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Versions: (draft-holmberg-sipcore-content-id) 00 01 02 03 04 05 06 07 08 09 10 RFC 8262

SIPCORE Working Group                                        C. Holmberg
Internet-Draft                                               I. Sedlacek
Updates: 5621 (if approved)                                     Ericsson
Intended status: Standards Track                          April 28, 2017
Expires: October 30, 2017


      Content-ID header field in Session Initiation Protocol (SIP)
                    draft-ietf-sipcore-content-id-03

Abstract

   This document specifies the Content-ID header field for usage in the
   Session Initiation Protocol (SIP).  The document also updates RFC
   5621, to enable a Content-ID URL to reference a complete message-body
   and metadata provided by some additional SIP header fields.

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 of the Internet Engineering
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   This Internet-Draft will expire on October 30, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Identifying a body part . . . . . . . . . . . . . . . . .   2
     1.2.  Referencing a body part . . . . . . . . . . . . . . . . .   3
     1.3.  Problem statement . . . . . . . . . . . . . . . . . . . .   3
     1.4.  Consequences  . . . . . . . . . . . . . . . . . . . . . .   3
       1.4.1.  Example 1 . . . . . . . . . . . . . . . . . . . . . .   3
       1.4.2.  Example 2 . . . . . . . . . . . . . . . . . . . . . .   4
     1.5.  Solution  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Content-ID header field . . . . . . . . . . . . . . . . . . .   4
     3.1.  Introduction  . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Syntax  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.3.  Semantics . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.4.  Procedures  . . . . . . . . . . . . . . . . . . . . . . .   5
       3.4.1.  UA procedures . . . . . . . . . . . . . . . . . . . .   5
       3.4.2.  Proxy procedures  . . . . . . . . . . . . . . . . . .   5
   4.  Update to RFC 5621  . . . . . . . . . . . . . . . . . . . . .   6
   5.  Security considerations . . . . . . . . . . . . . . . . . . .   6
   6.  IANA considerations . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Header field  . . . . . . . . . . . . . . . . . . . . . .   7
   7.  Change log  . . . . . . . . . . . . . . . . . . . . . . . . .   7
   8.  Normative references  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

1.1.  Identifying a body part

   A SIP message consists of a start-line, one or more header fields, an
   empty line indicating the end of the header fields, and an optional
   message-body, as specified in [RFC3261].

   The message-body can be a non-multipart message-body or a multipart
   message-body as specified in [RFC3261].

   [RFC5621] defines generic handling of a multipart message-body in a
   SIP message.

   A multipart message-body contains zero, one or several body parts,
   encoded using [RFC2045] format.

   A body part in the multipart message-body is described using header
   fields such as Content-Disposition, Content-Encoding, and Content-
   Type, which provide information on the content of the body part, as
   specified in [RFC5621].  A body part in the multipart message-body




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   can also contain a Content-ID header field with an ID value uniquely
   identifying the body part, as specified in [RFC2045].

1.2.  Referencing a body part

   A SIP header field can reference a body part using a Content-ID URL,
   as specified in [RFC5621].

   The Content-ID URL is specified in [RFC2392].  [RFC2392] specifies
   how to identify the body part referenced by a Content-ID URL.  The
   Content-ID URL value is included in the Content-ID header field of
   the body part.

   Examples of SIP header fields referencing a body part using a
   Content-ID URL are:

   o  [RFC6442] specifies how a Geolocation header field references a
      body part using a Content-ID URL, for providing location.
   o  [RFC5368] specifies how a Refer-To header field references a body
      part using a Content-ID URL, to provide a list of targets.

1.3.  Problem statement

   It is currently not specified how to uniquely identify a complete
   message-body of a SIP message using a Content-ID header field, and
   how to reference a complete message-body using a Content-ID URL.

1.4.  Consequences

   The examples below shows the consequences of the problem described
   above.

1.4.1.  Example 1

   If a UAC sends an INVITE request conveying location as specified in
   [RFC6442], if the UAC decides not to include an SDP offer, and if the
   location is conveyed by value, then the UAC needs to include one
   content only in the INVITE request.  This content can be e.g. of the
   application/pidf+xml MIME type.

   However, due to [RFC6442] requiring inclusion of a Geolocation header
   field referencing the body part with the location information, the
   UAC includes a multipart message-body with single body part in the
   INVITE request, and includes the location information of application/
   pidf+xml MIME type and an associated Content-ID header field in the
   body part.





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1.4.2.  Example 2

   If a UAC sends an REFER request including a list of targets as
   specified in [RFC5368], then the UAC needs to include one content
   only in the REFER request.  This content is of the application/
   resource-lists+xml MIME type.

   However, due to [RFC5368] requiring inclusion of a Refer-To header
   field referencing the body part containing the list of targets, the
   UAC includes a multipart message-body with single body part in the
   REFER request, and includes the list of targets of application/
   resource-lists+xml MIME type and an associated Content-ID header
   field in the body part.

1.5.  Solution

   In order to solve the problems described above, this document:

   o  Specifies and registers the Content-ID header field as a SIP
      header field; and
   o  Specifies that, when used as a SIP header field, the Content-ID
      header field identifies the complete message-body, and metadata
      provided by some additional SIP header fields, of the SIP message;
      and
   o  Updates [RFC5621], to enable a Content-ID URL to reference a
      complete message-body and metadata provided by some additional SIP
      header fields.

