From a3e3a240570c2beaf79db4bd6e70ff72f9747649 Mon Sep 17 00:00:00 2001
From: John Sully <john@csquare.ca>
Date: Sat, 9 Mar 2019 11:03:59 -0500
Subject: [PATCH] Replicas aren't allowed to run the replicaof command

---
 src/replication.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/replication.c b/src/replication.c
index 9175bb420..26313893d 100644
--- a/src/replication.c
+++ b/src/replication.c
@@ -2038,6 +2038,14 @@ void replicaofCommand(client *c) {
     } else {
         long port;
 
+        if (c->flags & CLIENT_SLAVE)
+        {
+            /* If a client is already a replica they cannot run this command,
+	     * because it involves flushing all replicas (including this client) */
+            addReplyError(c, "Command is not valid when client is a replica.");
+            return;
+        }
+
         if ((getLongFromObjectOrReply(c, c->argv[2], &port, NULL) != C_OK))
             return;