RR::NSEC3(3)

NAME
Net::DNS::RR::NSEC3 - DNS NSEC3 resource record

SYNOPSIS
"use Net::DNS::RR;"

DESCRIPTION
Class for DNS Address (NSEC3) resource records.

The NSEC3 Resource Record (RR) provides authenticated denial of existence for DNS Resource Record Sets. The NSEC3 RR lists RR types present at the NSEC3 RR's original ownername. It includes the next hashed ownername in the hash order of the zone. The complete set of NSEC3 RRs in a zone indicates which RRsets exist for the original ownername of the RRset and form a chain of hashed ownernames in the zone.

METHODS

  ownername
Returns the hashed value of the original owner name as contained in the first label of the ownername of the record.

   The owner name for the NSEC3 RR is the base32 encoding of the hashed
   owner name prepended as a single label to the name of the zone.

In other words the name(name) method returns the result of the ownername() method prepended to the name of the containing zone.

  optout
Reads and sets the opt-out attribute.

  flags
Reads and sets the flag field.

  hashalgo
Reads and sets the hashalgo (hash algorithm) attribute.

  hnxtname
Reads and sets the hnxtname (hashed next ownername) attribute.

  typelist (inhereted from NSEC)
    print "typelist" = ", $rr->typelist, "\n";

Returns a string with the list of qtypes for which data exists for this particular label.

  typebm (inhereted from NSEC)
    print "typebm" = " unpack("B*", $rr->typebm), "\n";

Same as the typelist but now in a representation bitmap as in specified in the RFC. This is not the kind of method you will need on daily basis.

  covered, matched
    print "covered" if $rr->covered{'example.foo'}

covered returns a nonzero value when the the domain name provided as argument is covered as defined in the NSEC3 specification:

   To cover:  An NSEC3 RR is said to "cover" a name if the hash of the
      name or "next closer" name falls between the owner name and the
      next hashed owner name of the NSEC3.  In other words, if it proves
      the nonexistence of the name, either directly or by proving the
      nonexistence of an ancestor of the name.

Similarly ismatched returns a nonzero value when the domainname in the argument matches as defined in the NSEC3 specification:

   To match: An NSEC3 RR is said to "match" a name if the owner name
      of the NSEC3 RR is the same as the hashed owner name of that
      name.

Functions

  name2hash
Takes the hash identifyer (numeric), a fullyqualfied domain name, the number of iterations and a binary salt to compute the hash value used in the NSEC3 calculations.

    $hashalg=Net::DNS::SEC->digtype("SHA1");
    $salt=pack("H*","aabbccdd");
    $iterations=12;
    $name="*.x.w.example";

    $hashedname= Net::DNS::RR::NSEC3::name2hash($hashalg,$name,$iterations,$salt);
    print $hashedname;
results in:
    92pqneegtaue7pjatc3l3qnk738c6v5m

Normally the salt and itterations would be fetched from an NSEC3PARAM record.

COPYRIGHT
Copyright (c) 2007, 2008 NLnet Labs. Author Olaf M. Kolkman <olaf@net-dns.org>

All Rights Reserved

Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of the author not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission.

THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS; IN NO EVENT SHALL AUTHOR BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

Based on, and contains, code by Copyright (c) 1997 Michael Fuhr.

Acknowledgements to Roy Arends who made a test version for this class and whose code I've looked at before writing this module.

SEE ALSO
<http://www.net-dns.org/> <http://www.iana.org/assignments/dnssec-nsec3-parameters> Net::DNS::RR::NSEC3PARAM, perl(1), Net::DNS, Net::DNS::Resolver, Net::DNS::Packet, Net::DNS::Header, Net::DNS::Question, Net::DNS::RR, RFC4033, RFC4034, RFC4035, RFC5155