From c77b95fd01cb6959005121b91e21037cd3da1c88 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Thu, 5 May 2016 10:02:42 +0200
Subject: [PATCH] Bind both IPv4 and IPv6 or exit with an error by default.

Thanks to @tushar2708 for the PR. I applied a slightly different fix.
Thanks to @cespare for reporting.

Close #3024
Close #3020
---
 src/server.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/server.c b/src/server.c
index bab8bb67..bd56ceeb 100644
--- a/src/server.c
+++ b/src/server.c
@@ -1789,17 +1789,19 @@ int listenToPort(int port, int *fds, int *count) {
             if (fds[*count] != ANET_ERR) {
                 anetNonBlock(NULL,fds[*count]);
                 (*count)++;
+
+                /* Bind the IPv4 address as well. */
+                fds[*count] = anetTcpServer(server.neterr,port,NULL,
+                    server.tcp_backlog);
+                if (fds[*count] != ANET_ERR) {
+                    anetNonBlock(NULL,fds[*count]);
+                    (*count)++;
+                }
             }
-            fds[*count] = anetTcpServer(server.neterr,port,NULL,
-                server.tcp_backlog);
-            if (fds[*count] != ANET_ERR) {
-                anetNonBlock(NULL,fds[*count]);
-                (*count)++;
-            }
-            /* Exit the loop if we were able to bind * on IPv4 or IPv6,
+            /* Exit the loop if we were able to bind * on IPv4 and IPv6,
              * otherwise fds[*count] will be ANET_ERR and we'll print an
              * error and return to the caller with an error. */
-            if (*count) break;
+            if (*count == 2) break;
         } else if (strchr(server.bindaddr[j],':')) {
             /* Bind IPv6 address. */
             fds[*count] = anetTcp6Server(server.neterr,port,server.bindaddr[j],