QPACK: Header Compression for HTTP/3
draft-ietf-quic-qpack-12

Document Type Active Internet-Draft (quic WG)
Last updated 2020-01-23
Replaces draft-bishop-quic-http-and-qpack, draft-ietf-quic-qcram
Stream IETF
Intended RFC status Proposed Standard
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QUIC                                                           C. Krasic
Internet-Draft                                                   Netflix
Intended status: Standards Track                               M. Bishop
Expires: 25 July 2020                                Akamai Technologies
                                                        A. Frindell, Ed.
                                                                Facebook
                                                         22 January 2020

                  QPACK: Header Compression for HTTP/3
                        draft-ietf-quic-qpack-12

Abstract

   This specification defines QPACK, a compression format for
   efficiently representing HTTP header fields, to be used in HTTP/3.
   This is a variation of HPACK header 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), which is archived at
   https://mailarchive.ietf.org/arch/search/?email_list=quic
   (https://mailarchive.ietf.org/arch/search/?email_list=quic).

   Working Group information can be found at https://github.com/quicwg
   (https://github.com/quicwg); source code and issues list for this
   draft can be found at https://github.com/quicwg/base-drafts/labels/-
   qpack (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 25 July 2020.

Krasic, et al.            Expires 25 July 2020                  [Page 1]
Internet-Draft                    QPACK                     January 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Conventions and Definitions . . . . . . . . . . . . . . .   4
     1.2.  Notational Conventions  . . . . . . . . . . . . . . . . .   4
   2.  Compression Process Overview  . . . . . . . . . . . . . . . .   5
     2.1.  Encoder . . . . . . . . . . . . . . . . . . . . . . . . .   5
       2.1.1.  Reference Tracking  . . . . . . . . . . . . . . . . .   6
       2.1.2.  Limits on Dynamic Table Insertions  . . . . . . . . .   6
       2.1.3.  Blocked Streams . . . . . . . . . . . . . . . . . . .   7
       2.1.4.  Known Received Count  . . . . . . . . . . . . . . . .   8
     2.2.  Decoder . . . . . . . . . . . . . . . . . . . . . . . . .   8
       2.2.1.  Blocked Decoding  . . . . . . . . . . . . . . . . . .   8
       2.2.2.  State Synchronization . . . . . . . . . . . . . . . .   9
       2.2.3.  Invalid References  . . . . . . . . . . . . . . . . .  10
   3.  Header Tables . . . . . . . . . . . . . . . . . . . . . . . .  10
     3.1.  Static Table  . . . . . . . . . . . . . . . . . . . . . .  10
     3.2.  Dynamic Table . . . . . . . . . . . . . . . . . . . . . .  11
       3.2.1.  Dynamic Table Size  . . . . . . . . . . . . . . . . .  11
       3.2.2.  Dynamic Table Capacity and Eviction . . . . . . . . .  11
       3.2.3.  Maximum Dynamic Table Capacity  . . . . . . . . . . .  12
       3.2.4.  Absolute Indexing . . . . . . . . . . . . . . . . . .  12
       3.2.5.  Relative Indexing . . . . . . . . . . . . . . . . . .  12
       3.2.6.  Post-Base Indexing  . . . . . . . . . . . . . . . . .  14
   4.  Wire Format . . . . . . . . . . . . . . . . . . . . . . . . .  14
     4.1.  Primitives  . . . . . . . . . . . . . . . . . . . . . . .  14
       4.1.1.  Prefixed Integers . . . . . . . . . . . . . . . . . .  14
       4.1.2.  String Literals . . . . . . . . . . . . . . . . . . .  14
     4.2.  Encoder and Decoder Streams . . . . . . . . . . . . . . .  15
     4.3.  Encoder Instructions  . . . . . . . . . . . . . . . . . .  16
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