nebula/overlay/tun_wintun_windows.go

184 lines
3.9 KiB
Go

package overlay
import (
"crypto"
"fmt"
"io"
"net"
"net/netip"
"unsafe"
"github.com/sirupsen/logrus"
"github.com/slackhq/nebula/cidr"
"github.com/slackhq/nebula/iputil"
"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
prefix netip.Prefix
MTU int
Routes []Route
routeTree *cidr.Tree4
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(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []Route) (*winTun, 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)
}
routeTree, err := makeRouteTree(l, routes, false)
if err != nil {
return nil, err
}
prefix, err := iputil.ToNetIpPrefix(*cidr)
if err != nil {
return nil, err
}
return &winTun{
Device: deviceName,
cidr: cidr,
prefix: prefix,
MTU: defaultMTU,
Routes: routes,
routeTree: routeTree,
tun: tunDevice.(*wintun.NativeTun),
}, nil
}
func (t *winTun) Activate() error {
luid := winipcfg.LUID(t.tun.LUID())
if err := luid.SetIPAddresses([]netip.Prefix{t.prefix}); err != nil {
return fmt.Errorf("failed to set address: %w", err)
}
foundDefault4 := false
routes := make([]*winipcfg.RouteData, 0, len(t.Routes)+1)
for _, r := range t.Routes {
if r.Via == nil || !r.Install {
// We don't allow route MTUs so only install routes with a via
continue
}
if !foundDefault4 {
if ones, bits := r.Cidr.Mask.Size(); ones == 0 && bits != 0 {
foundDefault4 = true
}
}
prefix, err := iputil.ToNetIpPrefix(*r.Cidr)
if err != nil {
return err
}
// Add our unsafe route
routes = append(routes, &winipcfg.RouteData{
Destination: prefix,
NextHop: r.Via.ToNetIpAddr(),
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(t.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 (t *winTun) RouteFor(ip iputil.VpnIp) iputil.VpnIp {
r := t.routeTree.MostSpecificContains(ip)
if r != nil {
return r.(iputil.VpnIp)
}
return 0
}
func (t *winTun) Cidr() *net.IPNet {
return t.cidr
}
func (t *winTun) Name() string {
return t.Device
}
func (t *winTun) Read(b []byte) (int, error) {
return t.tun.Read(b, 0)
}
func (t *winTun) Write(b []byte) (int, error) {
return t.tun.Write(b, 0)
}
func (t *winTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
return nil, fmt.Errorf("TODO: multiqueue not implemented for windows")
}
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(t.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 t.tun.Close()
}