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The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 8336.
Authors Mark Nottingham , Erik Nygren
Last updated 2016-11-20 (Latest revision 2016-09-27)
Replaces draft-nottingham-httpbis-origin-frame
RFC stream Internet Engineering Task Force (IETF)
Additional resources Mailing list discussion
Stream WG state Parked WG Document
Document shepherd Natasha Rooney
IESG IESG state Became RFC 8336 (Proposed Standard)
Consensus boilerplate Yes
Telechat date (None)
Responsible AD (None)
Send notices to "Natasha Rooney" <>
HTTP Working Group                                         M. Nottingham
Internet-Draft                                                 E. Nygren
Intended status: Standards Track                                  Akamai
Expires: April 1, 2017                                September 28, 2016

                        The ORIGIN HTTP/2 Frame


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

Note to Readers

   Discussion of this draft takes place on the HTTP working group
   mailing list (, which is archived at .

   Working Group information can be found at ;
   source code and issues list for this draft can be found at .

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

   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 April 1, 2017.

Copyright Notice

   Copyright (c) 2016 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

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   ( 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.  Notational Conventions  . . . . . . . . . . . . . . . . .   2
   2.  The ORIGIN HTTP/2 Frame . . . . . . . . . . . . . . . . . . .   2
     2.1.  The Origin Set  . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Processing ORIGIN Frames  . . . . . . . . . . . . . . . .   4
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   4.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   HTTP/2 [RFC7540] allows clients to coalesce different origins
   [RFC6454] onto the same connection when certain conditions are met.
   However, in certain cases, a connection is 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 what origins a connection is
   usable for.

1.1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

2.  The ORIGIN HTTP/2 Frame

   The ORIGIN HTTP/2 frame ([RFC7540], Section 4) allows a server to
   indicate what origin(s) [RFC6454] the server would like the client to
   consider as members of the Origin Set (Section 2.1) for the
   connection it occurs within.

   The ORIGIN frame type is 0xb (decimal 11).

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   |         Origin-Len (16)       | Origin? (*)                 ...

   The ORIGIN frame's payload contains the following fields, sets of
   which may be repeated within the frame to indicate multiple origins:

   Origin-Len:  An unsigned, 16-bit integer indicating the length, in
      octets, of the Origin field.

   Origin:  An optional sequence of characters containing the ASCII
      serialization of an origin ([RFC6454], Section 6.2) that the
      sender believes this connection is or could be authoritative for.

   The ORIGIN frame defines the following flags:

   CLEAR (0x1):  Indicates that the Origin Set MUST be reset to an empty
      set before processing the contents of the frame it occurs upon.

   REMOVE (0x2):  Indicates that the origin(s) carried in the payload
      must be removed from the Origin Set, if present; if not present,
      it/they have no effect.

2.1.  The Origin Set

   The set of origins (as per [RFC6454]) that a given connection might
   be used for is known in this specification as the Origin Set.

   When a connection is first established, its Origin Set is defined to
   be those origins that the client would normally consider the
   connection authoritative for; see [RFC7540], Section 10.1.

   The ORIGIN frame allows the server to modify the Origin Set. In

   1.  A server can add to its members by sending an ORIGIN frame
       (without any flags set);

   2.  A server can prune one or more origins from it by sending an
       ORIGIN frame with the REMOVE flag set;

   3.  A server can remove all its members and then add zero or more
       members by sending an ORIGIN frame with the CLEAR flag set and a
       payload containing the new origins.

   Adding to the Origin Set (cases 1 and 3 above) does not imply that
   the connection is authoritative for the added origins (in the sense

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   of [RFC7540], Section 10.1) on its own; this MUST be established by
   some other mechanism.

   A client that implements this specification MUST NOT use a connection
   for a given origin unless that origin appears in the Origin Set for
   the connection, regardless of whether or not it believes that the
   connection is authoritative for that origin.

2.2.  Processing ORIGIN Frames

   The ORIGIN frame is a non-critical extension to HTTP/2.  Endpoints
   that do not support this frame can safely ignore it upon receipt.

   When received by a client, it can be used to inform HTTP/2 connection
   coalescing (see Section 2.1), but does not relax the requirement
   there that the server is authoritative.

   The origin frame MUST be sent on stream 0; an ORIGIN frame on any
   other stream is invalid and MUST be ignored.

   The ORIGIN frame is processed hop-by-hop.  An intermediary MUST NOT
   forward ORIGIN frames.  Clients configured to use a proxy MUST ignore
   any ORIGIN frames received from it.

   The following algorithm illustrates how a client can handle received
   ORIGIN frames:

   1.  If the client is configured to use a proxy, ignore the frame and
       stop processing.

   2.  If the frame occurs upon any stream except stream 0, ignore the
       frame and stop processing.

   3.  If the CLEAR flag is set, remove all members from the Origin Set.

   4.  For each Origin field "origin_raw" in the frame payload:

       1.  Parse "origin_raw" as an ASCII serialization of an origin
           ([RFC6454], Section 6.2) and let the result be

       2.  If the REMOVE flag is set, remove any member of the Origin
           Set that is the same as "parsed_origin" (as per [RFC6454],
           Section 5), and continue to the next "parsed_origin".

       3.  Otherwise, add "parsed_origin" to the Origin Set.

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3.  Security Considerations

   Clients that blindly trust the ORIGIN frame's contents will be
   vulnerable to a large number of attacks; hence the reinforcement that
   this specification does not relax the requirement for server
   authority in [RFC7540], Section 10.1.

4.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC6454]  Barth, A., "The Web Origin Concept", RFC 6454,
              DOI 10.17487/RFC6454, December 2011,

   [RFC7540]  Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
              Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
              DOI 10.17487/RFC7540, May 2015,

Authors' Addresses

   Mark Nottingham


   Erik Nygren


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