Match IPs against CIDR specs
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IPSet Documentation

IPSet is a PHP library for matching IP addresses against a set of CIDR specifications.

Here is how you use it:

// At startup, calculate the optimized data structure for the set:
$ipset = new IPSet( array(
) );
// Runtime check against cached set (returns bool):
if ( $ipset->match( $ip ) ) {
    // ...

In rough benchmarking, this takes about 80% more time than in_array() checks on a short (a couple hundred at most) array of addresses. It's fast either way at those levels, though, and IPSet would scale better than in_array if the array were much larger.

For mixed-family CIDR sets, however, this code gives well over 100x speedup vs iterating IP::isInRange() over an array of CIDR specs.

The basic implementation is two separate binary trees (IPv4 and IPv6) as nested php arrays with keys named 0 and 1. The values false and true are terminal match-fail and match-success, otherwise the value is a deeper node in the tree.

A simple depth-compression scheme is also implemented: whole-byte tree compression at whole-byte boundaries only, where no branching occurs during that whole byte of depth. A compressed node has keys 'comp' (the byte to compare) and 'next' (the next node to recurse into if 'comp' matched successfully).

For example, given these inputs:

The v4 tree would look like:

root4 => array(
    'comp' => 25,
    'next' => array(
        0 => true,
        1 => array(
            0 => false,
            1 => true,

(multi-byte compression nodes were attempted as well, but were a net loss in my test scenarios due to additional match complexity)


Copyright 2014, 2015 Brandon Black blbla.nosp@m.ck@g.nosp@m.mail..nosp@m.com

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. http://www.gnu.org/copyleft/gpl.html