Cleanup most of the remaining nits (#578)

connection_manager_test.go

@@ -11,7 +11,6 @@ import (
 	"github.com/flynn/noise"
 	"github.com/slackhq/nebula/cert"
 	"github.com/slackhq/nebula/iputil"
-	"github.com/slackhq/nebula/overlay"
 	"github.com/slackhq/nebula/test"
 	"github.com/slackhq/nebula/udp"
 	"github.com/stretchr/testify/assert"
@@ -39,7 +38,7 @@ func Test_NewConnectionManagerTest(t *testing.T) {
 	lh := NewLightHouse(l, false, &net.IPNet{IP: net.IP{0, 0, 0, 0}, Mask: net.IPMask{0, 0, 0, 0}}, []iputil.VpnIp{}, 1000, 0, &udp.Conn{}, false, 1, false)
 	ifce := &Interface{
 		hostMap:          hostMap,
-		inside:           &overlay.Tun{},
+		inside:           &test.NoopTun{},
 		outside:          &udp.Conn{},
 		certState:        cs,
 		firewall:         &Firewall{},
@@ -108,7 +107,7 @@ func Test_NewConnectionManagerTest2(t *testing.T) {
 	lh := NewLightHouse(l, false, &net.IPNet{IP: net.IP{0, 0, 0, 0}, Mask: net.IPMask{0, 0, 0, 0}}, []iputil.VpnIp{}, 1000, 0, &udp.Conn{}, false, 1, false)
 	ifce := &Interface{
 		hostMap:          hostMap,
-		inside:           &overlay.Tun{},
+		inside:           &test.NoopTun{},
 		outside:          &udp.Conn{},
 		certState:        cs,
 		firewall:         &Firewall{},
@@ -217,7 +216,7 @@ func Test_NewConnectionManagerTest_DisconnectInvalid(t *testing.T) {
 	lh := NewLightHouse(l, false, &net.IPNet{IP: net.IP{0, 0, 0, 0}, Mask: net.IPMask{0, 0, 0, 0}}, []iputil.VpnIp{}, 1000, 0, &udp.Conn{}, false, 1, false)
 	ifce := &Interface{
 		hostMap:           hostMap,
-		inside:            &overlay.Tun{},
+		inside:            &test.NoopTun{},
 		outside:           &udp.Conn{},
 		certState:         cs,
 		firewall:          &Firewall{},

control_tester.go

@@ -65,7 +65,7 @@ func (c *Control) InjectLightHouseAddr(vpnIp net.IP, toAddr *net.UDPAddr) {
 
 // GetFromTun will pull a packet off the tun side of nebula
 func (c *Control) GetFromTun(block bool) []byte {
-	return c.f.inside.(*overlay.Tun).Get(block)
+	return c.f.inside.(*overlay.TestTun).Get(block)
 }
 
 // GetFromUDP will pull a udp packet off the udp side of nebula
@@ -78,7 +78,7 @@ func (c *Control) GetUDPTxChan() <-chan *udp.Packet {
 }
 
 func (c *Control) GetTunTxChan() <-chan []byte {
-	return c.f.inside.(*overlay.Tun).TxPackets
+	return c.f.inside.(*overlay.TestTun).TxPackets
 }
 
 // InjectUDPPacket will inject a packet into the udp side of nebula
@@ -115,7 +115,7 @@ func (c *Control) InjectTunUDPPacket(toIp net.IP, toPort uint16, fromPort uint16
 		panic(err)
 	}
 
-	c.f.inside.(*overlay.Tun).Send(buffer.Bytes())
+	c.f.inside.(*overlay.TestTun).Send(buffer.Bytes())
 }
 
 func (c *Control) GetUDPAddr() string {

overlay/tun_android.go

@@ -13,7 +13,7 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-type Tun struct {
+type tun struct {
 	io.ReadWriteCloser
 	fd           int
 	Device       string
@@ -26,10 +26,10 @@ type Tun struct {
 	l            *logrus.Logger
 }
 
-func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int) (ifce *Tun, err error) {
+func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int) (*tun, error) {
 	file := os.NewFile(uintptr(deviceFd), "/dev/net/tun")
 
-	ifce = &Tun{
+	return &tun{
 		ReadWriteCloser: file,
 		fd:              int(file.Fd()),
 		Device:          "android",
@@ -39,19 +39,18 @@ func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU in
 		Routes:          routes,
 		UnsafeRoutes:    unsafeRoutes,
 		l:               l,
-	}
-	return
+	}, nil
 }
 
-func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int, multiqueue bool) (ifce *Tun, err error) {
+func newTun(_ *logrus.Logger, _ string, _ *net.IPNet, _ int, _ []Route, _ []Route, _ int, _ bool) (*tun, error) {
 	return nil, fmt.Errorf("newTun not supported in Android")
 }
 
-func (c *Tun) WriteRaw(b []byte) error {
+func (t *tun) WriteRaw(b []byte) error {
 	var nn int
 	for {
 		max := len(b)
-		n, err := unix.Write(c.fd, b[nn:max])
+		n, err := unix.Write(t.fd, b[nn:max])
 		if n > 0 {
 			nn += n
 		}
@@ -69,18 +68,18 @@ func (c *Tun) WriteRaw(b []byte) error {
 	}
 }
 
-func (c Tun) Activate() error {
+func (t tun) Activate() error {
 	return nil
 }
 
-func (c *Tun) CidrNet() *net.IPNet {
-	return c.Cidr
+func (t *tun) CidrNet() *net.IPNet {
+	return t.Cidr
 }
 
-func (c *Tun) DeviceName() string {
-	return c.Device
+func (t *tun) DeviceName() string {
+	return t.Device
 }
 
-func (t *Tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for android")
 }

overlay/tun_darwin.go

@@ -16,7 +16,7 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-type Tun struct {
+type tun struct {
 	io.ReadWriteCloser
 	Device       string
 	Cidr         *net.IPNet
@@ -74,13 +74,7 @@ type ifreqMTU struct {
 	pad  [8]byte
 }
 
