package Net::DNS::ToolKit::RR::NULL; use strict; #use warnings; use Net::DNS::ToolKit qw( get16 put16 dn_comp dn_expand putstring getstring ); use Net::DNS::Codes qw(:constants); use vars qw($VERSION); $VERSION = do { my @r = (q$Revision: 0.02 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r }; =head1 NAME Net::DNS::ToolKit::RR::NULL - Resource Record Handler =head1 SYNOPSIS DO NOT use Net::DNS::ToolKit::RR::NULL DO NOT require Net::DNS::ToolKit::RR::NULL Net::DNS::ToolKit::RR::NULL is autoloaded by class Net::DNS::ToolKit::RR and its methods are instantiated in a 'special' manner. use Net::DNS::ToolKit::RR; ($get,$put,$parse) = new Net::DNS::ToolKit::RR; ($newoff,$name,$type,$class,$ttl,$rdlength, $anydata) = $get->NULL(\$buffer,$offset); Note: the $get->NULL method is normally called via: @stuff = $get->next(\$buffer,$offset); ($newoff,@dnptrs)=$put->NULL(\$buffer,$offset,\@dnptrs, $name,$type,$class,$ttl,$rdlength,$anydata); $NAME,$TYPE,$CLASS,$TTL,$rdlength,$anydata) = $parse->NULL($name,$type,$class,$ttl,$rdlength, $anydata); =head1 DESCRIPTION B appends an NULL resource record to a DNS packet under construction, recovers an NULL resource record from a packet being decoded, and converts the numeric/binary portions of the resource record to human readable form. Description from RFC1035.txt 3.2.1. Format All RRs have the same top level format shown below: 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | NAME | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | TYPE | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | CLASS | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | TTL | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | RDLENGTH | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--| | RDATA | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ NAME an owner name, i.e., the name of the node to which this resource record pertains. TYPE two octets containing one of the RR TYPE codes. CLASS two octets containing one of the RR CLASS codes. TTL a 32 bit signed integer that specifies the time interval that the resource record may be cached before the source of the information should again be consulted. Zero values are interpreted to mean that the RR can only be used for the transaction in progress, and should not be cached. For example, SOA records are always distributed with a zero TTL to prohibit caching. Zero values can also be used for extremely volatile data. RDLENGTH an unsigned 16 bit integer that specifies the length in octets of the RDATA field. RDATA a variable length string of octets that describes the resource. The format of this information varies according to the TYPE and CLASS of the resource record. 3.3.10. NULL RDATA format (EXPERIMENTAL) +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ / / / / +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ Anything at all may be in the RDATA field so long as it is 65535 octets or less. I NULL records cause no additional section processing. NULL RRs are not allowed in master files. NULLs are used as placeholders in some experimental extensions of the DNS. =over 4 =item * @stuff = $get->NULL(\$buffer,$offset); Get the contents of the resource record. USE: @stuff = $get->next(\$buffer,$offset); where: @stuff = ( $newoff $name,$type,$class,$ttl,$rdlength, $anydata ); All except the last item, B<$anydata>, is provided by the class loader, B. The code in this method knows how to retrieve B<$anydata>. input: pointer to buffer, offset into buffer returns: offset to next resource, @common RR elements, lots of bytes =cut sub get { my($self,$bp,$offset) = @_; (my $len,$offset) = get16($bp,$offset); # get rdlength (my $string,$offset) = getstring($bp,$offset,$len); return($offset,$string); } =item * ($newoff,@dnptrs)=$put->NULL(\$buffer,$offset,\@dnptrs, $name,$type,$class,$ttl,$rdlength,$anydata); Append a NULL record to $buffer. where @common = ( $name,$type,$class,$ttl); The method will insert the $rdlength and $anydata, then pass through the updated pointer to the array of compressed names The class loader, B, inserts the @common elements and returns updated @dnptrs. This module knows how to insert its RDATA and calculate the $rdlength. input: pointer to buffer, offset (normally end of buffer), pointer to compressed name array, @common RR elements, lots of bytes output: offset to next RR, new compressed name pointer array, or empty list () on error. =cut sub put { return () unless @_; # always return on error my($self,$bp,$off,$dnp,$textdata) = @_; my $rdlp = $off; # save pointer to rdlength my $doff; return () unless # check for valid offset and get ($doff = put16($bp,$off,0)) && # offset to text string ($off = putstring($bp,$doff,\$textdata)); # rdlength = new offset - previous offset put16($bp,$rdlp, $off - $doff); return($off,@$dnp); } =item * (@COMMON,$anydata) = $parse->NULL(@common,$anydata); Converts binary/numeric field data into human readable form. The common RR elements are supplied by the class loader, B. For NULL RR's, this is a null operation. input: lots of bytes returns: the same bytes =cut sub parse { shift; # $self return shift; } =back =head1 DEPENDENCIES Net::DNS::ToolKit Net::DNS::Codes Net::DNS::ToolKit::RR::TXT =head1 EXPORT none =head1 AUTHOR Michael Robinton =head1 COPYRIGHT Copyright 2003, Michael Robinton This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. =head1 See also: Net::DNS::Codes(3), Net::DNS::ToolKit(3) =cut 1;