From dc98907e5067c554250f9022ae13d877de971457 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Fri, 22 Jan 2016 13:26:43 +0100
Subject: [PATCH] Cluster announce ip: take myself->ip always in sync.

---
 src/cluster.c | 36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/src/cluster.c b/src/cluster.c
index 7fa120e87..9006e9cb6 100644
--- a/src/cluster.c
+++ b/src/cluster.c
@@ -1658,7 +1658,7 @@ int clusterProcessPacket(clusterLink *link) {
 
         /* We use incoming MEET messages in order to set the address
          * for 'myself', since only other cluster nodes will send us
-         * MEET messagses on handshakes, when the cluster joins, or
+         * MEET messages on handshakes, when the cluster joins, or
          * later if we changed address, and those nodes will use our
          * official address to connect to us. So by obtaining this address
          * from the socket is a simple way to discover / update our own
@@ -1667,13 +1667,12 @@ int clusterProcessPacket(clusterLink *link) {
          * However if we don't have an address at all, we update the address
          * even with a normal PING packet. If it's wrong it will be fixed
          * by MEET later. */
-        if (type == CLUSTERMSG_TYPE_MEET || myself->ip[0] == '\0') {
+        if ((type == CLUSTERMSG_TYPE_MEET || myself->ip[0] == '\0') &&
+            server.cluster_announce_ip == NULL)
+        {
             char ip[NET_IP_STR_LEN];
 
-            if (server.cluster_announce_ip) {
-                strncpy(myself->ip,server.cluster_announce_ip,NET_IP_STR_LEN);
-                myself->ip[NET_IP_STR_LEN-1] = '\0';
-            } else if (anetSockName(link->fd,ip,sizeof(ip),NULL) != -1 &&
+            if (anetSockName(link->fd,ip,sizeof(ip),NULL) != -1 &&
                 strcmp(ip,myself->ip))
             {
                 memcpy(myself->ip,ip,NET_IP_STR_LEN);
@@ -3118,6 +3117,31 @@ void clusterCron(void) {
 
     iteration++; /* Number of times this function was called so far. */
 
+    /* We want to take myself->ip in sync with the cluster-announce-ip option.
+     * The option can be set at runtime via CONFIG SET, so we periodically check
+     * if the option changed to reflect this into myself->ip. */
+    {
+        static char *prev_ip = NULL;
+        char *curr_ip = server.cluster_announce_ip;
+        int changed = 0;
+
+        if (prev_ip == NULL && curr_ip != NULL) changed = 1;
+        if (prev_ip != NULL && curr_ip == NULL) changed = 1;
+        if (prev_ip && curr_ip && strcmp(prev_ip,curr_ip)) changed = 1;
+
+        if (changed) {
+            prev_ip = curr_ip;
+            if (prev_ip) prev_ip = zstrdup(prev_ip);
+
+            if (curr_ip) {
+                strncpy(myself->ip,server.cluster_announce_ip,NET_IP_STR_LEN);
+                myself->ip[NET_IP_STR_LEN-1] = '\0';
+            } else {
+                myself->ip[0] = '\0'; /* Force autodetection. */
+            }
+        }
+    }
+
     /* The handshake timeout is the time after which a handshake node that was
      * not turned into a normal node is removed from the nodes. Usually it is
      * just the NODE_TIMEOUT value, but when NODE_TIMEOUT is too small we use