Using TLS Application-Layer Protocol Settings (ALPS) in HTTP
draft-vvv-httpbis-alps-00

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HTTP Working Group                                           V. Vasiliev
Internet-Draft                                                    Google
Intended status: Standards Track                             6 July 2020
Expires: 7 January 2021

      Using TLS Application-Layer Protocol Settings (ALPS) in HTTP
                       draft-vvv-httpbis-alps-00

Abstract

   This document describes the use of TLS Application-Level Protocol
   Settings (ALPS) in HTTP/2 and HTTP/3.  Additionally, it defines a set
   of additional HTTP SETTINGS parameters that would normally be
   impractical without ALPS.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Discussion of this document takes place on the HTTPBIS Working Group
   mailing list (httpbis@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/httpbis/
   (https://mailarchive.ietf.org/arch/browse/httpbis/).

   Source for this draft and an issue tracker can be found at
   https://github.com/vasilvv/httpbis-alps (https://github.com/vasilvv/
   httpbis-alps).

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 7 January 2021.

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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/
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   Please review these documents carefully, as they describe your rights
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  Use of ALPS in HTTP . . . . . . . . . . . . . . . . . . . . .   3
   4.  New Settings  . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   HTTP/2 defines a mechanism for exchanging the protocol settings using
   a SETTINGS frame ([RFC7540], Section 6.5).  HTTP/3 uses a similar
   mechanism ([HTTP3], Section 7.2.4).  One of the properties of the
   mechanism as defined by both of those protocols is that the parties
   start out without having access to the entirety of the peer's
   settings.  This means that they have to initially operate using the
   default settings, and after receiving the SETTINGS frame, they have
   to find a way to transition from the default to the exchanged
   settings.

   HTTP is commonly used in conjunction with TLS.  TLS performs its own
   handshake that precedes any data being exchanged by the HTTP layer
   itself.  The TLS Application-Level Protocol Settings extension [ALPS]
   allows settings negotiation to be performed within the TLS handshake,
   thus making the result immediately available to the HTTP layer as
   soon as the handshake completes.  This removes the need for
   synchronizing settings, and makes them available earlier than they
   would be otherwise.

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   This document defines how ALPS is used with HTTP/2 and HTTP/3, and
   introduces certain new settings that would not be practical without
   ALPS.

2.  Conventions and Definitions

   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