PHP Clean User Input

As a programmer, it's important to take precautions when handling user input in order to prevent security vulnerabilities such as SQL injection attacks or malicious code injection. In order to keep user input safe, it's important to "clean" it before it's used in any way. So, how can we clean user input in PHP? Here are a few tips.

Use Prepared Statements to Prevent SQL Injection

One of the most common security vulnerabilities that comes from user input is SQL injection. This is when a user inputs malicious SQL code with the intent of executing it on a database. One way to prevent this is to use prepared statements. Here's an example using PDO:

$stmt = $pdo->prepare('SELECT * FROM users WHERE username = :username');
$stmt->bindParam(':username', $username);
$stmt->execute();

This code uses a prepared statement and parameter binding to prevent SQL injection.

Validate Input to Prevent Malware or Code Injection

Another way to protect your application from malicious code injection attacks is to validate user input. This can help prevent things like file upload exploits or XSS attacks. Here's an example using the filter_var function:

$email = filter_var($_POST['email'], FILTER_SANITIZE_EMAIL);
if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
    // The email is valid, so proceed with the application
} else {
    // The email is not valid, so prompt the user to enter a valid one
}

This code validates user input to make sure it matches the expected format before it's used.

Sanitize Input to Remove Dangerous Characters

Finally, it's a good idea to sanitize user input by removing any dangerous characters. This can help prevent malicious code injection attacks as well as prevent legitimate data from being misinterpreted. Here's an example using the filter_var function:

$name = filter_var($_POST['name'], FILTER_SANITIZE_STRING); // remove any HTML and PHP tags

This code sanitizes user input by removing any HTML and PHP tags.

By following these tips, you can help keep your applications safe from user input vulnerabilities.