使用$ _SESSION ['url']将checklogin.php重定向到index.php

Question

I have a checklogin.php script that works fine to redirect a user to a specific page on successful login. I now want to set it to redirect to the original index.php page that redirected the user to the login form. At the top of index.php I include:

<?php
session_start();

$_SESSION['url'] = $_SERVER['REQUEST_URI'];

if(!session_is_registered(myusername)){
header("location:main_login.php");
}
?>

I have checked that $_SESSION['url'] is getting correctly set on this page.

main_login.php just contains the login form which is processed by checklogin.php:

<form name="form1" method="post" action="checklogin.php">

and $_SESSION['url'] is getting correctly set on this page too.

checklogin.php looks like this:

<?php
session_start();

print_r($_SESSION['url']);

ob_start();
$host="localhost"; // Host name 
$username=""; // Mysql username 
$password=""; // Mysql password 
$db_name=""; // Database name 
$tbl_name=""; // 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");

// Define $myusername and $mypassword 
$myusername=$_POST['myusername']; 
$mypassword=$_POST['mypassword']; 

// 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
$count=mysql_num_rows($result);

// If result matched $myusername and $mypassword, table row must be 1 row
if($count==1){

// Register $myusername, $mypassword and redirect to file "login_success.php"
session_register("myusername");
session_register("mypassword"); 
header("location:$_SESSION['url']");
}
else {
echo "Wrong Username or Password";
}
ob_end_flush();
?>

As you can see I am trying to print $_SESSION['url'] at the top of this script but nothing is getting returned.

Could someone help with this?

Thanks,

Nick

Answer 1

You cannot insert a "complex" variable like $_SESSION['url'] inside a litteral string, like the following statement:

header("location:$_SESSION['url']");

In my version of PHP (5.3.10), it produces the following error:

PHP Parse error: syntax error, unexpected T_ENCAPSED_AND_WHITESPACE, expecting T_STRING or T_VARIABLE or T_NUM_STRING in /home/.../test.php on line ...

Indeed, if you want to output a field in an array, you should use concatenation:

header("Location: " . $_SESSION['url']);

This may be the source of your problem. Depending on PHP configuration, it may not display the error and just output a blank page, check the php logs to be sure.

The best practice is to use this whenever you want to output the value of a variable in a string.

For example, do not use echo "Foo: $foo";, use instead echo "Foo : ". $foo;