Giúp em site upload php

<?php

//**********************************
// coded by papagei *
// free upload source *
// support : http://loiyeu.kiss.to* 
//**********************************

$idx= new upload;
class upload{

var $path="";
var $url="";

function upload(){

$bannips="123456,65431"; //ban ip
$this->path="upload/"; // trinh path
$this->allow_exs="jpg,gif,bmp,png,wma,zip,swf"; //type file cho phep upload
$this->url ="http://www.hosted.5gigs.com/"; //link cua website

if(@in_array(getenv("REMOTE_ADDR"),@explode(",",$bannips)))
{
$this->error("ip bi banned roi :D");
}

switch($_GET['do'])
{
case 'upload':
$this->doupload();
break;

default :
$this->index();
break;
}
}

function index()
{
echo gethostbyaddr(getenv("REMOTE_ADDR"));
$output = <<<PP
<table>
<form method="POST" action="?do=upload" enctype="multipart/form-data">
<input type="hidden" name="MAX_FILE_SIZE" value="2048000">
<tr>
<td><font face=verdana size=1> File upload : </font></td>
<td><input type="file" name="file"></td>
</tr>
<tr>
<td colspan="2">
<input type="submit" value="upload">
<input type="reset" value="reset"><br><font face=verdana size=1>
File Types allow :jpg,gif,bmp,png,wma,zip<BR>
Max :2048000 Byte.</font>
</td>
</tr>
</form>
</table>
PP;

echo $output;
}

function error($msg)
{
echo "ERROR : " .$msg;
exit();
}

function get_ex($file){
return @str_replace(".","",@strrchr($_FILES['file']['name'],"."));
}

function doupload()
{
$error="";
$output= <<< PP
<font face=verdana size=1>File duoc upload roi</font><br>
<hr width="20%">
<font face=verdana size=1>File name : </font><b><a href="{$this->url}<#name#>">{$this->url}<#name#></a></b>
PP;
if(empty($_FILES['file']['name']))
{
$error="<font face=verdana size=1>Phai chon file de upload</font>";
}elseif(!@in_array(@strtolower($this->get_ex($_FILES['file']['name'])),@explode(",",$this->allow_exs)))
{
$error="<font face=verdana size=1>Type file nay ko ho tro</font>";
}
if(file_exists($this->path.$_FILES['file']['name']))
{
$_FILES['file']['name']=str_replace(".","-".md5(time()).".",
$_FILES['file']['name']);
}

if($error !="")
{
$this->error($error);
}
elseif(!@move_uploaded_file($_FILES['file']['tmp_name'],$this->path.$_FILES['file']['name']))
{
$this->error("<font face=verdana size=1>Ko the upload file</font>");
}else{
echo str_replace("<#name#>",$this->path.$_FILES['file']['name'],$output);
}

}
}

?>