HTTPSSVC record draft

Ben, Mike, and I have submitted the first version of a proposal for an
"HTTPSSVC" DNS record.

TL;DR:  This attempts to address a number of problems (ESNI, QUIC
bootstrapping, HTTP-to-HTTPS redirection via DNS, SRV-equivalent for HTTP,
etc) in a holistic manner through a new extensible DNS record, rather than
in a piecemeal fashion.  It is based on some previous proposals such as
"Alt-Svc in the DNS" and "Service Bindings" but takes into account feedback
received in DNSOP and elsewhere.

Feedback is most welcome and we're looking forward to discussing with
people in Montreal.

Draft link:

      https://tools.ietf.org/html/draft-nygren-httpbis-httpssvc-01



From the abstract:

This document specifies an "HTTPSSVC" DNS resource record type to
facilitate the lookup of information needed to make connections for HTTPS
URIs.  The HTTPSSVC DNS RR mechanism allows an HTTPS origin hostname to be
served from multiple network services, each with associated parameters
(such as transport protocol and keying material for encrypting TLS SNI).
It also provides a solution for the inability of the DNS to allow a CNAME
to be placed at the apex of a domain name.  Finally, it provides a way to
indicate that the origin supports HTTPS without having to resort to
redirects, allowing clients to remove HTTP from the bootstrapping process.

By allowing this information to be bootstrapped in the DNS, it allows for
clients to learn of alternative services before their first contact with
the origin.  This arrangement offers potential benefits to both performance
and privacy.

This proposal is inspired by and based on recent DNS usage proposals such
as ALTSVC, ANAME, and ESNIKEYS (as well as long standing desires to have
SRV or a functional equivalent implemented for HTTP).  These proposals each
provide an important function but are potentially incompatible with each
other, such as when an origin is load-balanced across multiple hosting
providers (multi-CDN). Furthermore, these each add potential cases for
adding additional record lookups in-addition to AAAA/A lookups.  This
design attempts to provide a unified framework that encompasses the key
functionality of these proposals, as well as providing some extensibility
for addressing similar future challenges.

--

Some likely FAQs (with some others listed in an appendix):

Q: Why this is HTTP-specific?
A: This is because every protocol has different bootstrap requirements.
This draft is concerned with improving the efficiency and security of
bootstrapping HTTPS connections.  This proposal does offer room for
non-HTTPS protocols, but the nature of DNS requires underscore prefixing to
support protocol-keyed answers within a single RRTYPE.  It's also unlikely
that a single RR format would be the ideal bootstrap mechanism for every
protocol, and there's no reason that multiple protocols should have to
share an RRTYPE.

Q: Why is ESNI addressed directly?
A: This helps make a major motivation of this draft more clear.  Splitting
out those sections to a separate-but-associated "alt-svc attribute for ESNI
keys" draft might make sense, but keeping it here helps work through some
of the issues together.

Q: Why does this try to address the HSTS case?
A: This is a unique opportunity to fix HTTPS bootstrap and avoid providing
insecure defaults.  We'd originally proposed a separate Alt-Svc attribute
to indicate hsts-style behavior, but then realized that it would make sense
to push on that as the default here.

Best, Erik



---------- Forwarded message ---------
From: <internet-drafts@ietf.org>
Date: Wed, Jul 3, 2019 at 1:06 PM
Subject: New Version Notification for draft-nygren-httpbis-httpssvc-01.txt
To: Mike Bishop <mbishop@evequefou.be>, Erik Nygren <erik+ietf@nygren.org>,
Benjamin Schwartz <bemasc@google.com>



A new version of I-D, draft-nygren-httpbis-httpssvc-01.txt
has been successfully submitted by Benjamin Schwartz and posted to the
IETF repository.

Name:           draft-nygren-httpbis-httpssvc
Revision:       01
Title:          HTTPSSVC service location and parameter specification via
the DNS (DNS HTTPSSVC)
Document date:  2019-07-03
Group:          Individual Submission
Pages:          22
URL:
https://www.ietf.org/internet-drafts/draft-nygren-httpbis-httpssvc-01.txt
Status:
https://datatracker.ietf.org/doc/draft-nygren-httpbis-httpssvc/
Htmlized:       https://tools.ietf.org/html/draft-nygren-httpbis-httpssvc-01
Htmlized:
https://datatracker.ietf.org/doc/html/draft-nygren-httpbis-httpssvc
Diff:
https://www.ietf.org/rfcdiff?url2=draft-nygren-httpbis-httpssvc-01

Abstract:
   This document specifies an "HTTPSSVC" DNS resource record type to
   facilitate the lookup of information needed to make connections for
   HTTPS URIs.  The HTTPSSVC DNS RR mechanism allows an HTTPS origin
   hostname to be served from multiple network services, each with
   associated parameters (such as transport protocol and keying material
   for encrypting TLS SNI).  It also provides a solution for the
   inability of the DNS to allow a CNAME to be placed at the apex of a
   domain name.  Finally, it provides a way to indicate that the origin
   supports HTTPS without having to resort to redirects, allowing
   clients to remove HTTP from the bootstrapping process.

   By allowing this information to be bootstrapped in the DNS, it allows
   for clients to learn of alternative services before their first
   contact with the origin.  This arrangement offers potential benefits
   to both performance and privacy.

   TO BE REMOVED: This proposal is inspired by and based on recent DNS
   usage proposals such as ALTSVC, ANAME, and ESNIKEYS (as well as long
   standing desires to have SRV or a functional equivalent implemented
   for HTTP).  These proposals each provide an important function but
   are potentially incompatible with each other, such as when an origin
   is load-balanced across multiple hosting providers (multi-CDN).
   Furthermore, these each add potential cases for adding additional
   record lookups in-addition to AAAA/A lookups.  This design attempts
   to provide a unified framework that encompasses the key functionality
   of these proposals, as well as providing some extensibility for
   addressing similar future challenges.




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