draft-saintandre-impp-call-info.xml

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<rfc category="info" ipr="trust200902" docName="draft-saintandre-impp-call-info-04">

  <?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>

  <front>

    <title abbrev="Call-Info Purpose: IMPP">Instant Messaging and Presence Purpose for the Call-Info Header Field in the Session Initiation Protocol (SIP)</title>

    <author initials="P." surname="Saint-Andre" fullname="Peter Saint-Andre">
      <organization>Cisco Systems, Inc.</organization>
      <address>
        <postal>
          <street>1899 Wynkoop Street, Suite 600</street>
          <city>Denver</city>
          <region>CO</region>
          <code>80202</code>
          <country>USA</country>
        </postal>
        <phone>+1-303-308-3282</phone>
        <email>psaintan@cisco.com</email>
      </address>
    </author>

    <date/>

    <keyword>SIP</keyword>
    <keyword>Call-Info</keyword>
    <keyword>header field</keyword>
    <keyword>Instant Messaging</keyword>
    <keyword>Presence</keyword>
    
    <abstract>
      <t>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).</t>
    </abstract>

  </front>

  <middle>

    <section title="Introduction" anchor="intro">
      <t>To improve interoperability among real-time communication endpoints that support the combined use of the Session Initiation Protocol (SIP) <xref target='RFC3261'/> and the Extensible Messaging and Presence Protocol (XMPP) <xref target='RFC6120'/> (so-called "CUSAX" endpoints <xref target='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 <xref target='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 <xref target='RFC3261'/> with a value of "impp" ("instant messaging and presence protocol") for the "purpose" header field parameter.  An example follows.</t>
      <figure>
        <artwork><![CDATA[
Call-Info: <xmpp:juliet@example.com> ;purpose=impp
        ]]></artwork>
      </figure>
      <t>Although CUSAX endpoints constitute the primary use case for the "impp" purpose, a Uniform Resource Identifier (URI) <xref target='RFC3986'/> for an instant messaging and presence protocol other than XMPP could be included in the Call-Info header field.</t>
    </section>

    <section title="Security Considerations" anchor="security">
      <t>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.</t>
      <t>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.</t>
    </section>

    <section title="IANA Considerations" anchor="iana">
      <t>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:</t>
      <figure>
        <artwork><![CDATA[
  Header Field: Call-Info
  Parameter Name: purpose
  Predefined Values: Yes
  Reference: [RFC3261][RFC5367][RFC6910][this document]
        ]]></artwork>
      </figure>
    </section>

  </middle>

  <back>

    <references title="Normative References">

<reference anchor='RFC3261'>
<front>
<title>SIP: Session Initiation Protocol</title>
<author initials='J.' surname='Rosenberg' fullname='J. Rosenberg'>
<organization /></author>
<author initials='H.' surname='Schulzrinne' fullname='H. Schulzrinne'>
<organization /></author>
<author initials='G.' surname='Camarillo' fullname='G. Camarillo'>
<organization /></author>
<author initials='A.' surname='Johnston' fullname='A. Johnston'>
<organization /></author>
<author initials='J.' surname='Peterson' fullname='J. Peterson'>
<organization /></author>
<author initials='R.' surname='Sparks' fullname='R. Sparks'>
<organization /></author>
<author initials='M.' surname='Handley' fullname='M. Handley'>
<organization /></author>
<author initials='E.' surname='Schooler' fullname='E. Schooler'>
<organization /></author>
<date year='2002' month='June' />
<abstract>
<t>This document describes Session Initiation Protocol (SIP), an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants.  These sessions include Internet telephone calls, multimedia distribution, and multimedia conferences. [STANDARDS-TRACK]</t></abstract></front>
<seriesInfo name='RFC' value='3261' />
<format type='TXT' octets='647976' target='http://www.rfc-editor.org/rfc/rfc3261.txt' />
</reference>

