SIPCORE Working Group C. Holmberg Internet-Draft I. Sedlacek Updates: 5621 (if approved) Ericsson Intended status: Standards TrackEricsson Expires: September 9,April 25, 2017March 8,Expires: October 27, 2017Content IDContent-ID header field in Session Initiation Protocol (SIP)draft-ietf-sipcore-content-id-01draft-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 onSeptember 9,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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1.Setting up ID value uniquely identifyingIdentifying a body part . . . . . . . . . . . . . . . . . 2 1.2.Referencing the ID value uniquely identifyingReferring a body part . . . . . . . . . . . . . . . . . . 3 1.3. Problem statement . . . . . . . . . . . . . . . . . . . . 3 1.4.Examples of the problemConsequencies . . . . . . . . . . . . . . . . . . . . . . 3 1.4.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . 3 1.4.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . 4 1.5. Solution . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . .54 3. Content-ID header field . . . . . . . . . . . . . . . . . . .54 3.1. Introduction . . . . . . . . . . . . . . . . . . . . . .54 3.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3.SemanticSemantics . . . . . . . . . . . . . . . . . . . . . . . . 5 3.4. Procedures . . . . . . . . . . . . . . . . . . . . . . .65 3.4.1. UA procedures . . . . . . . . . . . . . . . . . . . .65 3.4.2. Proxy procedures . . . . . . . . . . . . . . . . . . 6 4.Security ConsiderationsUpdate to RFC 5621 . . . . . . . . . . . . . . . . . . . . . 6 5. Security considerations . . . . . . . . . . . . . . . . . . . 6 6. IANAConsiderationsconsiderations . . . . . . . . . . . . . . . . . . . . .6 5.1.7 6.1. HeaderFieldfield . . . . . . . . . . . . . . . . . . . . . .6 6.7 7. ChangeLoglog . . . . . . . . . . . . . . . . . . . . . . . . . 77.8. NormativeReferencesreferences . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction 1.1.Setting up ID value uniquely identifyingIdentifying 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].AThe message-body can be a non-multipart message-body or a multipart message-body as specified in [RFC3261]. [RFC5621] defines generic handling ofthea multipart message-body in a SIPmessage can containmessage. A multipart message-body contains zero, onebody onlyorcan containseveral 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[RFC3261] and[RFC5621]. A body partencoded using [RFC2045]in the multipart message-body can also contain a Content-ID header field with an ID value uniquely identifying the body part, as specified in [RFC2045].However, when the message-body of the SIP message contains one body only, there is no body part specified. Thus, there is also no defined method how to convey an ID value uniquely identifying the body part.1.2.Referencing the ID value uniquely identifyingReferring a body part A SIP header field cancontain a reference torefer a body part using a Content-ID URL, as specified in [RFC5621]. The Content-ID URL is specified in [RFC2392]. [RFC2392]alsospecifies how todiscoveridentify the body partreferencedreferred by a Content-ID URL. The Content-ID URL value is included in the Content-ID header field of the body part. Examples ofaSIP headerfield referencingfields referring a body part using aContent-IDContent- ID URL are: o [RFC6442] specifies how a Geolocation header fieldreferencesrefers a body part using a Content-ID URL, for providing location. o [RFC5368] specifies how a Refer-To header fieldreferencesrefers a body part using a Content-ID URL, to provide a list of targets. 1.3. Problem statementSince the Content-ID header fieldIt is currently nota defined SIP header field: o If solely one body needsspecified how tobe transported inuniquely identify a complete message-body of a SIP messageand the UAC does not need to include in the SIP messageusing aSIPContent-ID headerfield referencing the body part, then the UAC sets the message- body to the body. o However, if solely one body needs to be transported in a SIP messagefield, andthe UAC needshow toinclude in the SIP messagerefer aSIP header field referencing the body part, then the UAC sets thecomplete message-bodyto be of the "multipart" MIME type and includes one body part and associatedusing a Content-IDheader field.URL. 1.4.ExamplesConsequencies 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 onebodycontent only in the INVITE request. Thisbody contains the location information andcontent can be e.g. of the application/pidf+xml MIME type. However, due to [RFC6442] requiring inclusion of a Geolocation header fieldreferencingreferring the body partcontainingwith the location information, the UACneeds to includeincludes a multipart message-bodyof "multipart/mixed" MIME typewith single body part in the INVITE request, and includes theUAC needs to include a body partlocation information ofthe application/pidf+xmlapplication/ pidf+xml MIME type and an associated Content-ID header field in themessage-body of the "multipart/mixed" MIME type.body part. 