What is the best practice for creating a whitelist to validate $_GET parameters in PHP?

When working with user input from $_GET parameters in PHP, it is important to validate and sanitize the input to prevent security vulnerabilities such as SQL injection or cross-site scripting attacks. One way to do this is by creating a whitelist of allowed parameters and only allowing those specific parameters to be used in your application. 

// Define a whitelist of allowed parameters
$allowed_params = ['param1', 'param2', 'param3'];

// Check if the parameter passed in the URL is in the whitelist
if (isset($_GET['param']) && in_array($_GET['param'], $allowed_params)) {
    // Use the parameter in your application
    $param = $_GET['param'];
    // Perform any necessary validation or sanitization on $param
} else {
    // Handle invalid or unauthorized parameters
    echo "Invalid parameter";
}

Keywords

whitelist validate $_GET parameters PHP security

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