The ORIGIN HTTP/2 Frame
RFC 8336

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Internet Engineering Task Force (IETF)                     M. Nottingham
Request for Comments: 8336
Category: Standards Track                                      E. Nygren
ISSN: 2070-1721                                      Akamai Technologies
                                                              March 2018

                        The ORIGIN HTTP/2 Frame

Abstract

   This document specifies the ORIGIN frame for HTTP/2, to indicate what
   origins are available on a given connection.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8336.

Copyright Notice

   Copyright (c) 2018 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.

Nottingham & Nygren          Standards Track                    [Page 1]
RFC 8336                      ORIGIN Frames                   March 2018

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Notational Conventions  . . . . . . . . . . . . . . . . .   2
   2.  The ORIGIN HTTP/2 Frame . . . . . . . . . . . . . . . . . . .   3
     2.1.  Syntax  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Processing ORIGIN Frames  . . . . . . . . . . . . . . . .   3
     2.3.  The Origin Set  . . . . . . . . . . . . . . . . . . . . .   4
     2.4.  Authority, Push, and Coalescing with ORIGIN . . . . . . .   6
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     5.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Appendix A.  Non-Normative Processing Algorithm . . . . . . . . .  10
   Appendix B.  Operational Considerations for Servers . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   HTTP/2 [RFC7540] allows clients to coalesce different origins
   [RFC6454] onto the same connection when certain conditions are met.
   However, in some cases, a connection is not usable for a coalesced
   origin, so the 421 (Misdirected Request) status code ([RFC7540],
   Section 9.1.2) was defined.

   Using a status code in this manner allows clients to recover from
   misdirected requests, but at the penalty of adding latency.  To
   address that, this specification defines a new HTTP/2 frame type,
   "ORIGIN", to allow servers to indicate for which origins a connection
   is usable.

   Additionally, experience has shown that HTTP/2's requirement to
   establish server authority using both DNS and the server's
   certificate is onerous.  This specification relaxes the requirement
   to check DNS when the ORIGIN frame is in use.  Doing so has
   additional benefits, such as removing the latency associated with
   some DNS lookups.

1.1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

Nottingham & Nygren          Standards Track                    [Page 2]
RFC 8336                      ORIGIN Frames                   March 2018

2.  The ORIGIN HTTP/2 Frame

   This document defines a new HTTP/2 frame type ([RFC7540], Section 4)
   called ORIGIN, that allows a server to indicate what origin(s)
   [RFC6454] the server would like the client to consider as members of
   the Origin Set (Section 2.3) for the connection within which it
   occurs.

2.1.  Syntax

   The ORIGIN frame type is 0xc (decimal 12) and contains zero or more
   instances of the Origin-Entry field.

   +-------------------------------+-------------------------------+