Function runNetcheck

cmd/tailscale/cli/netcheck.go:69–155

(ctx context.Context, args []string)

}

func runNetcheck(ctx context.Context, args []string) error {
	logf := logger.WithPrefix(log.Printf, "portmap: ")
	bus := eventbus.New()
	defer bus.Close()
	netMon, err := netmon.New(bus, logf)
	if err != nil {
		return err
	}

	var pm portmappertype.Client
	if buildfeatures.HasPortMapper {
		// Ensure that we close the portmapper after running a netcheck; this
		// will release any port mappings created.
		pm = portmappertype.HookNewPortMapper.Get()(logf, bus, netMon, nil, nil)
		defer pm.Close()
	}

	flagsProvided := set.Set[string]{}
	netcheckFlagSet.Visit(func(f *flag.Flag) {
		flagsProvided.Add(f.Name)
	})

	c := &netcheck.Client{
		NetMon:      netMon,
		PortMapper:  pm,
		UseDNSCache: false, // always resolve, don't cache
	}
	if netcheckArgs.verbose {
		c.Logf = logger.WithPrefix(log.Printf, "netcheck: ")
		c.Verbose = true
	} else {
		c.Logf = logger.Discard
	}

	if strings.HasPrefix(netcheckArgs.format, "json") {
		fmt.Fprintln(Stderr, "# Warning: this JSON format is not yet considered a stable interface")
	}

	bind, err := createNetcheckBindString(
		netcheckArgs.bindAddress,
		flagsProvided.Contains("bind-address"),
		netcheckArgs.bindPort,
		flagsProvided.Contains("bind-port"),
		envknob.String("TS_DEBUG_NETCHECK_UDP_BIND"))
	if err != nil {
		return err
	}

	if err := c.Standalone(ctx, bind); err != nil {
		fmt.Fprintln(Stderr, "netcheck: UDP test failure:", err)
	}

	dm, err := localClient.CurrentDERPMap(ctx)
	noRegions := dm != nil && len(dm.Regions) == 0
	if noRegions {
		log.Printf("No DERP map from tailscaled; using default.")
	}
	if err != nil || noRegions {