# Net::DNS::Nameserver - DNS server class - perldoc - [phpMan]

## NAME
    [Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown) - DNS server class

## SYNOPSIS
        use [Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown);

        my $nameserver = [Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown)->new(
            LocalAddr       => ['::1', '127.0.0.1'],
            LocalPort       => 15353,
            ZoneFile        => 'filename'
            );

        my $nameserver = [Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown)->new(
            LocalAddr       => '10.1.2.3',
            LocalPort       => 15353,
            ReplyHandler    => \&reply_handler
        );

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

## DESCRIPTION
    [Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown)->new(
            LocalAddr       => ['::1', '127.0.0.1'],
            LocalPort       => 15353,
            ZoneFile        => "filename"
            );

        $nameserver = [Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown)->new(
            LocalAddr       => '10.1.2.3',
            LocalPort       => 15353,
            ReplyHandler    => \&reply_handler,
            Verbose         => 1,
            Truncate        => 0
        );

    Instantiates a [Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown) instance.

        use strict;
        use warnings;
        use [Test::More](https://www.chedong.com/phpMan.php/perldoc/Test%3A%3AMore/markdown);

        plan skip_all => '[Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown) not available'
                    unless eval { require [Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown) }
                    and [Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown)->can('start_server');
        plan tests => 2;

        my $resolver = [Net::DNS::Resolver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3AResolver/markdown)->new(
            nameserver => ['::1', '127.0.0.1'],
            port       => 15353
            );

        my $ns = [Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown)->new(
            LocalAddr => [$resolver->nameserver],
            LocalPort => $resolver->port,
            Verbose   => 0,
            ZoneFile  => \*DATA
            )
                    || die "couldn't create nameserver object";

        $ns->[start_server(10)](https://www.chedong.com/phpMan.php/man/startserver/10/markdown);

        my $reply = $resolver->send(qw(example.com SOA));
        is( ref($reply), '[Net::DNS::Packet](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3APacket/markdown)', '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](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown);

        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 $rr = [Net::DNS::RR](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ARR/markdown)->new("$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](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown)->new(
            LocalPort    => 15353,
            ReplyHandler => \&reply_handler,
            Verbose      => 1
            ) or die "couldn't create nameserver object";

        $ns->[start_server(60)](https://www.chedong.com/phpMan.php/man/startserver/60/markdown);

        exit;       # leaving nameserver processes running

## BUGS
    Limitations in perl make it impossible to guarantee that replies to UDP queries from
    [Net::DNS::Nameserver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ANameserver/markdown) 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
    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](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS/markdown) [Net::DNS::Resolver](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3AResolver/markdown) [Net::DNS::Packet](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3APacket/markdown) [Net::DNS::Update](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3AUpdate/markdown) [Net::DNS::Header](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3AHeader/markdown)
    [Net::DNS::Question](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3AQuestion/markdown) [Net::DNS::RR](https://www.chedong.com/phpMan.php/perldoc/Net%3A%3ADNS%3A%3ARR/markdown)

    RFC1035 <<https://tools.ietf.org/html/rfc1035>>

    IANA DNS parameters <<http://www.iana.org/assignments/dns-parameters>>