Update to the IANA CoAP Content-Formats Registration Procedures
draft-ietf-core-cf-reg-update-00

Constrained RESTful Environments                              T. Fossati
Internet-Draft                                                    Linaro
Updates: 7252 (if approved)                                      E. Dijk
Intended status: Standards Track                       IoTconsultancy.nl
Expires: 21 June 2025                                   18 December 2024

    Update to the IANA CoAP Content-Formats Registration Procedures
                    draft-ietf-core-cf-reg-update-00

Abstract

   This document updates the registration procedures for the "CoAP
   Content-Formats" registry, within the "CoRE Parameters" registry
   group, defined in Section 12.3 of RFC7252.  Specifically, those
   regarding the First Come First Served (FCFS) portion of the registry.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at https://core-
   wg.github.io/cf-reg-update/draft-ietf-core-cf-reg-update.html.
   Status information for this document may be found at
   https://datatracker.ietf.org/doc/draft-ietf-core-cf-reg-update/.

   Discussion of this document takes place on the Constrained RESTful
   Environments Working Group mailing list (mailto:core@ietf.org), which
   is archived at https://mailarchive.ietf.org/arch/browse/core/.
   Subscribe at https://www.ietf.org/mailman/listinfo/core/.

   Source for this draft and an issue tracker can be found at
   https://github.com/core-wg/cf-reg-update.

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."

Fossati & Dijk            Expires 21 June 2025                  [Page 1]
Internet-Draft  CoAP Content-Format Registrations Update   December 2024

   This Internet-Draft will expire on 21 June 2025.

Copyright Notice

   Copyright (c) 2024 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  (Bad) Examples  . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  The Media Type is Unknown . . . . . . . . . . . . . . . .   3
     3.2.  The Media Type Parameter is Unknown . . . . . . . . . . .   4
     3.3.  The Media Type Parameter Value is Invalid . . . . . . . .   4
     3.4.  The Content Coding is Unknown . . . . . . . . . . . . . .   4
     3.5.  Duplicate Entry with Default Media Type Parameters  . . .   5
     3.6.  Duplicate Entry with Default Content Coding . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
     5.1.  "Full" Expert Review Checks . . . . . . . . . . . . . . .   7
     5.2.  "Lightweight" Expert Review Checks  . . . . . . . . . . .   7
     5.3.  Temporary Note Removal  . . . . . . . . . . . . . . . . .   7
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Section 12.3 of [RFC7252] describes the registration procedures for
   the "CoAP Content-Formats" registry within the "CoRE Parameters"
   registry group [IANA.core-parameters].  (Note that the columns of
   this registry have been revised according to [Err4954].)  In
   particular, the text defines the rules for obtaining CoAP Content-
   Format identifiers from the First Come First Served (FCFS) portion of
   the registry (10000-64999).  These rules do not involve the
   Designated Expert (DE) and are managed solely by IANA personnel to

Fossati & Dijk            Expires 21 June 2025                  [Page 2]
Internet-Draft  CoAP Content-Format Registrations Update   December 2024

   finalize the registration.  Unfortunately, the instructions do not
   explicitly require checking that the combination of content-type
   (i.e., media type with optional parameters) and content coding
   associated with the requested CoAP Content-Format is semantically
   valid.  This task is generally non-trivial, requiring knowledge from
   multiple documents and technologies, which is unfair to demand solely
   from the registrar.  This lack of guidance may engender confusion in
   both the registering party and the registrar, and could eventually
   lead to erroneous registrations.

   Section 5 of this memo updates the registration procedures for the
   "CoAP Content-Formats" registry regarding its FCFS portion to reduce
   the risk of accidental or malicious errors.

2.  Conventions and Definitions

   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.

   This document uses the terms "media type", "content coding",
   "content-type" and "content format" as defined in Section 2 of
   [RFC9193].

3.  (Bad) Examples

   This section contains a few examples of registration requests for a
   CoAP Content-Format with identifier in the FCFS space (64999) that
   should not be allowed to succeed.

