Re: [Doh] POST and GET

[bert hubert <[e-mail]>]

On Tue, Sep 18, 2018 at 11:21:48AM +0800, Sebastiaan Deckers wrote:
> > DoH servers MUST implement both the POST and GET methods.
> What is meant by the word "implement"?

That you implement both methods and that they both work.

> I have *implemented* both GET and POST code paths. But do they need to
> exposed in every use case? I want to be able to support GET only for server

I see no exception or limitation in the text.

> GET requires much more processing from a DOH proxy. I.e. parse the DNS
> response packet to find the lowest TTL for HTTP cache-control header
> max-age. As an operator I may want to disable support for GET requests from
> the client and return 405 or 501.

If you do that, you violate the principle of least astonishment https://en.wikipedia.org/wiki/Principle_of_least_astonishment
Clients would rightfully be confused. They would also mess it up.

> I love the idea of pushing DNS responses as GET. This is lightweight and
> can be easily injected by a DOH proxy. However the current draft, in
> section 5.3, does not impose a similar "MUST implement both" requirement on
> the client. Should it?

What you are asking for is a sentence that says 'if GET did not work you
must retry as POST'. This complicates every client in existence with
fallback code. DNS is already riddled with fallbacks and retries.

So please no. 

	Bert