Anonymize IP according like Google Analytics (according to German laws)

anonymizeIp.php

<?php
/**
 * Last byte for IPv4 and last 80 bits for IPv6 are set to zero
 * @see https://support.google.com/analytics/answer/2763052?hl=en
 */
function anonymizeIp($ip)
{
    $binary = inet_pton($ip);
    if ($binary === false) {
        return false;
    }

    if (strlen($binary) === 16) {
        $maskIp = inet_pton('ffff:ffff:ffff:0000:0000:0000:0000:0000');
    } else {
        $maskIp = inet_pton('255.255.255.0');
    }

    return inet_ntop($binary & $maskIp);
}