3.1.  The Media Type is Unknown

   The registrant requests an FCFS Content-Format ID for an unknown
   media type:

   +==========================+================+=======+
   | Content Type             | Content Coding | ID    |
   +==========================+================+=======+
   | application/unknown+cbor | -              | 64999 |
   +--------------------------+----------------+-------+

       Table 1: Attempt at Registering Content-Format
                 for an Unknown Media Type

Fossati & Dijk            Expires 21 June 2025                  [Page 3]
Internet-Draft  CoAP Content-Format Registrations Update   December 2024

3.2.  The Media Type Parameter is Unknown

   The registrant requests an FCFS Content-Format ID for an existing
   media type with an unknown parameter:

   +=======================================+================+=======+
   | Content Type                          | Content Coding | ID    |
   +=======================================+================+=======+
   | application/cose; unknown-parameter=1 | -              | 64999 |
   +---------------------------------------+----------------+-------+

     Table 2: Attempt at Registering Content-Format for Media Type
                         with Unknown Parameter

3.3.  The Media Type Parameter Value is Invalid

   The registrant requests an FCFS Content-Format ID for an existing
   media type with an invalid parameter value:

   +=====================================+================+=======+
   | Content Type                        | Content Coding | ID    |
   +=====================================+================+=======+
   | application/cose; cose-type=invalid | -              | 64999 |
   +-------------------------------------+----------------+-------+

       Table 3: Attempt at Registering Content-Format for Media
                  Type with Invalid Parameter Value

3.4.  The Content Coding is Unknown

   The registrant requests an FCFS Content-Format ID for an existing
   media type with an unknown content coding, "inflate":

   +========================+================+=======+
   | Content Type           | Content Coding | ID    |
   +========================+================+=======+
   | application/senml+cbor | inflate        | 64999 |
   +------------------------+----------------+-------+

      Table 4: Attempt at Registering Content-Format
               with Unknown Content Coding

Fossati & Dijk            Expires 21 June 2025                  [Page 4]
Internet-Draft  CoAP Content-Format Registrations Update   December 2024

3.5.  Duplicate Entry with Default Media Type Parameters

   The registrant requests an FCFS Content-Format ID for a media type
   that includes a parameter set to its default value.  This media type
   is already registered without that parameter.  As a result, this
   could lead to the creation of two separate Content-Format IDs for the
   same "logical" entry.

   +===================================+================+=======+
   | Content Type                      | Content Coding | ID    |
   +===================================+================+=======+
   | application/my                    | -              | 64900 |
   +-----------------------------------+----------------+-------+
   | application/my; parameter=default | -              | 64999 |
   +-----------------------------------+----------------+-------+

       Table 5: Attempt at Registering an Equivalent Logical
            Entry with a Different Content-Format ID (1)

3.6.  Duplicate Entry with Default Content Coding

   The registrant requests an FCFS Content-Format ID for the "identity"
   Content Coding, which is the default coding.  If accepted, this
   request would duplicate an entry where the "Content Coding" field is
   left empty.

   +================+================+=======+
   | Content Type   | Content Coding | ID    |
   +================+================+=======+
   | application/my | -              | 64900 |
   +----------------+----------------+-------+
   | application/my | identity       | 64999 |
   +----------------+----------------+-------+

        Table 6: Attempt at Registering an
         Equivalent Logical Entry with a
         Different Content-Format ID (2)

4.  Security Considerations

   This memo hardens the registration procedures of CoAP Content-Formats
   in ways that reduce the chances of malicious manipulation of the
   associated registry.

   Other than that, it does not change the Security Considerations of
   [RFC7252].

Fossati & Dijk            Expires 21 June 2025                  [Page 5]
Internet-Draft  CoAP Content-Format Registrations Update   December 2024

5.  IANA Considerations

   The CoAP Content-Formats registration procedures defined in
   Section 12.3 of [RFC7252] are modified as shown in Table 7.

   +============================+==============+======================+
   | Range                      | Registration | Note                 |
   |                            | Procedures   |                      |
   +============================+==============+======================+
   | 0-255                      | Expert       | Full review          |
   |                            | Review       | described in         |
   |                            |              | RFCthis, Section 5.1 |
   +----------------------------+--------------+----------------------+
   | 256-9999                   | IETF Review  |                      |
   |                            | or IESG      |                      |
   |                            | Approval     |                      |
   +----------------------------+--------------+----------------------+
   | 10000-64999 (No parameters | First Come   | Corresponding media  |
   | and empty Content Coding   | First Served | type registration    |
   | and media type not yet     |              | required             |
   | used in this registry)     |              |                      |
   +----------------------------+--------------+----------------------+
   | 10000-64999 (Includes      | Expert       | Lightweight review   |
   | parameters and/or Content  | Review       | described in         |
   | Coding)                    |              | RFCthis, Section 5.2 |
   +----------------------------+--------------+----------------------+
   | 65000-65535                | Experimental |                      |
   |                            | use (no      |                      |
   |                            | operational  |                      |
   |                            | use)         |                      |
   +----------------------------+--------------+----------------------+

