Fix replica authentication failure when masterauth is below replicaof in the config file

Author: JohnSully

src/config.cpp

@@ -399,6 +399,8 @@ void loadServerConfigFromString(char *config) {
         } else if (!strcasecmp(argv[0],"masterauth") && argc == 2) {
             zfree(server.default_masterauth);
             server.default_masterauth = argv[1][0] ? zstrdup(argv[1]) : NULL;
+            // Loop through all existing master infos and update them (in case this came after the replicaof config)
+            updateMasterAuth();
         } else if ((!strcasecmp(argv[0],"slave-serve-stale-data") ||
                     !strcasecmp(argv[0],"replica-serve-stale-data"))
                     && argc == 2)

src/replication.cpp

@@ -3194,4 +3194,23 @@ void replicaReplayCommand(client *c)
     // call() will not propogate this for us, so we do so here
     alsoPropagate(server.rreplayCommand,c->db->id,c->argv,c->argc,PROPAGATE_AOF|PROPAGATE_REPL);
     return;
+}
+
+void updateMasterAuth()
+{
+    listIter li;
+    listNode *ln;
+
+    listRewind(server.masters, &li);
+    while ((ln = listNext(&li)))
+    {
+        redisMaster *mi = (redisMaster*)listNodeValue(ln);
+        zfree(mi->masterauth); mi->masterauth = nullptr;
+        zfree(mi->masteruser); mi->masteruser = nullptr;
+
+        if (server.default_masterauth)
+            mi->masterauth = zstrdup(server.default_masterauth);
+        if (server.default_masteruser)
+            mi->masteruser = zstrdup(server.default_masteruser);
+    }
 }

src/server.h

@@ -1824,6 +1824,7 @@ void clearReplicationId2(void);
 void chopReplicationBacklog(void);
 void replicationCacheMasterUsingMyself(struct redisMaster *mi);
 void feedReplicationBacklog(const void *ptr, size_t len);
+void updateMasterAuth();
 
 /* Generic persistence functions */
 void startLoading(FILE *fp);