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643 lines
20 KiB
643 lines
20 KiB
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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#
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# Copyright (C) 2013, 2014 James E. Carpenter
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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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#
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import socket
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import sys
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import os
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import select
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import fcntl
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import struct
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import termios
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import tty
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import time
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import argparse
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import traceback
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import logging
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log = logging.getLogger(__name__)
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# Escape characters
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ESC_CHAR = '^^' # can be overriden from command line
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ESC_QUIT = 'q'
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# IOU seems to only send *1* byte at a time. If
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# they ever fix that we'll be ready for it.
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BUFFER_SIZE = 1024
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# How long to wait before retrying a connection (seconds)
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RETRY_DELAY = 3
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# How often to test an idle connection (seconds)
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POLL_TIMEOUT = 3
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EXIT_SUCCESS = 0
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EXIT_FAILURE = 1
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EXIT_ABORT = 2
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# Mostly from:
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# 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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class FileLock:
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# struct flock { /* from fcntl(2) */
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# ...
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# short l_type; /* Type of lock: F_RDLCK,
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# F_WRLCK, F_UNLCK */
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# short l_whence; /* How to interpret l_start:
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# SEEK_SET, SEEK_CUR, SEEK_END */
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# off_t l_start; /* Starting offset for lock */
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# off_t l_len; /* Number of bytes to lock */
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# pid_t l_pid; /* PID of process blocking our lock
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# (F_GETLK only) */
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# ...
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# };
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_flock = struct.Struct('hhqql')
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def __init__(self, fname=None):
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self.fd = None
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self.fname = fname
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def get_lock(self):
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flk = self._flock.pack(fcntl.F_WRLCK, os.SEEK_SET,
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0, 0, os.getpid())
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flk = self._flock.unpack(
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fcntl.fcntl(self.fd, fcntl.F_GETLK, flk))
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# If it's not locked (or is locked by us) then return None,
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# otherwise return the PID of the owner.
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if flk[0] == fcntl.F_UNLCK:
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return None
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return flk[4]
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def lock(self):
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try:
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self.fd = open('{}.lck'.format(self.fname), 'a')
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except Exception as e:
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raise LockError("Couldn't get lock on {}: {}"
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.format(self.fname, e))
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flk = self._flock.pack(fcntl.F_WRLCK, os.SEEK_SET, 0, 0, 0)
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try:
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fcntl.fcntl(self.fd, fcntl.F_SETLK, flk)
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except BlockingIOError:
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raise LockError("Already connected. PID {} has lock on {}"
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.format(self.get_lock(), self.fname))
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# If we got here then we must have the lock. Store the PID.
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self.fd.truncate(0)
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self.fd.write('{}\n'.format(os.getpid()))
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self.fd.flush()
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def unlock(self):
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if self.fd:
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# Deleting first prevents a race condition
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try:
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os.unlink(self.fd.name)
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except FileNotFoundError as e:
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log.debug("{}".format(e))
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self.fd.close()
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def __enter__(self):
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self.lock()
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def __exit__(self, exc_type, exc_val, exc_tb):
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self.unlock()
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return False
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class Console:
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def fileno(self):
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raise NotImplementedError("Only routers have fileno()")
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class Router:
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pass
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class TTY(Console):
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def read(self, fileno, bufsize):
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return self.fd.read(bufsize)
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def write(self, buf):
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return self.fd.write(buf)
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def register(self, epoll):
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self.epoll = epoll
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epoll.register(self.fd, select.EPOLLIN | select.EPOLLET)
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def __enter__(self):
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try:
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self.fd = open('/dev/tty', 'r+b', buffering=0)
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except OSError as e:
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raise TTYError("Couldn't open controlling TTY: {}".format(e))
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# Save original flags
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self.termios = termios.tcgetattr(self.fd)
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self.fcntl = fcntl.fcntl(self.fd, fcntl.F_GETFL)
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# Update flags
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tty.setraw(self.fd, termios.TCSANOW)
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fcntl.fcntl(self.fd, fcntl.F_SETFL, self.fcntl | os.O_NONBLOCK)
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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# Restore flags to original settings
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termios.tcsetattr(self.fd, termios.TCSANOW, self.termios)
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fcntl.fcntl(self.fd, fcntl.F_SETFL, self.fcntl)
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self.fd.close()
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return False
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class TelnetServer(Console):
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def __init__(self, addr, port, stop_event):
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self.addr = addr
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self.port = port
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self.fd_dict = {}
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self.stop_event = stop_event
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def read(self, fileno, bufsize):
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# Someone wants to connect?