-type ifreqQLEN struct {
-	Name  [16]byte
-	Value int32
-	pad   [8]byte
-}
-
-func newTun(l *logrus.Logger, name string, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int, multiqueue bool) (ifce *Tun, err error) {
+func newTun(l *logrus.Logger, name string, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int, _ bool) (*tun, error) {
 	if len(routes) > 0 {
 		return nil, fmt.Errorf("route MTU not supported in Darwin")
 	}
@@ -106,7 +100,7 @@ func newTun(l *logrus.Logger, name string, cidr *net.IPNet, defaultMTU int, rout
 		ctlName [96]byte
 	}{}
 
-	copy(ctlInfo.ctlName[:], []byte(utunControlName))
+	copy(ctlInfo.ctlName[:], utunControlName)
 
 	err = ioctl(uintptr(fd), uintptr(_CTLIOCGINFO), uintptr(unsafe.Pointer(ctlInfo)))
 	if err != nil {
@@ -125,7 +119,7 @@ func newTun(l *logrus.Logger, name string, cidr *net.IPNet, defaultMTU int, rout
 		unix.SYS_CONNECT,
 		uintptr(fd),
 		uintptr(unsafe.Pointer(&sc)),
-		uintptr(sockaddrCtlSize),
+		sockaddrCtlSize,
 	)
 	if errno != 0 {
 		return nil, fmt.Errorf("SYS_CONNECT: %v", errno)
@@ -152,7 +146,7 @@ func newTun(l *logrus.Logger, name string, cidr *net.IPNet, defaultMTU int, rout
 
 	file := os.NewFile(uintptr(fd), "")
 
-	tun := &Tun{
+	tun := &tun{
 		ReadWriteCloser: file,
 		Device:          name,
 		Cidr:            cidr,
@@ -165,25 +159,25 @@ func newTun(l *logrus.Logger, name string, cidr *net.IPNet, defaultMTU int, rout
 	return tun, nil
 }
 
-func (t *Tun) deviceBytes() (o [16]byte) {
+func (t *tun) deviceBytes() (o [16]byte) {
 	for i, c := range t.Device {
 		o[i] = byte(c)
 	}
 	return
 }
 
-func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int) (ifce *Tun, err error) {
+func newTunFromFd(_ *logrus.Logger, _ int, _ *net.IPNet, _ int, _ []Route, _ []Route, _ int) (*tun, error) {
 	return nil, fmt.Errorf("newTunFromFd not supported in Darwin")
 }
 
-func (c *Tun) Close() error {
-	if c.ReadWriteCloser != nil {
-		return c.ReadWriteCloser.Close()
+func (t *tun) Close() error {
+	if t.ReadWriteCloser != nil {
+		return t.ReadWriteCloser.Close()
 	}
 	return nil
 }
 
-func (t *Tun) Activate() error {
+func (t *tun) Activate() error {
 	devName := t.deviceBytes()
 
 	var addr, mask [4]byte
@@ -231,7 +225,7 @@ func (t *Tun) Activate() error {
 	// Set the MTU on the device
 	ifm := ifreqMTU{Name: devName, MTU: int32(t.DefaultMTU)}
 	if err = ioctl(fd, unix.SIOCSIFMTU, uintptr(unsafe.Pointer(&ifm))); err != nil {
-		return fmt.Errorf("Failed to set tun mtu: %v", err)
+		return fmt.Errorf("failed to set tun mtu: %v", err)
 	}
 
 	/*
@@ -353,9 +347,7 @@ func addRoute(sock int, addr, mask *netroute.Inet4Addr, link *netroute.LinkAddr)
 	return nil
 }
 
-var _ io.ReadWriteCloser = (*Tun)(nil)
-
-func (t *Tun) Read(to []byte) (int, error) {
+func (t *tun) Read(to []byte) (int, error) {
 
 	buf := make([]byte, len(to)+4)
 
@@ -366,7 +358,7 @@ func (t *Tun) Read(to []byte) (int, error) {
 }
 
 // Write is only valid for single threaded use
-func (t *Tun) Write(from []byte) (int, error) {
+func (t *tun) Write(from []byte) (int, error) {
 	buf := t.out
 	if cap(buf) < len(from)+4 {
 		buf = make([]byte, len(from)+4)
@@ -385,7 +377,7 @@ func (t *Tun) Write(from []byte) (int, error) {
 	} else if ipVer == 6 {
 		buf[3] = syscall.AF_INET6
 	} else {
-		return 0, fmt.Errorf("Unable to determine IP version from packet")
+		return 0, fmt.Errorf("unable to determine IP version from packet")
 	}
 
 	copy(buf[4:], from)
@@ -394,19 +386,19 @@ func (t *Tun) Write(from []byte) (int, error) {
 	return n - 4, err
 }
 
-func (c *Tun) CidrNet() *net.IPNet {
-	return c.Cidr
+func (t *tun) CidrNet() *net.IPNet {
+	return t.Cidr
 }
 
-func (c *Tun) DeviceName() string {
-	return c.Device
+func (t *tun) DeviceName() string {
+	return t.Device
 }
 
-func (c *Tun) WriteRaw(b []byte) error {
-	_, err := c.Write(b)
+func (t *tun) WriteRaw(b []byte) error {
+	_, err := t.Write(b)
 	return err
 }
 
-func (t *Tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for darwin")
 }

overlay/tun_freebsd.go

@@ -18,7 +18,7 @@ import (
 
 var deviceNameRE = regexp.MustCompile(`^tun[0-9]+$`)
 
-type Tun struct {
+type tun struct {
 	Device       string
 	Cidr         *net.IPNet
 	MTU          int
@@ -28,20 +28,20 @@ type Tun struct {
 	io.ReadWriteCloser
 }
 
-func (c *Tun) Close() error {
-	if c.ReadWriteCloser != nil {
-		return c.ReadWriteCloser.Close()
+func (t *tun) Close() error {
+	if t.ReadWriteCloser != nil {
+		return t.ReadWriteCloser.Close()
 	}
 	return nil
 }
 
-func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int) (ifce *Tun, err error) {
+func newTunFromFd(_ *logrus.Logger, _ int, _ *net.IPNet, _ int, _ []Route, _ []Route, _ int) (*tun, error) {
 	return nil, fmt.Errorf("newTunFromFd not supported in FreeBSD")
 }
 
