http://www.perlmonks.org?node_id=1200603

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

This seems like a basic question, but I can't find what I'm looking for.

I'm looking for a module that does DNS name resolution *easy*. I can write the code to do getaddrinfo() / getnameinfo() and the legacy gethostby...() but that's lots of code I cut/paste into my scripts whenever I need name resolution. To make it worse, there are all sorts of checks for Socket version to accommodate for IPv6 - which I need my scripts to be aware of.

I'm looking for something like:

use Magic::Name::Resolution
...
host2addr('www.google.com'); # print 1st IP addr returned, 4 or 6
host2ipv4('www.google.com'); # print 1st IPv4 addr returned
host2ipv6('www.google.com'); # print 1st IPv6 addr returned
...

[download]

Hopefully you get the picture. All the messy stuff I do in code to resolve those names to addresses is obscured in a module. I thought of putting all my code in a module, but wanted to see what you all use since my CPAN searches for "DNS", "resolve", "host", "getaddr" turn up the usual suspects which require more "low-level" code writing (which again, I do, but I do repeatedly in all my scripts that need it). Looking for a nice simple API like above in a re-usable module instead of my current cut/paste approach.

Replies are listed 'Best First'.
Re: Name resolution module
by hippo (Bishop) on Oct 03, 2017 at 12:17 UTC
    All the messy stuff I do in code to resolve those names to addresses is obscured in a module. I thought of putting all my code in a module, but wanted to see what you all use

    TBH, with Net::DNS it is relatively simple so I've never bothered to code up a wrapper:

    #!/usr/bin/env perl 
use strict;
use warnings;
use Net::DNS;

my $res = Net::DNS::Resolver->new ();

print "Any:  " . $res->query('www.google.com')->pop('answer')->rdstrin
+g .  "\n";
print "IPv4: " . $res->query('www.google.com', 'A')->pop('answer')->rd
+string . "\n";
print "IPv6: " . $res->query('www.google.com', 'AAAA')->pop('answer')-
+>rdstring . "\n";

    [download]

    The advantage is that if you are interested in any other aspects of the responses or the resolver those are easily obtainable/settable.

[reply]
[d/l]

      Now that's interesting!! ++ I hadn't seen Net::DNS used that way. That could be what I'm looking for - thanks for the helpful usage; I'll have a deeper look.

[reply]
Re: Name resolution module
by 1nickt (Canon) on Oct 03, 2017 at 11:53 UTC

    Hi, I'm certain that you know far more than I do about networking, but have you tried Net::Nslookup which wraps Net::DNS::Resolver? 

    $ perl -Mstrict -MNet::Nslookup -E 'say scalar nslookup "www.google.co
+m"'
209.85.232.104

    [download]
    Not sure about IPv4 vs IPv6, but maybe you can extend it/steal the good parts?

    Also note that (as you probably know) Google and others use load-balanced DNS so you will likely get a different result each time you query.

    Hope this helps!


    The way forward always starts with a minimal test.
[reply]
[d/l]

      Thanks. I had seen Net::DNS::Resolver which is under Net::DNS. It just didn't provide the varied output I'm looking for - at least I think not - between IPv4/6 and reverse lookups. You need to specify the address family into the routine if I remember correctly.

      I'll have a look at Net::NSLookup.

[reply]
Re: Name resolution module
by holyghost (Beadle) on Oct 04, 2017 at 19:11 UTC
    If you want to write it yourself read rfc.org, if you want a Scheme version I have done such things in sunterlib. It depends if you want to write it yourself.
[reply]

Back to Seekers of Perl Wisdom