Net::DNS::RR (3)

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NAME

Net::DNS::RR - DNS resource record base class

SYNOPSIS

    use Net::DNS;

    $rr = new Net::DNS::RR('example.com IN A 192.0.2.99');

    $rr = new Net::DNS::RR(
            name    => 'example.com',
            type    => 'A',
            address => '192.0.2.99'
            );

DESCRIPTION

Net::DNS::RR is the base class for Resource Record () objects. See also the manual pages for each specific type.

METHODS

!!! Do not assume the objects you receive from a query are of a particular type --- you must always check the object type before calling any of its methods. If you call an unknown method, you will get an error message and execution will be terminated.

new (from string)

    $a     = new Net::DNS::RR('host.example.com. 86400 A 192.0.2.1');
    $mx    = new Net::DNS::RR('example.com. 7200 MX 10 mailhost.example.com.');
    $cname = new Net::DNS::RR('www.example.com 300 IN CNAME host.example.com');
    $txt   = new Net::DNS::RR('txt.example.com 3600 HS TXT "text data"');

Returns an

object of the appropriate type, or a "Net::DNS::RR" object if the type is not implemented.  The attribute values are
extracted from the string passed by the user. The syntax of the argument string follows the specification for zone files, and is compatible with the result returned by the string method.

The name and

type are required; all other information is optional. If omitted, the defaults to 0 and the class defaults to Omitting the optional fields is useful for creating the empty sections required for certain dynamic update operations. See the "Net::DNS::Update" manual page for additional examples.

All names are interpreted as fully qualified domain names. The trailing dot (.) is optional.

new (from hash)

    $rr = new Net::DNS::RR(
            name    => 'host.example.com',
            ttl     => 86400,
            class   => 'IN',
            type    => 'A',
            address => '192.0.2.1'
            );
 
    $rr = new Net::DNS::RR(
            name    => 'txt.example.com',
            type    => 'TXT',
            txtdata => [ 'one', 'two' ]
            );

Returns an

object of the appropriate type, or a "Net::DNS::RR" object if the type is not implemented.  See the manual pages for
each type to see what fields the type requires.

The "name" and "type" fields are required; all others are optional. If omitted, "ttl" defaults to 0 and "class" defaults to

Omitting the optional fields is useful for creating the empty sections required for certain dynamic update operations.

decode

    ( $rr, $next ) = decode Net::DNS::RR( \$data, $offset, @opaque );

Decodes a

resource record at the specified location within a packet.

The argument list consists of a reference to the buffer containing the packet data and offset indicating where resource record begins. Remaining arguments, if any, are passed as opaque data to subordinate decoders.

Returns a "Net::DNS::RR" object and the offset of the next record in the packet.

An exception is raised if the data buffer contains insufficient or corrupt data.

Any remaining arguments are passed as opaque data to subordinate decoders and do not form part of the published interface.

encode

    $data = $rr->encode( $offset, @opaque );

Returns the "Net::DNS::RR" in binary format suitable for inclusion in a

packet buffer.

The offset indicates the intended location within the packet data where the "Net::DNS::RR" is to be stored.

Any remaining arguments are opaque data which are passed intact to subordinate encoders.

canonical

    $data = $rr->canonical;

Returns the "Net::DNS::RR" in canonical binary format suitable for

signature validation.

The absence of the associative array argument signals to subordinate encoders that the canonical uncompressed lower case form of embedded domain names is to be used.

print

    $rr->print;

Prints the record to the standard output. Calls the string method to get the

string representation.

string

    print $rr->string, "\n";

Returns a string representation of the

using the zone file format described in All domain names are fully qualified with trailing dot. This differs from attribute methods, which omit the trailing dot.

owner name

    $owner = $rr->name;

Returns the owner name of the record.

type

    $type = $rr->type;

Returns the record type.

class

    $class = $rr->class;

Resource record class.

ttl

    $ttl = $rr->ttl;
    $ttl = $rr->ttl(3600);

Resource record time to live in seconds.

rdata

    $rr = new Net::DNS::RR( type => NULL, rdata => 'arbitrary' );

Resource record data section when viewed as opaque octets.

rdstring

    $rdstring = $rr->rdstring;

Returns a string representation of the RR-specific data.

plain

    $plain = $rr->plain;

Returns a simplified single line representation of the

using the zone file format defined in This facilitates interaction with programs like nsupdate which have simplified parsers.

token

    @token = $rr->token;

Returns a token list representation of the

zone file string.

Sorting of RR arrays

Sorting of arrays is done by Net::DNS::rrsort(), see documentation for Net::DNS. This package provides class methods to set the comparator function used for a particular based on its attributes.

set_rrsort_func

    Net::DNS::RR::MX->set_rrsort_func(
        'preference',
        sub { $Net::DNS::a->preference <=> $Net::DNS::b->preference }
        );

    Net::DNS::RR::MX->set_rrsort_func(
        'default_sort',
        Net::DNS::RR::MX->get_rrsort_func('preference')
        );

set_rrsort_func() must be called as a class method. The first argument is the attribute name on which the sorting is to take place. If you specify ``default_sort'' then that is the sort algorithm that will be used when rrsort() is called without an

attribute as argument.

The second argument is a reference to a comparison function that uses the global variables $a and $b in the Net::DNS package. During sorting, the variables $a and $b will contain references to objects of the class whose set_rrsort_func() was called. The above sorting function will only be applied to Net::DNS::RR::MX objects.

The above example is the sorting function implemented in

COPYRIGHT

Copyright (c)1997-2002 Michael Fuhr.

Portions Copyright (c)2002-2004 Chris Reinhardt.

Portions Copyright (c)2005-2007 Olaf Kolkman.

Portions Copyright (c)2007,2012 Dick Franks.

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::Question, Net::DNS::Packet, Net::DNS::Update, Section 4.1.3,