Web Development TutorialsWritten By Peter Kelly

CREATE TABLE `licenses` (
  `id` int(50) NOT NULL AUTO_INCREMENT,
  `domain` varchar(200) NOT NULL,
  `ip` varchar(50) NOT NULL,
  `status` varchar(20) NOT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM;

<?php
/**
 * To begin with we need to setup the configuration so we are able to connect to the database.
 */
$conn = mysql_connect("DB_HOST","DB_USER","DB_PASS"); // Replace DB_HOST with localtion of database usually localhost and DB_USER and DB_PASS with your database details
if (!$conn) die ("Could not connect MySQL"); // Check if could connect to mysql db.
mysql_select_db("DB_NAME",$conn) or die ("Could not open database"); // Replace DB_NAME with database name and open the database. If not die :).
 
/**
 * First we will retrieve the variables from the POST sent to us.
 * And we will make sure they are safe to be used.
 */
foreach ($_POST as $key => $value) // Go through all items in the $_POST array
{ // Carry out the foreach on the $field assigning the key and value of the array to $key and $value.
    $key = strip_tags($key); // Remove any tags from the key
    $value = strip_tags($value); // Remove any tags from the value
    $_POST[$key] = htmlentities($value, ENT_QUOTES); // Convert all applicable characters to HTML entities and assign them back to $_POST array.
}
/**
 * Now we need to check if the information passed to use is genuine
 */
$retrieve_q = mysql_query("SELECT * FROM `licenses` WHERE `domain` = '".$_POST['domain']."' && `ip` = '".$_POST['ip']."' && `status` = 'active'"); // Select from the licenses table where the domain, ip match the details passed from the local server and check if the license status is active.
if(!mysql_num_rows($retrieve_q)){ // Check if any rows match the criteria above.
	echo "invalid"; // If not echo invalid.
}
?>

<?php
/**
 * First we must retrieve the domain name and the server ip.
 */
$domain = str_ireplace("www.", "", $_SERVER['HTTP_HOST']); // Remove www. if it has it
$ip = $_SERVER['SERVER_ADDR']; // Get server ip
 
/**
 * Now we will create the function which will connect to the license server and retrieve the status.
 */
function license_check($url, $curl_data) // Start license_check function
{
        $options = array(CURLOPT_RETURNTRANSFER => true, // return web page
            CURLOPT_USERAGENT => $domain . "(" . $ip . ") LICENSE CHECK", // who am i
            CURLOPT_CONNECTTIMEOUT => 60, // timeout on connect
            CURLOPT_TIMEOUT => 60, // timeout on response
            CURLOPT_POST => 1, // i am sending post data
            CURLOPT_POSTFIELDS => $curl_data, // Post data
            );
 
    $ch = curl_init($url); // Start the connection to $url
	curl_setopt_array($ch, $options); // Set the options above into the curl
	$content = curl_exec($ch); // Execute the connection with the options and retrieve the page
	curl_close($ch); // Close Connecion
 
    return $content; // Return $content
}
 
/**
 * Now to use the function we just created and check the license if valid.
 */
$license = license_check("URL TO SERVER.PHP", "domain=" . $domain . "&ip=" . $ip); // Run the function connecting to the location of the server.php and with the domain and ip post variables
$license = trim($license);
if (empty($license)) // Check if $license returned valid or not.
{
	echo "You have a VALID License. :)"; // If it did echo valid
}else{
	die("Unable to find a valid license for this domain and server ip."); // If not show stop anything else running and show error message.
}
 
?>