Move all of tun into overlay (#577)

overlay/tun_wintun_windows.go

@@ -0,0 +1,153 @@
+package overlay
+
+import (
+	"crypto"
+	"fmt"
+	"io"
+	"net"
+	"unsafe"
+
+	"github.com/slackhq/nebula/wintun"
+	"golang.org/x/sys/windows"
+	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
+)
+
+const tunGUIDLabel = "Fixed Nebula Windows GUID v1"
+
+type WinTun struct {
+	Device       string
+	Cidr         *net.IPNet
+	MTU          int
+	UnsafeRoutes []Route
+
+	tun *wintun.NativeTun
+}
+
+func generateGUIDByDeviceName(name string) (*windows.GUID, error) {
+	// GUID is 128 bit
+	hash := crypto.MD5.New()
+
+	_, err := hash.Write([]byte(tunGUIDLabel))
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = hash.Write([]byte(name))
+	if err != nil {
+		return nil, err
+	}
+
+	sum := hash.Sum(nil)
+
+	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) {
+	guid, err := generateGUIDByDeviceName(deviceName)
+	if err != nil {
+		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)
+	}
+
+	ifce = &WinTun{
+		Device:       deviceName,
+		Cidr:         cidr,
+		MTU:          defaultMTU,
+		UnsafeRoutes: unsafeRoutes,
+
+		tun: tunDevice.(*wintun.NativeTun),
+	}
+
+	return ifce, nil
+}
+
+func (c *WinTun) Activate() error {
+	luid := winipcfg.LUID(c.tun.LUID())
+
+	if err := luid.SetIPAddresses([]net.IPNet{*c.Cidr}); err != nil {
+		return fmt.Errorf("failed to set address: %w", err)
+	}
+
+	foundDefault4 := false
+	routes := make([]*winipcfg.RouteData, 0, len(c.UnsafeRoutes)+1)
+
+	for _, r := range c.UnsafeRoutes {
+		if !foundDefault4 {
+			if cidr, bits := r.Cidr.Mask.Size(); cidr == 0 && bits != 0 {
+				foundDefault4 = true
+			}
+		}
+
+		// Add our unsafe route
+		routes = append(routes, &winipcfg.RouteData{
+			Destination: *r.Cidr,
+			NextHop:     *r.Via,
+			Metric:      uint32(r.Metric),
+		})
+	}
+
+	if err := luid.AddRoutes(routes); err != nil {
+		return fmt.Errorf("failed to add routes: %w", err)
+	}
+
+	ipif, err := luid.IPInterface(windows.AF_INET)
+	if err != nil {
+		return fmt.Errorf("failed to get ip interface: %w", err)
+	}
+
+	ipif.NLMTU = uint32(c.MTU)
+	if foundDefault4 {
+		ipif.UseAutomaticMetric = false
+		ipif.Metric = 0
+	}
+
+	if err := ipif.Set(); err != nil {
+		return fmt.Errorf("failed to set ip interface: %w", err)
+	}
+
+	return nil
+}
+
+func (c *WinTun) CidrNet() *net.IPNet {
+	return c.Cidr
+}
+
+func (c *WinTun) DeviceName() string {
+	return c.Device
+}
+
+func (c *WinTun) Read(b []byte) (int, error) {
+	return c.tun.Read(b, 0)
+}
+
+func (c *WinTun) Write(b []byte) (int, error) {
+	return c.tun.Write(b, 0)
+}
+
+func (c *WinTun) WriteRaw(b []byte) error {
+	_, err := c.Write(b)
+	return err
+}
+
+func (c *WinTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, fmt.Errorf("TODO: multiqueue not implemented for windows")
+}
+
+func (c *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.FlushRoutes(windows.AF_INET)
+	_ = luid.FlushIPAddresses(windows.AF_INET)
+	/* We don't support IPV6 yet
+	_ = luid.FlushRoutes(windows.AF_INET6)
+	_ = luid.FlushIPAddresses(windows.AF_INET6)
+	*/
+	_ = luid.FlushDNS(windows.AF_INET)
+
+	return c.tun.Close()
+}