具有Remember Me功能的登录表单和未经授权访问Login_success.php URL php的网站

我在实现一个登录系统时遇到了一点困难，该系统既允许用户通过cookie记住，又不允许使用网站URL 进行未经授权的访问

这是我成功登录的代码，问题就在这里，因为我得到了一个重定向错误：

<?php
session_start();
// IF USER NOT REMEMBERED OR NO SESSION THEN THROW HIM OUT TO LOGIN
 if (!isset($_SESSION['valid'])|| !isset($_COOKIE['myusername']))
 {
   header("Location: index.php");
 }
$host="localhost"; // Host name
$username="root"; // Mysql username
$password="*****"; // Mysql password
$db_name="secure_login"; // Database name
$tbl_name="users"; // Table name
// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
$sql="SELECT * FROM $tbl_name WHERE username='$myusername'";
$result=mysql_query($sql);

?>

会话有效，但一旦我关闭浏览器并重新打开它到我的网站，我就会得到一个REDIRECT LOOP

这是处理我的表单的代码：

<?php
session_start();
//CHECK IF EITHER SESSION OR COOKIE EXISTS THEN REDIRECT TO LOGIN_SUCCESS ELSE CONTINUE TO FORM
function loggedin()
{
 if (isset($SESSION['valid']) || isset($_COOKIE['myusername']))
 {
        $loggedin = TRUE;
        return $loggedin;
 }
}
if (loggedin())
{
   header("Location: login_success.php");
}
// REST OF CODE IS PROCESSED AFTER USER CLICKS SUBMIT ON LOGIN FORM
if(isset($_POST['submit']))
{
$host="localhost"; // Host name
$username="root"; // Mysql username
$password="*****"; // Mysql password
$db_name="secure_login"; // Database name
$tbl_name="users"; // Table name
// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
// username and password sent from form
$myusername=$_POST['username'];
$mypassword=$_POST['password'];
$rememberme=$_POST['rememberme'];
// To protect MySQL injection (more detail about MySQL injection)
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$myusername = mysql_real_escape_string($myusername);
$mypassword = mysql_real_escape_string($mypassword);
$encrypted_mypassword=md5($mypassword);
$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$encrypted_mypassword'";
$result=mysql_query($sql);
// Mysql_num_row is counting table row
if(mysql_num_rows($result) == 1) //user exists
{
  if ($rememberme=="on"){
      setcookie("myusername", $myusername, time()+7200);
   }
 elseif ($rememberme==""){
      $_SESSION['valid'] = 1;
  }
header('Location: login_success.php');
exit();
}
if($myusername=="phillip.k@fixnode.ca" && $encrypted_mypassword=="a66d83940f5d22fa54ee51ce"){
 header('Location: register.php');
}
else {
echo '<div class="alert">Incorrect Username or Password!</div>';
}
}
?>

所以基本上来说，当用户输入有效的用户名和密码并点击记住我时，即使用户关闭了浏览器（即记住我按钮中的COOKIE），我也希望浏览器重定向到login_success。但现在，如果用户关闭浏览器并重新打开我的网站，那么用户可能会因为cookie 而收到REDIRECT LOOP

非常感谢任何帮助

Phillip K