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diff --git a/doc/rfc/rfc9108.txt b/doc/rfc/rfc9108.txt new file mode 100644 index 0000000..0aa1e8f --- /dev/null +++ b/doc/rfc/rfc9108.txt @@ -0,0 +1,608 @@ + + + + +Internet Engineering Task Force (IETF) L. Lhotka +Request for Comments: 9108 CZ.NIC +Category: Standards Track P. Špaček +ISSN: 2070-1721 Internet Systems Consortium + September 2021 + + + YANG Types for DNS Classes and Resource Record Types + +Abstract + + This document introduces the YANG module "iana-dns-class-rr-type", + which contains derived types reflecting two IANA registries: DNS + CLASSes and Resource Record (RR) TYPEs. These YANG types are + intended as the minimum basis for future data modeling work. + +Status of This Memo + + This is an Internet Standards Track document. + + This document is a product of the Internet Engineering Task Force + (IETF). It represents the consensus of the IETF community. It has + received public review and has been approved for publication by the + Internet Engineering Steering Group (IESG). Further information on + Internet Standards is available in Section 2 of RFC 7841. + + Information about the current status of this document, any errata, + and how to provide feedback on it may be obtained at + https://www.rfc-editor.org/info/rfc9108. + +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. + +Table of Contents + + 1. Introduction + 2. Terminology + 3. YANG Design Considerations + 4. IANA Considerations + 4.1. URI Registrations + 4.2. YANG Module Registrations + 5. Security Considerations + 6. References + 6.1. Normative References + 6.2. Informative References + Appendix A. XSLT Stylesheet + Authors' Addresses + +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, and + + * 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 compromise 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 + 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 version of the YANG + module "iana-dns-class-rr-type", which 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 version 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 "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. + + 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 reference to a DNS resource record type + using either the assigned mnemonic name or numeric value."; + } + + 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 + + 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 version of the YANG module is available from the "YANG + Parameters" registry [IANA-YANG-PARAMETERS]. + + With the publication of this document, IANA has created and posted + the initial version of the "iana-dns-class-rr-type" YANG module by + applying the XSLT stylesheet from Appendix A to the XML version of + [IANA-DNS-PARAMETERS]. + + IANA has added 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. IANA "deprecated" maps to + YANG status "deprecated", and IANA "obsolete" maps to + YANG status "obsolete". + + "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. + + 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 has added this 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 [RFC9108]. + + The "Reference" text in the "DNS CLASSes" registry has been updated + as follows: + + OLD: + + | [RFC6895] + + NEW: + + | [RFC6895][RFC9108] + + The "Reference" text in the "Resource Record (RR) TYPEs" registry has + been updated as follows: + + OLD: + + | [RFC6895][RFC1035] + + NEW: + + | [RFC6895][RFC1035][RFC9108] + +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: + + Name: iana-dns-class-rr-type + Namespace: urn:ietf:params:xml:ns:yang:iana-dns-class-rr-type + Prefix: dnsct + Reference: RFC 9108 + +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 to this + document as well. + +6. References + +6.1. Normative References + + [IANA-DNS-PARAMETERS] + IANA, "Domain Name System (DNS) Parameters", + <https://www.iana.org/assignments/dns-parameters>. + + [IANA-YANG-PARAMETERS] + IANA, "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>. + + [W3C.REC-xslt-19991116] + Clark, J., "XSL Transformations (XSLT) Version 1.0", W3C + Recommendation REC-xslt-19991116, November 1999, + <https://www.w3.org/TR/1999/REC-xslt-19991116>. + +6.2. 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 + + This appendix contains an XSLT 1.0 stylesheet [W3C.REC-xslt-19991116] + that is to be used to generate 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 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 + + <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 + 12025 Waterfront Drive, Suite 300 + Los Angeles, CA 90094 + + Tel: +1 424 254 5300 + + <mailto:iana@iana.org>"; + + description + "This YANG module translates IANA registries 'DNS CLASSes' and + 'Resource Record (RR) TYPEs' to YANG-derived types. + + Copyright (c) 2021 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 version of this YANG module was generated from + the corresponding IANA registries using an XSLT stylesheet + from Appendix A of RFC 9108 + (https://www.rfc-editor.org/info/rfc9108); 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>

</text> + </variable> + + <template name="enum"> + <param name="id"/> + <value-of select="concat(' enum ', $id)"/> + <text> {
 value </text> + <value-of select="concat(iana:value, ';
')"/> + <if test="contains(iana:description, 'OBSOLETE')"> + <text> status obsolete;
</text> + </if> + <apply-templates select="iana:description"/> + <variable name="xrefs" select="iana:xref[@type!='note']"/> + <if test="$xrefs"> + <text> reference
 "</text> + <if test="count($xrefs)>1">- </if> + <apply-templates select="iana:xref[@type!='note']"/> + </if> + <text> }
</text> + </template> + + <template match="/"> + <value-of select="$module-intro"/> + <apply-templates select="iana:registry[@id='dns-parameters']"/> + <text>}
</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 + "RFC 9108: YANG Types for DNS Classes and Resource Record + Types"; + } + + /* Typedefs */

</text> + </template> + + <template match="iana:registry[@id='dns-parameters-2']"> + <text> typedef dns-class-name {
</text> + <text> type enumeration {
</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 reference to a DNS class using either the + assigned mnemonic name or numeric value."; + }

</text> + </template> + + <template match="iana:registry[@id='dns-parameters-4']"> + <text> typedef rr-type-name {
</text> + <text> type enumeration {
</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"; + } + + typedef rr-type { + type union { + type uint16; + type rr-type-name; + } + description + "This type allows reference to a DNS resource record type + using either the assigned mnemonic name or numeric value."; + }
</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
 </text> + <value-of select="concat($dq, ., $dq, ';
')"/> + </template> + + <template match="iana:xref"> + <choose> + <when test="@type='rfc'"> + <value-of + select="concat('RFC ', substring-after(@data, 'rfc'))"/> + </when> + <when test="@type='person'"> + <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>";
</text> + </when> + <otherwise> + <text>
 - </text> + </otherwise> + </choose> + </template> + + <template match="iana:person"> + <value-of select="concat(iana:name, ' <', iana:uri, '>')"/> + </template> + + </stylesheet> + <CODE ENDS> + +Authors' Addresses + + Ladislav Lhotka + CZ.NIC + Czech Republic + + Email: ladislav.lhotka@nic.cz + + + Petr Špaček + Internet Systems Consortium + Czech Republic + + Email: pspacek@isc.org |