SIPCORE Working Group C. Holmberg Internet-Draft I. Sedlacek Updates: 5621, 5368, 6442 (if approved) Ericsson Intended status: Standards Track September 2, 2017 Expires: March 6, 2018 Content-ID header field in Session Initiation Protocol (SIP) draft-ietf-sipcore-content-id-10 Abstract This document specifies the Content-ID header field for usage in the Session Initiation Protocol (SIP). The document also updates RFC 5621, which only allows a Content-ID URL to reference a body part that is part of a multipart message-body. This update enables a Content-ID URL to reference a complete message-body and metadata provided by some additional SIP header fields. This document updates RFC 5368 and RFC 6442, by clarifying their usage of the SIP Content-ID header field. 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 March 6, 2018. 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 Holmberg & Sedlacek Expires March 6, 2018 [Page 1]
Internet-Draft Content-ID in SIP September 2017 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. Identifying a body part . . . . . . . . . . . . . . . . . 2 1.2. Referencing a body part . . . . . . . . . . . . . . . . . 3 1.3. Problem statement . . . . . . . . . . . . . . . . . . . . 3 1.4. Consequences . . . . . . . . . . . . . . . . . . . . . . 4 1.4.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . 4 1.4.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . 5 1.5. Solution . . . . . . . . . . . . . . . . . . . . . . . . 6 1.6. Backward compatibility . . . . . . . . . . . . . . . . . 7 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Content-ID header field . . . . . . . . . . . . . . . . . . . 7 3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 7 3.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.3. Semantics . . . . . . . . . . . . . . . . . . . . . . . . 8 3.4. Procedures . . . . . . . . . . . . . . . . . . . . . . . 8 3.4.1. User Agent (UA) procedures . . . . . . . . . . . . . 8 3.4.2. Proxy procedures . . . . . . . . . . . . . . . . . . 9 3.4.3. Example . . . . . . . . . . . . . . . . . . . . . . . 9 4. Update to RFC 5368 . . . . . . . . . . . . . . . . . . . . . 10 5. Update to RFC 5621 . . . . . . . . . . . . . . . . . . . . . 10 6. Update to RFC 6442 . . . . . . . . . . . . . . . . . . . . . 11 7. Security considerations . . . . . . . . . . . . . . . . . . . 12 8. IANA considerations . . . . . . . . . . . . . . . . . . . . . 12 8.1. Header field . . . . . . . . . . . . . . . . . . . . . . 13 9. Change log . . . . . . . . . . . . . . . . . . . . . . . . . 13 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 10.1. Normative references . . . . . . . . . . . . . . . . . . 14 10.2. Informative references . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 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]. Holmberg & Sedlacek Expires March 6, 2018 [Page 2]
Internet-Draft Content-ID in SIP September 2017 [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 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 information. 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. NOTE: In [RFC5621], the Content-ID URL references a specific body part only. Some existing specifications, such as [RFC5368], contain examples that show usage of a SIP Content-ID header field referencing a complete message-body, even though such usage has never been specified. Many implementors have interpreted these examples to indicate that such usage is allowed by the corresponding specification, despite the absence of language allowing it. This Holmberg & Sedlacek Expires March 6, 2018 [Page 3]
