Net::DNS::Nameserver(3) 				User Contributed Perl Documentation				   Net::DNS::Nameserver(3)

NAME

       Net::DNS::Nameserver - DNS server class

SYNOPSIS

	   use Net::DNS::Nameserver;

	   $nameserver = new Net::DNS::Nameserver(
	       LocalAddr	=> ['::1' , '127.0.0.1' ],
	       LocalPort	=> "5353",
	       ReplyHandler => &reply_handler,
	       Verbose		=> 1,
	       Truncate 	=> 0
	   );

DESCRIPTION

       Instances of the "Net::DNS::Nameserver" class represent DNS server objects.  See "EXAMPLE" for an example.

METHODS

   new
	   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
	       );

       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.
	   NotifyHandler       Reference to reply-handling
			       subroutine for queries with
			       opcode NS_NOTIFY (RFC1996)
	   Verbose	       Print info about received
			       queries. 		       Defaults to 0 (off).
	   Truncate	       Truncates UDP packets that
			       are to 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 for $Net::DNS::Nameserver::VERSION>830 and uses the Net::DNS::Packet::truncate method with a size
       determinde by the advertised EDNS0 size in the query, or 512 if EDNS0 is not advertised in the query. Only UDP replies are truncated. If
       you want to do packet runcation yourself you should set Truncate to 0 and use the truncate method on the reply packet in the code you use
       for the ReplyHandler.

       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. Calling main_loop never returns.

   loop_once
	   $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.

   get_open_tcp
       In scalar context returns the number of TCP connections for which state is maintained. In array context it returns IO::Socket objects,
       these could be useful for troubleshooting but be careful using them.

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 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}. "
";
	       $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
";

	   $ns->main_loop;

BUGS

       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.  Thus a
       UDP socket created listening to INADDR_ANY (all available IP-addresses) will reply not necessarily with the source address being the one to
       which the request was sent, but rather with the address that the operating system choses. This is also often called "the closest address".
       This should really only be a problem on a server which has more than one IP-address (besides localhost - any experience with IPv6
       complications here, would be nice). If this is a problem for you, a work-around would be to not listen to INADDR_ANY but to specify each
       address that you want this module to listen on. A separate set of sockets will then be created for each IP-address.

COPYRIGHT

       Copyright (c)1997-2002 Michael Fuhr.

       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.

SEE ALSO

       perl, Net::DNS, Net::DNS::Resolver, Net::DNS::Packet, Net::DNS::Update, Net::DNS::Header, Net::DNS::Question, Net::DNS::RR, RFC 1035

perl v5.16.2							    2012-01-27						   Net::DNS::Nameserver(3)