On Thu, 25 Nov 2021, Dmitry Karpov via curl-library wrote:
It seems the problem is that even though libcurl implements Happy Eyeballs for DNS queries and runs A and AAAA queries in parallel, c-ares still goes through the list of name servers as they are listed in the resolv.conf.
All the name resolver solutions libcurl uses performs the entire name resolve phase first, before libcurl gets a chance to start trying to connect to the first address. This makes a slow name resolve affect the starting point of all connect attempts libcurl makes.
In an ideal world, libcurl could start trying to connect to addresses as they trickle in from the DNS servers, but since they need to be sorted and provided in a certain order, that's far easier said than done and the regular libc getaddrinfo() API doesn't allow for it either.
Is it possible to work around this issue somehow?
My immediate thought is that it needs to be dealt with in c-ares somehow. How does the regular getaddrinfo() function behave in this situation?
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