Using perl to find IPs belonging to a given country code

ip-cc.pl

#!/usr/bin/perl
use strict;
use IP::Country::Fast;

my $reg = IP::Country::Fast->new();

my $input = do { local $/; <>; };
my @ips = $input =~ /(.*?)(?:\/\d+)?\s/sg;

my %cc = map { $_ => $reg->inet_atocc($_) } @ips;
my @chinese = grep { $cc{$_} eq 'CN' } keys %cc;

print join( "\n", @chinese ),"\n";