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Net::DNS::ToolKit::RR:UserLContributed Perl DocuNet::DNS::ToolKit::RR::NULL(3)

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.

       o   @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

       o   ($newoff,@dnptrs)=$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.

       o   (@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::TXT

EXPORT
	       none

AUTHOR
       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)

perl v5.24.1			  2013-04-24	Net::DNS::ToolKit::RR::NULL(3)

NAME | SYNOPSIS | DESCRIPTION | DEPENDENCIES | EXPORT | AUTHOR | COPYRIGHT | See also:

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