NAME
Net::DNS::ToolKit::RR::NULL - Resource Record Handler
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,$anydata);
$NAME,$TYPE,$CLASS,$TTL,$rdlength,$anydata)
= $parse->NULL($name,$type,$class,$ttl,$anydata);DESCRIPTION
Net::DNS::ToolKit::RR:NULL 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> /
/ /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+Anything at all may be in the RDATA field so long as it is 65535 octets or less.
This is probably not correct. An entire resource record + question, etc... info must fit inside the 65535 record because that is the limitation imposed by TCP window size. See: extra_docs/draft-ietf-dnsext-axfr-clarify-05.txt section 3.1
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.
@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,$anydata );All except the last item, $anydata, is provided by the class loader, Net::DNS::ToolKit::RR. The code in this method knows how to retrieve $anydata.
input: pointer to buffer, offset into buffer returns: offset to next resource, @common RR elements, lots of bytes($newoff,@dnptrs)=$put->NULL(\$buffer,$offset,\@dnptrs, $name,$type,$class,$ttl,$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, Net::DNS::ToolKit::RR, inserts the @common elements and returns updated @dnptrs. This module knows how to insert its RDATA and calculate the $rdlength.
input: pointer to buffer, offset (normally end of buffer), pointer to compressed name array, @common RR elements, lots of bytes output: offset to next RR, new compressed name pointer array, or empty list () on error.(@COMMON,$anydata) = $parse->NULL(@common,$anydata);
Converts binary/numeric field data into human readable form. The common RR elements are supplied by the class loader, Net::DNS::ToolKit::RR. For NULL RR's, this is a null operation.
input: lots of bytes returns: the same bytes
DEPENDENCIES
Net::DNS::ToolKit
Net::DNS::Codes
Net::DNS::ToolKit::RR::TXTEXPORT
noneAUTHOR
Michael Robinton <michael@bizsystems.com>
COPYRIGHT
Copyright 2003 - 2011, Michael Robinton <michael@bizsystems.com>Michael Robinton <michael@bizsystems.com>
All rights reserved.
This program is free software; you can redistribute it and/or modify it under the terms of either:
a) the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any
later version, or
b) the "Artistic License" which comes with this distribution.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 either the GNU General Public License or the Artistic License for more details.
You should have received a copy of the Artistic License with this distribution, in the file named "Artistic". If not, I'll be glad to provide one.
You should also have received a copy of the GNU General Public License along with this program in the file named "Copying". If not, write to the
Free Software Foundation, Inc.
59 Temple Place, Suite 330
Boston, MA 02111-1307, USA or visit their web page on the internet at:
http://www.gnu.org/copyleft/gpl.html.See also:
Net::DNS::Codes(3), Net::DNS::ToolKit(3)