func()

in client/control.go [325:396]
63 lines of code
18 McCabe index (conditional complexity)

func (ctl *Control) msgHandler() {
	xl := ctl.xl
	defer func() {
		if err := recover(); err != nil {
			xl.Error("panic error: %v", err)
			xl.Error(string(debug.Stack()))
		}
	}()
	defer ctl.msgHandlerShutdown.Done()

	var hbSendCh <-chan time.Time
	// TODO(fatedier): disable heartbeat if TCPMux is enabled.
	// Just keep it here to keep compatible with old version frps.
	if ctl.clientCfg.HeartbeatInterval > 0 {
		hbSend := time.NewTicker(time.Duration(ctl.clientCfg.HeartbeatInterval) * time.Second)
		defer hbSend.Stop()
		hbSendCh = hbSend.C
	}

	var hbCheckCh <-chan time.Time
	// Check heartbeat timeout only if TCPMux is not enabled and users don't disable heartbeat feature.
	if ctl.clientCfg.HeartbeatInterval > 0 && ctl.clientCfg.HeartbeatTimeout > 0 && !ctl.clientCfg.TCPMux {
		hbCheck := time.NewTicker(time.Second)
		defer hbCheck.Stop()
		hbCheckCh = hbCheck.C
	}

	ctl.lastPong = time.Now()
	for {
		select {
		case <-hbSendCh:
			// send heartbeat to server
			xl.Debug("send heartbeat to server")
			pingMsg := &msg.Ping{}
			if err := ctl.authSetter.SetPing(pingMsg); err != nil {
				xl.Warn("error during ping authentication: %v", err)
				return
			}
			ctl.sendCh <- pingMsg
		case <-hbCheckCh:
			if time.Since(ctl.lastPong) > time.Duration(ctl.clientCfg.HeartbeatTimeout)*time.Second {
				xl.Warn("heartbeat timeout")
				// let reader() stop
				ctl.conn.Close()
				return
			}
		case rawMsg, ok := <-ctl.readCh:
			if !ok {
				return
			}

			switch m := rawMsg.(type) {
			case *msg.ReqWorkConn:
				go ctl.HandleReqWorkConn(m)
			case *msg.Kill:
				ctl.GracefulClose(0)
				os.Exit(0)
				return
			case *msg.NewProxyResp:
				ctl.HandleNewProxyResp(m)
			case *msg.Pong:
				if m.Error != "" {
					xl.Error("Pong contains error: %s", m.Error)
					ctl.conn.Close()
					return
				}
				ctl.lastPong = time.Now()
				xl.Debug("receive heartbeat from server")
			}
		}
	}
}