Add-cart.php Num _verified_ <SAFE | 2027>
Validate that the quantity is a positive integer and that the final price calculation on the server side is never affected by negative or zero values:
| Test Case | Expected Behavior | Your Result | |-----------|------------------|--------------| | num=abc | 400 Bad Request / No change to cart | | | num=-5 | Ignored or default to 1 | | | num=1.5 | Reject as invalid integer | | | num=9999999 | Reject (max allowed quantity) | | | num=1%20OR%201=1 | No SQL error, no data leak | | | No num parameter | 400 Bad Request | | | Repeated requests to same num | Throttled after X requests/second | | | CSRF token missing | Cart not modified | |
if (isset($_SESSION['cart'][$product_id])) $_SESSION['cart'][$product_id] += $quantity; else $_SESSION['cart'][$product_id] = $quantity;
?>
add-cart.php?num=5 add-cart.php?num=PROD123:2 add-cart.php num
Always validate num on the server side to ensure it's an integer and not a negative number, preventing malicious inputs.
Reassures the customer visually that their item was registered by the server. 5. Moving Beyond Sessions: Modern Alternatives
If the application fails to sanitize this input, the SQL query becomes: INSERT INTO cart (product_id, quantity) VALUES (1, '1'; DROP TABLE users;--')
Ensure num is always an integer. Use (int)$_GET['num'] in PHP to force the type. Validate that the quantity is a positive integer
$product_id = isset($_POST['product_id']) ? (int)$_POST['product_id'] : 0; $quantity = isset($_POST['num']) ? (int)$_POST['num'] : 1;
if (isset($_SESSION['cart'][$product_id])) $_SESSION['cart'][$product_id] += $quantity; else $_SESSION['cart'][$product_id] = $quantity;
…you will build a cart system that is not only functional but also resilient against the most common attacks.
add-cart.php?id=5
The num parameter (often named qty , quantity , or count ) tells the backend how many units of a product to place into the session array.
$productId = (int)$matches[1]; $quantity = (int)$matches[2]; if ($quantity < 1 || $quantity > 50) die('Quantity out of range');
The "add-cart.php" script plays a pivotal role in the e-commerce ecosystem. It enhances the user's shopping experience by: