YANG Types for DNS Classes and Resource Record Types
draft-ietf-dnsop-iana-class-type-yang-04

Document Type Active Internet-Draft (dnsop WG)
Authors Ladislav Lhotka  , Petr Špaček 
Last updated 2021-06-04
Replaces draft-lhotka-dnsop-iana-class-type-yang
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DNSOP Working Group                                            L. Lhotka
Internet-Draft                                                    CZ.NIC
Intended status: Standards Track                               P. Spacek
Expires: 6 December 2021                     Internet Systems Consortium
                                                             4 June 2021

          YANG Types for DNS Classes and Resource Record Types
                draft-ietf-dnsop-iana-class-type-yang-04

Abstract

   This document introduces the YANG module "iana-dns-class-rr-type"
   that contains derived types reflecting two IANA registries: DNS
   CLASSes and Resource Record (RR) TYPEs.  These YANG types are
   intended as a minimum basis for future data modeling work.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 6 December 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  YANG Design Considerations  . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  URI Registrations . . . . . . . . . . . . . . . . . . . .   6
     4.2.  YANG Module Registrations . . . . . . . . . . . . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   7.  Informative References  . . . . . . . . . . . . . . . . . . .   8
   Appendix A.  XSLT Stylesheet  . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   YANG [RFC7950] has become a de facto standard as a language for
   modeling configuration and state data, as well as specifying
   management operations and asynchronous notifications.  It is
   reasonable to expect that the approach based on utilizing such data
   models along with standard management protocols such as
   NETCONF [RFC6241] and RESTCONF [RFC8040] can be effectively used in
   DNS operations, too.  In fact, several efforts are currently underway
   that attempt to use NETCONF or RESTCONF for configuring and managing

   *  authoritative servers

   *  resolvers

   *  zone data.

   While it is possible to use the management protocols mentioned above
   with ad hoc or proprietary data models, their real potential can be
   realized only if there is a (completely or partly) unified data model
   supported by multiple DNS software implementations.  Operators can
   then, for instance, run several DNS server implementations in
   parallel, and use a common configuration and management interface and
   data for all of them.  Also, it becomes considerably easier to
   migrate to another implementation.

   Based on the previous experience from the IETF Routing Area, it is to
   be expected that the development of unified data models for DNS will
   be a lengthy and complicated process that will require active
   cooperation and compromises from the vendors and developers of major
   DNS server platforms.  Nevertheless, it is likely that any DNS-
   related data modeling effort will need to use various DNS parameters
   and enumerations that are specified in several IANA registries.  For
   use with YANG, these parameters and enumerations have to be

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   translated into corresponding YANG types or other structures.  Such
   translations should be straightforward and relatively
   uncontroversial.

   This document provides a translation of two fundamental DNS-related
   IANA registries to YANG.  It contains the initial revision of the
   YANG module "iana-dns-class-rr-type" that defines derived types for
   the common parameters of DNS resource records (RR): class and type.
   These YANG types, "dns-class" and "rr-type", reflect the IANA
   registries "DNS CLASSes" and "Resource Record (RR) TYPEs"
   [IANA-DNS-PARAMETERS].

   Appendix A contains an XSLT 1.0 stylesheet that is intended to be
   used by IANA for generating the initial revision of the "iana-dns-
   class-rr-type" YANG module.  Subsequently, whenever a new class or RR
   type is added to the above registries, IANA will also update the
   "iana-dns-class-rr-type" YANG module, following the instructions in
   Section 4 below.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   The terminology for describing YANG data models can be found in
   [RFC7950].  DNS terminology used in this document can be found in
   [RFC1035] and [RFC8499].

3.  YANG Design Considerations

   At the time of writing, the IANA document "Domain Name System (DNS)
   Parameters" [IANA-DNS-PARAMETERS] contains altogether thirteen
   registries.  The YANG module "iana-dns-class-rr-type" defines derived
   types corresponding to only two of the registries that are essential
   for data models involving zone data, namely "DNS CLASSes" and
   "Resource Record (RR) TYPEs".  It is expected that the remaining
   registries in [IANA-DNS-PARAMETERS], as well as other DNS-related
   IANA registries, will be analogously reflected in future YANG modules
   as necessary.  This way, an appropriate combination of YANG modules
   can be chosen depending on which YANG types are needed for a given
   data modeling purpose.