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if fileno == self.sock_fd.fileno():
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self._accept()
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return None
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self._cur_fileno = fileno
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# Read a maximum of _bufsize_ bytes without blocking. When it
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# would want to block it means there's no more data. An empty
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# buffer normally means that we've been disconnected.
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try:
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buf = self._read_cur(bufsize, socket.MSG_DONTWAIT)
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except BlockingIOError:
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return None
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if not buf:
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self._disconnect(fileno)
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# Process and remove any telnet commands from the buffer
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if IAC in buf:
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buf = self._IAC_parser(buf)
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return buf
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def write(self, buf):
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for fd in self.fd_dict.values():
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fd.send(buf)
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def register(self, epoll):
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self.epoll = epoll
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epoll.register(self.sock_fd, select.EPOLLIN)
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def _read_block(self, bufsize):
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buf = self._read_cur(bufsize, socket.MSG_WAITALL)
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# If we don't get everything we were looking for then the
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# client probably disconnected.
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if len(buf) < bufsize:
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self._disconnect(self._cur_fileno)
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return buf
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def _read_cur(self, bufsize, flags):
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return self.fd_dict[self._cur_fileno].recv(bufsize, flags)
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def _write_cur(self, buf):
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return self.fd_dict[self._cur_fileno].send(buf)
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def _IAC_parser(self, buf):
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skip_to = 0
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while not self.stop_event.is_set():
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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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buf.extend(self._read_block(1))
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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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self._write_cur(
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b'\r\nYour Are-You-There received. I am here.\r\n'
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)
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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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# interputed 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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buf.extend(self._read_block(1))
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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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self._write_cur(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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# Return the new copy of the buffer, minus telnet commands
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return buf
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def _accept(self):
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fd, addr = self.sock_fd.accept()
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self.fd_dict[fd.fileno()] = fd
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self.epoll.register(fd, select.EPOLLIN | select.EPOLLET)
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log.info("Telnet connection from {}:{}".format(addr[0], addr[1]))
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# This is a one-way negotiation. This is very basic so there
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# shouldn't be any problems with any decent client.
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fd.send(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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if args.telnet_limit and len(self.fd_dict) > args.telnet_limit:
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fd.send(b'\r\nToo many connections\r\n')
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self._disconnect(fd.fileno())
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log.warn("Client disconnected because of too many connections. "
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"(limit currently {})".format(args.telnet_limit))
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def _disconnect(self, fileno):
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fd = self.fd_dict.pop(fileno)
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log.info("Telnet client disconnected")
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try:
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fd.shutdown(socket.SHUT_RDWR)
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except OSError as e:
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log.warn("shutdown: {}".format(e))
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fd.close()
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def __enter__(self):
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# Open a socket and start listening
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sock_fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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sock_fd.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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try:
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sock_fd.bind((self.addr, self.port))
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except OSError:
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raise TelnetServerError("Cannot bind to {}:{}"
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.format(self.addr, self.port))
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sock_fd.listen(socket.SOMAXCONN)
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self.sock_fd = sock_fd
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log.info("Telnet server ready for connections on {}:{}".format(self.addr, self.port))
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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for fileno in list(self.fd_dict.keys()):
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self._disconnect(fileno)
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self.sock_fd.close()
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return False
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class IOU(Router):
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def __init__(self, ttyC, ttyS, stop_event):
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self.ttyC = ttyC
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self.ttyS = ttyS
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self.stop_event = stop_event
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def read(self, bufsize):
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try:
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buf = self.fd.recv(bufsize)
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except BlockingIOError:
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return None
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return buf
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def write(self, buf):
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self.fd.send(buf)
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def _open(self):
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self.fd = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
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self.fd.setblocking(False)
