add fulcrm_apiv2_prevent_loop to track inbound webhooks/etc

fulcrm_apiv2.module

@@ -30,6 +30,20 @@ function fulcrm_apiv2_menu() {
     return $items;
 }
 
+function fulcrm_apiv2_prevent_loop( $headers ) {
+    $incoming_client_ids = &drupal_static(__FUNCTION__);
+
+    if ( array_key_exists( 'X-fulcrm-Client-ID', $headers ) ) {
+        $incoming_client_ids = array_map( "trim", explode( ',', $headers[ 'X-fulcrm-Client-ID' ] ) );
+        if ( in_array( $client_id, $incoming_client_ids ) )
+            return false;
+    } else {
+        $incoming_client_ids = array();
+    }
+
+    return true;
+}
+
 function fulcrm_apiv2_http( $method, $object = null, $data = null, $query = null ) {
     $url = null;
 
@@ -76,7 +90,12 @@ function fulcrm_apiv2_http( $method, $object = null, $data = null, $query = null
         $request_headers[] = 'Content-Length: ' . strlen( $data );
     }
 
-    $request_headers[] = 'X-fulcrm-Client-ID: ' . variable_get( 'fulcrm_apiv2_client_id', $GLOBALS[ 'base_url' ] );
+    $incoming_client_ids = &drupal_static( 'fulcrm_apiv2_prevent_loop' );
+    if ( !is_array( $incoming_client_ids ) )
+        $incoming_client_ids = array();
+    $incoming_client_ids[] = variable_get( 'fulcrm_apiv2_client_id', $GLOBALS[ 'base_url' ] );
+
+    $request_headers[] = 'X-fulcrm-Client-ID: ' . implode( ', ', $incoming_client_ids );
 
     curl_setopt( $curl, CURLOPT_RETURNTRANSFER, true );
     curl_setopt( $curl, CURLOPT_FOLLOWLOCATION, true );