use strict;
use warnings;

use Socket qw( inet_aton );

sub is_private {
    my ($packed_ip) = @_;
    return $packed_ip =~ m{
        ^
        (?: \x0A             # 10.0.0.0/8
        |   \xAC[\x10-\x1F]  # 172.16.0.0/12
        |   \xC0\xA8         # 192.168.0.0/16
        )
    }x;
}

my $result = '';
for (qw(
    9.255.255.255    10.0.0.0     10.255.255.255   11.0.0.0
    172.15.255.255   172.16.0.0   172.31.255.255   172.32.0.0
    192.167.255.255  192.168.0.0  192.168.255.255  192.169.0.0
)) {
    my $packed_ip = inet_aton($_);
    $result .= is_private($packed_ip) ? 1 : 0;
}

print("got:    $result\n");
print("expect: ", "0110"x3, "\n");