Undefined address for Socket::pack_sockaddr

WithABeard has asked for the wisdom of the Perl Monks concerning the following question:

I am using Firefox::Marionette, and it works great (normally), but is now giving this error:

% perl -MFirefox::Marionette -e 'my $f=Firefox::Marionette->new()'
Undefined address for Socket::pack_sockaddr_in at /Users/<user>/perl5/
+lib/perl5/Firefox/Marionette.pm line 7134.
[download]

The line in question is this one:

    $sock_addr =
      Socket::pack_sockaddr_in( $port, Socket::inet_aton($host) );
[download]

So I'm guessing that Socket::inet_aton($host) is the culprit

metacpan.org/pod/Socket tells us that:

...If passed a hostname that cannot be resolved, returns undef.

From this I'll assume that the hostname cannot be resolved, but we're not even opening a url yet...

Testing Socket yields predictable results:

% perl -MSocket -e'defined (my $a=inet_aton("garbage")) or die"dead"; 
+print unpack "V", $a;'
dead at -e line 1.
% perl -MSocket -e'defined (my $a=inet_aton("127.0.0.1")) or die"dead"
+; print unpack "V", $a;'
16777343
[download]

It seems to do its job when passed something sensible

I usually work from home, but today I went in to the office, and got the error.
Could this be caused by a change in the network?
I'll know later today if it works at home.

System details:

MacOS 14.5
Apple M2
perl ver. 5.34.2

I tried flushing cache with sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder, but this made no difference

I also tried changing the perl version (using plenv), but then I have to install Firefox::Marionette for the new version, and surprise-surprise; installation fails with the same error :p

Is this the right way to flush DNS on MacOS 14.5?

How can I find out what is actually passed to inet_aton when it fails?

What else can I do to debug this?

Comment on Undefined address for Socket::pack_sockaddr_in Select or Download Code

Replies are listed 'Best First'.
Re: Undefined address for Socket::pack_sockaddr_in by Corion (Patriarch) on Jun 20, 2024 at 11:45 UTC
Walking up the call chain, it tries to resolve `_DEFAULT_HOST()`, which is `localhost`. Maybe `localhost` does not resolve to a good name for the chosen protocol? Maybe things work better if you explicitly supply a hostname, or a fixed IP address? `my $ff = Firefox::Marionette->new( host => '127.0.0.1', #host => 'localhost', #host => '::1', #host => 'hostname-of-the-machine', );` [download] Maybe `localhost` only resolves for IPv4 (or IPv6) and `pack_sockaddr_in` tries to pack an address for IPv6 (or IPv4)...	[reply] [d/l] [select]
Re^2: Undefined address for Socket::pack_sockaddr_in by WithABeard (Beadle) on Jun 20, 2024 at 11:54 UTC
You are right, "localhost" does not resolve: `% perl -MSocket -e'defined inet_aton("localhost") or die;' Died at -e line 1.` [download] I forgot that I meddled with /etc/hosts trying to resolve a different issue, and I guess I didn't restore it Now that I have restored it, the error is gone. Strange that I did not get this problem until now, as it has been days since this meddling...	[reply] [d/l]