Re: [DNSOP] [Doh] Alternate proposal for transport indication in draft-ietf-dnsop-dns-wireformat-http

[Ray Bellis <[e-mail]>]

On 03/04/2018 08:33, Martin Thomson wrote:
> This is intended to do what?  Indicate where the response came from? 
> Why does the client care?  I assume that it doesn't apply to
> requests, or that would get into draft-bellis-dnsop-xpf territory.

I think there's some overlap here, if the intent of the
'original_transport' field is to allow a server to make policy decisions
(e.g. truncation, RRL etc) based on that value.

However, my XPF co-authors and I think that a simple transport protocol
value is no longer sufficient for this.  In practise the servers don't
care about the *actual* transport, but instead care about the
meta-properties of that transport, i.e. "is it unspoofable", "does it
support large packets", "is it encrypted" ?

In "old" DNS the use of a single flag indicating "udp" or "tcp" was an
adequate proxy for those meta-properties, but now with DNS-over-TLS,
Cookies, etc, it won't do.

Ray