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   The registries "DNS CLASSes" and "Resource Record (RR) TYPEs" are
   transformed into YANG enumeration types "dns-class-name" and "rr-
   type-name", respectively.  This is the initial fragment of the
   former:

     typedef dns-class-name {
       type enumeration {
         enum IN {
           value 1;
           description
             "Internet (IN)";
           reference
             "RFC 1035";
         }
         ...
       }
       ...
     }

   The other derived type, "rr-type-name", is defined similarly.

   [RFC3597] introduced the option of specifying a class or RR type via
   its assigned decimal number, as an alternative to the mnemonic name.
   For example, the "IN" class can be equivalently written as "CLASS1",
   and "AAAA" type can be written as "TYPE28".

   Accordingly, the derived types "dns-class" and "rr-type" are defined
   in the YANG module as a union of two member types:

   *  16-bit decimal integer ("uint16")

   *  mnemonic name belonging to the enumerations "dns-class-name" and
      "rr-type-name", respectively.

   For instance, the "rr-type" type is defined as follows:

     typedef rr-type {
       type union {
         type uint16;
         type rr-type-name;
       }
       description
         "This type allows for referring to a DNS resource record type
          using either the assigned mnemonic name or numeric value.";
     }

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   As unassigned and reserved class and RR type values are not included
   in the mnemonic name enumerations, they can only be specified using
   their decimal values.

4.  IANA Considerations

   RFC Editor: In this section, replace all occurrences of "XXXX" with
   the actual RFC number (and remove this note).

   This section deals with actions and processes necessary for IANA to
   undertake to maintain the "iana-dns-class-rr-type" YANG module.  This
   YANG module is intended to reflect the "DNS CLASSes" and "Resource
   Record (RR) TYPEs" registries in [IANA-DNS-PARAMETERS].  The most
   recent revision of the YANG module is available from the "YANG
   Parameters" registry [IANA-YANG-PARAMETERS].

   Upon publication of this document, the initial revision of the "iana-
   dns-class-rr-type" YANG module SHALL be created by applying the XSLT
   stylesheet from Appendix A to the XML version of
   [IANA-DNS-PARAMETERS].

   IANA SHALL add this note to the "iana-dns-class-rr-type" item of the
   "YANG Module Names" registry [IANA-YANG-PARAMETERS]:

   |  Classes and types of DNS resource records must not be directly
   |  added to the "iana-dns-class-rr-type" YANG module.  They must
   |  instead be added to the "DNS CLASSes" and "Resource Record (RR)
   |  TYPEs" registries, respectively.

   When a new DNS class or RR type is added to the "DNS CLASSes" or
   "Resource Record (RR) TYPEs" registry, a new "enum" statement SHALL
   be added to the "dns-class-name" or "rr-type-name" type,
   respectively.  The assigned name defined by the "enum" statement
   SHALL be the same as the mnemonic name of the new class or type.  The
   following substatements to the "enum" statement SHALL be defined:

   "value":  Use the decimal value from the registry.

   "status":  Include only if a class or type registration has been
      deprecated or obsoleted.  In both cases, use the value "obsolete"
      as the argument of the "status" statement.

   "description":  Replicate the corresponding information from the
      registry, namely the full name of the new DNS class, or the
      meaning of the new RR type, if any.

   "reference":  Replicate the reference(s) from the registry.

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   Unassigned or reserved values SHALL NOT be included in the "dns-
   class-name" and "rr-type-name" enumeration types.

   Each time the "iana-dns-class-rr-type" YANG module is updated, a new
   "revision" statement SHALL be added before the existing "revision"
   statements.

   IANA SHALL add this new note to the "DNS CLASSes" and "Resource
   Record (RR) TYPEs" registries:

   |  When this registry is modified, the YANG module "iana-dns-class-
   |  rr-type" must be updated as defined in RFC XXXX.

   The "Reference" text in the "DNS CLASSes" registry SHALL be updated
   as follows:

   |     OLD:
   |       [RFC6895]
   |  
   |     NEW:
   |       [RFC6895][RFCXXXX]

   The "Reference" text in the "Resource Record (RR) TYPEs" registry
   SHALL be updated as follows:

   |     OLD:
   |       [RFC6895][RFC1035]
   |  
   |     NEW:
   |       [RFC6895][RFC1035][RFCXXXX]

4.1.  URI Registrations

   This document registers a URI in the "IETF XML Registry" [RFC3688].
   The following registration has been made:

   |     URI: urn:ietf:params:xml:ns:yang:iana-dns-class-rr-type
   |     Registrant Contact: The IESG.
   |     XML: N/A, the requested URI is an XML namespace.