<reference anchor='RFC3986'>
<front>
<title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
<author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
<organization abbrev='W3C/MIT'>World Wide Web Consortium</organization>
<address>
<postal>
<street>Massachusetts Institute of Technology</street>
<street>77 Massachusetts Avenue</street>
<city>Cambridge</city>
<region>MA</region>
<code>02139</code>
<country>USA</country></postal>
<phone>+1-617-253-5702</phone>
<facsimile>+1-617-258-5999</facsimile>
<email>timbl@w3.org</email>
<uri>http://www.w3.org/People/Berners-Lee/</uri></address></author>
<author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
<organization abbrev='Day Software'>Day Software</organization>
<address>
<postal>
<street>5251 California Ave., Suite 110</street>
<city>Irvine</city>
<region>CA</region>
<code>92617</code>
<country>USA</country></postal>
<phone>+1-949-679-2960</phone>
<facsimile>+1-949-679-2972</facsimile>
<email>fielding@gbiv.com</email>
<uri>http://roy.gbiv.com/</uri></address></author>
<author initials='L.' surname='Masinter' fullname='Larry Masinter'>
<organization abbrev='Adobe Systems'>Adobe Systems Incorporated</organization>
<address>
<postal>
<street>345 Park Ave</street>
<city>San Jose</city>
<region>CA</region>
<code>95110</code>
<country>USA</country></postal>
<phone>+1-408-536-3024</phone>
<email>LMM@acm.org</email>
<uri>http://larry.masinter.net/</uri></address></author>
<date year='2005' month='January' />
<area>Applications</area>
<keyword>uniform resource identifier</keyword>
<keyword>URI</keyword>
<keyword>URL</keyword>
<keyword>URN</keyword>
<keyword>WWW</keyword>
<keyword>resource</keyword>
<abstract>
<t>
A Uniform Resource Identifier (URI) is a compact sequence of characters
that identifies an abstract or physical resource.  This specification
defines the generic URI syntax and a process for resolving URI references
that might be in relative form, along with guidelines and security
considerations for the use of URIs on the Internet.
The URI syntax defines a grammar that is a superset of all valid URIs,
allowing an implementation to parse the common components of a URI
reference without knowing the scheme-specific requirements of every
possible identifier.  This specification does not define a generative
grammar for URIs; that task is performed by the individual
specifications of each URI scheme.
</t></abstract></front>
<seriesInfo name='STD' value='66' />
<seriesInfo name='RFC' value='3986' />
<format type='TXT' octets='141811' target='http://www.rfc-editor.org/rfc/rfc3986.txt' />
<format type='HTML' octets='213584' target='http://xml.resource.org/public/rfc/html/rfc3986.html' />
<format type='XML' octets='163534' target='http://xml.resource.org/public/rfc/xml/rfc3986.xml' />
</reference>

<reference anchor='RFC6120'>
<front>
<title>Extensible Messaging and Presence Protocol (XMPP): Core</title>
<author initials='P.' surname='Saint-Andre' fullname='P. Saint-Andre'>
<organization /></author>
<date year='2011' month='March' />
<abstract>
<t>The Extensible Messaging and Presence Protocol (XMPP) is an application profile of the Extensible Markup Language (XML) that enables the near-real-time exchange of structured yet extensible data between any two or more network entities.  This document defines XMPP's core protocol methods: setup and teardown of XML streams, channel encryption, authentication, error handling, and communication primitives for messaging, network availability ("presence"), and request-response interactions.  This document obsoletes RFC 3920. [STANDARDS-TRACK]</t></abstract></front>
<seriesInfo name='RFC' value='6120' />
<format type='TXT' octets='451942' target='http://www.rfc-editor.org/rfc/rfc6120.txt' />
</reference>

    </references>

    <references title="Informative References">

<reference anchor='I-D.ivov-xmpp-cusax'>
<front>
<title>Combined Use of the Session Initiation Protocol (SIP) and the Extensible Messaging and Presence Protocol (CUSAX)</title>
<author initials='E' surname='Ivov' fullname='Emil Ivov'>
    <organization />
</author>
<author initials='P' surname='Saint-Andre' fullname='Peter Saint-Andre'>
    <organization />
</author>
<author initials='E' surname='Marocco' fullname='Enrico Marocco'>
    <organization />
</author>
<date month='May' day='2' year='2013' />
<abstract><t>This document describes suggested practices for combined use of the Session Initiation Protocol (SIP) and the Extensible Messaging and Presence Protocol (XMPP). Such practices aim to provide a single fully featured real-time communication service by using complementary subsets of features from each of the protocols. Typically such subsets would include telephony capabilities from SIP and instant messaging and presence capabilities from XMPP. This specification does not define any new protocols or syntax for either SIP or XMPP. However, implementing it may require modifying or at least reconfiguring existing client and server-side software. Also, it is not the purpose of this document to make recommendations as to whether or not such combined use should be preferred to the mechanisms provided natively by each protocol (for example, SIP's SIMPLE or XMPP's Jingle).  It merely aims to provide guidance to those who are interested in such a combined use.</t></abstract>
</front>
<seriesInfo name='Internet-Draft' value='draft-ivov-xmpp-cusax-05' />
<format type='TXT'
        target='http://www.ietf.org/internet-drafts/draft-ivov-xmpp-cusax-05.txt' />
</reference>

<reference anchor="XEP-0152">
  <front>
    <title>Reachability Addresses</title>
    <author initials="P." surname="Saint-Andre" fullname="Peter Saint-Andre">
      <organization/>
      <address>
        <email>stpeter@jabber.org</email>
      </address>
    </author>
    <author initials="J." surname="Hildebrand" fullname="Joe Hildebrand">
      <organization/>
      <address>
        <email>jhildebr@cisco.com</email>
      </address>
    </author>
    <date day="05" month="February" year="2013"/>
  </front>
  <seriesInfo name="XSF XEP" value="0152"/>
  <format type="HTML" target="http://xmpp.org/extensions/xep-0152.html"/>
</reference>

    </references>

    <section title="Acknowledgements" anchor="acks">
      <t>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.</t>
    </section>

  </back>

</rfc>