Re: [Doh] No truncation for DNS over HTTPS

On Thu, Mar 22, 2018 at 10:24 AM Ray Bellis <ray@bellis.me.uk> wrote:

> On 22/03/2018 09:20, Davey Song wrote:
>
> > Although the dns-udpwireformat MIME type was defined, the dns wireformat
> > data should not be treated as a datagram encapsulted in a HTTPs header
> > but a new byte stream over HTTPs (similar with DNS TCP usage). No
> > truncation loop is needed. Peopole may take it for granted, but It
> > should be explicitely mentioned in this draft.
>
> If the DNS API Server is proxying between DOH and a real UDP DNS server
> then the UDP DNS server might still set the TC bit and the proxy could
> return that, so the client may still have to cope with +TC.
>
> The alternative is that the proxy has to have sufficient smarts to
> recognise the returned +TC and re-issue the request over TCP to the
> backend DNS server.

There is not much the client can be doing with the TC but here right. I
mean it is using tcp already. When producing, IMO the proxy should be aware
of the TC bit and retry over TCP when it happens.
Manu

>
>
> Ray
>
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