Internet-Draft Content-ID in SIP September 2017 document updates the normative language in the affected documents to explicitly allow such usage. 1.4. Consequences The examples below shows the consequences of the problem described above. 1.4.1. Example 1 If a User Agent Client (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 only one MIME entity in the INVITE request. This MIME entity can be, for example, 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. Example message (SIP INVITE): INVITE sips:bob@biloxi.example.com SIP/2.0 Via: SIPS/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bK74bf9 Max-Forwards: 70 To: Bob <sips:bob@biloxi.example.com> From: Alice <sips:alice@atlanta.example.com>;tag=9fxced76sl Call-ID: 3848276298220188511@atlanta.example.com Geolocation: <cid:target123@atlanta.example.com> Geolocation-Routing: no Accept: application/sdp, application/pidf+xml CSeq: 31862 INVITE Contact: <sips:alice@atlanta.example.com> Content-Type: multipart/mixed; boundary=boundary1 Content-Length: ... --boundary1 Content-Type: application/pidf+xml Content-ID: <target123@atlanta.example.com> <?xml version="1.0" encoding="UTF-8"?> <presence xmlns="urn:ietf:params:xml:ns:pidf" Holmberg & Sedlacek Expires March 6, 2018 [Page 4]
Internet-Draft Content-ID in SIP September 2017 xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10" xmlns:gbp="urn:ietf:params:xml:ns:pidf:geopriv10:basicPolicy" xmlns:cl="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr" xmlns:gml="http://www.opengis.net/gml" xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model" entity="pres:alice@atlanta.example.com" > <dm:device id="target123-1"> <gp:geopriv> <gp:location-info> <gml:location> <gml:Point srsName="urn:ogc:def:crs:EPSG::4326"> <gml:pos>32.86726 -97.16054</gml:pos> </gml:Point> </gml:location> </gp:location-info> <gp:usage-rules> <gbp:retransmission-allowed>false </gbp:retransmission-allowed> <gbp:retention-expiry>2010-11-14T20:00:00Z </gbp:retention-expiry> </gp:usage-rules> <gp:method>802.11</gp:method> </gp:geopriv> <dm:deviceID>mac:1234567890ab</dm:deviceID> <dm:timestamp>2010-11-04T20:57:29Z</dm:timestamp> </dm:device> </presence> --boundary1-- 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 only one MIME entity in the REFER request. This MIME entity 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. Holmberg & Sedlacek Expires March 6, 2018 [Page 5]
Internet-Draft Content-ID in SIP September 2017 Example message (SIP REFER): REFER sip:conf-123@example.com;gruu;opaque=hha9s8d-999a SIP/2.0 Via: SIP/2.0/TCP client.chicago.example.com;branch=z9hG4bKhjhs8ass83 Max-Forwards: 70 To: "Conference 123" <sip:conf-123@example.com> From: Carol <sip:carol@chicago.example.com>;tag=32331 Call-ID: d432fa84b4c76e66710 CSeq: 2 REFER Contact: <sip:carol@client.chicago.example.com> Refer-To: <cid:cn35t8jf02@example.com> Refer-Sub: false Require: multiple-refer, norefersub Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY Allow-Events: dialog Accept: application/sdp, message/sipfrag Content-Type: multipart/mixed; boundary=boundary1 Content-Length: ... --boundary1 Content-Type: application/resource-lists+xml Content-Disposition: recipient-list Content-ID: <cn35t8jf02@example.com> <?xml version="1.0" encoding="UTF-8"?> <resource-lists xmlns="urn:ietf:params:xml:ns:resource-lists" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" > <list> <entry uri="sip:bill@example.com?method=BYE"/> <entry uri="sip:joe@example.org?method=BYE"/> <entry uri="sip:ted@example.net?method=BYE"/> </list> </resource-lists> --boundary1-- 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 Holmberg & Sedlacek Expires March 6, 2018 [Page 6]
Internet-Draft Content-ID in SIP September 2017 o Updates [RFC5621], to enable a Content-ID URL to reference a complete message-body and metadata provided by some additional SIP header fields. o Updates [RFC5368] and [RFC6442] by adding explicit text saying that a SIP Content-ID header field can be used. 1.6. Backward compatibility If an existing specification only defines the usage of a multipart message-body for carrying a single body part to be referenced by a Content-ID URL, implementations MUST NOT carry the MIME entity in a non-multipart message-body unless the specification is updated to explicitly allow it. 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 [RFC5234] for the Content-ID header field is: Holmberg & Sedlacek Expires March 6, 2018 [Page 7]
