HPACK - Header Compression for HTTP/2
draft-ietf-httpbis-header-compression-11

The information below is for an old version of the document
Document Type Active Internet-Draft (httpbis WG)
Last updated 2015-02-10
Replaces draft-rpeon-httpbis-header-compression, draft-ruellan-http-header-compression, draft-ruellan-headerdiff
Stream IETF
Intended RFC status Proposed Standard
Formats pdf htmlized bibtex
Reviews
Stream WG state Submitted to IESG for Publication
Document shepherd Mark Nottingham
Shepherd write-up Show (last changed 2014-12-17)
IESG IESG state Approved-announcement to be sent::Point Raised - writeup needed
Consensus Boilerplate Yes
Telechat date
Responsible AD Barry Leiba
Send notices to mnot@mnot.net, draft-ietf-httpbis-header-compression.all@ietf.org, httpbis-chairs@ietf.org, ietf-http-wg@w3.org
IANA IANA review state Version Changed - Review Needed
HTTPbis Working Group                                            R. Peon
Internet-Draft                                               Google, Inc
Intended status: Standards Track                              H. Ruellan
Expires: August 14, 2015                                       Canon CRF
                                                       February 10, 2015

                 HPACK - Header Compression for HTTP/2
                draft-ietf-httpbis-header-compression-11

Abstract

   This specification defines HPACK, a compression format for
   efficiently representing HTTP header fields, to be used in HTTP/2.

Editorial Note (To be removed by RFC Editor)

   Discussion of this draft takes place on the HTTPBIS working group
   mailing list (ietf-http-wg@w3.org), which is archived at [1].

   Working Group information can be found at [2]; that specific to
   HTTP/2 are at [3].

   The changes in this draft are summarized in Appendix D.2.

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 August 14, 2015.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Peon & Ruellan           Expires August 14, 2015                [Page 1]
Internet-Draft                    HPACK                    February 2015

   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  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Conventions . . . . . . . . . . . . . . . . . . . . . . .   5
     1.3.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
   2.  Compression Process Overview  . . . . . . . . . . . . . . . .   6
     2.1.  Header List Ordering  . . . . . . . . . . . . . . . . . .   6
     2.2.  Encoding and Decoding Contexts  . . . . . . . . . . . . .   6
     2.3.  Indexing Tables . . . . . . . . . . . . . . . . . . . . .   6
       2.3.1.  Static Table  . . . . . . . . . . . . . . . . . . . .   6
       2.3.2.  Dynamic Table . . . . . . . . . . . . . . . . . . . .   6
       2.3.3.  Index Address Space . . . . . . . . . . . . . . . . .   7
     2.4.  Header Field Representation . . . . . . . . . . . . . . .   8
   3.  Header Block Decoding . . . . . . . . . . . . . . . . . . . .   8
     3.1.  Header Block Processing . . . . . . . . . . . . . . . . .   8
     3.2.  Header Field Representation Processing  . . . . . . . . .   9
   4.  Dynamic Table Management  . . . . . . . . . . . . . . . . . .   9
     4.1.  Calculating Table Size  . . . . . . . . . . . . . . . . .  10
     4.2.  Maximum Table Size  . . . . . . . . . . . . . . . . . . .  10
     4.3.  Entry Eviction when Dynamic Table Size Changes  . . . . .  11
     4.4.  Entry Eviction when Adding New Entries  . . . . . . . . .  11
   5.  Primitive Type Representations  . . . . . . . . . . . . . . .  11
     5.1.  Integer Representation  . . . . . . . . . . . . . . . . .  11
     5.2.  String Literal Representation . . . . . . . . . . . . . .  13
   6.  Binary Format . . . . . . . . . . . . . . . . . . . . . . . .  14
     6.1.  Indexed Header Field Representation . . . . . . . . . . .  14
     6.2.  Literal Header Field Representation . . . . . . . . . . .  15
       6.2.1.  Literal Header Field with Incremental Indexing  . . .  15
       6.2.2.  Literal Header Field without Indexing . . . . . . . .  16
       6.2.3.  Literal Header Field never Indexed  . . . . . . . . .  17
     6.3.  Dynamic Table Size Update . . . . . . . . . . . . . . . .  18
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  19
     7.1.  Probing Dynamic Table State . . . . . . . . . . . . . . .  19
       7.1.1.  Applicability to HPACK and HTTP . . . . . . . . . . .  20
       7.1.2.  Mitigation  . . . . . . . . . . . . . . . . . . . . .  20
Show full document text