On Wed, 10 Dec 2014, Seppo Heikkilä wrote:
If you take multi-app.c example:
http://curl.haxx.se/libcurl/c/multi-app.html and use it to connect to a
server that is using DNS load balancing (has several IPs for one hostname),
such as google.com, it seems all connections will be established with the
same IP address.
Well, yes most likely. libcurl will traverse the list of address in the same
order every time it tries to connect to a host that is kept in the DNS cache,
and that will most likely lead to it connecting to the first address in there.
DNS load balancing is quite common so this should work quite easily.
It isn't easy. getaddrinfo() returns the addresses in a prio order and we go
through the addresses in that order. How are you suggesting we change this
without overriding the users' /etc/gai.conf, RFC 3484 and whatever more that
need to be taken into account?
Of course, involving c-ares complicates matters slightly more too since then
the resolving job is done with the c-ares API instead and that doesn't sort
the entries like getaddrinfo (one of the many tiny ways c-ares is not a
drop-in compatible name resolver).
I'm open for suggestions and patches on how to improve this.
--
/ daniel.haxx.se
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