Net::DNS::RR(3)

NAME
Net::DNS::RR - DNS Resource Record class

SYNOPSIS
"use Net::DNS::RR"

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

METHODS
WARNING!!! Don't assume the RR objects you receive from a query are of a particular type -- always check an object's type before calling any of its methods. If you call an unknown method, you'll get a nasty warning message and "Net::DNS::RR" will return "undef" to the caller.

  new (from string)
 $a     = Net::DNS::RR->new("foo.example.com. 86400 A 10.1.2.3");
 $mx    = Net::DNS::RR->new("example.com. 7200 MX 10 mailhost.example.com.");
 $cname = Net::DNS::RR->new("www.example.com 300 IN CNAME www1.example.com");
 $txt   = Net::DNS::RR->new('baz.example.com 3600 HS TXT "text record"');

Returns a "Net::DNS::RR" object of the appropriate type and initialized from the string passed by the user. The format of the string is that used in zone files, and is compatible with the string returned by "Net::DNS::RR->string".

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

All names must be fully qualified. The trailing dot (.) is optional.

  new (from hash)
 $rr = Net::DNS::RR->new(
         name    => "foo.example.com",
         ttl     => 86400,
         class   => "IN",
         type    => "A",
         address => "10.1.2.3",
 );

 $rr = Net::DNS::RR->new(
         name => "foo.example.com",
         type => "A",
 );

Returns an RR object of the appropriate type, or a "Net::DNS::RR" object if the type isn't implemented. See the manual pages for each RR 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 IN. Omitting the optional fields is useful for creating the empty RDATA sections required for certain dynamic update operations.

The fields are case-insensitive, but starting each with uppercase is recommended.

  parse
    ($rrobj, $offset) = Net::DNS::RR->parse(\$data, $offset);

Parses a DNS resource record at the specified location within a DNS packet. The first argument is a reference to the packet data. The second argument is the offset within the packet where the resource record begins.

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

Parsing is aborted if the object could not be created (e.g., corrupt or insufficient data).

  print
    $rr->print;

Prints the record to the standard output. Calls the string method to get the RR's string representation.

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

Returns a string representation of the RR. Calls the rdatastr method to get the RR-specific data.

  rdatastr
    $s = $rr->rdatastr;

Returns a string containing RR-specific data. Subclasses will need to implement this method.

  name
    $name = $rr->name;

Returns the record's domain name.

  type
    $type = $rr->type;

Returns the record's type.

  class
    $class = $rr->class;

Returns the record's class.

  ttl
    $ttl = $rr->ttl;

Returns the record's time-to-live (TTL).

  rdlength
    $rdlength = $rr->rdlength;

Returns the length of the record's data section.

  rdata
    $rdata = $rr->rdata

Returns the record's data section as binary data.

Sorting of RR arrays
As of version 0.55 there is functionality to help you sort RR arrays. The sorting is done by Net::DNS::rrsort(), see the Net::DNS documentation. This package provides class methods to set the sorting functions used for a particular RR based on a particular attribute.

  set_rrsort_func
Net::DNS::RR::SRV->set_rrsort_func("priority",
                   sub {
                   my ($a,$b)=($Net::DNS::a,$Net::DNS::b);
                   $a->priority <=> $b->priority
                   ||
                   $b->weight <=> $a->weight
                     }

Net::DNS::RR::SRV->set_rrsort_func("default_sort",
                   sub {
                   my ($a,$b)=($Net::DNS::a,$Net::DNS::b);
                   $a->priority <=> $b->priority
                   ||
                   $b->weight <=> $a->weight
                     }

set_rrsort_func needs to be called as a class method. The first argument is the attribute name on which the sorting will need to take place. If you specify "default_sort" than that is the sort algorithm that will be used in the case that rrsort() is called without an RR attribute as argument.

The second argument is a reference to a function that uses the variables $a and $b global to the "from Net::DNS"(!!)package for the sorting. During the sorting $a and $b will contain references to objects from the class you called the set_prop_sort from. In other words, you can rest assured that the above sorting function will only get Net::DNS::RR::SRV objects.

The above example is the sorting function that actually is implemented in SRV.

BUGS
This version of "Net::DNS::RR" does little sanity checking on user-created RR objects.

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 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.

EDNS0 extensions by Olaf Kolkman.

SEE ALSO
perl(1), Net::DNS, Net::DNS::Resolver, Net::DNS::Packet, Net::DNS::Update, Net::DNS::Header, Net::DNS::Question, RFC 1035 Section 4.1.3