From cc81c041857f68691551054ca6a6920b2dcb69ad Mon Sep 17 00:00:00 2001
From: Israel Lot <israel.lot@gmail.com>
Date: Tue, 12 Mar 2019 18:29:12 -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 2081b5d5..0e218936 100644
--- a/src/replication.c
+++ b/src/replication.c
@@ -2154,6 +2154,14 @@ void slaveofCommand(client *c) {
     } else {
         PORT_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;