Re: [Doh] re original_transport indicator
Paul Vixie <paul@redbarn.org> Fri, 06 April 2018 23:29 UTC
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Date: Fri, 06 Apr 2018 19:29:36 -0400
From: Paul Vixie <paul@redbarn.org>
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To: Martin Thomson <martin.thomson@gmail.com>
CC: Patrick McManus <pmcmanus@mozilla.com>, dnsop <dnsop@ietf.org>, DoH WG <doh@ietf.org>, Ted Lemon <mellon@fugue.com>, Ray Bellis <ray@bellis.me.uk>
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Subject: Re: [Doh] re original_transport indicator
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Martin Thomson wrote: > +1 to this. > > And maybe there is an outcome that doesn't need this parameter. I > probably misunderstood some of the expectations people have for the > parameter. With the benefit of time and sleep, it's possible that I > now understand the disconnect. > > My model of content-type - and by extension its parameters - is of a > description of the content. However, it appears as though at least > some people had different uses for the parameter: for requests, it > would be an instruction/suggestion to the server to make a DNS request > using the identified transport; for responses, it would be a > description of where the DNS request came from. my original design added an http header, which was seen as even worse. someone suggested adding to the content-type, and i went along with it even though there is no difference in actual type of actual content. > I never considered that interpretation, but - assuming that this is > what it was - and the intent was to provide a means for the client to > control how the server makes requests (and to see how they were made). > In that case, I have a possible alternative design for the use case in > the dnsop draft. > > Right now, DOH doesn't really say how a DNS API Server gets its > responses. It could be that the API server is part of a resolver, or > it could be that the DNS API Server makes a request to another > resolver. But specific uses of the DOH protocol could come with > additional constraints that would enable the use cases in the dnsop > draft, at least as I understand them. this all sounds good to me. > If the goal of the dnsop draft is to extend the reach of a DNS client > (note: not a DNS API client) across a network that is in some way less > hostile to HTTP than it is to DNS, then I think that it can still use > DOH. A DNS API server could be configured to operate in a very simple > mode with no caching, just direct transposition of a request from HTTP > to a request on UDP or TCP. A DNS client could be configured with two > DNS API clients. Each client uses a different DNS API Server > endpoint. Those endpoints would be specifically configured to use > only UDP or TCP. > > For instance: > https://use.only/tcp{?dns} would cause the server to make a request using TCP. > https://use.only/udp{?dns} would cause the server to make a request using UDP. > > At this point, this is simple DOH, but with extra contextual > information about server operation. i am generally supportive of this approach; in fact i wish i'd thought of it. the specifics will be different, as in: /proxy_dns?proto=tcp /proxy_dns?proto=udp but i agree that encoding the original transport in the URI is better than either extending the content-type or adding another http header. --- i object, as before, to "dns-udpwireformat" as a name. these are dns messages, which when carried by udp are raw, and when carried in tcp are preceded by a two-octet length indicator for framing of multiple messages sharing the same stream. so, the string to be registered should be "dns-message". -- P Vixie
- [Doh] re original_transport indicator Patrick McManus
- Re: [Doh] re original_transport indicator Hewitt, Rory
- Re: [Doh] re original_transport indicator Martin Thomson
- Re: [Doh] re original_transport indicator Paul Vixie
- Re: [Doh] re original_transport indicator Martin Thomson
- Re: [Doh] [DNSOP] re original_transport indicator Dave Lawrence
- Re: [Doh] media type name, was Re: re original_tr… Tony Finch
- Re: [Doh] re original_transport indicator Davey Song
- Re: [Doh] re original_transport indicator Paul Vixie