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Re^2: Regexp: Private IP Addresses

by Sewi (Friar)
on Aug 25, 2009 at 18:36 UTC ( #791151=note: print w/ replies, xml ) Need Help??

in reply to Re: Regexp: Private IP Addresses
in thread Regexp: Private IP Addresses

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:

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.

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Re^3: Regexp: Private IP Addresses
by andreas1234567 (Vicar) on Aug 26, 2009 at 08:29 UTC
    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 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( ) + ); sub netip { my $regexp = create_iprange_regexp( qw( + ) ); 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('') }, 'netip_init_once' => sub { netip_init_once('') }, 'regexp' => sub { regexp('') }, } ); __END__ $ perl 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% + --

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