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Diffstat (limited to 'examples/rfc2217_server.py')
| -rwxr-xr-x | examples/rfc2217_server.py | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/examples/rfc2217_server.py b/examples/rfc2217_server.py new file mode 100755 index 0000000..42660dd --- /dev/null +++ b/examples/rfc2217_server.py @@ -0,0 +1,188 @@ +#!/usr/bin/env python +# +# redirect data from a TCP/IP connection to a serial port and vice versa +# using RFC 2217 +# +# (C) 2009-2015 Chris Liechti <cliechti@gmx.net> +# +# SPDX-License-Identifier: BSD-3-Clause + +import logging +import socket +import sys +import time +import threading +import serial +import serial.rfc2217 + + +class Redirector(object): + def __init__(self, serial_instance, socket, debug=False): + self.serial = serial_instance + self.socket = socket + self._write_lock = threading.Lock() + self.rfc2217 = serial.rfc2217.PortManager( + self.serial, + self, + logger=logging.getLogger('rfc2217.server') if debug else None) + self.log = logging.getLogger('redirector') + + def statusline_poller(self): + self.log.debug('status line poll thread started') + while self.alive: + time.sleep(1) + self.rfc2217.check_modem_lines() + self.log.debug('status line poll thread terminated') + + def shortcircuit(self): + """connect the serial port to the TCP port by copying everything + from one side to the other""" + self.alive = True + self.thread_read = threading.Thread(target=self.reader) + self.thread_read.daemon = True + self.thread_read.name = 'serial->socket' + self.thread_read.start() + self.thread_poll = threading.Thread(target=self.statusline_poller) + self.thread_poll.daemon = True + self.thread_poll.name = 'status line poll' + self.thread_poll.start() + self.writer() + + def reader(self): + """loop forever and copy serial->socket""" + self.log.debug('reader thread started') + while self.alive: + try: + data = self.serial.read(self.serial.in_waiting or 1) + if data: + # escape outgoing data when needed (Telnet IAC (0xff) character) + self.write(b''.join(self.rfc2217.escape(data))) + except socket.error as msg: + self.log.error('{}'.format(msg)) + # probably got disconnected + break + self.alive = False + self.log.debug('reader thread terminated') + + def write(self, data): + """thread safe socket write with no data escaping. used to send telnet stuff""" + with self._write_lock: + self.socket.sendall(data) + + def writer(self): + """loop forever and copy socket->serial""" + while self.alive: + try: + data = self.socket.recv(1024) + if not data: + break + self.serial.write(b''.join(self.rfc2217.filter(data))) + except socket.error as msg: + self.log.error('{}'.format(msg)) + # probably got disconnected + break + self.stop() + + def stop(self): + """Stop copying""" + self.log.debug('stopping') + if self.alive: + self.alive = False + self.thread_read.join() + self.thread_poll.join() + + +if __name__ == '__main__': + import argparse + + parser = argparse.ArgumentParser( + description="RFC 2217 Serial to Network (TCP/IP) redirector.", + epilog="""\ +NOTE: no security measures are implemented. Anyone can remotely connect +to this service over the network. + +Only one connection at once is supported. When the connection is terminated +it waits for the next connect. +""") + + parser.add_argument('SERIALPORT') + + parser.add_argument( + '-p', '--localport', + type=int, + help='local TCP port, default: %(default)s', + metavar='TCPPORT', + default=2217) + + parser.add_argument( + '-v', '--verbose', + dest='verbosity', + action='count', + help='print more diagnostic messages (option can be given multiple times)', + default=0) + + args = parser.parse_args() + + if args.verbosity > 3: + args.verbosity = 3 + level = (logging.WARNING, + logging.INFO, + logging.DEBUG, + logging.NOTSET)[args.verbosity] + logging.basicConfig(level=logging.INFO) + #~ logging.getLogger('root').setLevel(logging.INFO) + logging.getLogger('rfc2217').setLevel(level) + + # connect to serial port + ser = serial.serial_for_url(args.SERIALPORT, do_not_open=True) + ser.timeout = 3 # required so that the reader thread can exit + # reset control line as no _remote_ "terminal" has been connected yet + ser.dtr = False + ser.rts = False + + logging.info("RFC 2217 TCP/IP to Serial redirector - type Ctrl-C / BREAK to quit") + + try: + ser.open() + except serial.SerialException as e: + logging.error("Could not open serial port {}: {}".format(ser.name, e)) + sys.exit(1) + + logging.info("Serving serial port: {}".format(ser.name)) + settings = ser.get_settings() + + srv = socket.socket(socket.AF_INET, socket.SOCK_STREAM) + srv.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) + srv.bind(('', args.localport)) + srv.listen(1) + logging.info("TCP/IP port: {}".format(args.localport)) + while True: + try: + client_socket, addr = srv.accept() + logging.info('Connected by {}:{}'.format(addr[0], addr[1])) + client_socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1) + ser.rts = True + ser.dtr = True + # enter network <-> serial loop + r = Redirector( + ser, + client_socket, + args.verbosity > 0) + try: + r.shortcircuit() + finally: + logging.info('Disconnected') + r.stop() + client_socket.close() + ser.dtr = False + ser.rts = False + # Restore port settings (may have been changed by RFC 2217 + # capable client) + ser.apply_settings(settings) + except KeyboardInterrupt: + sys.stdout.write('\n') + break + except socket.error as msg: + logging.error(str(msg)) + + logging.info('--- exit ---') |