-func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int, multiqueue bool) (ifce *Tun, err error) {
+func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, _ int, _ bool) (*tun, error) {
 	if len(routes) > 0 {
-		return nil, fmt.Errorf("Route MTU not supported in FreeBSD")
+		return nil, fmt.Errorf("route MTU not supported in FreeBSD")
 	}
 	if strings.HasPrefix(deviceName, "/dev/") {
 		deviceName = strings.TrimPrefix(deviceName, "/dev/")
@@ -49,7 +49,7 @@ func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int
 	if !deviceNameRE.MatchString(deviceName) {
 		return nil, fmt.Errorf("tun.dev must match `tun[0-9]+`")
 	}
-	return &Tun{
+	return &tun{
 		Device:       deviceName,
 		Cidr:         cidr,
 		MTU:          defaultMTU,
@@ -58,30 +58,30 @@ func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int
 	}, nil
 }
 
-func (c *Tun) Activate() error {
+func (t *tun) Activate() error {
 	var err error
-	c.ReadWriteCloser, err = os.OpenFile("/dev/"+c.Device, os.O_RDWR, 0)
+	t.ReadWriteCloser, err = os.OpenFile("/dev/"+t.Device, os.O_RDWR, 0)
 	if err != nil {
-		return fmt.Errorf("Activate failed: %v", err)
+		return fmt.Errorf("activate failed: %v", err)
 	}
 
 	// TODO use syscalls instead of exec.Command
-	c.l.Debug("command: ifconfig", c.Device, c.Cidr.String(), c.Cidr.IP.String())
-	if err = exec.Command("/sbin/ifconfig", c.Device, c.Cidr.String(), c.Cidr.IP.String()).Run(); err != nil {
+	t.l.Debug("command: ifconfig", t.Device, t.Cidr.String(), t.Cidr.IP.String())
+	if err = exec.Command("/sbin/ifconfig", t.Device, t.Cidr.String(), t.Cidr.IP.String()).Run(); err != nil {
 		return fmt.Errorf("failed to run 'ifconfig': %s", err)
 	}
-	c.l.Debug("command: route", "-n", "add", "-net", c.Cidr.String(), "-interface", c.Device)
-	if err = exec.Command("/sbin/route", "-n", "add", "-net", c.Cidr.String(), "-interface", c.Device).Run(); err != nil {
+	t.l.Debug("command: route", "-n", "add", "-net", t.Cidr.String(), "-interface", t.Device)
+	if err = exec.Command("/sbin/route", "-n", "add", "-net", t.Cidr.String(), "-interface", t.Device).Run(); err != nil {
 		return fmt.Errorf("failed to run 'route add': %s", err)
 	}
-	c.l.Debug("command: ifconfig", c.Device, "mtu", strconv.Itoa(c.MTU))
-	if err = exec.Command("/sbin/ifconfig", c.Device, "mtu", strconv.Itoa(c.MTU)).Run(); err != nil {
+	t.l.Debug("command: ifconfig", t.Device, "mtu", strconv.Itoa(t.MTU))
+	if err = exec.Command("/sbin/ifconfig", t.Device, "mtu", strconv.Itoa(t.MTU)).Run(); err != nil {
 		return fmt.Errorf("failed to run 'ifconfig': %s", err)
 	}
 	// Unsafe path routes
-	for _, r := range c.UnsafeRoutes {
-		c.l.Debug("command: route", "-n", "add", "-net", r.Cidr.String(), "-interface", c.Device)
-		if err = exec.Command("/sbin/route", "-n", "add", "-net", r.Cidr.String(), "-interface", c.Device).Run(); err != nil {
+	for _, r := range t.UnsafeRoutes {
+		t.l.Debug("command: route", "-n", "add", "-net", r.Cidr.String(), "-interface", t.Device)
+		if err = exec.Command("/sbin/route", "-n", "add", "-net", r.Cidr.String(), "-interface", t.Device).Run(); err != nil {
 			return fmt.Errorf("failed to run 'route add' for unsafe_route %s: %s", r.Cidr.String(), err)
 		}
 	}
@@ -89,19 +89,19 @@ func (c *Tun) Activate() error {
 	return nil
 }
 
-func (c *Tun) CidrNet() *net.IPNet {
-	return c.Cidr
+func (t *tun) CidrNet() *net.IPNet {
+	return t.Cidr
 }
 
-func (c *Tun) DeviceName() string {
-	return c.Device
+func (t *tun) DeviceName() string {
+	return t.Device
 }
 
-func (c *Tun) WriteRaw(b []byte) error {
-	_, err := c.Write(b)
+func (t *tun) WriteRaw(b []byte) error {
+	_, err := t.Write(b)
 	return err
 }
 
-func (t *Tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for freebsd")
 }

overlay/tun_ios.go

@@ -15,36 +15,35 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-type Tun struct {
+type tun struct {
 	io.ReadWriteCloser
 	Device string
 	Cidr   *net.IPNet
 }
 
-func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int, multiqueue bool) (ifce *Tun, err error) {
+func newTun(_ *logrus.Logger, _ string, _ *net.IPNet, _ int, _ []Route, _ []Route, _ int, _ bool) (*tun, error) {
 	return nil, fmt.Errorf("newTun not supported in iOS")
 }
 
-func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int) (ifce *Tun, err error) {
+func newTunFromFd(_ *logrus.Logger, deviceFd int, cidr *net.IPNet, _ int, routes []Route, _ []Route, _ int) (*tun, error) {
 	if len(routes) > 0 {
 		return nil, fmt.Errorf("route MTU not supported in Darwin")
 	}
 
 	file := os.NewFile(uintptr(deviceFd), "/dev/tun")
-	ifce = &Tun{
+	return &tun{
 		Cidr:            cidr,
 		Device:          "iOS",
 		ReadWriteCloser: &tunReadCloser{f: file},
-	}
-	return
+	}, nil
 }
 
-func (c *Tun) Activate() error {
+func (t *tun) Activate() error {
 	return nil
 }
 
-func (c *Tun) WriteRaw(b []byte) error {
-	_, err := c.Write(b)
+func (t *tun) WriteRaw(b []byte) error {
+	_, err := t.Write(b)
 	return err
 }
 
@@ -59,62 +58,62 @@ type tunReadCloser struct {
 	wBuf []byte
 }
 
-func (t *tunReadCloser) Read(to []byte) (int, error) {
-	t.rMu.Lock()
-	defer t.rMu.Unlock()
+func (tr *tunReadCloser) Read(to []byte) (int, error) {
+	tr.rMu.Lock()
+	defer tr.rMu.Unlock()
 
