Commonly used network configuration tools write scoped IPv6 nameserver
addresses to /etc/resolv.conf. libirs only handles these when it is
compiled with -DIRS_HAVE_SIN6_SCOPE_ID, which is not the default, and
only handles numeric scopes, which is not what network configuration
tools typically use. This causes dig to be practically unable to handle
scoped IPv6 nameserver addresses in /etc/resolv.conf.
Fix the problem by:
- not requiring a custom compile-time flag to be set in order for
scoped IPv6 addresses to be processed by getaddrinfo(),
- parsing non-numeric scope identifiers using if_nametoindex(),
- setting the sin6_scope_id field in struct sockaddr_in6 structures
returned by getaddrinfo() even if the AI_CANONNAME flag is not set.
The "sortlist-v4.conf" unit test for irs_resconf_load() is always run
twice due to a duplicate entry in the "tests" table. Remove one of them
to prevent this.
irs_resconf_load() stores the value returned by add_search() into ret
without consulting its current value first. This causes any previous
errors raised while parsing resolv.conf to be ignored as long as any
"domain" or "search" statement is present in the file.
Prevent this by returning early in case an error is detected while
parsing resolv.conf. Ensure that "searchlist" and "magic" members of
the created irs_resconf_t structure are always initialized before
isc_resconf_destroy() is called.
