<?php
// File name:	ipv4addr.inc.php
// Description:	PHP subroutine to handle the IPv4 addresses
// Date:	2007-01-30
// Author:	imacat <imacat@pristine.com.tw>
// Copyright:	Copyright (C) 2007 Pristine Communications

// ipv4_in_network: If an IP is in a network
function ipv4_in_network($network, $ip)
{
    // Network in ddd.ddd.ddd.ddd/mm format
    if (preg_match("/^(\d+)\.(\d+)\.(\d+)\.(\d+)\/(\d+)$/", $network, $m)) {
        // Sanity check
        settype($m[5], "integer");
        if ($m[5] > 32) {
            return null;
        }
        for ($i = 1; $i <= 4; $i++) {
            settype($m[$i], "integer");
            if ($m[$i] > 255) {
                return null;
            }
        }
        // Get the subnetwork mask
        $masklen = $m[5];
        for ($i = 0, $submask = 0; $i < $masklen; $i++) {
            $submask |= 1 << (31 - $i);
        }
        $network = ip2long(sprintf("%d.%d.%d.%d", $m[1], $m[2], $m[3], $m[4]));
        $network &= $submask;
    
    // Malformed network
    } else {
        return null;
    }
    
    // IP in ddd.ddd.ddd.ddd format
    if (preg_match("/^(\d+)\.(\d+)\.(\d+)\.(\d+)$/", $ip, $m)) {
        // Sanity check
        for ($i = 1; $i <= 4; $i++) {
            settype($m[$i], "integer");
            if ($m[$i] > 255) {
                return null;
            }
        }
        $ip = ip2long(sprintf("%d.%d.%d.%d", $m[1], $m[2], $m[3], $m[4]));
    
    // Malformed IP
    } else {
        return null;
    }
    
    return (($ip & $submask) == $network);
}

?>