Supporting Redirect Responses in DNS Queries over HTTPS (DoH)
draft-btw-add-rfc8484-clarification-01

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Last updated 2020-04-17
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ADD                                                         M. Boucadair
Internet-Draft                                                    Orange
Updates: 8484 (if approved)                                      N. Cook
Intended status: Standards Track                            Open-Xchange
Expires: October 19, 2020                                       T. Reddy
                                                                  McAfee
                                                                 D. Wing
                                                                  Citrix
                                                          April 17, 2020

     Supporting Redirect Responses in DNS Queries over HTTPS (DoH)
                 draft-btw-add-rfc8484-clarification-01

Abstract

   This document clarifies whether DNS-over-HTTPS (DoH) redirection is
   allowed and specifies how redirection is thus performed.

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
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   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 October 19, 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
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   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .   2
   4.  RFC8484 Update  . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Resolving the Redirect Domain . . . . . . . . . . . . . . . .   4
   6.  Applicability to DoH Server Redirect  . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   7
     10.2.  Informative References . . . . . . . . . . . . . . . . .   8
   Appendix A.  Server Push  . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   This document clarifies the intent of DNS-over-HTTPS (DoH) [RFC8484]
   whether redirection is allowed (Section 4), and subsequently
   specifies how redirection is performed (Section 5).

   This document adheres to Section 4.3 of [I-D.ietf-httpbis-bcp56bis]
   which discusses the need for protocols using HTTP to specify redirect
   handling to avoid interoperability problems.

2.  Terminology

   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
   capitals, as shown here.

   "A/AAAA" is used to refer to "A and/or AAAA records".

3.  Discussion

   [RFC8484] indicates that the support of HTTP redirection is one of
   DoH design goals (Section 1):

      "The described approach is more than a tunnel over HTTP.  It
      establishes default media formatting types for requests and
      responses but uses normal HTTP content negotiation mechanisms for

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      selecting alternatives that endpoints may prefer in anticipation
      of serving new use cases.  In addition to this media type
      negotiation, it aligns itself with HTTP features such as caching,
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