From 2dc9d119b19db57ce1b6f652a2374acef46937a1 Mon Sep 17 00:00:00 2001
From: Norman Maurer <norman_maurer@apple.com>
Date: Wed, 15 Feb 2017 19:43:52 +0100
Subject: [PATCH] Guard against having NetworkInterface.getNetworkInterfaces()
 return null

Motivation:

NetworkInterface.getNetworkInterfaces() may return null if no network interfaces are found. We should guard against it.

Modifications:

Check for null return value.

Result:

Fixes [#6384]
---
 common/src/main/java/io/netty/util/NetUtil.java | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/common/src/main/java/io/netty/util/NetUtil.java b/common/src/main/java/io/netty/util/NetUtil.java
index d4f2354f10..ed48665f42 100644
--- a/common/src/main/java/io/netty/util/NetUtil.java
+++ b/common/src/main/java/io/netty/util/NetUtil.java
@@ -154,11 +154,14 @@ public final class NetUtil {
         // Retrieve the list of available network interfaces.
         List<NetworkInterface> ifaces = new ArrayList<NetworkInterface>();
         try {
-            for (Enumeration<NetworkInterface> i = NetworkInterface.getNetworkInterfaces(); i.hasMoreElements();) {
-                NetworkInterface iface = i.nextElement();
-                // Use the interface with proper INET addresses only.
-                if (SocketUtils.addressesFromNetworkInterface(iface).hasMoreElements()) {
-                    ifaces.add(iface);
+            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
+            if (interfaces != null) {
+                while (interfaces.hasMoreElements()) {
+                    NetworkInterface iface = interfaces.nextElement();
+                    // Use the interface with proper INET addresses only.
+                    if (SocketUtils.addressesFromNetworkInterface(iface).hasMoreElements()) {
+                        ifaces.add(iface);
+                    }
                 }
             }
         } catch (SocketException e) {