4.2.  YANG Module Registrations

   This document registers a YANG module in the "YANG Module Names"
   registry [RFC6020].  The following registration has been made:

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   |     name:      iana-dns-class-rr-type
   |     namespace: urn:ietf:params:xml:ns:yang:iana-dns-class-rr-type
   |     prefix:    dnsct
   |     reference: RFC XXXX

5.  Security Considerations

   This document translates two IANA registries into YANG data types and
   otherwise introduces no technology or protocol.  The definitions
   themselves have no security impact on the Internet, but their use in
   concrete YANG modules might have.  The security considerations
   spelled out in the YANG specification [RFC7950] apply for this
   document as well.

6.  Normative References

   [IANA-DNS-PARAMETERS]
              Internet Assigned Numbers Authority, "Domain Name System
              (DNS) Parameters",
              <https://www.iana.org/assignments/dns-parameters>.

   [IANA-YANG-PARAMETERS]
              Internet Assigned Numbers Authority, "YANG Parameters",
              <https://www.iana.org/assignments/yang-parameters>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

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   [W3C.REC-xslt-19991116]
              Clark, J., "XSL Transformations (XSLT) Version 1.0", World
              Wide Web Consortium Recommendation REC-xslt-19991116, 16
              November 1999,
              <https://www.w3.org/TR/1999/REC-xslt-19991116>.

7.  Informative References

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
              November 1987, <https://www.rfc-editor.org/info/rfc1035>.

   [RFC3597]  Gustafsson, A., "Handling of Unknown DNS Resource Record
              (RR) Types", RFC 3597, DOI 10.17487/RFC3597, September
              2003, <https://www.rfc-editor.org/info/rfc3597>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8499]  Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
              Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
              January 2019, <https://www.rfc-editor.org/info/rfc8499>.

Appendix A.  XSLT Stylesheet

   RFC Editor: In this section, replace all occurrences of "XXXX" with
   the actual RFC number (and remove this note).

   This appendix contains an XSLT 1.0 stylesheet [W3C.REC-xslt-19991116]
   that is intended to be used for generating the initial revision of
   the "iana-dns-class-rr-type" YANG module.  This is achieved by
   applying the stylesheet to the XML version of the IANA registry
   "Domain Name System (DNS) Parameters" [IANA-DNS-PARAMETERS] that was
   current at the time when this document was published.

   Using the ubiquitous xsltproc tool, the YANG module text can be
   generated with this command:

       $ xsltproc iana-dns-class-rr-type.xsl dns-parameters.xml

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   <CODE BEGINS> file "iana-dns-class-rr-type.xsl"
   <?xml version="1.0" standalone="yes"?>
   <stylesheet xmlns="http://www.w3.org/1999/XSL/Transform"
               xmlns:iana="http://www.iana.org/assignments"
               version="1.0">
     <output method="text"/>
     <strip-space elements="*"/>

     <variable name="dq">"</variable>
     <variable name="sq">'</variable>

     <variable name="module-intro">
       <text>module iana-dns-class-rr-type {
     yang-version 1.1;
     namespace
       "urn:ietf:params:xml:ns:yang:iana-dns-class-rr-type";
     prefix dnsct;

     organization
       "Internet Assigned Numbers Authority (IANA)";

     contact
       "        Internet Assigned Numbers Authority

        Postal: ICANN
                4676 Admiralty Way, Suite 330
                Marina del Rey, CA 90292

        Tel:    +1 310 823 9358

        &lt;mailto:iana@iana.org&gt;";

     description
       "This YANG module translates IANA registries 'DNS CLASSes' and
        'Resource Record (RR) TYPEs' to YANG derived types.

        Copyright (c) 2020 IETF Trust and the persons identified as
        authors of the code. All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject to
        the license terms contained in, the Simplified BSD License set
        forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        This initial version of this YANG module was generated from
        the corresponding IANA registries using an XSLT stylesheet

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        from Appendix A of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
        for full legal notices.";

     reference
       "IANA 'Domain Name System (DNS) Parameters' registry
        https://www.iana.org/assignments/dns-parameters";</text>
        <text>&#xA;&#xA;</text>
     </variable>

     <template name="enum">
       <param name="id"/>
       <value-of select="concat('      enum ', $id)"/>
       <text> {&#xA;        value </text>
       <value-of select="concat(iana:value, ';&#xA;')"/>
       <if test="contains(iana:description, 'OBSOLETE')">
         <text>        status obsolete;&#xA;</text>
       </if>
       <apply-templates select="iana:description"/>
       <variable name="xrefs" select="iana:xref[@type!='note']"/>
       <if test="$xrefs">
         <text>        reference&#xA;          "</text>
         <if test="count($xrefs)&gt;1">- </if>
         <apply-templates select="iana:xref[@type!='note']"/>
       </if>
       <text>      }&#xA;</text>
     </template>