-	if cap(t.rBuf) < len(to)+4 {
-		t.rBuf = make([]byte, len(to)+4)
+	if cap(tr.rBuf) < len(to)+4 {
+		tr.rBuf = make([]byte, len(to)+4)
 	}
-	t.rBuf = t.rBuf[:len(to)+4]
+	tr.rBuf = tr.rBuf[:len(to)+4]
 
-	n, err := t.f.Read(t.rBuf)
-	copy(to, t.rBuf[4:])
+	n, err := tr.f.Read(tr.rBuf)
+	copy(to, tr.rBuf[4:])
 	return n - 4, err
 }
 
-func (t *tunReadCloser) Write(from []byte) (int, error) {
+func (tr *tunReadCloser) Write(from []byte) (int, error) {
 
 	if len(from) == 0 {
 		return 0, syscall.EIO
 	}
 
-	t.wMu.Lock()
-	defer t.wMu.Unlock()
+	tr.wMu.Lock()
+	defer tr.wMu.Unlock()
 
-	if cap(t.wBuf) < len(from)+4 {
-		t.wBuf = make([]byte, len(from)+4)
+	if cap(tr.wBuf) < len(from)+4 {
+		tr.wBuf = make([]byte, len(from)+4)
 	}
-	t.wBuf = t.wBuf[:len(from)+4]
+	tr.wBuf = tr.wBuf[:len(from)+4]
 
 	// Determine the IP Family for the NULL L2 Header
 	ipVer := from[0] >> 4
 	if ipVer == 4 {
-		t.wBuf[3] = syscall.AF_INET
+		tr.wBuf[3] = syscall.AF_INET
 	} else if ipVer == 6 {
-		t.wBuf[3] = syscall.AF_INET6
+		tr.wBuf[3] = syscall.AF_INET6
 	} else {
 		return 0, errors.New("unable to determine IP version from packet")
 	}
 
-	copy(t.wBuf[4:], from)
+	copy(tr.wBuf[4:], from)
 
-	n, err := t.f.Write(t.wBuf)
+	n, err := tr.f.Write(tr.wBuf)
 	return n - 4, err
 }
 
-func (t *tunReadCloser) Close() error {
-	return t.f.Close()
+func (tr *tunReadCloser) Close() error {
+	return tr.f.Close()
 }
 
-func (c *Tun) CidrNet() *net.IPNet {
-	return c.Cidr
+func (t *tun) CidrNet() *net.IPNet {
+	return t.Cidr
 }
 
-func (c *Tun) DeviceName() string {
-	return c.Device
+func (t *tun) DeviceName() string {
+	return t.Device
 }
 
-func (t *Tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for ios")
 }

overlay/tun_linux.go

@@ -16,7 +16,7 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-type Tun struct {
+type tun struct {
 	io.ReadWriteCloser
 	fd           int
 	Device       string
@@ -43,26 +43,6 @@ func ioctl(a1, a2, a3 uintptr) error {
 	return nil
 }
 
-/*
-func ipv4(addr string) (o [4]byte, err error) {
-	ip := net.ParseIP(addr).To4()
-	if ip == nil {
-		err = fmt.Errorf("failed to parse addr %s", addr)
-		return
-	}
-	for i, b := range ip {
-		o[i] = b
-	}
-	return
-}
-*/
-
-const (
-	cIFF_TUN         = 0x0001
-	cIFF_NO_PI       = 0x1000
-	cIFF_MULTI_QUEUE = 0x0100
-)
-
 type ifreqAddr struct {
 	Name [16]byte
 	Addr unix.RawSockaddrInet4
@@ -81,11 +61,11 @@ type ifreqQLEN struct {
 	pad   [8]byte
 }
 
-func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int) (ifce *Tun, err error) {
+func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int) (*tun, error) {
 
 	file := os.NewFile(uintptr(deviceFd), "/dev/net/tun")
 
-	ifce = &Tun{
+	return &tun{
 		ReadWriteCloser: file,
 		fd:              int(file.Fd()),
 		Device:          "tun0",
@@ -95,20 +75,19 @@ func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU in
 		Routes:          routes,
 		UnsafeRoutes:    unsafeRoutes,
 		l:               l,
-	}
-	return
+	}, nil
 }
 
-func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int, multiqueue bool) (ifce *Tun, err error) {
+func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int, multiqueue bool) (*tun, error) {
 	fd, err := unix.Open("/dev/net/tun", os.O_RDWR, 0)
 	if err != nil {
 		return nil, err
 	}
 
 	var req ifReq
-	req.Flags = uint16(cIFF_TUN | cIFF_NO_PI)
+	req.Flags = uint16(unix.IFF_TUN | unix.IFF_NO_PI)
 	if multiqueue {
-		req.Flags |= cIFF_MULTI_QUEUE
+		req.Flags |= unix.IFF_MULTI_QUEUE
 	}
 	copy(req.Name[:], deviceName)
 	if err = ioctl(uintptr(fd), uintptr(unix.TUNSETIFF), uintptr(unsafe.Pointer(&req))); err != nil {
@@ -125,7 +104,7 @@ func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int
 		}
 	}
 
-	ifce = &Tun{
+	return &tun{
 		ReadWriteCloser: file,
 		fd:              int(file.Fd()),
 		Device:          name,
@@ -136,19 +115,18 @@ func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int
 		Routes:          routes,
 		UnsafeRoutes:    unsafeRoutes,
 		l:               l,
-	}
-	return
+	}, nil
 }
 
-func (c *Tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	fd, err := unix.Open("/dev/net/tun", os.O_RDWR, 0)
 	if err != nil {
 		return nil, err
 	}
 
 	var req ifReq
-	req.Flags = uint16(cIFF_TUN | cIFF_NO_PI | cIFF_MULTI_QUEUE)
-	copy(req.Name[:], c.Device)
+	req.Flags = uint16(unix.IFF_TUN | unix.IFF_NO_PI | unix.IFF_MULTI_QUEUE)
+	copy(req.Name[:], t.Device)
 	if err = ioctl(uintptr(fd), uintptr(unix.TUNSETIFF), uintptr(unsafe.Pointer(&req))); err != nil {
 		return nil, err
 	}
@@ -158,11 +136,11 @@ func (c *Tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return file, nil
 }
 
