Function NewUserspaceEngine

wgengine/userspace.go:321–645

NewUserspaceEngine creates the named tun device and returns a Tailscale Engine running on it.

(logf logger.Logf, conf Config)

// NewUserspaceEngine creates the named tun device and returns a
// Tailscale Engine running on it.
func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error) {
	var closePool closeOnErrorPool
	defer closePool.closeAllIfError(&reterr)

	if testenv.InTest() && conf.HealthTracker == nil {
		panic("NewUserspaceEngine called without HealthTracker (being strict in tests)")
	}

	if conf.Metrics == nil {
		return nil, errors.New("NewUserspaceEngine: opts.Metrics is required, please pass a *usermetric.Registry")
	}

	if conf.Tun == nil {
		logf("[v1] using fake (no-op) tun device")
		conf.Tun = tstun.NewFake()
	}
	if conf.Router == nil {
		logf("[v1] using fake (no-op) OS network configurator")
		conf.Router = router.NewFake(logf)
	}
	if conf.DNS == nil {
		logf("[v1] using fake (no-op) DNS configurator")
		d, err := dns.NewNoopManager()
		if err != nil {
			return nil, err
		}
		conf.DNS = d
	}
	if conf.Dialer == nil {
		conf.Dialer = &tsdial.Dialer{Logf: logf}
		if conf.EventBus != nil {
			conf.Dialer.SetBus(conf.EventBus)
		}
	}

	var tsTUNDev *tstun.Wrapper
	if conf.IsTAP {
		tsTUNDev = tstun.WrapTAP(logf, conf.Tun, conf.Metrics, conf.EventBus)
	} else {
		tsTUNDev = tstun.Wrap(logf, conf.Tun, conf.Metrics, conf.EventBus)
	}
	closePool.add(tsTUNDev)

	rtr := conf.Router
	if version.IsMobile() {
		// Android and iOS don't handle large numbers of routes well, so we
		// wrap the Router with one that consolidates routes down to the
		// smallest number possible.
		//
		// On Android, too many routes at VPN configuration time result in an
		// android.os.TransactionTooLargeException because Android's VPNBuilder
		// tries to send the entire set of routes to the VPNService as a single
		// Bundle, which is typically limited to 1 MB. The number of routes
		// that's too much seems to be very roughly around 4000.
		//
		// On iOS, the VPNExtension is limited to only 50 MB of memory, so
		// keeping the number of routes down helps with memory consumption.
		rtr = router.ConsolidatingRoutes(logf, rtr)