docker-vulnerable-dvwa/dvwa/vulnerabilities/xss_s/source/impossible.php

<?php

if( isset( $_POST[ 'btnSign' ] ) ) {
	// Check Anti-CSRF token
	checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );

	// Get input
	$message = trim( $_POST[ 'mtxMessage' ] );
	$name    = trim( $_POST[ 'txtName' ] );

	// Sanitize message input
	$message = stripslashes( $message );
	$message = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"],  $message ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));
	$message = htmlspecialchars( $message );

	// Sanitize name input
	$name = stripslashes( $name );
	$name = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"],  $name ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));
	$name = htmlspecialchars( $name );

	// Update database
	$data = $db->prepare( 'INSERT INTO guestbook ( comment, name ) VALUES ( :message, :name );' );
	$data->bindParam( ':message', $message, PDO::PARAM_STR );
	$data->bindParam( ':name', $name, PDO::PARAM_STR );
	$data->execute();
}

// Generate Anti-CSRF token
generateSessionToken();

?>