-func (c *Tun) WriteRaw(b []byte) error {
+func (t *tun) WriteRaw(b []byte) error {
 	var nn int
 	for {
 		max := len(b)
-		n, err := unix.Write(c.fd, b[nn:max])
+		n, err := unix.Write(t.fd, b[nn:max])
 		if n > 0 {
 			nn += n
 		}
@@ -180,24 +158,24 @@ func (c *Tun) WriteRaw(b []byte) error {
 	}
 }
 
-func (c *Tun) Write(b []byte) (int, error) {
-	return len(b), c.WriteRaw(b)
+func (t *tun) Write(b []byte) (int, error) {
+	return len(b), t.WriteRaw(b)
 }
 
-func (c Tun) deviceBytes() (o [16]byte) {
-	for i, c := range c.Device {
+func (t tun) deviceBytes() (o [16]byte) {
+	for i, c := range t.Device {
 		o[i] = byte(c)
 	}
 	return
 }
 
-func (c Tun) Activate() error {
-	devName := c.deviceBytes()
+func (t tun) Activate() error {
+	devName := t.deviceBytes()
 
 	var addr, mask [4]byte
 
-	copy(addr[:], c.Cidr.IP.To4())
-	copy(mask[:], c.Cidr.Mask)
+	copy(addr[:], t.Cidr.IP.To4())
+	copy(mask[:], t.Cidr.Mask)
 
 	s, err := unix.Socket(
 		unix.AF_INET,
@@ -235,17 +213,17 @@ func (c Tun) Activate() error {
 	}
 
 	// Set the MTU on the device
-	ifm := ifreqMTU{Name: devName, MTU: int32(c.MaxMTU)}
+	ifm := ifreqMTU{Name: devName, MTU: int32(t.MaxMTU)}
 	if err = ioctl(fd, unix.SIOCSIFMTU, uintptr(unsafe.Pointer(&ifm))); err != nil {
 		// This is currently a non fatal condition because the route table must have the MTU set appropriately as well
-		c.l.WithError(err).Error("Failed to set tun mtu")
+		t.l.WithError(err).Error("Failed to set tun mtu")
 	}
 
 	// Set the transmit queue length
-	ifrq := ifreqQLEN{Name: devName, Value: int32(c.TXQueueLen)}
+	ifrq := ifreqQLEN{Name: devName, Value: int32(t.TXQueueLen)}
 	if err = ioctl(fd, unix.SIOCSIFTXQLEN, uintptr(unsafe.Pointer(&ifrq))); err != nil {
 		// If we can't set the queue length nebula will still work but it may lead to packet loss
-		c.l.WithError(err).Error("Failed to set tun tx queue length")
+		t.l.WithError(err).Error("Failed to set tun tx queue length")
 	}
 
 	// Bring up the interface
@@ -255,36 +233,36 @@ func (c Tun) Activate() error {
 	}
 
 	// Set the routes
-	link, err := netlink.LinkByName(c.Device)
+	link, err := netlink.LinkByName(t.Device)
 	if err != nil {
 		return fmt.Errorf("failed to get tun device link: %s", err)
 	}
 
 	// Default route
-	dr := &net.IPNet{IP: c.Cidr.IP.Mask(c.Cidr.Mask), Mask: c.Cidr.Mask}
+	dr := &net.IPNet{IP: t.Cidr.IP.Mask(t.Cidr.Mask), Mask: t.Cidr.Mask}
 	nr := netlink.Route{
 		LinkIndex: link.Attrs().Index,
 		Dst:       dr,
-		MTU:       c.DefaultMTU,
-		AdvMSS:    c.advMSS(Route{}),
+		MTU:       t.DefaultMTU,
+		AdvMSS:    t.advMSS(Route{}),
 		Scope:     unix.RT_SCOPE_LINK,
-		Src:       c.Cidr.IP,
+		Src:       t.Cidr.IP,
 		Protocol:  unix.RTPROT_KERNEL,
 		Table:     unix.RT_TABLE_MAIN,
 		Type:      unix.RTN_UNICAST,
 	}
 	err = netlink.RouteReplace(&nr)
 	if err != nil {
-		return fmt.Errorf("failed to set mtu %v on the default route %v; %v", c.DefaultMTU, dr, err)
+		return fmt.Errorf("failed to set mtu %v on the default route %v; %v", t.DefaultMTU, dr, err)
 	}
 
 	// Path routes
-	for _, r := range c.Routes {
+	for _, r := range t.Routes {
 		nr := netlink.Route{
 			LinkIndex: link.Attrs().Index,
 			Dst:       r.Cidr,
 			MTU:       r.MTU,
-			AdvMSS:    c.advMSS(r),
+			AdvMSS:    t.advMSS(r),
 			Scope:     unix.RT_SCOPE_LINK,
 		}
 
@@ -295,13 +273,13 @@ func (c Tun) Activate() error {
 	}
 
 	// Unsafe path routes
-	for _, r := range c.UnsafeRoutes {
+	for _, r := range t.UnsafeRoutes {
 		nr := netlink.Route{
 			LinkIndex: link.Attrs().Index,
 			Dst:       r.Cidr,
 			MTU:       r.MTU,
 			Priority:  r.Metric,
-			AdvMSS:    c.advMSS(r),
+			AdvMSS:    t.advMSS(r),
 			Scope:     unix.RT_SCOPE_LINK,
 		}
 
@@ -320,22 +298,22 @@ func (c Tun) Activate() error {
 	return nil
 }
 
-func (c *Tun) CidrNet() *net.IPNet {
-	return c.Cidr
+func (t *tun) CidrNet() *net.IPNet {
+	return t.Cidr
 }
 
-func (c *Tun) DeviceName() string {
-	return c.Device
+func (t *tun) DeviceName() string {
+	return t.Device
 }
 
-func (c Tun) advMSS(r Route) int {
+func (t tun) advMSS(r Route) int {
 	mtu := r.MTU
 	if r.MTU == 0 {
-		mtu = c.DefaultMTU
+		mtu = t.DefaultMTU
 	}
 
