Examples/PythonPublishAlias

Version 1 (modified by DamjanGeorgievski, 7 years ago)

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This simple Python script registers aliases for you own computer. It does this by creating CNAME entries that point back to your hostname. Your hostname is laready published by Avahi (by default).

I've used this to publish several name based Apache virtual hosts on my laptop, when I needed to present them. For added pleasure I've implemented support for international DNS names - although I'm not sure how correct it is, it seems to work for me.

Usage:

avahi-alias.py test.local somethingelse.local æȯè.local

#! /usr/bin/env python
# avahi-alias.py

import avahi, dbus
from encodings.idna import ToASCII

# Got these from /usr/include/avahi-common/defs.h
CLASS_IN = 0x01
TYPE_CNAME = 0x05

TTL = 60

def publish_cname(cname):
    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 = createRR(server.GetHostNameFqdn())
    cname = encode_dns(cname)

    group.AddRecord(avahi.IF_UNSPEC, avahi.PROTO_UNSPEC, dbus.UInt32(0),
        cname, CLASS_IN, TYPE_CNAME, TTL, rdata)
    group.Commit()


def encode_dns(name):
    out = []
    for part in name.split('.'):
        if len(part) == 0: continue
        out.append(ToASCII(part))
    return '.'.join(out)

def createRR(name):
    out = []
    for part in name.split('.'):
        if len(part) == 0: continue
        out.append(chr(len(part)))
        out.append(ToASCII(part))
    out.append('\0')
    return ''.join(out)

if __name__ == '__main__':
    import time, sys, locale
    for each in sys.argv[1:]:
        name = unicode(each, locale.getpreferredencoding())
        publish_cname(name)
    try:
        # Just loop forever
        while 1: time.sleep(60)
    except KeyboardInterrupt:
        print "Exiting"