bohwaz (2012-02-06 00:52:16)

Please note that FILTER_FLAG_HOST_REQUIRED and FILTER_FLAG_SCHEME_REQUIRED have disappeared. They were previously mentioned in the constants page but it seems that host and scheme are now required by default for the validate_url filter.

php dot net at ewood dot users dot cementhorizon dot com (2010-10-19 16:42:13)

In order to filter on loopback addresses try this :

<?php
function FILTER_FLAG_NO_LOOPBACK_RANGE($value) {
    // Fails validation for the following loopback IPv4 range: 127.0.0.0/8
    // This flag does not apply to IPv6 addresses
    return filter_var($value, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) ? $value :
        (((ip2long($value) & 0xff000000) == 0x7f000000) ? FALSE : $value);
}

$var = filter_var('127.0.0.1', FILTER_CALLBACK, array('options' => 'FILTER_FLAG_NO_LOOPBACK_RANGE'));
// Returns FALSE

$var = filter_var('74.125.19.103', FILTER_CALLBACK, array('options' => 'FILTER_FLAG_NO_LOOPBACK_RANGE'));
// Returns '74.125.19.103'

// To filter Private IP ranges and Loopback ranges
$var = filter_var('127.0.0.1', FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE)
    && filter_var('127.0.0.1', FILTER_CALLBACK, array('options' => 'FILTER_FLAG_NO_LOOPBACK_RANGE'));
// Returns FALSE
?>

(If someone wants to write in handling for the IPv6 loopback interface at "::1" go for it.)

-Gene Wood