help with php ipn for digital goods.

[joshlittlewood]

hello, so i've been developing this website ( http://www.ultimate-dimension.co.uk/NewRAL/store1.php ) for a while now, and the owner wanted a  shopping cart implemented. However another coder began the coding of this shopping cart. The cart works perfectly besides that fact that after the Paypal payment as been made I cannot make the system redirect the user to a page where they can download the files that they have ordered.

 

Here is the shopping cart code...

<?php

session_start();

$page = 'store1.php';

if (isset($_GET['add'])) {
	$quantity = mysql_query('SELECT id, quantity FROM filesTable WHERE id='.mysql_real_escape_string((int)$_GET['add']));
		while ($quantity_row = mysql_fetch_assoc($quantity)) {
			if ($quantity_row['quantity']!=$_SESSION['cart_'.(int)$_GET['add']]) {
				$_SESSION['cart_'.(int)$_GET['add']]+='1';	
			}	
	}
	header('location:'.$page);
}

if (isset($_GET['remove'])) {
	$_SESSION['cart_'.(int)$_GET['remove']]--;
	header('location:'.$page);
}
	
if (isset($_GET['delete'])) {
	$_SESSION['cart_'.(int)$_GET['delete']]='0';
	header('location:'.$page);
}

function products() {
	$get = mysql_query('SELECT id, name, description, price, shipping FROM filesTable WHERE quantity > 0 ORDER BY id DESC');
	if (mysql_num_rows($get)==0) {
		echo "There are no products to display :/";
	}
	else {
		while ($get_row = mysql_fetch_assoc($get)) {
			echo '<p>'.$get_row['name'].'<br />'.$get_row['description'].'<br /> &pound'.number_format($get_row['price'], 2).' <br /> <a href="cart.php?add='.$get_row['id'].'">ADD</a></p> <br /><hr><br />';
		}
	}
}
 
function paypal_items() {
	$num==0;
	foreach ($_SESSION as $name => $value) {
		if ($value!=0) {
			if (substr($name, 0, 5)=='cart_') {
				$id = substr($name, 5, strlen($name)-5);
				$get = mysql_query('SELECT id, name, price, shipping FROM filesTable WHERE id='.mysql_real_escape_string((int)$id));
				while ($get_row = mysql_fetch_assoc($get)) {
					$num++;
					echo '<input type="hidden" name="item_number_'.$num.'" value="'.$id.'">';
					echo '<input type="hidden" name="item_name_'.$num.'" value="'.$get_row['name'].'">';
					echo '<input type="hidden" name="amount_'.$num.'" value="'.$get_row['price'].'">';
					echo '<input type="hidden" name="shipping_'.$num.'" value="'.$get_row['shipping'].'">';
					echo '<input type="hidden" name="shipping2_'.$num.'" value="'.$get_row['shipping'].'">';
					echo '<input type="hidden" name="quantity_'.$num.'" value="'.$value.'">';
				}
			}
		}
	}
}

function cart() {
	foreach ($_SESSION as $name => $value) {
		if ($value>0) {
			if (substr($name, 0, 5)=='cart_') {
				$id = substr($name, 5, (strlen($name)-5));
				$get = mysql_query('SELECT id, name, description, price, shipping FROM filesTable WHERE id='.mysql_real_escape_string((int)$id));
				while ($get_row = mysql_fetch_assoc($get)) {
					$sub = $get_row['price']*$value;
					echo $get_row['name'].' x '.$value.' @ &pound'.number_format($get_row['price'], 2).' = &pound'.number_format($sub, 2).' <a href="cart.php?remove='.$id.'">[ - ]</a> <a href="cart.php?add='.$id.'">[ + ]</a> <a href="cart.php?delete='.$id.'">[ DELETE ]</a> <br><br>';
				}
			}
	
			$total += $sub;

		}
	}

	if ($total==0) {
		echo "Your cart is empty :/";
	}
	else {
		echo '<br><p class="rightAlignCart">Total: £'.number_format($total, 2).'</p>';

	?>	
	<p>
		<form  class="rightAlignCart" action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">
		<input type="hidden" name="cmd" value="_cart">
		<input type="hidden" name="upload" value="1">
		<input type="hidden" name="business" value="joshlittlewood@ultimate-dimension.co.uk">
		<?php paypal_items(); ?>
		<input type="hidden" name="currency_code" value="GBP">
		<input type="hidden" name="amount" value="<?php echo $total; ?>">
		<input type="image" src="http://www.paypal.com/en_US/i/btn/x-click-but06.gif" name="submit" alt="Make payments with PayPal - it's fast,                 free and secure!">
		</form>
	</p>
	<?php
	}		

}

?>

By the way the store is running in sandbox mode, for anyone who wants to try it.

 

I believe that Paypal's IPN is the way to do it, but I just can't get it to work with the current shopping cart system. Any help on how do do this would be greatly appreciated!