Greasing HTTP
draft-nottingham-http-grease-00

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Network Working Group                                      M. Nottingham
Internet-Draft                                              July 7, 2020
Intended status: Informational
Expires: January 8, 2021

                             Greasing HTTP
                    draft-nottingham-http-grease-00

Abstract

   Like many network protocols, HTTP is vulnerable to ossification of
   its extensibility points.  This draft specifies how they should be
   exercised ('greased') to assure their continued usability.

Note to Readers

   _RFC EDITOR: please remove this section before publication_

   The issues list for this draft can be found at
   https://github.com/mnot/I-D/labels/http-grease [1].

   The most recent (often, unpublished) draft is at
   https://mnot.github.io/I-D/http-grease/ [2].

   Recent changes are listed at https://github.com/mnot/I-D/commits/gh-
   pages/http-grease [3].

   See also the draft's current status in the IETF datatracker, at
   https://datatracker.ietf.org/doc/draft-nottingham-http-grease/ [4].

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 January 8, 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/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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  What to Grease? . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  How to Grease?  . . . . . . . . . . . . . . . . . . . . .   3
     1.3.  Notational Conventions  . . . . . . . . . . . . . . . . .   4
   2.  The HTTP Grease Process . . . . . . . . . . . . . . . . . . .   4
     2.1.  Greasing HTTP Request Header Fields . . . . . . . . . . .   5
     2.2.  Greasing HTTP Request Cache Directives  . . . . . . . . .   6
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   4.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     4.2.  Informative References  . . . . . . . . . . . . . . . . .   7
     4.3.  URIs  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   Appendix A.  Bootstrapping the HTTP Grease Process  . . . . . . .   8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Like many network protocols, HTTP is vulnerable to ossification of
   its extensibility points.  Those that are rarely exercised risk
   'rusting shut' because recipients assume that they will not be used.
   This happens in practice for several reasons, including implementer
   convenience, performance optimisation, or traffic characterisation.

   Because extensibility is a primary mechanism for protocol evolution,
   it is important to keep these extension points flexible.  For points
   that are rarely used, one proven way (pioneered by [RFC8701]) to
   assure this is through sending 'grease' values - i.e., extension
   values that are hard to predict and have no effect on correct
   protocol operation.

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   This document specifies how HTTP's extension points should be
   greased, to assure their continued usability.  It focuses on generic
   HTTP features; other documents cover versioned extensibility points
   (e.g., see [I-D.bishop-httpbis-grease]).

1.1.  What to Grease?

   HTTP has several extension mechanisms.  While keeping all of them
   available for use is desirable, this document currently targets two
   specific extensibility points - HTTP request header fields and
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