#!/usr/bin/perl --

# 

use strict;
use warnings;

my $qname = "_sip._udp.www.google.com";
warn substr $qname,  index $qname, 'www';
warn substr $qname,  length('_udp.') + index $qname, '_udp.';
__END__
www.google.com at substr.index.pl line 9.
www.google.com at substr.index.pl line 10.