Constrained RESTful Environments T. Fossati
Internet-Draft Linaro
Updates: 7252 (if approved) E. Dijk
Intended status: Standards Track IoTconsultancy.nl
Expires: 24 May 2025 20 November 2024
Update to the IANA CoAP Content-Formats Registration Procedures
draft-fossati-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://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
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/thomas-fossati/draft-cf-reg-update.
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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 . . . . . . . . . . . 3
3.3. The Media Type Parameter Value is Invalid . . . . . . . . 4
3.4. The Content Coding is Unknown . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 6
6.2. Informative References . . . . . . . . . . . . . . . . . 6
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
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
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
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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 C-F ID for an unknown media type:
+==========================+================+=======+
| Content Type | Content Coding | ID |
+==========================+================+=======+
| application/unknown+cbor | - | 64999 |
+--------------------------+----------------+-------+
Table 1: Attempt at Registering C-F for an
Unknown Media Type
3.2. The Media Type Parameter is Unknown
The registrant requests an FCFS C-F ID for an existing media type
with an unknown parameter:
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+=======================================+================+=======+
| Content Type | Content Coding | ID |
+=======================================+================+=======+
| application/cose; unknown-parameter=1 | - | 64999 |
+---------------------------------------+----------------+-------+
Table 2: Attempt at Registering C-F for Media Type with
Unknown Parameter
3.3. The Media Type Parameter Value is Invalid
The registrant requests an FCFS C-F 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 C-F for Media Type with
Invalid Parameter Value
3.4. The Content Coding is Unknown
The registrant requests an FCFS C-F 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 C-F with
Unknown Content Coding
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 updated as follows:
+=============+=======================================+
| Range | Registration Procedures |
+=============+=======================================+
| 0-255 | Expert Review (Full) |
+-------------+---------------------------------------+
| 256-9999 | IETF Review or IESG Approval |
+-------------+---------------------------------------+
| 10000-64999 | Expert Review (Expert Check: FCFS+) |
+-------------+---------------------------------------+
| 65000-65535 | Experimental use (no operational use) |
+-------------+---------------------------------------+
Table 5: Updated CoAP Content-Formats Registration
Procedures
The DE checks consist of the following steps:
1. The content-type associated with the requested Content-Format
must be associated with an already registered CoAP Content-
Format;
2. The media type associated with the requested Content-Format must
exist in the "Media Types" registry [IANA.media-types], or IANA
has approved its registration;
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 in the "HTTP
Content Coding Registry" of the "Hypertext Transfer Protocol
(HTTP) Parameters" [IANA.http-parameters], or IANA has approved
its registration.
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 new "Expert Review (Expert Check:
FCFS+)" policy that applies to the 10000-64999 range. For the 0-255
range, the DE must also evaluate the requested codepoint in relation
to the limited availability of the 1-byte codepoint space. For the
10000-64999 range, this critierion does not apply.
6. References
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6.1. Normative References
[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 Carsten Bormann, Francesca Palombini and Marco Tiloca for
your reviews and comments.
Authors' Addresses
Thomas Fossati
Linaro
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Email: thomas.fossati@linaro.org
Esko Dijk
IoTconsultancy.nl
Email: esko.dijk@iotconsultancy.nl
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