<?php
function create_guid($namespace = '') {
    static $guid = '';
    $uid = uniqid("", true);
    $data = $namespace;
    $data .= $_SERVER['REQUEST_TIME'];
    $data .= $_SERVER['HTTP_USER_AGENT'];
    //$data .= $_SERVER['LOCAL_ADDR'];
    //$data .= $_SERVER['LOCAL_PORT'];
    $data .= $_SERVER['REMOTE_ADDR'];
    $data .= $_SERVER['REMOTE_PORT'];
    $hash = strtoupper(hash('ripemd128', $uid . $guid . md5($data)));
    $guid = substr($hash, 0, 4).'-'.substr($hash, 8, 4).'-'.substr($hash, 12, 4).'-'.substr($hash, 16, 4).'-'.substr($hash, 20, 4);
    return $guid;
}
