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Versions: 00 01 02                                                      
INTERNET-DRAFT                                   Donald E. Eastlake, 3rd
                                                                     IBM
Expires December 1999                                          June 1999




                    The Kitchen Sink Resource Record
                    --- ------- ---- -------- ------

                         Donald E. Eastlake 3rd



Status of This Document

   This draft, file name draft-ietf-dnsind-kitchen-sink-00.txt, is
   intended to be become a Proposed Standard RFC.  Distribution of this
   document is unlimited. Comments should be sent to
   <namedroppers@internic.net> or to the author.

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.  Internet-Drafts are working
   documents of the Internet Engineering Task Force (IETF), its areas,
   and its working groups.  Note that other groups may also distribute
   working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months.  Internet-Drafts may be updated, replaced, or obsoleted by
   other documents at any time.  It is not appropriate to use Internet-
   Drafts as reference material or to cite them other than as a
   ``working draft'' or ``work in progress.''

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  http://www.ietf.org/ietf/1id-abstracts.txt

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  http://www.ietf.org/shadow.html.


   To view the entire list of current Internet-Drafts, please check the
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Abstract

   Periodically people are seized with a desire to put proprietary,
   complex, and/or obscure data into the Domain Name System (DNS).  This
   draft defines a kitchen sink Resource Record that will satisfy this
   desire for the storage of miscellaneous structured information.








D. Eastlake 3rd                                                 [Page 1]


INTERNET-DRAFT                          The Kitchen Sink Resource Record


Acknowledgements

   The suggestions of the following persons have improved this document
   and they are gratefully acknowledged:

            Rob Austein
            Johnny Eriksson
            Michael A. Patton



Table of Contents

      Status of This Document....................................1
      Abstract...................................................1

      Acknowledgements...........................................2
      Table of Contents..........................................2

      1. Introduction............................................3
      2. Kitchen Sink Resource Record............................3
      2.1 The Meaning Octet......................................4
      2.2 The Coding and Subcoding Octets........................5
      2.2.1 ASN.* Subcodings.....................................7
      2.2.2 MIME Subcodings......................................7
      2.2.3 Text Subcodings......................................8
      3. Master File Representation..............................8
      4. Performance Considerations..............................9
      5. Security Considerations.................................9
      6. IANA Considerations.....................................9

      References................................................10

      Author's Address..........................................11
      Expiration and File Name..................................11

















D. Eastlake 3rd                                                 [Page 2]


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1. Introduction

   The Domain Name System (DNS) provides a replicated distributed secure
   hierarchical database which stores "resource records" (RRs) under
   hierarchical domain names.  This data is structured into zones which
   are independently maintained.  [RFC 1034, 1035]

   Numerous types of RRs have been defined.  These support such critical
   functions as host name to address translation (A, AAAA, etc.  RRs),
   automatic mail routing (MX etc. RRs), and other functions. In
   addition, there are RRs defined related to the zone structure and
   administration of the DNS (SOA, NS, and RP RRs), security (SIG, KEY,
   and NXT RRs), etc.  There is a TXT RR for the inclusion of general
   human readable text.

   New RRs that are reasonably spar tan and designed with some care are
   periodically added via the IETF standards process as new needs become
   apparent.  But there are periodically people who want to put some
   prorietary, complex and/or large structured data in the DNS.  They
   frequently come up with some way of reinterpreting the TXT RR, since
   that is one of the least constrained RR.  This is likely a bad idea
   since all previous ways to reinterpreting the TXT RR have sunk
   without a trace.  (Well, if they actually got an RFC out, it's still
   there, but, practically speaking, nobody actually uses it.)

   If a new type of data is strongly needed for common interoperable use
   in the DNS, the best course is to design a new RR that efficiently
   meets the need through the IETF standards process.  This draft
   defines an extremely general and flexible RR which can be used for
   other data, such as proprietary data where global interoperability is
   not a consideration.  It includes representations of OSI ASN.1, MIME,
   XML, and, recursively, DNS RRs.




2. Kitchen Sink Resource Record

   The symbol for the kitchen sink resource record is SINK.  Its type
   number is <TBA>.