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def _bind(self):
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try:
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os.unlink(self.ttyC)
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except FileNotFoundError:
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pass
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except Exception as e:
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raise NetioError("Couldn't unlink socket {}: {}".format(self.ttyC, e))
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try:
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self.fd.bind(self.ttyC)
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except Exception as e:
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raise NetioError("Couldn't create socket {}: {}".format(self.ttyC, e))
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def _connect(self):
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# Keep trying until we connect or die trying
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while not self.stop_event.is_set():
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try:
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self.fd.connect(self.ttyS)
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except FileNotFoundError:
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log.debug("Waiting to connect to {}".format(self.ttyS))
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time.sleep(RETRY_DELAY)
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except Exception as e:
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raise NetioError("Couldn't connect to socket {}: {}".format(self.ttyS, e))
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else:
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break
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def register(self, epoll):
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self.epoll = epoll
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epoll.register(self.fd, select.EPOLLIN | select.EPOLLET)
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def fileno(self):
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return self.fd.fileno()
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def __enter__(self):
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self._open()
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self._bind()
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self._connect()
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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os.unlink(self.ttyC)
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self.fd.close()
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return False
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class IOUConError(Exception):
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pass
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class LockError(IOUConError):
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pass
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class NetioError(IOUConError):
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pass
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class TTYError(IOUConError):
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pass
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class TelnetServerError(IOUConError):
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pass
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class ConfigError(IOUConError):
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pass
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def mkdir_netio(netio_dir):
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try:
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os.mkdir(netio_dir)
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except FileExistsError:
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pass
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except Exception as e:
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raise NetioError("Couldn't create directory {}: {}".format(netio_dir, e))
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def send_recv_loop(console, router, esc_char, stop_event):
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epoll = select.epoll()
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router.register(epoll)
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console.register(epoll)
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router_fileno = router.fileno()
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esc_quit = bytes(ESC_QUIT.upper(), 'ascii')
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esc_state = False
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while not stop_event.is_set():
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event_list = epoll.poll(timeout=POLL_TIMEOUT)
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# When/if the poll times out we send an empty datagram. If IOU
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# has gone away then this will toss a ConnectionRefusedError
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# exception.
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if not event_list:
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router.write(b'')
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continue
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for fileno, event in event_list:
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buf = bytearray()
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# IOU --> tty(s)
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if fileno == router_fileno:
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while not stop_event.is_set():
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data = router.read(BUFFER_SIZE)
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if not data:
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break
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buf.extend(data)
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console.write(buf)
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# tty --> IOU
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else:
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while not stop_event.is_set():
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data = console.read(fileno, BUFFER_SIZE)
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if not data:
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break
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buf.extend(data)
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# If we just received the escape character then
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# enter the escape state.
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#
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# If we are in the escape state then check for a
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# quit command. Or if it's the escape character then
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# send the escape character. Else, send the escape
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# character we ate earlier and whatever character we
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# just got. Exit escape state.
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#
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# If we're not in the escape state and this isn't an
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# escape character then just send it to IOU.
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if esc_state:
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if buf.upper() == esc_quit:
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sys.exit(EXIT_SUCCESS)
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elif buf == esc_char:
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router.write(esc_char)
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else:
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router.write(esc_char)
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router.write(buf)
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esc_state = False
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elif buf == esc_char:
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esc_state = True
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else:
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router.write(buf)
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def get_args():
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parser = argparse.ArgumentParser(
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description='Connect to an IOU console port.')