     <template match="/">
       <value-of select="$module-intro"/>
       <apply-templates select="iana:registry[@id='dns-parameters']"/>
       <text>}&#xA;</text>
     </template>

     <template match="iana:registry[@id='dns-parameters']">
       <apply-templates select="iana:updated"/>
       <apply-templates
           select="iana:registry[@id='dns-parameters-2']"/>
       <apply-templates
           select="iana:registry[@id='dns-parameters-4']"/>
     </template>

     <template match="iana:updated">
       <value-of select="concat('  revision ', ., ' {')"/>
       <text>
       description
         "Initial revision.";
       reference

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         "RFC XXXX: YANG Types for DNS Classes and Resource Record
          Types";
     }

     /* Typedefs */&#xA;&#xA;</text>
     </template>

     <template match="iana:registry[@id='dns-parameters-2']">
       <text>  typedef dns-class-name {&#xA;</text>
       <text>    type enumeration {&#xA;</text>
       <apply-templates
           select="iana:record[not(iana:description='Unassigned' or
                   starts-with(iana:description,'Reserved'))]"
           mode="class"/>
       <text>    }
       description
         "This enumeration type defines mnemonic names and corresponding
          numeric values of DNS classes.";
       reference
         "RFC 6895: Domain Name System (DNS) IANA Considerations";
     }

     typedef dns-class {
       type union {
         type uint16;
         type dns-class-name;
       }
       description
         "This type allows for referring to a DNS class using either the
          assigned mnemonic name or numeric value.";
     }&#xA;&#xA;</text>
     </template>

     <template match="iana:registry[@id='dns-parameters-4']">
       <text>  typedef rr-type-name {&#xA;</text>
       <text>    type enumeration {&#xA;</text>
       <apply-templates
           select="iana:record[iana:type!='Unassigned' and
                   iana:type!='Private use' and iana:type!='Reserved']"
           mode="rr-type"/>
       <text>    }
       description
         "This enumeration type defines mnemonic names and corresponding
          numeric values of DNS resource record types.";
       reference
         "- RFC 6895: Domain Name System (DNS) IANA Considerations

          - RFC 1035: Domain Names - Implementation and Specification";

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     }

     typedef rr-type {
       type union {
         type uint16;
         type rr-type-name;
       }
       description
         "This type allows for referring to a DNS resource record type
          using either the assigned mnemonic name or numeric value.";
     }&#xA;</text>
     </template>

     <template match="iana:record" mode="class">
       <call-template name="enum">
         <with-param name="id">
           <choose>
             <when test="contains(iana:description,'(')">
               <value-of select="substring-before(substring-after(
                                 iana:description, '('), ')')"/>
             </when>
             <otherwise>
               <value-of
                   select="substring-after(iana:description, ' ')"/>
             </otherwise>
           </choose>
         </with-param>
       </call-template>
     </template>

     <template match="iana:record" mode="rr-type">
       <call-template name="enum">
         <with-param name="id" select="iana:type"/>
       </call-template>
     </template>

     <template match="iana:description">
       <text>        description&#xA;          </text>
       <value-of select="concat($dq, ., $dq, ';&#xA;')"/>
     </template>

     <template match="iana:xref">
       <choose>
         <when test="@type='rfc'">
           <value-of
               select="concat('RFC ', substring-after(@data, 'rfc'))"/>
         </when>
         <when test="@type='person'">

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           <apply-templates
               select="/iana:registry/iana:people/iana:person[
                       @id=current()/@data]"/>
         </when>
         <when test="@type='text'">
           <value-of select="translate(., $dq, $sq)"/>
         </when>
         <otherwise>
           <value-of select="@data"/>
         </otherwise>
       </choose>
       <choose>
         <when test="position()=last()">
           <text>";&#xA;</text>
         </when>
         <otherwise>
           <text>&#xA;           - </text>
         </otherwise>
       </choose>
     </template>

     <template match="iana:person">
       <value-of select="concat(iana:name, ' &lt;', iana:uri, '&gt;')"/>
     </template>

   </stylesheet>
   <CODE ENDS>

Authors' Addresses

   Ladislav Lhotka
   CZ.NIC
   Czech Republic

   Email: ladislav.lhotka@nic.cz

   Petr Spacek
   Internet Systems Consortium
   Czech Republic

   Email: pspacek@isc.org

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