Re: [DNSOP] Multiplexing DNS & HTTP over TLS

Shane Kerr <shane@time-travellers.org> Thu, 14 February 2019 13:24 UTC

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From: Shane Kerr <shane@time-travellers.org>
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Date: Thu, 14 Feb 2019 14:23:59 +0100
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Subject: Re: [DNSOP] Multiplexing DNS & HTTP over TLS
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Klaus,

On 14/02/2019 14.00, Klaus Malorny wrote:
> On 14.02.19 11:03, Shane Kerr wrote:
> 
>> Is there a write-up on this?
>>
>> Thinking about it naively, a demultiplexer really only needs to say 
>> "is there a non-ASCII character in the first 2 or 3 bytes of a TLS 
>> session?".
>>
> please think of HTTP/2, which is a binary protocol (although I don't 
> know what the first bytes are). But I guess ALPN (RFC 7301) would do the 
> trick.

I think that HTTP/2 preserves the initial handshake of HTTP/1.1.

But looking at ALPN, it was designed for exactly this the multiplexing 
use case. In principle all that would be needed is adding an identifier 
to the ALPN protocol IDs:

https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#alpn-protocol-ids

It would also address Joe's concerns about other protocols.

Maybe creating an ALPN protocol ID for DNS-over-TLS is something for the 
DPRIVE working group? 🤔

Cheers,

--
Shane