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#!/usr/bin/env python3.7
#
# Copyright (c) 2016-2024 by Ron Frederick <ronf@timeheart.net> and others.
#
# This program and the accompanying materials are made available under
# the terms of the Eclipse Public License v2.0 which accompanies this
# distribution and is available at:
#
# http://www.eclipse.org/legal/epl-2.0/
#
# This program may also be made available under the following secondary
# licenses when the conditions for such availability set forth in the
# Eclipse Public License v2.0 are satisfied:
#
# GNU General Public License, Version 2.0, or any later versions of
# that license
#
# SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-or-later
#
# Contributors:
# Ron Frederick - initial implementation, API, and documentation
# To run this program, the file ``ssh_host_key`` must exist with an SSH
# private key in it to use as a server host key. An SSH host certificate
# can optionally be provided in the file ``ssh_host_key-cert.pub``.
#
# The file ``ssh_user_ca`` must exist with a cert-authority entry of
# the certificate authority which can sign valid client certificates.
import asyncio, asyncssh, sys
from typing import List, cast
class ChatClient:
_clients: List['ChatClient'] = []
def __init__(self, process: asyncssh.SSHServerProcess):
self._process = process
@classmethod
async def handle_client(cls, process: asyncssh.SSHServerProcess):
await cls(process).run()
async def readline(self) -> str:
return cast(str, self._process.stdin.readline())
def write(self, msg: str) -> None:
self._process.stdout.write(msg)
def broadcast(self, msg: str) -> None:
for client in self._clients:
if client != self:
client.write(msg)
async def run(self) -> None:
self.write('Welcome to chat!\n\n')
self.write('Enter your name: ')
name = (await self.readline()).rstrip('\n')
self.write(f'\n{len(self._clients)} other users are connected.\n\n')
self._clients.append(self)
self.broadcast(f'*** {name} has entered chat ***\n')
try:
async for line in self._process.stdin:
self.broadcast(f'{name}: {line}')
except asyncssh.BreakReceived:
pass
self.broadcast(f'*** {name} has left chat ***\n')
self._clients.remove(self)
async def start_server() -> None:
await asyncssh.listen('', 8022, server_host_keys=['ssh_host_key'],
authorized_client_keys='ssh_user_ca',
process_factory=ChatClient.handle_client)
loop = asyncio.new_event_loop()
try:
loop.run_until_complete(start_server())
except (OSError, asyncssh.Error) as exc:
sys.exit('Error starting server: ' + str(exc))
loop.run_forever()
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