Re: Regexp: Private IP Addresses

[markkawika]

You can use Net::IP::Match::Regexp to do this:

use Net::IP::Match::Regexp qw( create_iprange_regexp match_ip );
    
my $regexp = create_iprange_regexp(
   qw( 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 )
);
if (match_ip($my_ip, $regexp)) {
   ...
}

[Sewi]

If you know you have an IP-address (got it from a network socket, for example), it would be much more efficient to match it with a one-line regexp:

/^(10\.\d+|172\.(1[6-9]|2\d|3[0-1])|192\.168)(\.\d+){2}$/;

If you got it from a non-network input (like a user form), don't trust in it, it may be 10.9999.1234.666.

[andreas1234567]

Yes, using a regular expression is "much more efficient", but yours is in some cases, as you point out, incorrect. And using Net::IP::Match::Regexp you can still do more than sixty seven thousand comparisons per second (on my old and rusty laptop, anyway) if the regexp is initialized once only. So what do you want:
• Superfast and possibly incorrect, or
• Fast and correct?

$ cat 791149.pl
use strict;
use warnings;

use Net::IP::Match::Regexp qw( create_iprange_regexp match_ip );
use Benchmark qw / cmpthese /;

my $regexp_init_once =
  create_iprange_regexp( qw( 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 )
+ );

sub netip {
  my $regexp =
    create_iprange_regexp( qw( 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
+ ) );
  return ( match_ip( $_[0], $regexp ) );
}

sub netip_init_once {
  return match_ip( $_[0], $regexp_init_once );
}

sub regexp {
  return $_[0] =~ /^(10\.\d+|172\.(1[6-9]|2\d|3[0-1])|192\.168)(\.\d+)
+{2}$/;
}

cmpthese(
  -1,
  {
    'netip'           => sub { netip('1.2.3.4') },
    'netip_init_once' => sub { netip_init_once('1.2.3.4') },
    'regexp'          => sub { regexp('1.2.3.4') },
  }
);

__END__
$ perl 791149.pl
                     Rate           netip netip_init_once          reg
+exp
netip              2438/s              --            -96%           -1
+00%
netip_init_once   67622/s           2674%              --            -
+95%
regexp          1390157/s          56918%           1956%             
+ --