Michael Robinton


Net::DNS::ToolKit::RR - Resource Record class loader


  use Net::DNS::ToolKit::RR;

  ($get,$put,$parse) = new Net::DNS::ToolKit::RR;
  ($get,$put,$parse) = Net::DNS::ToolKit::RR->new;

        retrieve the next record (type unknown)
        = $get->next(\$buffer,$offset);

        parse the current record (type in input fields)
        = $parse->RR($name,$type,$class,$ttl,$rdlength,


  The 'get' and 'parse' operations can also be done
  by specific record type...
  ...but why would you use them instead of 'next' & 'RR'?

        = $get->XYZ(\$buffer,$offset);

        = $parse->XYZ($name,$type,$class,$ttl,$rdlength,

        or you can use the individual methods 
        directly without calling "new"


The Question section is a special case:

  ($newoff,$name,type,class) = 
  ($newoff,@dnptrs) = 
  ($name,$typeTXT,$classTXT) =


An alternate method for put is available for class specific submissions. This eliminates the need to specify TYPE and CLASS when doing a put. The generic form of a put command using this method is shown below but NOT detailed in the method descriptions.

  ($get,$put,$parse) = new Net::DNS::ToolKit::RR(class_type);
  ($get,$put,$parse) = Net::DNS::ToolKit::RR->new(C_IN);

The generic form of a put operation then becomes:


The only class currently supported at this time is C_IN.

NOTE: the use of this alternate method changes the number of required arguments to ALL put RR operations. These changes are NOT noted below in the method descriptions.


Net::DNS::ToolKit::RR is the class loader for Resource Record classes. It provides an extensible wrapper for existing classes as well as the framework to easily add new RR classes. See: Net::DNS::ToolKit::RR::Template

  From RFC 1035

  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.
  • ($get,$put,$parse) = new Net::DNS::ToolKit::RR;

    Retrieves the method pointers to get, put, and parse for Queston section and Resource Records of a particular type.

  • ($newoff,@common,$rdata,...) = $get->next(\$buffer,$offset);

    Get the next Resource Record.

      input:        pointer to buffer,
                    offset into buffer
      returns:      offset to next RR or section,
                    (items common to all RR's)
       i.e. $name,$type,$class,$ttl,$rdlength,
                    $rdata,.... for this RR
                or  undef if the RR is unsupported.

    HERE IS THE OPPORTUNITY FOR YOU TO ADD TO THIS PACKAGE. If your RR of interest is not supported, see:

      Net::DNS::ToolKit::RR::Template in:

    Build the support for your Resource Record and submit it to CPAN as an extension to this package.

    UN-IMPLEMENTED methods: $get->[unimplemented] returns a correct offset to the following RR, correct @common data and a single $rdata element containing a null ... "\0" to be precise. This works as either a numeric 0 (zero) or an end of string.

  • ($newoff,@dnptrs)=$put->XYZ(\$buffer,$offset,\@dnptrs, $name,$type,$class,$ttl,$rdata,...);

    Append a resource record of type XYZ to the current buffer. This is the generic form of a put.

      input:        pointer to buffer,
                    offset, [should be end of buffer]
                    pointer to compressed name array,
                    (items common to all RR's)
       i.e. $name,$type,$class,$ttl,
                    $rdata,.... for this RR
                    in binary form if appropriate
      returns:      offset to end of RR,
                    new pointer array,
               or   empty list if the RR type is
      See: note above about writing new RR's

    UN-IMPLEMENTED methods: $put->[unimplemented] fails miserably with a DIE statement identifying the offending method.

  • (@COMMON,$RDATA) = $parse->XYZ(@common,$rdata,...);

    Convert non-printable and numeric data common to all records and the RR specific rdata into ascii text. In many cases this is a null operation. i.e. for a TXT record. However, for a RR of type A, the operation would be as follows:

      name       is already text.
      type       numeric to text
      class      numeric to text
      ttl        numeric to text
      rdlength   is a number
      rdata      RR specific conversion

    Resource Record A returns $rdata containing a packed IPv4 network address. The parse operation would be:


      name       foo.bar.com
      type       1
      class      1
      ttl        123
      rdlength   4
      rdata      a packed IPv4 address


      name       foo.bar.com
      type       T_A
      class      C_IN
      ttl        123 # 2m 3s
      rdlength   4

    The rdata conversion is implemented internally as:

      $dotquad = inet_ntoa($networkaddress);
      where $dotquad is a printable IP address like

    UN-IMPLEMENTED methods: $parse->[unimplemented] returns correct @common elements insofar as the type and class are present in Net::DNS::Codes. Other elements are passed through unchanged. i.e. garbage-in, garbage-out.

  • ($newoff,$name,type,class) = $get->Question(\$buffer,$offset);

      Get the Question.
      input:        pointer to buffer,
      returns:      domain name,
                    question type,
                    question class
  • ($newoff,@dnptrs) = $put->Question(\$buffer,$offset, $name,$type,$class,\@dnptrs);

    Append a question to the $buffer. Returns a new pointer array for compressed names and the offset to the next RR.

    NOTE: it is up to the user to update the question count. See: put_qdcount

    Since the question usually is the first record to be appended to the buffer, @dnptrs may be ommitted. See the details at dn_comp.

    Usage: ($newoff,@dnptrs)=$put->Question(\$buffer,$offset, $name,$type,$class);

      input:        pointer to buffer,
                    offset into buffer,
                    domain name,
                    question type,
                    question class,
                    pointer to array of
                      previously compressed names,
      returns:      offset to next record,
                    updated array of offsets to
                      previous compressed names
  • ($name,$typeTXT,$classTXT) = $parse->Question($name,$type,$class);

    Convert non-printable and numeric data into ascii text.

      input:        domain name,
                    question type (numeric)
                    question class (numeric)
      returns:      domain name,
                    type TEXT,
                    class TEXT






Michael Robinton <michael@bizsystems.com>


    Copyright 2003 - 2011, 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:


See also:

Net::DNS::Codes(3), Net::DNS::ToolKit(3), Net::DNS::ToolKit::RR::Template(3)