HTTP Client Hints
draft-ietf-httpbis-client-hints-15

Document Type Active Internet-Draft (httpbis WG)
Last updated 2020-07-20 (latest revision 2020-07-03)
Replaces draft-grigorik-http-client-hints
Stream IETF
Intended RFC status Experimental
Formats plain text pdf htmlized (tools) htmlized bibtex
Reviews
Stream WG state Submitted to IESG for Publication (wg milestone: - Submit Client Hints... )
Document shepherd Mark Nottingham
Shepherd write-up Show (last changed 2020-04-09)
IESG IESG state RFC Ed Queue
Consensus Boilerplate Yes
Telechat date
Responsible AD Barry Leiba
Send notices to "Mark Nottingham" <mnot@mnot.net>
IANA IANA review state IANA OK - Actions Needed
IANA action state RFC-Ed-Ack
IANA expert review state Reviews assigned
RFC Editor RFC Editor state EDIT
Details
HTTP Working Group                                           I. Grigorik
Internet-Draft                                                  Y. Weiss
Intended status: Experimental                                     Google
Expires: January 4, 2021                                    July 3, 2020

                           HTTP Client Hints
                   draft-ietf-httpbis-client-hints-15

Abstract

   HTTP defines proactive content negotiation to allow servers to select
   the appropriate response for a given request, based upon the user
   agent's characteristics, as expressed in request headers.  In
   practice, user agents are often unwilling to send those request
   headers, because it is not clear whether they will be used, and
   sending them impacts both performance and privacy.

   This document defines an Accept-CH response header that servers can
   use to advertise their use of request headers for proactive content
   negotiation, along with a set of guidelines for the creation of such
   headers, colloquially known as "Client Hints."

Note to Readers

   Discussion of this draft takes place on the HTTP working group
   mailing list (ietf-http-wg@w3.org), which is archived at
   https://lists.w3.org/Archives/Public/ietf-http-wg/ [1].

   Working Group information can be found at http://httpwg.github.io/
   [2]; source code and issues list for this draft can be found at
   https://github.com/httpwg/http-extensions/labels/client-hints [3].

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 https://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."

Grigorik & Weiss         Expires January 4, 2021                [Page 1]
Internet-Draft              HTTP Client Hints                  July 2020

   This Internet-Draft will expire on January 4, 2021.

Copyright Notice

   Copyright (c) 2020 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
   (https://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  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Notational Conventions  . . . . . . . . . . . . . . . . .   4
   2.  Client Hint Request Header Fields . . . . . . . . . . . . . .   4
     2.1.  Sending Client Hints  . . . . . . . . . . . . . . . . . .   4
     2.2.  Server Processing of Client Hints . . . . . . . . . . . .   5
   3.  Advertising Server Support  . . . . . . . . . . . . . . . . .   5
     3.1.  The Accept-CH Response Header Field . . . . . . . . . . .   5
     3.2.  Interaction with Caches . . . . . . . . . . . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
     4.1.  Information Exposure  . . . . . . . . . . . . . . . . . .   7
     4.2.  Deployment and Security Risks . . . . . . . . . . . . . .   9
     4.3.  Abuse Detection . . . . . . . . . . . . . . . . . . . . .   9
   5.  Cost of Sending Hints . . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
     6.1.  Accept-CH . . . . . . . . . . . . . . . . . . . . . . . .  10
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  11
     7.3.  URIs  . . . . . . . . . . . . . . . . . . . . . . . . . .  11
   Appendix A.  Changes  . . . . . . . . . . . . . . . . . . . . . .  11
     A.1.  Since -00 . . . . . . . . . . . . . . . . . . . . . . . .  11
     A.2.  Since -01 . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.3.  Since -02 . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.4.  Since -03 . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.5.  Since -04 . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.6.  Since -05 . . . . . . . . . . . . . . . . . . . . . . . .  12
     A.7.  Since -06 . . . . . . . . . . . . . . . . . . . . . . . .  12
Show full document text