   The RDATA portion of the SINK RR is structured as follows:










D. Eastlake 3rd                                                 [Page 3]


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                                          1  1  1  1  1  1
            0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
          +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
          |        meaning        |        coding         |
          +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
          |       subcoding       |                       /
          +--+--+--+--+--+--+--+--+                       /
          /                             data              /
          /                                               /
          +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

   The "meaning", "coding", and "subcoding" octets are always present.
   The "data" portion is variable length and could be null in some
   cases.  The size of the "data" portion can always be determined by
   subtracting 2 from the SINK resource record RDLENGTH.  The coding
   octet gives the general structure of the data.  The subcoding octet
   provides additional information depending on the value of the coding
   nibble.

   [The primary objection to the previous version of this draft (draft-
   eastlake-kitchen-sink-05.txt) which I do not feel is answered by
   revision is as follows: If several different uses of SINK become
   popular, then DNS retrievals, which are based on RR type only, will
   get them all possibly resulting in wasted transfer bandwidth,
   unnecessary TCP (as opposed to UDP) transfers, etc.

   I do not think this will be a serious problem and if it becomes one,
   future changes can be made such as a special DNS "extended query"
   that allows finer specification.

   The only alternative I have thought of is to allocate a block of RR
   types to SINK.  Then determine the actual RR type to use based on a
   hash of the meaning, coding, and subcoding octets and of any prefixes
   in the "data" fields based on those octets.  But this would not
   guarantee that two or more popular SINK RRs wouldn't collide.]



2.1 The Meaning Octet

   The meaning octet indicates whether any semantic labeling appears at
   the beginning of the data field and the format of such semantic
   labeling.  This contrasts with the coding and subcoding octets which
   merely indicate format.

   The types of labels available are chosen to be globally unique and
   under the control of some "owner".  The owner designates the meaning
   associated with the labels they control.  Where the label is a URI,
   it is recommended that a retrieval from the URI fetch material that
   would be helpful in determining this meaning.  No a priori method is


D. Eastlake 3rd                                                 [Page 4]


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   defined for determining the meaning of other labels other than an out
   of band to the owner.

        INITIAL ASSIGNED MEANING VALUES

     0 - reserved.

     1 - none.
     2 - OID.
     3 - domain name.
     4 - URI.

     5-254 - available for assignment, see section 6.

     255 - reserved.

   A meaning octet value of 1 indicates that there is no semantic
   labeling at the beginning of the data area.  The information,
   whatever it is, coded according to the coding and subcoding octets,
   starts at the beginning of the data field.

   Meaning octet values of 2, 3, or 4, indicate, on the other hand, that
   a semantic label is present.  A value of two indicates that a BER
   [BER] encoded OID appears prefixed by an OID length count as a single
   unsigned octet.  A value of three indicates that a DNS domain name
   appears in wire format with name compression prohibited.  And a value
   of four indicates that a null octet terminated URI appears.



2.2 The Coding and Subcoding Octets

   The coding octet gives the major method by which the data in the data
   field is encoded.  It should always have a meaningful value.  The
   subcoding octet is intended to give additional coding details.
   Although the subcoding octet is always present, it must be
   interpreted in the context of the coding octet.  For any coding octet
   value which does not specify subcoding octet value meanings, the
   subcoding octet MUST be ignored and SHOULD be zero.

   While not explicitly mentioned below, the data field will actually
   start with a semantic label is indicated by the meaning octet.  If
   such a semantic label is present, any data prefix required by the
   coding or subcoding octet.








D. Eastlake 3rd                                                 [Page 5]


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   CODING OCTET VALUES

        0 - reserved.

        1 - ASN.1.  See section 2.2.1.

        2 - DNS RRs. The data portion consists of DNS resource records
        as they would be transmitted in a DNS response section.  The
        subcoding octet is the number of RRs in the data area as an
        unsigned integer.  Domain names may be compressed via pointers
        as in DNS replies.  The origin for the pointers is the beginning
        of the RDATA section of the SINK RR.  Thus the SINK RR is safe
        to cache since only code that knows how to parse the data
        portion of a SINK RR need know of and can expand these
        compressions.

        3 - MIME structured data [RFC 2045, 2046].  The data portion is
        a MIME structured message.  The "MIME-Version:" header line may
        be omitted unless the version is other than "1.0".  The top
        level Content-Transfer-Encoding may be encoded into the
        subcoding octet (see section 2.2.2).  Note that, to some extent,
        the size limitations of DNS RRs may be overcome in the MIME case
        by using the "Content-Type: message/external-body" mechanism.

