User system

<?php
class User
{
	public $Data = false;
	
	public function __construct()
	{
		$UID = $_COOKIE["userid"];
		$PW = $_COOKIE["passhash"];

		
		$Res1 = mysql_query("SELECT ID FROM users WHERE ID = '".mysql_real_escape_string($UID)."'");
		
		if(strlen($PW) !== 32 || mysql_num_rows($Res1) !== 1)
			return;
					
		$Query = "SELECT 
				  ID,
				  Username,
				  Passhash,
				  Email,
				  Enabled,
				  IP
				  FROM users
				  WHERE ID = '".mysql_real_escape_string($UID)."' AND um.Passhash = '".mysql_real_escape_string($PW)."' AND Enabled = 'yes'";

		$Res2 = mysql_query($Query);
		if(mysql_num_rows($Res2) !== 1)
			return;
		
		$this->Data = (object)mysql_fetch_array($Res2);
	}

	public function MustLogin()
	{
		if($this->Data === false)
		{
			header("Location: ".SITEURL."/login.php");
			exit();
		}
	}
	
	public function Login($Username, $Password)
	{
		global $Security;
		if($Security->IsValidUsername($Username))
		{
			$Res1 = mysql_query("SELECT ID, Passhash, Secret Enabled FROM users WHERE Username = '".mysql_real_escape_string($Username)."'");
			
			if(mysql_num_rows($Res1) !== 1)
				die("Uporabnik ne obstaja!");
				
			list($UID, $PH, $Secret, $Enabled) = mysql_fetch_array($Res1);
			
			$Passhash = $Security->MakePassword($Password, $Secret);
			
			if($PH != $Passhash)
				die("Napačno geslo!");
			if($Enabled != "yes")
				die("Ta račun je bil onemogočen!");
				
			setcookie("userid", $UID, 0x7fffffff, "/");
			setcookie("passhash", $Passhash, 0x7fffffff, "/");

			header("Location: ./");
		}
	}
	
	public function Logout()
	{
		setcookie("userid", "", 0x7fffffff, "/");
		setcookie("passhash", "", 0x7fffffff, "/");
		header("Location: ./");
	}
}
?>

<?php
require_once("include/include.php");
$User->MustLogin();

/*
	Prikaz strani
*/
?>

<?php
/*
Tvoja koda, ki se izvede na vsaki strani
*/
require_once("/include/class/user.php");
$User = new User();
?>