[FIXED] Allow kick to work on leafnodes as well. (#5587)

Kick was designed for any client connection but was intended to also
work on leafnodes. This allows for rebalancing etc.

Resolves: #1556 #5527 

Signed-off-by: Derek Collison <derek@nats.io>

server/leafnode_test.go

@@ -7859,3 +7859,47 @@ func TestLeafNodeDupeDeliveryQueueSubAndPlainSub(t *testing.T) {
 	require_NoError(t, err)
 	require_Equal(t, n, 1)
 }
+
+func TestLeafNodeServerKickClient(t *testing.T) {
+	stmpl := `
+		listen: 127.0.0.1:-1
+		server_name: test-server
+		leaf { listen: 127.0.0.1:-1 }
+	`
+	conf := createConfFile(t, []byte(stmpl))
+	s, o := RunServerWithConfig(conf)
+	defer s.Shutdown()
+
+	tmpl := `
+		listen: 127.0.0.1:-1
+		server_name: test-leaf
+		leaf { remotes: [ { urls: [ nats-leaf://127.0.0.1:{LEAF_PORT} ] } ] }
+	`
+	tmpl = strings.Replace(tmpl, "{LEAF_PORT}", fmt.Sprintf("%d", o.LeafNode.Port), 1)
+	lConf := createConfFile(t, []byte(tmpl))
+	l, _ := RunServerWithConfig(lConf)
+	defer l.Shutdown()
+
+	checkLeafNodeConnected(t, l)
+
+	// We want to make sure we can kick the leafnode connections as well as client connections.
+	conns, err := s.Connz(&ConnzOptions{Account: globalAccountName})
+	require_NoError(t, err)
+	require_Equal(t, len(conns.Conns), 1)
+	lid := conns.Conns[0].Cid
+
+	disconnectTime := time.Now()
+	err = s.DisconnectClientByID(lid)
+	require_NoError(t, err)
+
+	// Wait until we are reconnected.
+	checkLeafNodeConnected(t, s)
+
+	// Look back up again and make sure start time indicates a restart, meaning kick worked.
+	conns, err = s.Connz(&ConnzOptions{Account: globalAccountName})
+	require_NoError(t, err)
+	require_Equal(t, len(conns.Conns), 1)
+	ln := conns.Conns[0]
+	require_True(t, lid != ln.Cid)
+	require_True(t, ln.Start.After(disconnectTime))
+}

server/server.go

@@ -4474,8 +4474,11 @@ func (s *Server) DisconnectClientByID(id uint64) error {
 	if client := s.getClient(id); client != nil {
 		client.closeConnection(Kicked)
 		return nil
+	} else if client = s.GetLeafNode(id); client != nil {
+		client.closeConnection(Kicked)
+		return nil
 	}
-	return errors.New("no such client id")
+	return errors.New("no such client or leafnode id")
 }
 
 // LDMClientByID sends a Lame Duck Mode info message to a client by connection ID