#!/usr/bin/env python2.7
#
# requires python-avahi, python-dbus, python-gdbm

import avahi, dbus
from encodings.idna import ToASCII
from time import sleep

ttl = 60

def publish(name):
	name = unicode(name, locale.getpreferredencoding())

	bus = dbus.SystemBus()
	server = dbus.Interface(bus.get_object(avahi.DBUS_NAME, avahi.DBUS_PATH_SERVER), avahi.DBUS_INTERFACE_SERVER)
	group = dbus.Interface(bus.get_object(avahi.DBUS_NAME, server.EntryGroupNew()), avahi.DBUS_INTERFACE_ENTRY_GROUP)

	rdata = create_rr(server.GetHostNameFqdn())
	cname = encode_dns(name)

	group.AddRecord(avahi.IF_UNSPEC, avahi.PROTO_UNSPEC, dbus.UInt32(0), cname, 0x01, 0x05, ttl, rdata)
	group.Commit()

def encode_dns(name):
	return '.'.join([ToASCII(part) for part in name.split('.') if part])

def create_rr(name):
	return ''.join(["%s%s" % (chr(len(part)), ToASCII(part)) for part in name.split('.') if part]) + '\0'

def load_aliases(filename):
	with open(filename, 'r') as f:
		aliases = f.readlines()
		return [alias.strip() for alias in aliases if alias and not alias.startswith('#')]

if __name__ == '__main__':
	import sys, locale
	if len(sys.argv) > 1:
		for hostname in sys.argv[1:]:
			publish(hostname)
	else:
		for hostname in load_aliases('/etc/avahi/aliases'):
			publish(hostname)

	while True:
		sleep(30)