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RE: [EXTERNAL] Re: HTTPS records
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From: Daniel Stenberg via curl-library <curl-library_at_lists.haxx.se>
Date: Wed, 7 Dec 2022 23:52:35 +0100 (CET)
On Wed, 7 Dec 2022, Dmitry Karpov via curl-library wrote:
> Exactly! Honoring exact TTLs will be a very good feature. I heard complaints
> from some backend services who manipulated DNS records for load balancing
> and used 20s TTL that libcurl didn't honor it and it created performance
> issues. So, it will be definitely a good addition to the library.
Sure, just a little complicated.
A primary reason the default name resolving in libcurl is still done with
getaddrinfo() and not with a third party library like c-ares is that it is
mighty hard to replicate its functionality. And getaddrinfo() does not return
TTL.
If we want to know the TTL for A and AAAA records while remaining 100%
compatible with names used all over, we need to use getaddrinfo() *AND* do a
separate lookup for the A and AAAA entries and use any possible TTL values we
get back. Double the number of DNS requests. Not ideal.
Date: Wed, 7 Dec 2022 23:52:35 +0100 (CET)
On Wed, 7 Dec 2022, Dmitry Karpov via curl-library wrote:
> Exactly! Honoring exact TTLs will be a very good feature. I heard complaints
> from some backend services who manipulated DNS records for load balancing
> and used 20s TTL that libcurl didn't honor it and it created performance
> issues. So, it will be definitely a good addition to the library.
Sure, just a little complicated.
A primary reason the default name resolving in libcurl is still done with
getaddrinfo() and not with a third party library like c-ares is that it is
mighty hard to replicate its functionality. And getaddrinfo() does not return
TTL.
If we want to know the TTL for A and AAAA records while remaining 100%
compatible with names used all over, we need to use getaddrinfo() *AND* do a
separate lookup for the A and AAAA entries and use any possible TTL values we
get back. Double the number of DNS requests. Not ideal.
-- / daniel.haxx.se | Commercial curl support up to 24x7 is available! | Private help, bug fixes, support, ports, new features | https://curl.se/support.html -- Unsubscribe: https://lists.haxx.se/listinfo/curl-library Etiquette: https://curl.se/mail/etiquette.htmlReceived on 2022-12-07