#
# Copyright (C) 2010-2017 Samuel Abels
# The MIT License (MIT)
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
"""
Base class for all servers.
"""
from __future__ import print_function
from builtins import str
import select
import socket
from multiprocessing import Process, Pipe
[docs]class Server(Process):
"""
Base class of the Telnet and SSH servers. Servers are intended to be
used for tests and attempt to emulate a device using the behavior of
the associated :class:`Exscript.emulators.VirtualDevice`. Sample usage::
device = VirtualDevice('myhost')
daemon = Telnetd('localhost', 1234, device)
device.add_command('ls', 'ok', prompt = True)
device.add_command('exit', daemon.exit_command)
daemon.start() # Start the server.
daemon.exit() # Stop the server.
daemon.join() # Wait until it terminates.
"""
[docs] def __init__(self, host, port, device, encoding='utf8'):
"""
Constructor.
:type host: str
:param host: The address against which the daemon binds.
:type port: str
:param port: The TCP port on which to listen.
:type device: VirtualDevice
:param device: A virtual device instance.
:type encoding: str
:param encoding: The encoding of data between client and server.
"""
Process.__init__(self, target=self._run)
self.host = host
self.port = int(port)
self.timeout = .5
self.dbg = 0
self.running = False
self.buf = b''
self.socket = None
self.device = device
self.encoding = encoding
self.to_child, self.to_parent = Pipe()
self.processes = []
def _dbg(self, level, msg):
if self.dbg >= level:
print(self.host + ':' + str(self.port), '-', end=' ')
print(msg)
def _poll_child_process(self):
if not self.to_parent.poll():
return False
try:
msg = self.to_parent.recv()
except socket.error:
self.running = False
return False
if msg == 'shutdown':
self.running = False
return False
if not self.running:
return False
return True
def _handle_connection(self, conn):
raise NotImplementedError()
def _run(self):
self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.socket.bind((self.host, self.port))
self.socket.listen(1)
self.running = True
while self.running:
self._poll_child_process()
r, w, x = select.select([self.socket], [], [], self.timeout)
if not r:
continue
conn, addr = self.socket.accept()
proc = Process(target=self._handle_connection, args=(conn,))
self.processes.append(proc)
proc.start()
for proc in self.processes:
proc.join()
self.processes = []
self.socket.close()
[docs] def exit(self):
"""
Stop the daemon without waiting for the thread to terminate.
"""
self.to_child.send('shutdown')
[docs] def exit_command(self, cmd):
"""
Like exit(), but may be used as a handler in add_command.
:type cmd: str
:param cmd: The command that causes the server to exit.
"""
self.exit()
return ''