   NOTE: In [RFC5621], the Content-ID URL references a specific body
   part only.

2.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  Content-ID header field

3.1.  Introduction

   This section defines the usage of the Content-ID header field for
   SIP.








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3.2.  Syntax

   The ABNF for the Content-ID header fields is:


      Content-ID = "Content-ID" HCOLON msg-id

      msg-id     = "<" id-left "@" id-right ">"

      NOTE: id-left and id-right are specified in [RFC5322].

      NOTE: When used in a SIP header field, the msg-id syntax has been
      simplified compared to the syntax in [RFC5322].


3.3.  Semantics

   The Content-ID header field included in the header fields of a SIP
   message identifies the message-body of the SIP message, and the
   metadata provided by:

   o  a MIME-Version header field, if included in the header fields of
      the SIP message; and
   o  any 'Content-' prefixed header fields (including the Content-ID
      header field itself) included in the header fields of the SIP
      message.

   The Content-ID header field can be included in any SIP message which
   is allowed to contain a message-body.

3.4.  Procedures

3.4.1.  UA procedures

   A UA MAY include a Content-ID header field in any SIP message which
   is allowed to contain a message-body.

   A UA MUST NOT include a Content-ID header field in any SIP message
   which is not allowed to contain a message-body.

   The UA MUST set the value of the Content-ID header field to a
   globally unique value.

3.4.2.  Proxy procedures

   A proxy MUST NOT add a Content-ID header field in a SIP message.





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   A proxy MUST NOT modify a Content-ID header field included in a SIP
   message.

   A proxy MUST NOT delete a Content-ID header field from a SIP message.

4.  Update to RFC 5621

   This section updates section 9.1 of [RFC5621], by allowing a Content-
   ID URL to reference a message-body and the related metadata
   (Section 3.3), in addition to allowing a reference to a body part.


 OLD TEXT:

    Content-ID URLs allow creating references to body parts.  A given
    Content-ID URL [RFC2392], which can appear in a header field or
    within a body part (e.g., in an SDP attribute), points to a
    particular body part.


 NEW TEXT:

    Content-ID URLs allow creating references to body parts or
    message-bodies (and the header fields describing the
    message-bodies). A given Content-ID URL [RFC2392], which can appear
    in a header field or within a body part (e.g., in an SDP attribute),
    points to a particular body part or the message-body (and the
    header fields describing the message-body).


5.  Security considerations

   The Content-ID header field value MUST NOT reveal sensitive user
   information.

   If the message-body associated with the Content-ID header field is an
   encrypted body, it MUST NOT be possible to derive a key that can be
   used to decrypt the body from the Content-ID header field value.

6.  IANA considerations

   This specification registers a new SIP header field according to the
   procedures in [RFC3261].








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6.1.  Header field

   [RFC EDITOR NOTE: Please replace XXXX with the RFC number of this
   document when publishing]

      RFC Number:  RFC XXXX

      Header Field Name:  Content-ID

      Compact Form:  none

7.  Change log

   [RFC EDITOR NOTE: Please remove this section when publishing]

   Changes from draft-ietf-sipcore-content-id-02

   o  Editorial changes based on comments from Paul Kyzivat.

   Changes from draft-ietf-sipcore-content-id-01

   o  Update to RFC 5621 added.
   o  Editorial changes.

8.  Normative references

   [RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part One: Format of Internet Message
              Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
              <http://www.rfc-editor.org/info/rfc2045>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC2392]  Levinson, E., "Content-ID and Message-ID Uniform Resource
              Locators", RFC 2392, DOI 10.17487/RFC2392, August 1998,
              <http://www.rfc-editor.org/info/rfc2392>.

   [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 5322,
              DOI 10.17487/RFC5322, October 2008,
              <http://www.rfc-editor.org/info/rfc5322>.








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   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              DOI 10.17487/RFC3261, June 2002,
              <http://www.rfc-editor.org/info/rfc3261>.

   [RFC5368]  Camarillo, G., Niemi, A., Isomaki, M., Garcia-Martin, M.,
              and H. Khartabil, "Referring to Multiple Resources in the
              Session Initiation Protocol (SIP)", RFC 5368,
              DOI 10.17487/RFC5368, October 2008,
              <http://www.rfc-editor.org/info/rfc5368>.

   [RFC5621]  Camarillo, G., "Message Body Handling in the Session
              Initiation Protocol (SIP)", RFC 5621,
              DOI 10.17487/RFC5621, September 2009,
              <http://www.rfc-editor.org/info/rfc5621>.

   [RFC6442]  Polk, J., Rosen, B., and J. Peterson, "Location Conveyance
              for the Session Initiation Protocol", RFC 6442,
              DOI 10.17487/RFC6442, December 2011,
              <http://www.rfc-editor.org/info/rfc6442>.

Authors' Addresses

   Christer Holmberg
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   Email: christer.holmberg@ericsson.com


   Ivo Sedlacek
   Ericsson
   Sokolovska 79
   Praha  18600
   Czech Republic

   Email: ivo.sedlacek@ericsson.com











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