dns: add setDefaultResolver and getDefaultResolver
Since dns.Resolver
was added, it gives a chance to manage the default
resolver by ourselves. So dns.setDefaultResolver
and
dns.getDefaultResolver
is added here.
Checklist
-
make -j4 test
(UNIX) -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines
Affected core subsystem(s)
dns