      Table 7: Updated CoAP Content-Formats Registration Procedures

   The 10000-64999 range now has two separate registration procedures.
   If the registration consists solely of a registered media type name
   in the "Content Type" field, without any parameter names or "Content
   Coding", and the media type has not yet been used in this registry,
   then the policy is FCFS, as before.  In all other cases, the policy
   will be Expert Review, following the checklist described in
   Section 5.2.

   A new column with the title "Note" has been added to the registry,
   which contains information about expected checks.

Fossati & Dijk            Expires 21 June 2025                  [Page 6]
Internet-Draft  CoAP Content-Format Registrations Update   December 2024

5.1.  "Full" Expert Review Checks

   The registration procedure for the 0-255 range has been slightly
   modified -- from "Expert Review" to "Expert Review (Full)" -- to
   clearly distinguish it from the "lightweight" Expert Review that may
   apply to the 10000-64999 range.  For the 0-255 range, in addition to
   the checks described in Section 5.2, the DE must also evaluate the
   requested codepoint concerning the limited availability of the 1-byte
   codepoint space.  For the 10000-64999 range, this criterion does not
   apply.

5.2.  "Lightweight" Expert Review Checks

   The "lightweight" Designated Expert review checklist for the CoAP
   Content-Formats registry consists of the following steps:

   1.  The combination of content-type and content coding for which the
       registration is requested must not be already present in the
       "CoAP Content-Formats" registry;

   2.  The media type associated with the requested Content-Format must
       exist (or must have been approved for registration) in the "Media
       Types" registry [IANA.media-types];

   3.  The optional parameter names must exist in association with the
       media type, and any parameter values associated with such
       parameter names are as expected;

   4.  If a Content Coding is specified, it must exist (or must have
       been approved for registration) in the "HTTP Content Coding
       Registry" of the "Hypertext Transfer Protocol (HTTP) Parameters"
       [IANA.http-parameters].

5.3.  Temporary Note Removal

   The following note has been added to the registry as a temporary fix:

      "Note: The validity of the combination of Content Coding, Content
      Type and parameters is checked prior to assignment."

   IANA is instructed to remove it when the this document is approved
   for publication.

6.  References

6.1.  Normative References

Fossati & Dijk            Expires 21 June 2025                  [Page 7]
Internet-Draft  CoAP Content-Format Registrations Update   December 2024

   [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/rfc/rfc2119>.

   [RFC7252]  Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
              Application Protocol (CoAP)", RFC 7252,
              DOI 10.17487/RFC7252, June 2014,
              <https://www.rfc-editor.org/rfc/rfc7252>.

   [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/rfc/rfc8174>.

6.2.  Informative References

   [Err4954]  RFC Errata Report 4954, RFC 7252,
              <https://www.rfc-editor.org/errata/eid4954>.

   [IANA.core-parameters]
              IANA, "Constrained RESTful Environments (CoRE)
              Parameters",
              <https://www.iana.org/assignments/core-parameters>.

   [IANA.http-parameters]
              IANA, "Hypertext Transfer Protocol (HTTP) Parameters",
              <https://www.iana.org/assignments/http-parameters>.

   [IANA.media-types]
              IANA, "Media Types",
              <https://www.iana.org/assignments/media-types>.

   [RFC9193]  Keränen, A. and C. Bormann, "Sensor Measurement Lists
              (SenML) Fields for Indicating Data Value Content-Format",
              RFC 9193, DOI 10.17487/RFC9193, June 2022,
              <https://www.rfc-editor.org/rfc/rfc9193>.

Acknowledgments

   Thank you Amanda Baber, Carsten Bormann, Francesca Palombini and
   Marco Tiloca for your reviews, comments, suggestions and fixes.

Authors' Addresses

   Thomas Fossati
   Linaro
   Email: thomas.fossati@linaro.org

Fossati & Dijk            Expires 21 June 2025                  [Page 8]
Internet-Draft  CoAP Content-Format Registrations Update   December 2024

   Esko Dijk
   IoTconsultancy.nl
   Email: esko.dijk@iotconsultancy.nl

Fossati & Dijk            Expires 21 June 2025                  [Page 9]