use Net::DNS::Nameserver;
$nameserver = new Net::DNS::Nameserver(
LocalAddr => ['::1' , '127.0.0.1' ],
LocalPort => "5353",
ReplyHandler => \&reply_handler,
Verbose => 1,
Truncate => 0
);
my $ns = new Net::DNS::Nameserver(
LocalAddr => "10.1.2.3",
LocalPort => "5353",
ReplyHandler => \&reply_handler,
Verbose => 1
);
my $ns = new Net::DNS::Nameserver(
LocalAddr => ['::1' , '127.0.0.1' ],
LocalPort => "5353",
ReplyHandler => \&reply_handler,
Verbose => 1,
Truncate => 0
);
Returns a Net::DNS::Nameserver object, or undef if the object could not be created.
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.
NotifyHandler Reference to reply-handling
subroutine for queries with
opcode NOTIFY (RFC1996)
Verbose Print info about received
queries. Defaults to 0 (off).
Truncate Truncates UDP packets that
are too big for the reply Defaults to 1 (on)
IdleTimeout TCP clients are disconnected
if they are idle longer than
this duration. Defaults to 120 (secs)
The LocalAddr attribute may alternatively be specified as a list of IP addresses to listen 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 the peerhost, the incoming query, and the name of the incoming socket (sockethost). It must either return the response code and references to the answer, authority, and additional sections of the response, or undef to leave the query unanswered. 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 it may also contain a headermask 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.
Packet Truncation is new functionality available in VERSION > 830. Only UDP replies are truncated. The size limit is determined by the advertised EDNS0 size in the query, otherwise 512 is used.
If you want to do packet truncation yourself you should set Truncate to 0 and truncate the reply packet in the code of the ReplyHandler.
See ``EXAMPLE'' for an example.
$ns->main_loop;
Start accepting queries. Calling main_loop never returns.
$ns->loop_once( [TIMEOUT_IN_SECONDS] );
Start accepting queries, but returns. If called without a parameter, the call will not return until a request has been received (and replied to). If called with a number, that number specifies how many seconds (even fractional) to maximum wait before returning. If called with 0 it will return immediately unless there's something to do.
Handling a request and replying obviously depends on the speed of ReplyHandler. Assuming ReplyHandler is super fast, loop_once should spend just a fraction of a second, if called with a timeout value of 0 seconds. One exception is when an AXFR has requested a huge amount of data that the OS is not ready to receive in full. In that case, it will keep running through a loop (while servicing new requests) until the reply has been sent.
In case loop_once accepted a TCP connection it will immediatly check if there is data to be read from the socket. If not it will return and you will have to call loop_once() again to check if there is any data waiting on the socket to be processed. In most cases you will have to count on calling ``loop_once'' twice.
A code fragment like:
$ns->loop_once(10);
while( $ns->get_open_tcp() ){
$ns->loop_once(0);
}
Would wait for 10 seconds for the initial connection and would then process all TCP sockets until none is left.
#!/usr/bin/perl
use strict;
use warnings;
use Net::DNS::Nameserver;
sub reply_handler {
my ($qname, $qclass, $qtype, $peerhost,$query,$conn) = @_;
my ($rcode, @ans, @auth, @add);
print "Received query from $peerhost to ". $conn->{sockhost}. "\n";
$query->print;
if ($qtype eq "A" && $qname eq "foo.example.com" ) {
my ($ttl, $rdata) = (3600, "10.1.2.3");
my $rr = new Net::DNS::RR("$qname $ttl $qclass $qtype $rdata");
push @ans, $rr;
$rcode = "NOERROR";
}elsif( $qname eq "foo.example.com" ) {
$rcode = "NOERROR";
}else{
$rcode = "NXDOMAIN";
}
# mark the answer as authoritive (by setting the 'aa' flag
return ($rcode, \@ans, \@auth, \@add, { aa => 1 });
}
my $ns = new Net::DNS::Nameserver(
LocalPort => 5353,
ReplyHandler => \&reply_handler,
Verbose => 1
) || die "couldn't create nameserver object\n";
$ns->main_loop;
Portions Copyright (c)2002-2004 Chris Reinhardt.
Portions Copyright (c)2005-2009 O.M, Kolkman, RIPE NCC.
Portions Copyright (c)2005 Robert Martin-Legene.
All rights reserved.
This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.