        4 - Text tagged data.  The data potion consists of text formated
        as specified in the TXT RR except that the first and every
        subsequent odd numbered text item is considered to be a tag
        labeling the immediately following text item.  If there are an
        odd number of text items overall, then the last is considered to
        label a null text item.  Syntax of the tags is as specified in
        RFC 2396 for the "Authority Component" without the two leading
        slashes ("//") or trailing slash using the DNS for authority.
        Thus any organization with a domain name can assign tags without
        fear of conflict.  The subcodings octet specifies the encoding
        of the labeled text items as specified in section 2.2.3.

        5 - HTML.  The subcoding octet indicates the version of HTML.

        6 - XML.  The subcoding octet is not used.

        7-251 - Available for assignment, see section 6.

        252 - Private coding format indicated by an OID.  The format of
        the data portion is indicated by an initial BER encoded OID
        which is prefixed by an OID octet count give as an unsigned
        octet.  The subcoding octet is available for whatever use the
        private formating wishes to make of it.

        253 - Private coding format indicated by a domain name.  The
        format of the data portion is indicated by an initial wire


D. Eastlake 3rd                                                 [Page 6]


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        format domain name with compression prohibited.  The subcoding
        octet is available for whatever use the private formating wishes
        to make of it.

        254 - Private coding format indicated by a URI.  The format of
        the data portion is indicated by an initial URI [RFC 2396] which
        is terminated by a zero valued octet followed by the data with
        that format.  The subcoding octet is available for whatever use
        the private formating wishes to make of it.  The manner in which
        the URL specifies the format is not defined but presumably the
        retriever will recognize the URI.

        255 - reserved.

   NOTE: the existence of a DNS RR coding and the infinite possibilities
   of ASN.*s, XML, and MIME permit one to SINK to even greater depths by
   nesting SINKs.



2.2.1 ASN.* Subcodings

   If the coding octet indicates the data is ASN.1 derived, then the
   data is prefixed by an OID designating the version of ASN.1 used.
   [Can anyone provide the values for the common varieties of ASN.1?]

   For ASN.* data, a specific concrete encoding must be chosen as
   indicated by the subcoding octet.

   ASN.* SUBCODINGS

   0 - reserved.
   1 - BER ( Basic Encoding Rules [BER] ).
   2 - DER ( Distinguished Encoding Rules [DER] ).
   3 - PER ( Packed Encoding Rules ) Aligned.
   4 - PER Unaligned.
   5 - CER ( Canonical Encoding Rules ).
   6-253 - available for assignment, see section 6.
   254 - private.  This subcoding will never be assigned to a standard
        set of encoding rules.  An OID preceded by a one octet unsigned
        length appears at the beginning of the data area after the ASN
        coding OID.
   255 - reserved.



2.2.2 MIME Subcodings

   If the coding octet indicates the data is MIME structured, the
   precise encoding is given by the subcoding octets as listed below.


D. Eastlake 3rd                                                 [Page 7]


INTERNET-DRAFT                          The Kitchen Sink Resource Record


   MIME SUBCODINGS

   0 - reserved, see section 6.
   1 - 7bit.
   2 - 8bit.
   3 - binary.
   4 - quoted-printable.
   5 - base64.
   6 - 253 - available for assignment, see section 6.
   254 - private.  The data portion must start with an "x-" token
        denoting the private content-transfer-encoding immediately
        followed by one null (zero) octet followed by the remainder of
        the MIME object.
   255 - reserved, see section 6.



2.2.3 Text Subcodings

   If the coding octet indicates the data is text, the exact encoding of
   the text items is indicated by the subcoding octet as follows:

   TEXT SUBCODINGS

   0 - reserved, see section 6.
   1 - ASCII.
   2 - UTF-7 [RFC 1642].
   3 - UTF-8 [RFC 2044].
   4 - ASCII with MIME header escapes [RFC 2047].
   5 - 253 - available for assignment, see section 6.
   254 - private.  Each text item must start with a domain name [RFC
        1034] denoting the private text encoding immediately followed by
        one null (zero) octet followed by the remainder of the text
        item.
   255 - reserved, see section 6.



