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
 );

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 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 refused

For 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-parameters

The 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;


=head1 BUGS

Net::DNS::Nameserver objects can handle only one query at a time.