Display php script in the text box at student log in form

Display php script in the text box at student log in form

I have the code below checking to see if cookies are set & if they are set then display the page & if they aren't set then to display the login box. When I login with correct username & password I set 2 cookies which hold encrypted un & pw. For some reason it is like the cookies that ARE set are only being read if I go directly to the page by typing in the page in the URL & won't be read if I go to the page by link from another page.

Step I
After I login I am taken to the index.php by header("Location: index.php");…If I type in the URL domain.com/page2.php & click the " Go " button or hit the enter key it will display my page for me.

Step II
After I login I am taken to the index.php by header("Location: index.php");…Instead of typing in the URL page2.php, I click on a link in the index.php page to take me to page2.php it will not display the page. I can then immediately click the " Go " button for the URL to take me to the page2.php it will display the page for me.

My login.php page:<?php
require("left.php");
require("cdb.php");

if(isset($_GET['do']))
{
$show = $_GET['do'];
If ($show == 'Login')
{
echo'<div id="content">';
echo'<div class="feature" align="center">';
echo'<br>';
include("login_box.php");
echo'</div>';
echo'</div>';
}
elseif ($show == 'login')
{
if((isset($_COOKIE['username'])) && (isset($_COOKIE['password'])))
{
echo'<div id="content">';
echo'<div class="feature" align="center">';
echo'<div class="error">You are already logged in!';
echo'<br>';
echo'</div>';
echo'</div>';
}
else
{
$username = $_POST['username'];
$password = md5(md5($_POST['password']));
$loguser = mysql_query("SELECT * FROM $customer_table WHERE customers_username = '$username' AND customers_password = '$password'");
$rows = @mysql_num_rows($loguser);
if($rows == 0)
{
echo'<div id="content">';
echo'<div class="feature" align="center">';
echo'<div class="error">Incorrect Login Credentials!';
echo'<br>';
echo'<br>';
echo'Please try again</div>';
echo'<br>';
include("login_box.php");
echo'</div>';
echo'</div>';
}
else
{
setcookie("username", $username, time()+3600); //Lasts for 1 Hr
setcookie("password", $password, time()+3600); //Lasts for 1 Hr
echo 'Successfully Logged in!';
header("Location: index.php");
}
}
}
elseif ($show == 'logout')
{
if((isset($_COOKIE['username'])) && (isset($_COOKIE['password'])))
{
$username = $_COOKIE['username'];
$password = $_COOKIE['password'];
setcookie("username", $username, time()-3600);
setcookie("password", $password, time()-3600);
echo 'Loged Out Successfully!';
require("login_box.php");
}
else
{
echo'<div id="content">';
echo'<div class="feature" align="center">';
echo'<div class="error">You are not logged in!';
echo'<br>';
echo'<br>';
echo'Please try again below:</div>';
echo'<br>';
include("login_box.php");
echo'</div>';
echo'</div>';
}
}
}
else
{
header("Location: index.php");
}
?>

My page2.php <?php
require("left.php");
if((isset($_COOKIE['username'])) && (isset($_COOKIE['password'])))
{
require("main/bankwire.php");
}
else
{
echo'<div id="content">';
echo'<div class="feature" align="center">';
echo'<div class="error">You must be logged in to complete an order';
echo'<br>';
echo'Please login below</div>';
echo'<br>';
include("login_box.php");
echo'</div>';
echo'</div>';
}
?>