SIPCORE Working Group
Internet Engineering Task Force (IETF) R. Sparks
Request for Comments: 9366 March 2023
Updates: 3326 (if approved)
Intended status:
Category: Standards Track
Expires: 24 February 2023
ISSN: 2070-1721
Multiple SIP Reason Header Field Values
draft-ietf-sipcore-multiple-reasons-01
Abstract
The SIP Reason Header Field header field as defined in RFC 3326 allows only one
Reason value per protocol value. Experience with more recently
defined protocols shows it is useful to allow multiple values with
the same protocol value. This update to document updates RFC 3326 allows to allow
multiple values for an indicated registered protocol when that
protocol defines what the presence of multiple values means.
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 an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of six months RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained 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 24 February 2023.
https://www.rfc-editor.org/info/rfc9366.
Copyright Notice
Copyright (c) 2022 2023 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)
(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 . . . . . . . . . . . . . . . . . 2
3. Update to RFC3326 . . . . . . . . . . . . . . . . . . . . . . 3 RFC 3326
4. Security Considerations . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 3
6.1. Normative References . . . . . . . . . . . . . . . . . . 3
6.2. Informative References . . . . . . . . . . . . . . . . . 4
Appendix A.
Acknowledgments . . . . . . . . . . . . . . . . . . 4
Appendix B. Changelog . . . . . . . . . . . . . . . . . . . . . 4
B.1. 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
B.2. 01 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
The SIP Reason Header Field header field as defined in RFC 3326 allows only one
Reason value per protocol value. Experience with more recently
defined protocols shows it is useful to allow multiple values with
the same protocol value [STIRREASONS]. This update to document updates RFC
3326
allows to allow multiple values for an indicated registered protocol
when that protocol defines what the presence of multiple values
means. It does not change the requirement in RFC 3326 restricting
the header field contents to one value per protocol for those
protocols that do not define what multiple values mean.
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.
3. Update to RFC3326 RFC 3326
The last paragraph of section Section 2 of [RFC3326] is replaced as follows:
OLD:
| A SIP message MAY contain more than one Reason value (i.e.,
| multiple Reason lines), but all of them MUST have different
| protocol values (e.g., one SIP and another Q.850). An
| implementation is free to ignore Reason values that it does not
| understand.
NEW:
| A SIP message MAY contain more than one Reason value (i.e.,
| multiple Reason lines). If the registered protocol for the Reason
| value specifies what it means for multiple values to occur in one
| message, more than one value for that protocol MAY be present.
| Otherwise, there MUST be only one value per protocol provided
| (e.g., one SIP and another Q.850). An implementation is free to
| ignore Reason values that it does not understand.
4. Security Considerations
This document adds no security considerations to the use of SIP. The
security considerations in [RFC3326] and those in any registered
protocols used in Reason header field values should be considered.
5. IANA Considerations
This document has no IANA actions.
6. References
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>.
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3326] Schulzrinne, H., Oran, D., and G. Camarillo, "The Reason
Header Field for the Session Initiation Protocol (SIP)",
RFC 3326, DOI 10.17487/RFC3326, December 2002,
<https://www.rfc-editor.org/rfc/rfc3326>.
<https://www.rfc-editor.org/info/rfc3326>.
[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>. <https://www.rfc-editor.org/info/rfc8174>.
6.2. Informative References
[STIRREASONS]
Wendt, C., "Identity Header Errors Handling", Handling for STIR",
Work in Progress, Internet-Draft, draft-ietf-stir-identity-header-
errors-handling-03, 19 August 2022, draft-ietf-stir-
identity-header-errors-handling-08, 25 February 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-stir-
identity-header-errors-handling-03>.
Appendix A.
identity-header-errors-handling-08>.
Acknowledgments
This text is based on discussions at a STIR working group Working Group interim
meeting. Jean Mahoney and Russ Housley provided suggestions that
vastly improved the first attempts at assembling these words.
Christer Holmberg, Dale Worley, Brian Rosen, Chris Wendt, and Paul
Kyzivat provided constructive discussion during SIPCORE working group Working Group
adoption.
Appendix B. Changelog
(This section to be removed by the RFC editor.)
B.1. 00
* rename draft-sparks to draft-ietf. Add changelog.
B.2. 01
* expand a little on "Practice shows", referring to [STIRREASONS]
Author's Address
Robert Sparks
Email: rjsparks@nostrum.com