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Re: HTTPS records

From: Niall O'Reilly via curl-library <curl-library_at_lists.haxx.se>
Date: Mon, 05 Dec 2022 11:42:17 +0000

On 27 Nov 2022, at 22:31, Daniel Stenberg via curl-library wrote:

> I've started to write down some details and thoughts on how curl
> should or could support HTTPS DNS records going forward:
>
> https://github.com/curl/curl/wiki/HTTPS-record

I'm delighted to see this, in particular because SVCB/HTTPS records
provide the means to publish ECH configuration data in the DNS.

> I'm sure I've missed lots of details, but hey, it's a wiki!

I'm not sure which is preferable as as means to give feedback:
here on the list, or by submitting PRs for the wiki. For now,
the "lazy method" of using the list suits me better, but I'm
happy to use whatever is most convenient for others.

I think there are two key design decisions to be made for libcurl
in order to go "beyond getaddrinfo()". These are not entirely
independent of each other.

The first of these is whether to develop new functionality in
c-ares or rather to use instead a modern library, developed
by DNS specialists, as the "DNS engine" for libcurl. Ones that
come to my mind are [connectbyname][] and [getdns][]).

The second is how to extend libcurl's DNS cache so as to represent
the additional DNS data which will be available. IIUC, the current
cache maps a key tuple (hostname, port) to an address-information
object (or list of such objects). SVCB and compatible DNS records,
such as HTTPS, are keyed on (hostname, scheme, port), so it seems
that not just the target information object of the map, but also
the key, will need to be extended.

I hope this helps.

Niall

---
[getdns]:
https://getdnsapi.org/documentation/readme/
[connectbyname]:
https://nlnetlabs.nl/projects/connectbyname/about/


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Received on 2022-12-05