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 onebodycontent only in the REFER request. Thisbody contains the list of targets andcontent is of the application/ resource-lists+xml MIME type. However, due to [RFC5368] requiring inclusion of a Refer-To header fieldreferencingreferring the body part containing the list of targets, the UACneeds to includeincludes a multipart message-bodyof the "multipart/mixed" MIME typewith single body part in the REFERrequestrequest, and includes theUAC needs to include a body partlist ofthe application/resource-lists+xmltargets of application/resource- lists+xml MIME type and an associatedContent- IDContent-ID header field in themessage-body of the "multipart/mixed" MIME type.body part. 1.5. SolutionTo avoid the unnecessary usage of a message-body of a "multipart" MIME type when only one body needsIn order tobe included in a SIP message,solve the problems described above, thisdocument specifies adocument: o Specifies and registers the Content-ID header field as a SIP headerfield. The Content-ID header field included in header fields of a SIP message identifies a body part consisting of the message-body of the SIP message and: 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-ID 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;field; and o Specifies that, when used as aContent-LengthSIP header field,if included inthe Content-ID headerfieldsfield identifies the complete message-body, and metadata provided by some additional SIP header fields, of the SIP message; and o Updates [RFC5621], to enable aContent-Type header field, if included in theContent-ID URL to refer a complete message-body and metadata provided by some additional SIP headerfields offields. NOTE: In [RFC5621], theSIP message.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. 3.2. Syntax The ABNF for the Content-ID header fields is: Content-ID = "Content-ID" HCOLON msg-idNOTE:msg-idis= "<" 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.Semantic ASemantics The Content-ID header field included in the header fields of a SIP messageindicates a globally unique identification of a body part consisting ofidentifies the message-body of the SIPmessage and:message, and the metadata provided by: oa MIME-Version header field, if included inthe Content-ID headerfields of the SIP message;field itself; o aContent-DispositionMIME-Version header field, if included in the header fields of the SIP message; o aContent-EncodingContent-Disposition header field, if included in the header fields of the SIP message; o aContent-IDContent-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. 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. SecurityConsiderationsconsiderations The Content-ID header field value MUST NOT reveal sensitive user information. If the message-body associated with the Content-ID header fieldcontainsis an encryptedcontent,body, it MUST NOT be possible to derive a key that can be used to decrypt themessage-body contentbody from the Content-ID header field value.5.6. IANAConsiderationsconsiderations This specification registers a new SIP header field according to the procedures in [RFC3261].5.1.6.1. HeaderFieldfield [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: none6.7. ChangeLoglog [RFC EDITOR NOTE: Please remove this section when publishing] Changesin draft-ietf-sipcore-content-id-01: o Clean up of section 1, including shortening introduction and cleaning up of "body" and "body part" usages.from draft-ietf-sipcore-content-id-01 oClarify that the SIP header fields forming the body part are not requiredUpdate tobe present in the SIP message.RFC 5621 added. oMIME-Version header field included as one of the SIP header fields forming the body part; 7.Editorial changes. 8. NormativeReferencesreferences [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>.[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, DOI 10.17487/RFC2046, November 1996, <http://www.rfc-editor.org/info/rfc2046>.[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>. [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