simple xss protection

xss-protec.php

<?php

function _array_map_recursive($func, $arr) {
    $new = array();
    foreach($arr as $key => $value) {
        $new[$key] = (is_array($value) ? _array_map_recursive($func, $value) : ( is_array($func) ? call_user_func_array($func, $value) : $func($value) ) );
    }
    return $new;
}

function _escape_html($string) {
    // 4th parameter for double_encode set to false, ignore if already encoded
    return htmlspecialchars($string, ENT_QUOTES, 'UTF-8', false);
}

function _escape_xss($data) {
    if ( is_array($data) ) {
        return _array_map_recursive('_escape_html',$data);
    }
    return ( !is_null($data) ? _escape_html($data) : null );
}


if ( !empty($_GET) ) $_GET = _array_map_recursive('_escape_html', $_GET);
if ( !empty($_POST) ) $_POST = _array_map_recursive('_escape_html', $_POST);
if ( !empty($_REQUEST) ) $_REQUEST = _array_map_recursive('_escape_html', $_REQUEST);
if ( !empty($_COOKIE) ) $_COOKIE = _array_map_recursive('_escape_html', $_COOKIE);