plucky (3) Net::DNS::Nameserver.3pm.gz

Provided by: libnet-dns-perl_1.49-1ubuntu1_all bug

NAME

       Net::DNS::Nameserver - DNS server class

SYNOPSIS

           use Net::DNS::Nameserver;

           my $nameserver = Net::DNS::Nameserver->new(
               LocalAddr       => ['::1', '127.0.0.1'],
               LocalPort       => 15353,
               ZoneFile        => 'filename'
               );

           my $nameserver = Net::DNS::Nameserver->new(
               LocalAddr       => '10.1.2.3',
               LocalPort       => 15353,
               ReplyHandler    => \&reply_handler
           );

           $nameserver->start_server($timeout);
           $nameserver->stop_server;

DESCRIPTION

       Net::DNS::Nameserver offers a simple mechanism for instantiation of customised DNS server objects
       intended to provide test responses to queries emanating from a client resolver.

       It is not, nor will it ever be, a general-purpose DNS nameserver implementation.

       See "EXAMPLES" below for further details.

METHODS

   new
           $nameserver = Net::DNS::Nameserver->new(
               LocalAddr       => ['::1', '127.0.0.1'],
               LocalPort       => 15353,
               ZoneFile        => "filename"
               );

           $nameserver = Net::DNS::Nameserver->new(
               LocalAddr       => '10.1.2.3',
               LocalPort       => 15353,
               ReplyHandler    => \&reply_handler,
               Verbose         => 1,
               Truncate        => 0
           );

       Instantiates a Net::DNS::Nameserver object.  An exception is raised if the object could not be created.

       Each instance is configured using the following optional arguments:

           LocalAddr           IP address on which to listen   Defaults to loopback address
           LocalPort           Port on which to listen
           ZoneFile            Name of file containing RRs
                               accessed using the internal
                               reply-handling subroutine
           ReplyHandler        Reference to customised
                               reply-handling subroutine
           NotifyHandler       Reference to reply-handling
                               subroutine for queries with
                               opcode NOTIFY (RFC1996)
           UpdateHandler       Reference to reply-handling
                               subroutine for queries with
                               opcode UPDATE (RFC2136)
           Verbose             Report internal activity        Defaults to 0 (off)
           Truncate            Truncates UDP packets that
                               are too big for the reply       Defaults to 1 (on)

       The LocalAddr attribute may alternatively be specified as an array of IP addresses to listen to.

       The ReplyHandler subroutine is passed the query name, query class, query type, peerhost, query record,
       and connection descriptor.  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}

       EDNS options may be specified in a similar manner using the optionmask:      {$optioncode => $value,
       $optionname => $value}

       See RFC1035 and IANA DNS parameters file for more information:

       The nameserver will listen for both UDP and TCP connections.  On linux and other Unix-like systems,
       unprivileged users are denied access to ports below 1024.

       UDP reply truncation functionality was introduced in Net::DNS 0.66.  The size limit is determined by the
       EDNS0 size advertised in the query, otherwise 512 is used.  If you want to do packet truncation yourself
       you should set Truncate=>0 and truncate the reply packet in the code of the ReplyHandler.

   start_server
           $ns->start_server( <TIMEOUT_IN_SECONDS> );

       Starts a server process for each of the specified UDP and TCP sockets which continuously responds to user
       connections.

       The timeout parameter specifies the time the server is to remain active.  If called with no parameter a
       default timeout of 10 minutes is applied.

   stop_server
           $ns->stop_server();

       Terminates all server processes in an orderly fashion.

EXAMPLES

   Example 1: Test script with embedded nameserver
       The following example is a self-contained test script which queries DNS zonefile data served by an
       embedded Net::DNS::Nameserver instance.

           use strict;
           use warnings;
           use Test::More;

           plan skip_all => 'Net::DNS::Nameserver not available'
                       unless eval { require Net::DNS::Nameserver }
                       and Net::DNS::Nameserver->can('start_server');
           plan tests => 2;

           my $resolver = Net::DNS::Resolver->new(
               nameserver => ['::1', '127.0.0.1'],
               port       => 15353
               );

           my $ns = Net::DNS::Nameserver->new(
               LocalAddr => [$resolver->nameserver],
               LocalPort => $resolver->port,
               Verbose   => 0,
               ZoneFile  => \*DATA
               )
                       || die "couldn't create nameserver object";

           $ns->start_server(10);

           my $reply = $resolver->send(qw(example.com SOA));
           is( ref($reply), 'Net::DNS::Packet', 'received reply packet' );
           my ($rr) = $reply->answer;
           is( $rr->type, 'SOA', 'answer contains SOA record' );

           $ns->stop_server();

           exit;

           __DATA__
           $ORIGIN example.com.
           @   IN SOA  mname rname 2023 2h 1h 2w 1h
           www IN A    93.184.216.34

   Example 2: Free-standing customised DNS nameserver
       The following example will listen on port 15353 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 a per-host basis may be applied.

           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 $rr = Net::DNS::RR->new("$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 authoritative (by setting the 'aa' flag)
               my $headermask = {aa => 1};

               # specify EDNS options  { option => value }
               my $optionmask = {};

               return ( $rcode, \@ans, \@auth, \@add, $headermask, $optionmask );
           }

           my $ns = Net::DNS::Nameserver->new(
               LocalPort    => 15353,
               ReplyHandler => \&reply_handler,
               Verbose      => 1
               ) or die "couldn't create nameserver object";

           $ns->start_server(60);

           exit;       # leaving nameserver processes running

BUGS

       Limitations in perl make it impossible to guarantee that replies to UDP queries from Net::DNS::Nameserver
       are sent from the IP-address to which the query was directed, the source address being chosen by the
       operating system based upon its notion of "closest address". This limitation is mitigated by creating a
       separate set of sockets and server subprocesses bound to each IP address.

       Copyright (c)2000 Michael Fuhr.

       Portions Copyright (c)2002-2004 Chris Reinhardt.

       Portions Copyright (c)2005 Robert Martin-Legene.

       Portions Copyright (c)2005-2009 O.M.Kolkman, RIPE NCC.

       Portions Copyright (c)2017-2024 R.W.Franks.

       All rights reserved.

LICENSE

       Permission to use, copy, modify, and distribute this software and its documentation for any purpose and
       without fee is hereby granted, provided that the original copyright notices appear in all copies and that
       both copyright notice and this permission notice appear in supporting documentation, and that the name of
       the author not be used in advertising or publicity pertaining to distribution of the software without
       specific prior written permission.

       THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
       LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO
       EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
       IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
       THE USE OR OTHER DEALINGS IN THE SOFTWARE.

SEE ALSO

       perl Net::DNS Net::DNS::Resolver Net::DNS::Packet Net::DNS::Update Net::DNS::Header Net::DNS::Question
       Net::DNS::RR