PHP 登录类

class Auth
{
    var $user_id;
    var $username;
    var $password;
    var $ok;
    var $salt = "34asdf34";
    var $domain = ".domain.com";
 
    function Auth()
    {
        global $db;
 
        $this->user_id = 0;
        $this->username = "Guest";
        $this->ok = false;
 
        if(!$this->check_session()) $this->check_cookie();
 
        return $this->ok;
    }
 
    function check_session()
    {
        if(!empty($_SESSION['auth_username']) && !empty($_SESSION['auth_password']))
            return $this->check($_SESSION['auth_username'], $_SESSION['auth_password']);
        else
            return false;
    }
 
    function check_cookie()
    {
        if(!empty($_COOKIE['auth_username']) && !empty($_COOKIE['auth_password']))
            return $this->check($_COOKIE['auth_username'], $_COOKIE['auth_password']);
        else
            return false;
    }
 
    function login($username, $password)
    {
        global $db;
        $db->query("SELECT user_id FROM users WHERE username = '$username' AND password = '$password'");
        if(mysql_num_rows($db->result) == 1)
        {
            $this->user_id = mysql_result($db->result, 0, 0);
            $this->username = $username;
            $this->ok = true;
 
            $_SESSION['auth_username'] = $username;
            $_SESSION['auth_password'] = md5($password . $this->salt);
            setcookie("auth_username", $username, time()+60*60*24*30, "/", $this->domain);
            setcookie("auth_password", md5($password . $this->salt), time()+60*60*24*30, "/", $this->domain);
 
            return true;
        }
        return false;
    }        
 
    function check($username, $password)
    {
        global $db;
        $db->query("SELECT user_id, password FROM users WHERE username = '$username'");
        if(mysql_num_rows($db->result) == 1)
        {
            $db_password = mysql_result($db->result, 0, 1);
            if(md5($db_password . $this->salt) == $password)
            {
                $this->user_id = mysql_result($db->result, 0, 0);
                $this->username = $username;
                $this->ok = true;
                return true;
            }
        }            
        return false;
    }
 
    function logout()
    {
        $this->user_id = 0;
        $this->username = "Guest";
        $this->ok = false;
 
        $_SESSION['auth_username'] = "";
        $_SESSION['auth_password'] = "";
 
        setcookie("auth_username", "", time() - 3600, "/", $this->domain);
        setcookie("auth_password", "", time() - 3600, "/", $this->domain);
    }
 
}