1: <?php
  2: namespace Ctct\WebHooks;
  3: 
  4: use Ctct\Exceptions\CtctException;
  5: 
  6: /**
  7:  * Main Webhook Utility class.<br/>
  8:  * This is meant to be used by users to validate and parse Webhooks received from ConstantContact.<br/>
  9:  *
 10:  * @package     WebHooks
 11:  * @author      Constant Contact
 12:  */
 13: class CTCTWebhookUtil
 14: {
 15: 
 16:     /**
 17:      * The client secret associated with the api key
 18:      */
 19:     private $clientSecret = '';
 20: 
 21: 
 22:     /**
 23:      * Constructor that creates a validation Object for WebHooks.
 24:      * 
 25:      * @param string $clientSecret - The client secret associated with the api key
 26:      * @return  CTCTWebhookUtil
 27:      */
 28:     function __construct($clientSecret='')
 29:     {
 30:         $this->setClientSecret($clientSecret);
 31:     }
 32: 
 33: 
 34:     /**
 35:      * CTCTWebhookUtil::getClientSecret()
 36:      * 
 37:      * @return string - the secret API key  
 38:      */
 39:     public function getClientSecret()
 40:     {
 41:         return $this->clientSecret;
 42:     }
 43: 
 44: 
 45:     /**
 46:      * CTCTWebhookUtil::setClientSecret()
 47:      * Set the clientSecret
 48:      * 
 49:      * @param string $clientSecret - The client secret associated with the api key
 50:      * @return void
 51:      */
 52:     public function setClientSecret($clientSecret)
 53:     {
 54:         $this->clientSecret = $clientSecret;
 55:     }
 56: 
 57:     /**
 58:      * Get Billing Change Notification.<br/>
 59:      *
 60:      * Validates and parses the bodyMessage into 
 61:      *
 62:      * @param xCtctHmacSHA256 The value in the x-ctct-hmac-sha256 header.
 63:      * @param bodyMessage The body message from the POST received from ConstantContact in Webhook callback.
 64:      * @return The object corresponding to bodyMessage in case of success; an exception is thrown otherwise.
 65:      * @throws CtctException Thrown when :
 66:      * <ul>
 67:      * <li>message encryption does not correspond with x-ctct-hmac-sha256 header value;</li>
 68:      * <li>or an error is raised when parsing the bodyMessage.</li>
 69:      * </ul>
 70:      * <p/>
 71:      */
 72:     public function getBillingChangeNotification($xCtctHmacSHA256, $bodyMessage)
 73:     {
 74:         if ($this->isValidWebhook($xCtctHmacSHA256, $bodyMessage))
 75:         {
 76:             return json_decode($bodyMessage);            
 77:         } else
 78:         {
 79:             throw new CtctException("Invalid WebHook");
 80:         }
 81:     }
 82: 
 83:     /**
 84:      * Check if a Webhook message is valid or not.<br/>
 85:      *
 86:      * @param xCtctHmacSHA256 The value in the x-ctct-hmac-sha256 header.
 87:      * @param bodyMessage The body message from the POST received from ConstantContact in Webhook callback.
 88:      * @return true if in case of success; false if the Webhook is invalid.
 89:      * 
 90:      */
 91:     public function isValidWebhook($xCtctHmacSHA256, $bodyMessage)
 92:     {    
 93:         if ($this->getClientSecret() == null)
 94:         {
 95:             throw new CtctException("NO_CLIENT_SECRET");
 96:         }
 97:         $encodedString = hash_hmac("sha256", $bodyMessage, $this->clientSecret);
 98:         
 99:         return ($encodedString == $xCtctHmacSHA256)?true:false;
100:     }
101: }
102: