Update to the IANA CoAP Content-Formats Registration Procedures
draft-fossati-core-cf-reg-update-03
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| Document | Type | Active Internet-Draft (candidate for core WG) | |
|---|---|---|---|
| Authors | Thomas Fossati , Esko Dijk | ||
| Last updated | 2024-12-11 (Latest revision 2024-12-03) | ||
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draft-fossati-core-cf-reg-update-03
Constrained RESTful Environments T. Fossati
Internet-Draft Linaro
Updates: 7252 (if approved) E. Dijk
Intended status: Standards Track IoTconsultancy.nl
Expires: 6 June 2025 3 December 2024
Update to the IANA CoAP Content-Formats Registration Procedures
draft-fossati-core-cf-reg-update-03
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://thomas-
fossati.github.io/draft-cf-reg-update/draft-fossati-core-cf-reg-
update.html. Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-fossati-core-cf-reg-update/.
Discussion of this document takes place on the Constrained RESTful
Environments Working Group mailing list (mailto:core@ietf.org), which
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Subscribe at https://www.ietf.org/mailman/listinfo/core/.
Source for this draft and an issue tracker can be found at
https://github.com/thomas-fossati/draft-cf-reg-update.
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This Internet-Draft will expire on 6 June 2025.
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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
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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
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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
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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].
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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.
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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
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[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
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Esko Dijk
IoTconsultancy.nl
Email: esko.dijk@iotconsultancy.nl
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