How best to support IPv4/v6 in Perl server

[VinsWorldcom]

QUESTION:What's the best cross-platform / backward compatible way to support IPv4 and IPv6 in Perl servers?

My research / testing:

I have a few modules on CPAN that create simple servers for listening and parsing of messages (shameless plug: Net::Syslogd and Net::SNMPTrapd). Currently, they support IPv4 by creating the listener with IO::Socket::INET.

I've been doing some work / testing and some reading on Perl support for IPv6 lately (IPv6 Name Resolution). I'm wondering what the best way to support both IPv4 and IPv6 in a Perl server would be?

Currently, I've done something with IO::Select and both IO::Socket::INET/6. Psuedo code below:

...
# determine v4 or v6, nothing selected - then both
if (!defined($opt{ipv4}) && !defined($opt{ipv6})) {
    $opt{ipv4} = $opt{ipv6} = 1
}

...

# server (select between v4 and v6 if both exist)
my $server = IO::Select->new();

# v4 server
if ($opt{ipv4}) {
    my $server4 = IO::Socket::INET->new(
                                        Proto => 'tcp',
                                        LocalPort => $opt{port},
                                        Listen => SOMAXCONN,
                                        Reuse => 1
                                       ) or die "$0:  Unable to create
+ IPv4 server: $!\n";
    $server->add($server4)
}

# v6 server
if ($opt{ipv6}) {
    my $server6 = IO::Socket::INET6->new(
                                         Proto => 'tcp',
                                         LocalPort => $opt{port},
                                         Listen => SOMAXCONN,
                                         Reuse => 1
                                        ) or die "$0:  Unable to creat
+e IPv6 server: $!\n";
    $server->add($server6)
}

...

# determine which server has data
while (my @servers = $server->can_read) {
    # loop servers
    for my $svr (@servers) {
        # read from v4 or v6 server that has data
        while(my $client = $svr->accept()) {

#DO STUFF

        }
    }
}

The code works fine - no problem / debug there. According to 'corelist', Socket6, IO::Socket::INET6 and "the new drop-in replacement" IO::Socket::IP aren't in 5.12.3 (the version I'm using) and don't appear to be in 5.14 according to http://perldoc.perl.org/index-modules-I.html.

So what are your opinions on the best way to support IPv4 and IPv6 in Perl servers:

• IO::Select with IO::Socket::INET / INET6
• IO::Socket::IP
• Socket and Socket6 with some fierce coding
• Something else?

[Anonymous Monk]

That's easy. If you have Perl 5.14 or later, use IO::Socket::INET (core module, IP-dualstack). Any other Perl, install and use IO::Socket::IP (CPAN module, IP-dualstack).

[VinsWorldcom]

Didn't realize that - so in 5.14 and on, IO::Socket::INET *includes* IPv6?

Of course, as you point out, that won't be backward compatible, I'll still need to 'use' IO::Socket::IP or IO::Socket::INET6 for older Perl versions.

Thanks!

Anyone else have an opinion?

[Rhandom]

Sorry. I'm not done quite yet. I've had changes pending in Net::Server for nearly a year adding IPv6 support (thanks to patches from half a dozen people). Once I'm done then you can just start up Net::Server and you get IPv4 and 6 for free.