SIPCORE Working Group C. Holmberg Internet-Draft I. Sedlacek Updates: 5621 (if approved) Ericsson Intended status: Standards Track April 25, 2017 Expires: October 27, 2017 Content-ID header field in Session Initiation Protocol (SIP) draft-ietf-sipcore-content-id-02 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 refer 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 Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents 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 October 27, 2017. Copyright Notice Copyright (c) 2017 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 (http://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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Holmberg & Sedlacek Expires October 27, 2017 [Page 1]
Internet-Draft Content-ID in SIP April 2017 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Identifying a body part . . . . . . . . . . . . . . . . . 2 1.2. Referring a body part . . . . . . . . . . . . . . . . . . 3 1.3. Problem statement . . . . . . . . . . . . . . . . . . . . 3 1.4. Consequencies . . . . . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . . . . 6 4. Update to RFC 5621 . . . . . . . . . . . . . . . . . . . . . 6 5. Security considerations . . . . . . . . . . . . . . . . . . . 6 6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 7 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 Holmberg & Sedlacek Expires October 27, 2017 [Page 2]
Internet-Draft Content-ID in SIP April 2017 can also contain a Content-ID header field with an ID value uniquely identifying the body part, as specified in [RFC2045]. 1.2. Referring a body part A SIP header field can refer 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 referred 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 referring a body part using a Content- ID URL are: o [RFC6442] specifies how a Geolocation header field refers a body part using a Content-ID URL, for providing location. o [RFC5368] specifies how a Refer-To header field refers 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 refer a complete message-body using a Content-ID URL. 1.4. Consequencies The examples below shows the consequencies 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 referring 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. Holmberg & Sedlacek Expires October 27, 2017 [Page 3]
Internet-Draft Content-ID in SIP April 2017 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 referring 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 refer a complete message-body and metadata provided by some additional SIP header fields. NOTE: In [RFC5621], the Content-ID URL refers 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. Holmberg & Sedlacek Expires October 27, 2017 [Page 4]
Internet-Draft Content-ID in SIP April 2017 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 the Content-ID header field itself; o a MIME-Version header field, if included in the header fields of the SIP message; o a Content-Disposition header field, if included in the header fields of the SIP message; o a Content-Encoding header field, if included in the header fields of the SIP message; o a Content-Language header field, if included in the header fields of the SIP message; o a Content-Length header field, if included in the header fields of the SIP message; and o a Content-Type header field, if 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. Holmberg & Sedlacek Expires October 27, 2017 [Page 5]
Internet-Draft Content-ID in SIP April 2017 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. 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 to reference to a body part.A 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. Holmberg & Sedlacek Expires October 27, 2017 [Page 6]
Internet-Draft Content-ID in SIP April 2017 6. IANA considerations This specification registers a new SIP header field according to the procedures in [RFC3261]. 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-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>. Holmberg & Sedlacek Expires October 27, 2017 [Page 7]
Internet-Draft Content-ID in SIP April 2017 [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 Holmberg & Sedlacek Expires October 27, 2017 [Page 8]
