NAME
Net::DNS::Nameserver - DNS server class
SYNOPSIS
use Net::DNS::Nameserver;
DESCRIPTION
Instances of the Net::DNS::Nameserver class represent simple DNS server objects. See "EXAMPLE" for an example.
METHODS
new
my $ns = Net::DNS::Nameserver->new(
LocalAddr => "10.1.2.3",
LocalPort => "5353",
ReplyHandler => \&reply_handler,
Verbose => 1
);
my $ns = Net::DNS::Nameserver->new(
LocalAddr => ['::1' , '127.0.0.1' ],
LocalPort => "5353",
ReplyHandler => \&reply_handler,
Verbose => 1
);Creates a nameserver object. Attributes are:
LocalAddr IP address on which to listen. Defaults to INADDR_ANY.
LocalPort Port on which to listen. Defaults to 53.
ReplyHandler Reference to reply-handling
subroutine Required.
Verbose Print info about received
queries. Defaults to 0 (off).The LocalAddr attribute may alternatively be specified as a list of IP addresses to liten to.
If IO::Socket::INET6 and Socket6 are available on the system you can also list IPv6 addresses and the default is '0' (listen on all interfaces on IPv6 and IPv4);
The ReplyHandler subroutine is passed the query name, query class, query type and optionally an argument containing header bit settings (see below). It must return the response code and references to the answer, authority, and additional sections of the response. Common response codes are:
NOERROR No error
FORMERR Format error
SERVFAIL Server failure
NXDOMAIN Non-existent domain (name doesn't exist)
NOTIMP Not implemented
REFUSED Query refusedFor advanced usage there is an optional argument containing an hashref with the settings for the aa, ra, and ad header bits. The argument is of the form { ad => 1, aa => 0, ra => 1 }.
See RFC 1035 and the IANA dns-parameters file for more information:
ftp://ftp.rfc-editor.org/in-notes/rfc1035.txt
http://www.isi.edu/in-notes/iana/assignments/dns-parametersThe nameserver will listen for both UDP and TCP connections. On Unix-like systems, the program will probably have to run as root to listen on the default port, 53. A non-privileged user should be able to listen on ports 1024 and higher.
Returns a Net::DNS::Nameserver object, or undef if the object couldn't be created.
See "EXAMPLE" for an example.
main_loop
$ns->main_loop;Start accepting queries.
EXAMPLE
The following example will listen on port 5353 and respond to all queries for A records with the IP address 10.1.2.3. All other queries will be answered with NXDOMAIN. Authority and additional sections are left empty. The $peerhost variable catches the IP address of the peer host, so that additional filtering on its basis may be applied.
#!/usr/bin/perl
use Net::DNS;
use strict;
use warnings;
sub reply_handler {
my ($qname, $qclass, $qtype, $peerhost) = @_;
my ($rcode, @ans, @auth, @add);
if ($qtype eq "A") {
my ($ttl, $rdata) = (3600, "10.1.2.3");
push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype $rdata");
$rcode = "NOERROR";
} else {
$rcode = "NXDOMAIN";
}
# mark the answer as authoritive (by setting the 'aa' flag
return ($rcode, \@ans, \@auth, \@add, { aa => 1 });
}
my $ns = Net::DNS::Nameserver->new(
LocalPort => 5353,
ReplyHandler => \&reply_handler,
Verbose => 1,
) || die "couldn't create nameserver object\n";
$ns->main_loop;
BUGS
Net::DNS::Nameserver objects can handle only one query at a time.
Limitations in perl 5.8.6 makes it impossible to guarantee that replies to UDP queries from Net::DNS::Nameserver are sent from the IP-address they were received on. This is a problem for machines with multiple IP-addresses and causes violation of RFC2181 section 4.
COPYRIGHT
Copyright (c) 1997-2002 Michael Fuhr.
Portions Copyright (c) 2002-2004 Chris Reinhardt.
Portions Copyright (c) 2005 O.M, Kolkman, RIPE NCC.
All rights reserved. This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.
SEE ALSO
perl(1), Net::DNS, Net::DNS::Resolver, Net::DNS::Packet, Net::DNS::Update, Net::DNS::Header, Net::DNS::Question, Net::DNS::RR, RFC 1035