 	// We only need to set advmss if the route MTU does not match the device MTU
-	if mtu != c.MaxMTU {
+	if mtu != t.MaxMTU {
 		return mtu - 40
 	}
 	return 0

overlay/tun_linux_test.go

@@ -7,19 +7,19 @@ import "testing"
 
 var runAdvMSSTests = []struct {
 	name     string
-	tun      Tun
+	tun      tun
 	r        Route
 	expected int
 }{
 	// Standard case, default MTU is the device max MTU
-	{"default", Tun{DefaultMTU: 1440, MaxMTU: 1440}, Route{}, 0},
-	{"default-min", Tun{DefaultMTU: 1440, MaxMTU: 1440}, Route{MTU: 1440}, 0},
-	{"default-low", Tun{DefaultMTU: 1440, MaxMTU: 1440}, Route{MTU: 1200}, 1160},
+	{"default", tun{DefaultMTU: 1440, MaxMTU: 1440}, Route{}, 0},
+	{"default-min", tun{DefaultMTU: 1440, MaxMTU: 1440}, Route{MTU: 1440}, 0},
+	{"default-low", tun{DefaultMTU: 1440, MaxMTU: 1440}, Route{MTU: 1200}, 1160},
 
 	// Case where we have a route MTU set higher than the default
-	{"route", Tun{DefaultMTU: 1440, MaxMTU: 8941}, Route{}, 1400},
-	{"route-min", Tun{DefaultMTU: 1440, MaxMTU: 8941}, Route{MTU: 1440}, 1400},
-	{"route-high", Tun{DefaultMTU: 1440, MaxMTU: 8941}, Route{MTU: 8941}, 0},
+	{"route", tun{DefaultMTU: 1440, MaxMTU: 8941}, Route{}, 1400},
+	{"route-min", tun{DefaultMTU: 1440, MaxMTU: 8941}, Route{MTU: 1440}, 1400},
+	{"route-high", tun{DefaultMTU: 1440, MaxMTU: 8941}, Route{MTU: 8941}, 0},
 }
 
 func TestTunAdvMSS(t *testing.T) {

overlay/tun_tester.go

@@ -11,7 +11,7 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-type Tun struct {
+type TestTun struct {
 	Device       string
 	Cidr         *net.IPNet
 	MTU          int
@@ -22,8 +22,8 @@ type Tun struct {
 	TxPackets chan []byte // Packets transmitted outside by nebula
 }
 
-func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, _ []Route, unsafeRoutes []Route, _ int, _ bool) (ifce *Tun, err error) {
-	return &Tun{
+func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, _ []Route, unsafeRoutes []Route, _ int, _ bool) (*TestTun, error) {
+	return &TestTun{
 		Device:       deviceName,
 		Cidr:         cidr,
 		MTU:          defaultMTU,
@@ -34,28 +34,28 @@ func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int
 	}, nil
 }
 
-func newTunFromFd(_ *logrus.Logger, _ int, _ *net.IPNet, _ int, _ []Route, _ []Route, _ int) (ifce *Tun, err error) {
+func newTunFromFd(_ *logrus.Logger, _ int, _ *net.IPNet, _ int, _ []Route, _ []Route, _ int) (*TestTun, error) {
 	return nil, fmt.Errorf("newTunFromFd not supported")
 }
 
 // Send will place a byte array onto the receive queue for nebula to consume
 // These are unencrypted ip layer frames destined for another nebula node.
 // packets should exit the udp side, capture them with udpConn.Get
-func (c *Tun) Send(packet []byte) {
-	c.l.WithField("dataLen", len(packet)).Info("Tun receiving injected packet")
-	c.rxPackets <- packet
+func (t *TestTun) Send(packet []byte) {
+	t.l.WithField("dataLen", len(packet)).Info("Tun receiving injected packet")
+	t.rxPackets <- packet
 }
 
 // Get will pull an unencrypted ip layer frame from the transmit queue
 // nebula meant to send this message to some application on the local system
 // packets were ingested from the udp side, you can send them with udpConn.Send
-func (c *Tun) Get(block bool) []byte {
+func (t *TestTun) Get(block bool) []byte {
 	if block {
-		return <-c.TxPackets
+		return <-t.TxPackets
 	}
 
 	select {
-	case p := <-c.TxPackets:
+	case p := <-t.TxPackets:
 		return p
 	default:
 		return nil
@@ -66,40 +66,40 @@ func (c *Tun) Get(block bool) []byte {
 // Below this is boilerplate implementation to make nebula actually work
 //********************************************************************************************************************//
 
-func (c *Tun) Activate() error {
+func (t *TestTun) Activate() error {
 	return nil
 }
 
-func (c *Tun) CidrNet() *net.IPNet {
-	return c.Cidr
+func (t *TestTun) CidrNet() *net.IPNet {
+	return t.Cidr
 }
 
-func (c *Tun) DeviceName() string {
-	return c.Device
+func (t *TestTun) DeviceName() string {
+	return t.Device
 }
 
-func (c *Tun) Write(b []byte) (n int, err error) {
-	return len(b), c.WriteRaw(b)
+func (t *TestTun) Write(b []byte) (n int, err error) {
+	return len(b), t.WriteRaw(b)
 }
 
-func (c *Tun) Close() error {
-	close(c.rxPackets)
+func (t *TestTun) Close() error {
+	close(t.rxPackets)
 	return nil
 }
 
-func (c *Tun) WriteRaw(b []byte) error {
+func (t *TestTun) WriteRaw(b []byte) error {
 	packet := make([]byte, len(b), len(b))
 	copy(packet, b)
-	c.TxPackets <- packet
+	t.TxPackets <- packet
 	return nil
 }
 
-func (c *Tun) Read(b []byte) (int, error) {
-	p := <-c.rxPackets
+func (t *TestTun) Read(b []byte) (int, error) {
+	p := <-t.rxPackets
 	copy(b, p)
 	return len(p), nil
 }
 
-func (c *Tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+func (t *TestTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented")
 }

overlay/tun_water_windows.go

@@ -10,7 +10,7 @@ import (
 	"github.com/songgao/water"
 )
 
-type WindowsWaterTun struct {
+type waterTun struct {
 	Device       string
 	Cidr         *net.IPNet
 	MTU          int
@@ -19,37 +19,37 @@ type WindowsWaterTun struct {
 	*water.Interface
 }
 
