Passing the nameserver(s) doesn't take preference over /etc/resolv.conf

[ibc]

It seems that udns always takes the list of nameservers from /etc/resolv.conf, regardless of the existance of the NAMESERVERS enviroment variable. Extracted from udns documentation:

When initializing resolver context, the library uses information from system file /etc/resolv.conf (see resolv.conf(5)), consults environment variables $LOCALDOMAIN, $DNSCACHEIP, $NAMESERVERS and $RES_OPTIONS, and local host name to obtain list of local nameservers, domain name search list and various resolver options.

So passing an IP (a nameserver) to EM::Udns::Resolver.new doesn't work. Must be investigated and the documentation fixed after that.

[ibc]

Michael Tokarev probed that it can work if the enviroment variable NAMESERVERS is set:

The only trap that comes to mind is that you didn't export NAMESERVERS variable so it's not available in subprocesses.

Check this:

NAMESERVERS=127.0.0.2 dnsget -vv foo.bar

it will tell where it is sending queries to (if nothing is listening on 127.0.0.2 it will just time out).

NAMESERVERS=127.0.0.2; dnsget -vv foo.bar

(note the semicolon) -- this will change nothing, dnsget will use regular nameservers listed in /etc/resolv.conf. And this:

export NAMESERVERS=127.0.0.2; dnsget -vv foo.bar

will use 127.0.0.1 again.

So it seems that the way I set the enviroment NAMESERVERS variable:

ENV["NAMESERVERS"] = .....

is not valid as udns doesn't see it as an enviroment variable. I must fix that.

[ibc]

I must set ENV["NAMESERVERS"] before initializing the EM::Udns::Resolver instance, as udns is loaded when allocating the class (which happens before "initialize" method). So I must create a new class method for it.

[ibc]

Fixed by commit https://github.com/ibc/em-udns/commit/4e1a1c26faf3a8b40d6c5adcee5e61fbd7211408