Network Working Group P. Saint-Andre
Internet-Draft Cisco Systems, Inc.
Intended status: Informational May 30, 2013
Expires: December 1, 2013
Instant Messaging and Presence Purpose for the Call-Info Header Field in
the Session Initiation Protocol (SIP)
draft-saintandre-impp-call-info-04
Abstract
This document defines and registers a value of "impp" ("instant
messaging and presence protocol") for the "purpose" header field
parameter of the Call-Info header field in the Session Initiation
Protocol (SIP).
Status of this Memo
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This Internet-Draft will expire on December 1, 2013.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Security Considerations . . . . . . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 3
4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Normative References . . . . . . . . . . . . . . . . . . . 4
4.2. Informative References . . . . . . . . . . . . . . . . . . 4
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
To improve interoperability among real-time communication endpoints
that support the combined use of the Session Initiation Protocol
(SIP) [RFC3261] and the Extensible Messaging and Presence Protocol
(XMPP) [RFC6120] (so-called "CUSAX" endpoints [I-D.ivov-xmpp-cusax]),
it can be helpful to communicate the endpoint's SIP address over XMPP
and the endpoint's XMPP address over SIP to provide hints about the
endpoints communication capabilities. The former feature is enabled
by an XMPP extension protocol called Reachability Addresses
[XEP-0152]. As to the latter feature, discussion in the SIP
community led to the conclusion that it would be best to use the
Call-Info header field [RFC3261] with a value of "impp" ("instant
messaging and presence protocol") for the "purpose" header field
parameter. An example follows.
Call-Info: <xmpp:juliet@example.com> ;purpose=impp
Although CUSAX endpoints constitute the primary use case for the
"impp" purpose, a Uniform Resource Identifier (URI) [RFC3986] for an
instant messaging and presence protocol other than XMPP could be
included in the Call-Info header field.
2. Security Considerations
Advertising an endpoint's XMPP address over SIP could inform
malicious entities about an alternative attack vector. Because the
"purpose" header field parameter could be spoofed, the receiving
endpoint ought to check the value against an authoritative source
such as a user directory. Clients can integrity protect and encrypt
this header field using end-to-end mechanisms such as S/MIME or hop-
by-hop mechanisms such as TLS.
This specification provides a new way to correlate otherwise possibly
unconnected identifiers. Because such correlations can be privacy
sensitive, user agents ought to provide a means for users to control
whether or not these values are sent.
3. IANA Considerations
This document defines and registers a new predefined value "impp" for
the "purpose" header field parameter of the Call-Info header field.
The IANA can complete this action by adding this RFC as a reference
to the line for the header field "Call-Info" and parameter name
"purpose" in the Header Field Parameters and Parameter Values section
of the Session Initiation Protocol (SIP) Parameters registry:
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Header Field: Call-Info
Parameter Name: purpose
Predefined Values: Yes
Reference: [RFC3261][RFC5367][RFC6910][this document]
4. References
4.1. Normative References
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 6120, March 2011.
4.2. Informative References
[I-D.ivov-xmpp-cusax]
Ivov, E., Saint-Andre, P., and E. Marocco, "Combined Use
of the Session Initiation Protocol (SIP) and the
Extensible Messaging and Presence Protocol (CUSAX)",
draft-ivov-xmpp-cusax-05 (work in progress), May 2013.
[XEP-0152]
Saint-Andre, P. and J. Hildebrand, "Reachability
Addresses", XSF XEP 0152, February 2013.
Appendix A. Acknowledgements
Thanks to Gonzalo Camarillo, Keith Drage, Saul Ibarra, Emil Ivov,
Cullen Jennings, Olle Johanssen, Paul Kyzivat, Gonzalo Salgueiro,
Dean Willis, and Dale Worley for their input. Elwyn Davies,
Salvatore Loreto, Glen Zorn, and Mehmet Ersue completed reviews on
behalf of the General Area Review Team, Applications Area
Directorate, Security Directorate, and Operations and Management
Directorate, respectively. Stephen Farrell and Pete Resnick provided
substantive feedback during IESG review. Thanks to Yana Stamcheva
for her helpful comments and for shepherding the document.
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Author's Address
Peter Saint-Andre
Cisco Systems, Inc.
1899 Wynkoop Street, Suite 600
Denver, CO 80202
USA
Phone: +1-303-308-3282
Email: psaintan@cisco.com
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