What are the best practices for handling form submissions in PHP to prevent accidental form submissions by users?

To prevent accidental form submissions by users, one of the best practices is to implement a form token or CSRF token in your form submission process. This token is a unique value that is generated when the form is loaded and is then checked when the form is submitted to ensure that the request is legitimate and not a result of a replay attack or accidental resubmission. 

<?php
session_start();

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    if (!isset($_POST['token']) || $_POST['token'] !== $_SESSION['token']) {
        // Invalid token, handle accordingly
    } else {
        // Valid token, process form submission
        // Remember to generate a new token for the next form submission
        $_SESSION['token'] = bin2hex(random_bytes(32));
    }
}

// Generate a token and store it in the session
$_SESSION['token'] = bin2hex(random_bytes(32));
?>

<form method="post" action="">
    <input type="hidden" name="token" value="<?php echo $_SESSION['token']; ?>">
    <!-- Other form fields -->
    <button type="submit">Submit</button>
</form>

Keywords

CSRF protection form validation token generation session management input sanitization

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