Internet-Draft Content-ID in SIP September 2017 Content-ID = "Content-ID" HCOLON msg-id msg-id = "<" id-left "@" id-right ">" NOTE: id-left and id-right are specified in [RFC5322]. HCOLON is defined in [RFC3261]. NOTE: When used in a SIP header field, the msg-id syntax has been simplified, compared to the syntax in [RFC5322], to disallow the use of comments and to adopt to the SIP usage of leading white space. The value of Content-Id header field value must be unique in the context of a given SIP message, including any embedded MIME Content-Id header field values. Note that the SIP Content-ID header field value is not expected to be unique among all SIP messages; it has no meaning outside of the message in which it is included. 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. NOTE: The message-body identified by the Content-ID header field can be a non-multipart message-body or a multipart message-body. 3.4. Procedures 3.4.1. User Agent (UA) procedures A UA MAY include a Content-ID header field in any SIP message that is allowed to contain a message-body. A UA MUST NOT include a Content-ID header field in any SIP message that is not allowed to contain a message-body. The UA MUST set the value of the Content-ID header field to a value that is unique in the context of the SIP message. Holmberg & Sedlacek Expires March 6, 2018 [Page 8]
Internet-Draft Content-ID in SIP September 2017 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. 3.4.3. Example The figure shows an example from [RFC5368], where the SIP Content-ID header field is used to reference the message-body (non-multipart) of a SIP message. REFER sip:conf-123@example.com;gruu;opaque=hha9s8d-999a SIP/2.0 Via: SIP/2.0/TCP client.chicago.example.com ;branch=z9hG4bKhjhs8ass83 Max-Forwards: 70 To: "Conference 123" <sip:conf-123@example.com> From: Carol <sip:carol@chicago.example.com>;tag=32331 Call-ID: d432fa84b4c76e66710 CSeq: 2 REFER Contact: <sip:carol@client.chicago.example.com> Refer-To: <cid:cn35t8jf02@example.com> Refer-Sub: false Require: multiple-refer, norefersub Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY Allow-Events: dialog Accept: application/sdp, message/sipfrag Content-Type: application/resource-lists+xml Content-Disposition: recipient-list Content-Length: 362 Content-ID: <cn35t8jf02@example.com> <?xml version="1.0" encoding="UTF-8"?> <resource-lists xmlns="urn:ietf:params:xml:ns:resource-lists" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <list> <entry uri="sip:bill@example.com?method=BYE" /> <entry uri="sip:joe@example.org?method=BYE" /> <entry uri="sip:ted@example.net?method=BYE" /> </list> </resource-lists> Holmberg & Sedlacek Expires March 6, 2018 [Page 9]
Internet-Draft Content-ID in SIP September 2017 4. Update to RFC 5368 This section updates the second paragraph in section 7 of [RFC5368], by allowing usage of either a MIME Content-ID header field or a SIP Content-ID header field to label the body part or the message-body carrying the URI list. OLD TEXT: The Refer-To header field of a REFER request with multiple REFER- Targets MUST contain a pointer (i.e., a Content-ID Uniform Resource Locator (URL) as per RFC 2392 [RFC2392]) that points to the body part that carries the URI list. The REFER-Issuer SHOULD NOT include any particular URI more than once in the URI list. NEW TEXT: The Refer-To header field of a REFER request with multiple REFER- Targets MUST contain a pointer (i.e., a Content-ID Uniform Resource Locator (URL) as per RFC 2392 [RFC2392]) that points to the body part or message-body that carries the URI list. The REFER-Issuer SHOULD NOT include any particular URI more than once in the URI list. The REFER request can use either a MIME Content-ID header field [RFC4483] or a SIP Content-ID header field [RFCXXXX] to label the body part or the message-body. 5. 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. Holmberg & Sedlacek Expires March 6, 2018 [Page 10]
Internet-Draft Content-ID in SIP September 2017 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 the creation of 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). 6. Update to RFC 6442 This section updates the second paragraph in section 3.1 of [RFC6442], by allowing usage of either a MIME Content-ID header field or a SIP Content-ID header field to label the body part or the message-body carrying the location data. Holmberg & Sedlacek Expires March 6, 2018 [Page 11]
Internet-Draft Content-ID in SIP September 2017 OLD TEXT: In Figure 1, Alice is both the Target and the LS that is conveying her location directly to Bob, who acts as an LR. This conveyance is point-to-point: it does not pass through any SIP-layer intermediary. A Location Object appears by-value in the initial SIP request as a MIME body, and Bob responds to that SIP request as appropriate. There is a 'Bad Location Information' response code introduced within this document to specifically inform Alice if she conveys bad location to Bob (e.g., Bob "cannot parse the location provided", or "there is not enough location information to determine where Alice is"). NEW TEXT: In Figure 1, Alice is both the Target and the LS that is conveying her location directly to Bob, who acts as an LR. This conveyance is point-to-point: it does not pass through any SIP-layer intermediary. A Location Object appears by-value in the initial SIP request as a MIME body, and Bob responds to that SIP request as appropriate. Either a MIME Content-ID header field [RFC4483] or the SIP Content-ID header field [RFCXXXX] MUST be used to label the location information. There is a 'Bad Location Information' response code introduced within this document to specifically inform Alice if she conveys bad location to Bob (e.g., Bob "cannot parse the location provided", or "there is not enough location information to determine where Alice is"). 7. 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. 8. IANA considerations This specification registers a new SIP header field according to the procedures in [RFC3261]. Holmberg & Sedlacek Expires March 6, 2018 [Page 12]
Internet-Draft Content-ID in SIP September 2017 8.1. Header field The header field described in Section 3 has been registered in the "Header Fields" sub-registry of the "Session Initiation Protocol (SIP) Parameters" registry by adding a row with these values: [RFC EDITOR NOTE: Please replace XXXX with the RFC number of this document when publishing] Header Name: Content-ID compact: Reference: RFCXXXX 9. Change log [RFC EDITOR NOTE: Please remove this section when publishing] Changes from draft-ietf-sipcore-content-id-09 o Editorial change based on comment from Adam Roach. Changes from draft-ietf-sipcore-content-id-08 o Editorial change based on comment from Ben Campbell. Changes from draft-ietf-sipcore-content-id-07 o Updates to affected RFCs. o Editorial changes and clarifications based on IESG review. Changes from draft-ietf-sipcore-content-id-06 o Editorial changes and clarifications based on Gen-ART review from Elwyn Davies. Changes from draft-ietf-sipcore-content-id-05 o Changes based on AD comments from Ben Campbell: o - Clarifying that Content-ID header field value is unique within the scope of a SIP message. Changes from draft-ietf-sipcore-content-id-04 o Minor editorial fix. Changes from draft-ietf-sipcore-content-id-03 Holmberg & Sedlacek Expires March 6, 2018 [Page 13]
Internet-Draft Content-ID in SIP September 2017 o Changes based on doc shepherd review: o - Reference to RFC 5234 added. o - SIP message example added. o - Editorial changes. 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. 10. References 10.1. 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, <https://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, <https://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, <https://www.rfc-editor.org/info/rfc2392>. [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/RFC5234, January 2008, <https://www.rfc- editor.org/info/rfc5234>. [RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322, DOI 10.17487/RFC5322, October 2008, <https://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, <https://www.rfc- editor.org/info/rfc3261>. Holmberg & Sedlacek Expires March 6, 2018 [Page 14]
Internet-Draft Content-ID in SIP September 2017 [RFC5621] Camarillo, G., "Message Body Handling in the Session Initiation Protocol (SIP)", RFC 5621, DOI 10.17487/RFC5621, September 2009, <https://www.rfc- editor.org/info/rfc5621>. 10.2. Informative references [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, <https://www.rfc- editor.org/info/rfc5368>. [RFC6442] Polk, J., Rosen, B., and J. Peterson, "Location Conveyance for the Session Initiation Protocol", RFC 6442, DOI 10.17487/RFC6442, December 2011, <https://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 March 6, 2018 [Page 15]