Create webhook-endpoint.php

Author: Ashraf-RnD

webhook-endpoint.php

@@ -0,0 +1,105 @@
+<?php
+    
+    //payload
+    $payload  = (array)json_decode(file_get_contents('php://input'));
+    writeLog('Payload',$payload);
+
+    // headers
+    $messageType = $_SERVER['HTTP_X_AMZ_SNS_MESSAGE_TYPE'];
+    
+
+    //logics
+
+    
+    //verify signature
+    $signingCertURL = $payload['SigningCertURL'];
+    $certUrlValidation = validateUrl($signingCertURL);
+    if($certUrlValidation == '1'){
+        $pubCert = get_content($signingCertURL); 
+    
+        $signature = $payload['Signature'];
+        $signatureDecoded = base64_decode($signature);
+        
+        $content = getStringToSign($payload);
+        if($content!=''){
+            $verified = openssl_verify($content, $signatureDecoded, $pubCert, OPENSSL_ALGO_SHA1);
+            if($verified=='1'){
+                if($messageType=="SubscriptionConfirmation"){  
+                    
+                        $subscribeURL = $payload['SubscribeURL'];
+                        writeLog('Subscribe',$subscribeURL);
+                        //subscribe
+                        $url = curl_init($subscribeURL);
+                        curl_exec($url);
+                    
+                }
+                else if($messageType=="Notification"){
+                    
+                    $notificationData = $payload['Message'];
+                    writeLog('NotificationData-Message',$notificationData);
+                    
+                }
+            }
+        }
+        
+    }
+    
+    function writeLog($logName, $logData){
+        file_put_contents('./log-'.$logName.date("j.n.Y").'.log',$logData,FILE_APPEND);
+    }
+    
+    
+    function get_content($URL){
+      $ch = curl_init();
+      curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
+      curl_setopt($ch, CURLOPT_URL, $URL);
+      $data = curl_exec($ch);
+      curl_close($ch);
+      return $data;
+    }
+    
+    function getStringToSign($message)
+    {
+        $signableKeys = [
+            'Message',
+            'MessageId',
+            'Subject',
+            'SubscribeURL',
+            'Timestamp',
+            'Token',
+            'TopicArn',
+            'Type'
+        ];
+        
+        $stringToSign = '';
+        
+        if ($message['SignatureVersion'] !== '1') {
+            $errorLog =  "The SignatureVersion \"{$message['SignatureVersion']}\" is not supported.";
+            writeLog('SignatureVersion-Error', $errorLog);
+        }
+        else{
+            foreach ($signableKeys as $key) {
+                if (isset($message[$key])) {
+                    $stringToSign .= "{$key}\n{$message[$key]}\n";
+                }
+            }
+            writeLog('StringToSign', $stringToSign."\n");
+        }
+        return $stringToSign;
+    }
+    
+    function validateUrl($url)
+    {
+        $defaultHostPattern = '/^sns\.[a-zA-Z0-9\-]{3,}\.amazonaws\.com(\.cn)?$/';
+        $parsed = parse_url($url);
+        
+        if (empty($parsed['scheme']) || empty($parsed['host']) || $parsed['scheme'] !== 'https' || substr($url, -4) !== '.pem' || !preg_match($defaultHostPattern, $parsed['host']) ) {
+            return false;
+        }
+        else{
+            return true;
+        }
+    }
+
+    
+?>