From 3ec580546401c461d6e4b4bfb8b98c54d7f966b8 Mon Sep 17 00:00:00 2001
From: Jisheng Xing <jisheng.xing@citrix.com>
Date: Thu, 22 Feb 2018 18:21:12 +0800
Subject: [PATCH] add some check when resolving a reference

---
 XenModel/XenAPI-Extensions/PIF.cs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/XenModel/XenAPI-Extensions/PIF.cs b/XenModel/XenAPI-Extensions/PIF.cs
index 30d20f327..772e697ab 100644
--- a/XenModel/XenAPI-Extensions/PIF.cs
+++ b/XenModel/XenAPI-Extensions/PIF.cs
@@ -57,8 +57,14 @@ namespace XenAPI
             }
             else if(sriov_logical_PIF_of.Count != 0)
             {
+                if (Connection == null)
+                    return "";
                 Network_sriov network_s = Connection.Resolve(sriov_logical_PIF_of[0]);
+                if (network_s == null)
+                    return "";
                 PIF pif = Connection.Resolve(network_s.physical_PIF);
+                if (pif == null)
+                    return "";
                 return pif.Name();
             }
             else