#!/usr/bin/env python3.5
#
# Copyright (c) 2013-2017 by Ron Frederick <ronf@timeheart.net>.
# All rights reserved.
#
# This program and the accompanying materials are made available under
# the terms of the Eclipse Public License v1.0 which accompanies this
# distribution and is available at:
#
#     http://www.eclipse.org/legal/epl-v10.html
#
# 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

async def handle_client(process):
    if process.env:
        keywidth = max(map(len, process.env.keys()))+1
        process.stdout.write('Environment:\n')
        for key, value in process.env.items():
            process.stdout.write('  %-*s %s\n' % (keywidth, key+':', value))
        process.exit(0)
    else:
        process.stderr.write('No environment sent.\n')
        process.exit(1)

async def start_server():
    await asyncssh.listen('', 8022, server_host_keys=['ssh_host_key'],
                          authorized_client_keys='ssh_user_ca',
                          process_factory=handle_client)

loop = asyncio.get_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()
