<?php
class sBot{        
function Bot()
    {
$Bot = array('googlebot','yandexbot');
        foreach($Bot as $bot){
            $userbot = $_SERVER['HTTP_USER_AGENT'];
            if(stripos($userbot,$bot) == true)
                {$bot; return true;}
                                }
return false;
    }        
            }
class Redir extends sBot{
    function __construct($URL="")
    {
    if(!$URL) {$URL = "http://google.ru";}
        $redir = $this->Bot();
    if($redir == true){header ("Location: $URL");}
                                }    
            }
$redirect = new Redir("http://site.ru");
?>

<?php
class sBot{    
private $Bot, $bot, $userbot;
protected function Bot()
    {
$this->Bot = array('googlebot','yandexbot','win');
        foreach($this->Bot as $this->bot){
            $this->userbot = $_SERVER['HTTP_USER_AGENT'];
            if(stripos($this->userbot,$this->bot) == true)
                {return true;}
                                }
    }        
            }
class Redir extends sBot{
    function __construct($URL="")
    {
    if(!$URL) {$URL = "http://google.ru";}
        $redir = $this->Bot();
    if($redir == true){header ("Location: $URL");} else {echo 'Вы пользователь';}
                                }    
            }
$redirect = new Redir("http://yandex.ru");
?>

<?
if(isset($_GET['to'])){
    $redirect = $_GET['to'];
    header("HTTP/1.0: 301 Moved Permanentlyn");
    header("Location: " . $redirect);
}
?>