network_writer.drain()
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# Return the new copy of the buffer, minus telnet commands
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return buf
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if __name__ == '__main__':
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loop = asyncio.get_event_loop()
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process = loop.run_until_complete(asyncio.async(asyncio.subprocess.create_subprocess_exec("bash",
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stdout=asyncio.subprocess.PIPE,
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stderr=asyncio.subprocess.STDOUT,
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stdin=asyncio.subprocess.PIPE)))
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server = AsyncioTelnetServer(reader=process.stdout, writer=process.stdin)
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coro = asyncio.start_server(server.run, '127.0.0.1', 2222, loop=loop)
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s = loop.run_until_complete(coro)
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try:
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loop.run_forever()
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except KeyboardInterrupt:
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pass
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# Close the server
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s.close()
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loop.run_until_complete(s.wait_closed())
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loop.close()
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