From 92075cdc27730a51b81bd6b680e49270e05f8dd7 Mon Sep 17 00:00:00 2001
From: John Lee <ubwhole@yahoo.com>
Date: Thu, 13 Jul 2017 19:39:37 -0500
Subject: [PATCH] Update is_valid_signature() to support proxied requests from
 Shopify

---
 lib/shopify.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/shopify.js b/lib/shopify.js
index 5ed2dba..2980d2b 100644
--- a/lib/shopify.js
+++ b/lib/shopify.js
@@ -52,6 +52,7 @@ ShopifyAPI.prototype.is_valid_signature = function(params, non_state) {
     }
 
     var hmac = params['hmac'],
+        theHash = params['hmac'] || params['signature'],
         secret = this.config.shopify_shared_secret,
         parameters = [],
         digest,
@@ -63,14 +64,14 @@ ShopifyAPI.prototype.is_valid_signature = function(params, non_state) {
         }
     }
 
-    message = parameters.sort().join('&');
+    message = parameters.sort().join(hmac ? '&' : '');
 
     digest = crypto
                 .createHmac('SHA256', secret)
                 .update(message)
                 .digest('hex');
 
-    return (digest === hmac);
+    return ( digest === theHash );
 };
 
 ShopifyAPI.prototype.exchange_temporary_token = function(query_params, callback) {