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parser.add_argument('-d', '--debug', action='store_true',
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help='display some debugging information')
|
|
parser.add_argument('-e', '--escape',
|
|
help='set escape character (default: %(default)s)',
|
|
default=ESC_CHAR, metavar='CHAR')
|
|
parser.add_argument('-t', '--telnet-server',
|
|
help='start telnet server listening on ADDR:PORT',
|
|
metavar='ADDR:PORT', default=False)
|
|
parser.add_argument('-l', '--telnet-limit',
|
|
help='maximum number of simultaneous '
|
|
'telnet connections (default: %(default)s)',
|
|
metavar='LIMIT', type=int, default=1)
|
|
parser.add_argument('appl_id', help='IOU instance identifier')
|
|
return parser.parse_args()
|
|
|
|
|
|
def get_escape_character(escape):
|
|
|
|
# Figure out the escape character to use.
|
|
# Can be any ASCII character or a spelled out control
|
|
# character, like "^e". The string "none" disables it.
|
|
if escape.lower() == 'none':
|
|
esc_char = b''
|
|
elif len(escape) == 2 and escape[0] == '^':
|
|
c = ord(escape[1].upper()) - 0x40
|
|
if not 0 <= c <= 0x1f: # control code range
|
|
raise ConfigError("Invalid control code")
|
|
esc_char = bytes([c])
|
|
elif len(escape) == 1:
|
|
try:
|
|
esc_char = bytes(escape, 'ascii')
|
|
except ValueError as e:
|
|
raise ConfigError("Invalid escape character") from e
|
|
else:
|
|
raise ConfigError("Invalid length for escape character")
|
|
|
|
return esc_char
|
|
|
|
|
|
def start_ioucon(cmdline_args, stop_event):
|
|
|
|
global args
|
|
args = cmdline_args
|
|
|
|
if args.debug:
|
|
logging.basicConfig(level=logging.DEBUG)
|
|
else:
|
|
# default logging level
|
|
logging.basicConfig(level=logging.INFO)
|
|
|
|
# Create paths for the Unix domain sockets
|
|
netio = '/tmp/netio{}'.format(os.getuid())
|
|
ttyC = '{}/ttyC{}'.format(netio, args.appl_id)
|
|
ttyS = '{}/ttyS{}'.format(netio, args.appl_id)
|
|
|
|
try:
|
|
mkdir_netio(netio)
|
|
with FileLock(ttyC):
|
|
esc_char = get_escape_character(args.escape)
|
|
|
|
if args.telnet_server:
|
|
addr, _, port = args.telnet_server.partition(':')
|
|
nport = 0
|
|
try:
|
|
nport = int(port)
|
|
except ValueError:
|
|
pass
|
|
if addr == '' or nport == 0:
|
|
raise ConfigError('format for --telnet-server must be '
|
|
'ADDR:PORT (like 127.0.0.1:20000)')
|
|
|
|
while not stop_event.is_set():
|
|
try:
|
|
if args.telnet_server:
|
|
with TelnetServer(addr, nport, stop_event) as console:
|
|
with IOU(ttyC, ttyS, stop_event) as router:
|
|
send_recv_loop(console, router, b'', stop_event)
|
|
else:
|
|
with IOU(ttyC, ttyS, stop_event) as router, TTY() as console:
|
|
send_recv_loop(console, router, esc_char, stop_event)
|
|
except ConnectionRefusedError:
|
|
pass
|
|
except KeyboardInterrupt:
|
|
sys.exit(EXIT_ABORT)
|
|
finally:
|
|
# Put us at the beginning of a line
|
|
if not args.telnet_server:
|
|
print()
|
|
|
|
except IOUConError as e:
|
|
if args.debug:
|
|
traceback.print_exc(file=sys.stderr)
|
|
else:
|
|
log.error("ioucon: {}".format(e))
|
|
sys.exit(EXIT_FAILURE)
|
|
|
|
log.info("exiting...")
|
|
|
|
|
|
def main():
|
|
|
|
import threading
|
|
stop_event = threading.Event()
|
|
args = get_args()
|
|
start_ioucon(args, stop_event)
|
|
|
|
if __name__ == '__main__':
|
|
main()
|