-func newWindowsWaterTun(deviceName string, cidr *net.IPNet, defaultMTU int, unsafeRoutes []Route, txQueueLen int) (ifce *WindowsWaterTun, err error) {
+func newWaterTun(cidr *net.IPNet, defaultMTU int, unsafeRoutes []Route) (*waterTun, error) {
 	// NOTE: You cannot set the deviceName under Windows, so you must check tun.Device after calling .Activate()
-	return &WindowsWaterTun{
+	return &waterTun{
 		Cidr:         cidr,
 		MTU:          defaultMTU,
 		UnsafeRoutes: unsafeRoutes,
 	}, nil
 }
 
-func (c *WindowsWaterTun) Activate() error {
+func (t *waterTun) Activate() error {
 	var err error
-	c.Interface, err = water.New(water.Config{
+	t.Interface, err = water.New(water.Config{
 		DeviceType: water.TUN,
 		PlatformSpecificParams: water.PlatformSpecificParams{
 			ComponentID: "tap0901",
-			Network:     c.Cidr.String(),
+			Network:     t.Cidr.String(),
 		},
 	})
 	if err != nil {
-		return fmt.Errorf("Activate failed: %v", err)
+		return fmt.Errorf("activate failed: %v", err)
 	}
 
-	c.Device = c.Interface.Name()
+	t.Device = t.Interface.Name()
 
 	// TODO use syscalls instead of exec.Command
 	err = exec.Command(
 		`C:\Windows\System32\netsh.exe`, "interface", "ipv4", "set", "address",
-		fmt.Sprintf("name=%s", c.Device),
+		fmt.Sprintf("name=%s", t.Device),
 		"source=static",
-		fmt.Sprintf("addr=%s", c.Cidr.IP),
-		fmt.Sprintf("mask=%s", net.IP(c.Cidr.Mask)),
+		fmt.Sprintf("addr=%s", t.Cidr.IP),
+		fmt.Sprintf("mask=%s", net.IP(t.Cidr.Mask)),
 		"gateway=none",
 	).Run()
 	if err != nil {
@@ -57,19 +57,19 @@ func (c *WindowsWaterTun) Activate() error {
 	}
 	err = exec.Command(
 		`C:\Windows\System32\netsh.exe`, "interface", "ipv4", "set", "interface",
-		c.Device,
-		fmt.Sprintf("mtu=%d", c.MTU),
+		t.Device,
+		fmt.Sprintf("mtu=%d", t.MTU),
 	).Run()
 	if err != nil {
 		return fmt.Errorf("failed to run 'netsh' to set MTU: %s", err)
 	}
 
-	iface, err := net.InterfaceByName(c.Device)
+	iface, err := net.InterfaceByName(t.Device)
 	if err != nil {
-		return fmt.Errorf("failed to find interface named %s: %v", c.Device, err)
+		return fmt.Errorf("failed to find interface named %s: %v", t.Device, err)
 	}
 
-	for _, r := range c.UnsafeRoutes {
+	for _, r := range t.UnsafeRoutes {
 		err = exec.Command(
 			"C:\\Windows\\System32\\route.exe", "add", r.Cidr.String(), r.Via.String(), "IF", strconv.Itoa(iface.Index), "METRIC", strconv.Itoa(r.Metric),
 		).Run()
@@ -81,27 +81,27 @@ func (c *WindowsWaterTun) Activate() error {
 	return nil
 }
 
-func (c *WindowsWaterTun) CidrNet() *net.IPNet {
-	return c.Cidr
+func (t *waterTun) CidrNet() *net.IPNet {
+	return t.Cidr
 }
 
-func (c *WindowsWaterTun) DeviceName() string {
-	return c.Device
+func (t *waterTun) DeviceName() string {
+	return t.Device
 }
 
-func (c *WindowsWaterTun) WriteRaw(b []byte) error {
-	_, err := c.Write(b)
+func (t *waterTun) WriteRaw(b []byte) error {
+	_, err := t.Write(b)
 	return err
 }
 
-func (c *WindowsWaterTun) Close() error {
-	if c.Interface == nil {
+func (t *waterTun) Close() error {
+	if t.Interface == nil {
 		return nil
 	}
 
-	return c.Interface.Close()
+	return t.Interface.Close()
 }
 
-func (t *WindowsWaterTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+func (t *waterTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for windows")
 }

overlay/tun_windows.go

@@ -5,7 +5,6 @@ package overlay
 
 import (
 	"fmt"
-	"io"
 	"net"
 	"os"
 	"path/filepath"
@@ -15,41 +14,34 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-type Tun struct {
-	Device
-}
-
-func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int) (ifce *Tun, err error) {
+func newTunFromFd(_ *logrus.Logger, _ int, _ *net.IPNet, _ int, _ []Route, _ []Route, _ int) (Device, error) {
 	return nil, fmt.Errorf("newTunFromFd not supported in Windows")
 }
 
-func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int, multiqueue bool) (ifce *Tun, err error) {
+func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, _ int, _ bool) (Device, error) {
 	if len(routes) > 0 {
 		return nil, fmt.Errorf("route MTU not supported in Windows")
 	}
 
 	useWintun := true
-	if err = checkWinTunExists(); err != nil {
+	if err := checkWinTunExists(); err != nil {
 		l.WithError(err).Warn("Check Wintun driver failed, fallback to wintap driver")
 		useWintun = false
 	}
 
-	var inside Device
 	if useWintun {
-		inside, err = newWinTun(deviceName, cidr, defaultMTU, unsafeRoutes, txQueueLen)
-		if err != nil {
-			return nil, fmt.Errorf("Create Wintun interface failed, %w", err)
-		}
-	} else {
-		inside, err = newWindowsWaterTun(deviceName, cidr, defaultMTU, unsafeRoutes, txQueueLen)
+		device, err := newWinTun(deviceName, cidr, defaultMTU, unsafeRoutes)
 		if err != nil {
-			return nil, fmt.Errorf("Create wintap driver failed, %w", err)
+			return nil, fmt.Errorf("create Wintun interface failed, %w", err)
 		}
+		return device, nil
 	}
 
