PHP 中的 ERR_TOO_MANY_REDIRECTS

Question

My logout.php file is like this. Is there any mistake in my code

logout.php

<?php
session_start();
session_destroy();
header('Location:index.php');
exit;
?>

Here is my index.php file. If I am set $_SESSION['s_activId'] then it is working properly but when I am trying to put condition if $_SESSION['s_activId'] is not set at that time I want to pass header on index page sometimes it works sometimes it does not work.

<?php
include('include/config.inc.php');
if(!isset($_SESSION['s_activId']))
{
  $_SESSION['s_urlRedirectDir'] = $_SERVER['REQUEST_URI'];
    header("Location:index.php");
}
else
{
  $wrong = '';
  if(isset($_POST['submit']))
  {
    $checkLogin = "SELECT userName,password,userType
                     FROM user
                    WHERE BINARY userName = '".$_POST['userName']."'
                      AND BINARY password = '".$_REQUEST['password']."'";
    $checkLoginresult = mysql_query($checkLogin);
    if($userLoginRow = mysql_fetch_array($checkLoginresult))
    {
      $_SESSION['s_activId']   = $userLoginRow['userName'];
      $_SESSION['s_password']  = $userLoginRow['password'];
      $_SESSION['hg_userType'] = $userLoginRow['userType'];
     
     if(!$_SESSION['s_urlRedirectDir'])
      {
        header("Location:index.php");
      }
      else
      {
        header("Location:reminder.php");
      }
    }
    else
    {
      $wrong = "UserId And Password Is Not Valid";
    }
  }
}
include("bottom.php");
$smarty->assign('wrong',$wrong);
$smarty->display("index.tpl");
?>

Answer 1

The problem arise in the condition below in index.php :

if(!isset($_SESSION['s_activId']))
{
    $_SESSION['s_urlRedirectDir'] = $_SERVER['REQUEST_URI'];
    header("Location:index.php");
}

When you logout, you are calling session_destroy() on logout.php and redirecting on index.php and the condition above gets true as s_activId is not set in session and again you are redirecting on index.php (without setting s_activId in session). The above condition will be true until the variable s_activId set in session and because of this you are getting ERR_TOO_MANY_REDIRECTS error.

The solution is, on index.php set the variable s_activId in session before calling the header method. Refer the code below:

if(!isset($_SESSION['s_activId']))
{
    $_SESSION['s_urlRedirectDir'] = $_SERVER['REQUEST_URI'];
    $_SESSION['s_activId'] = true;
    header("Location:index.php");
}

Answer 2

Dont redirect index.php to index.php. you having redirects loop. Also if you have code below that also can fire add die in if because after redirect code below still executes. I didnt read your code, maybe there isnt problems with this but after

header("Location: lalala"); always add die(); or exit();