3. Master File Representation

   SINK resource records may appear as lines in zone master files.  The
   meaning, coding, and subcoding appear as unsigned decimal integers.
   The data portion can be quite long.  It is represented in base 64
   [RFC 2045] and may be divided up into any number of white space
   separated substrings, down to single base 64 digits, which are
   concatenated to obtain the full data.  These substrings can span
   lines using the standard parenthesis.  (This type of base64 master
   file data is also required to support the DNS KEY and SIG security
   RRs [RFC 2535] in any case.)



D. Eastlake 3rd                                                 [Page 8]


INTERNET-DRAFT                          The Kitchen Sink Resource Record


4. Performance Considerations

   Currently DNS is optimized for small data transfers, generally not
   exceeding 512 octets including overhead.  Larger transfers are less
   efficient but do work correctly and efforts are underway to make them
   more efficient.

   It is easy to create very large RRs or RR sets using SINK.  DNS
   administrators should think carefully about this and may wish to
   discourage large RRs or RR sets.  Consideration should also be given
   to putting zones from which large RRs or RR sets will be commonly
   retrieved on separate hosts which can be tuned for the load this will
   represent.



5. Security Considerations

   Since the SINK resource record can be used to store arbitrary data in
   the DNS, this data could have security consequences, particularly if
   it is control, executable, macro, or interpretable information or
   very large and might cause buffer overflow.  Due care should be
   taken.  [RFC 2535] covers data original authentication of the data in
   the domain name system including SINK RRs.



6. IANA Considerations

   Assignment of specific meaning to the values listed herein as
   "reserved" requires an IETF standards action.

   All other assignments are by IETF consensus.

   The many provisions for private indicita specified by separately
   allocated OIDs, domain names, or URIs should cover most requirements
   for private or proprietary values.















D. Eastlake 3rd                                                 [Page 9]


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References

   [ASN.1] Abstract Syntax Notation One, C.C.I.T.T. X.208.

   [BER] Basic Encoding Rules for ASN.1, C.C.I.T.T. X.209.

   [DER] Distinguished Encoding Rules for ASN.1, ISO/IEC 8825-1 | ITU-T
   Rec. X.690..

   [RFC 1034] - P. Mockapetris, "Domain names - concepts and
   facilities", 11/01/1987.

   [RFC 1035] - P. Mockapetris, "Domain names - implementation and
   specification", 11/01/1987.

   [RFC 1642] - D. Goldsmith, M. Davis, "UTF-7 - A Mail-Safe
   Transformation Format of Unicode", 07/13/1994.

   [RFC 2044] - F. Yergeau, "UTF-8, a transformation format of Unicode
   and ISO 10646", 10/30/1996.

   [RFC 2045] - N. Freed, N. Borenstein, "Multipurpose Internet Mail
   Extensions (MIME) Part One:  Format of Internet Message Bodies",
   12/02/1996.

   [RFC 2046] - N. Freed, N. Borenstein, "Multipurpose Internet Mail
   Extensions (MIME) Part Two:  Media Types", 12/02/1996.

   [RFC 2047] - K. Moore, "MIME (Multipurpose Internet Mail Extensions)
   Part Three: Message Header Extensions for Non-ASCII Text",
   12/02/1996.

   [RFC 2396] - T.  Berners-Lee, R. Fielding, L. Masinter, "Uniform
   Resource Identifiers (URI): Generic Syntax", August 1998.

   [RFC 2535] - D. Eastlake, "Domain Name System Security Extensions",
   March 1999.















D. Eastlake 3rd                                                [Page 10]


INTERNET-DRAFT                          The Kitchen Sink Resource Record


Author's Address

   Donald E. Eastlake 3rd
   IBM
   65 Shindegan Hill Road
   Carmel, 10512 USA

   Telephone:   +1 914-276-2668 (h)
                +1 914-784-7913 (w)
   FAX:         +1 914-784-3833 (w)
   EMail:       dee3@us.ibm.com



Expiration and File Name

   This draft expires December 1999.

   Its file name is draft-ietf-dnsind-kitchen-sink-00.txt.

































D. Eastlake 3rd                                                [Page 11]