QPACK: Header Compression for HTTP/3
draft-ietf-quic-qpack-19

Document Type Active Internet-Draft (quic WG)
Authors Charles Krasic  , Mike Bishop  , Alan Frindell 
Last updated 2020-11-16 (latest revision 2020-10-20)
Replaces draft-bishop-quic-http-and-qpack, draft-ietf-quic-qcram
Stream IETF
Intended RFC status Proposed Standard
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Stream WG state Submitted to IESG for Publication (wg milestone: Jul 2020 - QPACK: Header Compre... )
Document shepherd Lucas Pardue
Shepherd write-up Show (last changed 2020-09-25)
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Responsible AD Magnus Westerlund
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IANA IANA review state IANA OK - Actions Needed
QUIC                                                           C. Krasic
Internet-Draft                                                   Netflix
Intended status: Standards Track                               M. Bishop
Expires: 23 April 2021                               Akamai Technologies
                                                        A. Frindell, Ed.
                                                                Facebook
                                                         20 October 2020

                  QPACK: Header Compression for HTTP/3
                        draft-ietf-quic-qpack-19

Abstract

   This specification defines QPACK, a compression format for
   efficiently representing HTTP fields, to be used in HTTP/3.  This is
   a variation of HPACK compression that seeks to reduce head-of-line
   blocking.

Note to Readers

   Discussion of this draft takes place on the QUIC working group
   mailing list (quic@ietf.org (mailto:quic@ietf.org)), which is
   archived at https://mailarchive.ietf.org/arch/
   search/?email_list=quic.

   Working Group information can be found at https://github.com/quicwg;
   source code and issues list for this draft can be found at
   https://github.com/quicwg/base-drafts/labels/-qpack.

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."

   This Internet-Draft will expire on 23 April 2021.

Krasic, et al.            Expires 23 April 2021                 [Page 1]
Internet-Draft                    QPACK                     October 2020

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  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Conventions and Definitions . . . . . . . . . . . . . . .   4
     1.2.  Notational Conventions  . . . . . . . . . . . . . . . . .   5
   2.  Compression Process Overview  . . . . . . . . . . . . . . . .   5
     2.1.  Encoder . . . . . . . . . . . . . . . . . . . . . . . . .   6
       2.1.1.  Limits on Dynamic Table Insertions  . . . . . . . . .   6
       2.1.2.  Blocked Streams . . . . . . . . . . . . . . . . . . .   7
       2.1.3.  Avoiding Flow Control Deadlocks . . . . . . . . . . .   8
       2.1.4.  Known Received Count  . . . . . . . . . . . . . . . .   9
     2.2.  Decoder . . . . . . . . . . . . . . . . . . . . . . . . .   9
       2.2.1.  Blocked Decoding  . . . . . . . . . . . . . . . . . .   9
       2.2.2.  State Synchronization . . . . . . . . . . . . . . . .  10
       2.2.3.  Invalid References  . . . . . . . . . . . . . . . . .  11
   3.  Reference Tables  . . . . . . . . . . . . . . . . . . . . . .  11
     3.1.  Static Table  . . . . . . . . . . . . . . . . . . . . . .  11
     3.2.  Dynamic Table . . . . . . . . . . . . . . . . . . . . . .  12
       3.2.1.  Dynamic Table Size  . . . . . . . . . . . . . . . . .  12
       3.2.2.  Dynamic Table Capacity and Eviction . . . . . . . . .  12
       3.2.3.  Maximum Dynamic Table Capacity  . . . . . . . . . . .  13
       3.2.4.  Absolute Indexing . . . . . . . . . . . . . . . . . .  13
       3.2.5.  Relative Indexing . . . . . . . . . . . . . . . . . .  14
       3.2.6.  Post-Base Indexing  . . . . . . . . . . . . . . . . .  15
   4.  Wire Format . . . . . . . . . . . . . . . . . . . . . . . . .  15
     4.1.  Primitives  . . . . . . . . . . . . . . . . . . . . . . .  15
       4.1.1.  Prefixed Integers . . . . . . . . . . . . . . . . . .  15
       4.1.2.  String Literals . . . . . . . . . . . . . . . . . . .  15
     4.2.  Encoder and Decoder Streams . . . . . . . . . . . . . . .  16
     4.3.  Encoder Instructions  . . . . . . . . . . . . . . . . . .  17
       4.3.1.  Set Dynamic Table Capacity  . . . . . . . . . . . . .  17
       4.3.2.  Insert With Name Reference  . . . . . . . . . . . . .  18
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