Function sc_sock_connect() picks wrong address faimily

[svladykin]

Connecting in non-blocking mode AF_INET6 socket with sc_sock_connect("localhost") where both IPv4 and IPv6 addresses are assigned to "localhost" but the server listens on IPv6 only.

It fails with Connection refused because getaddrinfo looks for any available address with AF_UNSPEC and wrongly picks IPv4. And since it is non-blocking mode it can not retry after the failure.

This change makes sc_sock_connect() give more respect to the configured socket family: the first iteration we try to connect to addresses with the matching family, the second iteration we try to connect to the rest.

[svladykin]

The diff looks horrible, but actually the change is this:

for (int i = 0; i < 2; i++) {
        for (p = sinfo; p != NULL; p = p->ai_next) {
            if (i == 0 ^ p->ai_family == family) {
                continue;
            }

[codecov[bot]]

Codecov Report

Merging #87 (2d957b4) into master (871e848) will increase coverage by 0.00%. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master      #87   +/-   ##
=======================================
  Coverage   99.81%   99.81%           
=======================================
  Files          21       21           
  Lines        2188     2192    +4     
  Branches      383      385    +2     
=======================================
+ Hits         2184     2188    +4     
  Partials        4        4           

Impacted Files	Coverage Δ
socket/sc_sock.c	100.00% <100.00%> (ø)

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[svladykin]

With Hide whitespace enabled the diff looks better.

[tezc]

@svladykin Thanks, it perfectly makes sense.