$_GET[...] not working - database not updating - php

Question

I've asked a few questions about this piece of code on this site.
Basically, my database is not updating when I use - $id = $GET_['id']; (at the top of the code below). The id gets passed to this page from the previous page - the url of the page is 'http:// www.21orange.com/CCC/changepassword.php?id=1'. There is an 'id' field in my database.
When I change the above line of code to - $id = '1' - the code runs perfectly and the database is updated. It only stops working when I use the $GET_['id']. Why is this?
// First we execute our common code to connection to the database and start the session
require("common.php");
$id = $_GET['id'];
// This if statement checks to determine whether the registration form has been submitted
// If it has, then the registration code is run, otherwise the form is displayed
if(!empty($_POST))
{
// Ensure that the user has entered a non-empty password
if(empty($_POST['password']))
{
die("Please enter a password.");
}
// Ensure that the user has entered a non-empty username
if(empty($_POST['confirmpassword']))
{
// Note that die() is generally a terrible way of handling user errors
// like this. It is much better to display the error with the form
// and allow the user to correct their mistake. However, that is an
// exercise for you to implement yourself.
die("Please confirm your password.");
}
if ($_POST['password'] == $_POST['confirmpassword']) {
// An INSERT query is used to add new rows to a database table.
// Again, we are using special tokens (technically called parameters) to
// protect against SQL injection attacks.
$query = "UPDATE Staff SET password=:password, salt=:salt WHERE id=:id";
// A salt is randomly generated here to protect again brute force attacks
// and rainbow table attacks. The following statement generates a hex
// representation of an 8 byte salt. Representing this in hex provides
// no additional security, but makes it easier for humans to read.
$salt = dechex(mt_rand(0, 2147483647)) . dechex(mt_rand(0, 2147483647));
// This hashes the password with the salt so that it can be stored securely
// in your database. The output of this next statement is a 64 byte hex
// string representing the 32 byte sha256 hash of the password. The original
// password cannot be recovered from the hash.
$password = hash('sha256', $_POST['password'] . $salt);
// Next we hash the hash value 65536 more times. The purpose of this is to
// protect against brute force attacks. Now an attacker must compute the hash 65537
// times for each guess they make against a password, whereas if the password
// were hashed only once the attacker would have been able to make 65537 different
// guesses in the same amount of time instead of only one.
for($round = 0; $round < 65536; $round++)
{
$password = hash('sha256', $password . $salt);
}
try
{
// Execute the query to create the user
$stmt = $db->prepare($query);
$stmt->execute(array(
'password' => $password,
'salt' => $salt,
'id' => $id));
}
catch(PDOException $ex)
{
// Note: On a production website, you should not output $ex->getMessage().
// It may provide an attacker with helpful information about your code.
die("Failed to run query: " . $ex->getMessage());
}
// This redirects the user back to the login page after they register
header("Location: stafflist.php");
// Calling die or exit after performing a redirect using the header function
// is critical. The rest of your PHP script will continue to execute and
// will be sent to the user if you do not die or exit.
die("Redirecting to stafflist.php");
}
die("Passwords do not match.");
}
I'm new to php, so forgive my naivety. P.s. I know the method I'm using is fairly old school, but it's only a test.
Thanks,
Joe

Answer 1

You can't do both GET and POST in a single HTTP Request.
However, you can use an hidden input field to get around this limitation:
In your HTML markup, you can add the following:
<input type="hidden" name="id"
value="<?php echo htmlspecialchars($_GET['id'], ENT_QUOTES); ?>" />
And your $_GET['id'] should work just fine.

Answer 2

To avoide this error
Undefined index: id in /home/content/47/11368447/html/CCC/changepassword.php on line 6
first test if the index exists :
if(isset($_GET['id'])) {
$id = $_GET['id'];
} else {
// here you can set a value for the id
}
Otherwise, you can add your $id var in your if test :
if(!empty($_POST) && $id)
{
//...
}

Answer 3

It looks like you are passing the 'id' to the action URL but for some reason the $_GET variable is not having it. Please double check:
Are you really passing the 'id' to the URL ? Please make sure.
Please check the code in common.php to see if the $_GET variable is modified in it.
Is that script behind a rewrite settings (e.g in .htaccess) ? if yes, $_GET parameters could be gone due to inappropriate rewrite settings. You can further test it out by putting print_r($_GET); in the beginning and visit that script directly ( GET instead of POST )

Answer 4

$id = $_GET['id'];
first check there is any value in $id to print the $id through echo