-	return &Tun{
-		Device: inside,
-	}, nil
+	device, err := newWaterTun(cidr, defaultMTU, unsafeRoutes)
+	if err != nil {
+		return nil, fmt.Errorf("create wintap driver failed, %w", err)
+	}
+	return device, nil
 }
 
 func checkWinTunExists() error {
@@ -68,7 +60,3 @@ func checkWinTunExists() error {
 	_, err = syscall.LoadDLL(filepath.Join(filepath.Dir(myPath), "dist", "windows", "wintun", "bin", arch, "wintun.dll"))
 	return err
 }
-
-func (t *Tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
-	return nil, fmt.Errorf("TODO: multiqueue not implemented for windows")
-}

overlay/tun_wintun_windows.go

@@ -14,7 +14,7 @@ import (
 
 const tunGUIDLabel = "Fixed Nebula Windows GUID v1"
 
-type WinTun struct {
+type winTun struct {
 	Device       string
 	Cidr         *net.IPNet
 	MTU          int
@@ -42,40 +42,38 @@ func generateGUIDByDeviceName(name string) (*windows.GUID, error) {
 	return (*windows.GUID)(unsafe.Pointer(&sum[0])), nil
 }
 
-func newWinTun(deviceName string, cidr *net.IPNet, defaultMTU int, unsafeRoutes []Route, txQueueLen int) (ifce *WinTun, err error) {
+func newWinTun(deviceName string, cidr *net.IPNet, defaultMTU int, unsafeRoutes []Route) (*winTun, error) {
 	guid, err := generateGUIDByDeviceName(deviceName)
 	if err != nil {
-		return nil, fmt.Errorf("Generate GUID failed: %w", err)
+		return nil, fmt.Errorf("generate GUID failed: %w", err)
 	}
 
 	tunDevice, err := wintun.CreateTUNWithRequestedGUID(deviceName, guid, defaultMTU)
 	if err != nil {
-		return nil, fmt.Errorf("Create TUN device failed: %w", err)
+		return nil, fmt.Errorf("create TUN device failed: %w", err)
 	}
 
-	ifce = &WinTun{
+	return &winTun{
 		Device:       deviceName,
 		Cidr:         cidr,
 		MTU:          defaultMTU,
 		UnsafeRoutes: unsafeRoutes,
 
 		tun: tunDevice.(*wintun.NativeTun),
-	}
-
-	return ifce, nil
+	}, nil
 }
 
-func (c *WinTun) Activate() error {
-	luid := winipcfg.LUID(c.tun.LUID())
+func (t *winTun) Activate() error {
+	luid := winipcfg.LUID(t.tun.LUID())
 
-	if err := luid.SetIPAddresses([]net.IPNet{*c.Cidr}); err != nil {
+	if err := luid.SetIPAddresses([]net.IPNet{*t.Cidr}); err != nil {
 		return fmt.Errorf("failed to set address: %w", err)
 	}
 
 	foundDefault4 := false
-	routes := make([]*winipcfg.RouteData, 0, len(c.UnsafeRoutes)+1)
+	routes := make([]*winipcfg.RouteData, 0, len(t.UnsafeRoutes)+1)
 
-	for _, r := range c.UnsafeRoutes {
+	for _, r := range t.UnsafeRoutes {
 		if !foundDefault4 {
 			if cidr, bits := r.Cidr.Mask.Size(); cidr == 0 && bits != 0 {
 				foundDefault4 = true
@@ -99,7 +97,7 @@ func (c *WinTun) Activate() error {
 		return fmt.Errorf("failed to get ip interface: %w", err)
 	}
 
-	ipif.NLMTU = uint32(c.MTU)
+	ipif.NLMTU = uint32(t.MTU)
 	if foundDefault4 {
 		ipif.UseAutomaticMetric = false
 		ipif.Metric = 0
@@ -112,35 +110,35 @@ func (c *WinTun) Activate() error {
 	return nil
 }
 
-func (c *WinTun) CidrNet() *net.IPNet {
-	return c.Cidr
+func (t *winTun) CidrNet() *net.IPNet {
+	return t.Cidr
 }
 
-func (c *WinTun) DeviceName() string {
-	return c.Device
+func (t *winTun) DeviceName() string {
+	return t.Device
 }
 
-func (c *WinTun) Read(b []byte) (int, error) {
-	return c.tun.Read(b, 0)
+func (t *winTun) Read(b []byte) (int, error) {
+	return t.tun.Read(b, 0)
 }
 
-func (c *WinTun) Write(b []byte) (int, error) {
-	return c.tun.Write(b, 0)
+func (t *winTun) Write(b []byte) (int, error) {
+	return t.tun.Write(b, 0)
 }
 
-func (c *WinTun) WriteRaw(b []byte) error {
-	_, err := c.Write(b)
+func (t *winTun) WriteRaw(b []byte) error {
+	_, err := t.Write(b)
 	return err
 }
 
-func (c *WinTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+func (t *winTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for windows")
 }
 
-func (c *WinTun) Close() error {
+func (t *winTun) Close() error {
 	// It seems that the Windows networking stack doesn't like it when we destroy interfaces that have active routes,
 	// so to be certain, just remove everything before destroying.
-	luid := winipcfg.LUID(c.tun.LUID())
+	luid := winipcfg.LUID(t.tun.LUID())
 	_ = luid.FlushRoutes(windows.AF_INET)
 	_ = luid.FlushIPAddresses(windows.AF_INET)
 	/* We don't support IPV6 yet
@@ -149,5 +147,5 @@ func (c *WinTun) Close() error {
 	*/
 	_ = luid.FlushDNS(windows.AF_INET)
 
-	return c.tun.Close()
+	return t.tun.Close()
 }

test/tun.go

@@ -0,0 +1,47 @@
+package test
+
+import (
+	"errors"
+	"io"
+	"net"
+
+	"github.com/slackhq/nebula/iputil"
+)
+
+type NoopTun struct{}
+
+func (NoopTun) RouteFor(iputil.VpnIp) iputil.VpnIp {
+	return 0
+}
+
+func (NoopTun) Activate() error {
+	return nil
+}
+
+func (NoopTun) CidrNet() *net.IPNet {
+	return nil
+}
+
+func (NoopTun) DeviceName() string {
+	return "noop"
+}
+
+func (NoopTun) Read([]byte) (int, error) {
+	return 0, nil
+}
+
+func (NoopTun) Write([]byte) (int, error) {
+	return 0, nil
+}
+
+func (NoopTun) WriteRaw([]byte) error {
+	return nil
+}
+
+func (NoopTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, errors.New("unsupported")
+}
+
+func (NoopTun) Close() error {
+	return nil
+}