Align with go library layout

1 files changed, 475 insertions, 0 deletions

diff --git a/tun_windows.go b/tun_windows.go
new file mode 100644
index 0000000..0711032
--- /dev/null
+++ b/tun_windows.go
@@ -0,0 +1,475 @@
+package main
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"golang.org/x/sys/windows"
+	"golang.org/x/sys/windows/registry"
+	"net"
+	"sync"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+/* Relies on the OpenVPN TAP-Windows driver (NDIS 6 version)
+ *
+ * https://github.com/OpenVPN/tap-windows
+ */
+
+type NativeTUN struct {
+	fd     windows.Handle
+	rl     sync.Mutex
+	wl     sync.Mutex
+	ro     *windows.Overlapped
+	wo     *windows.Overlapped
+	events chan TUNEvent
+	name   string
+}
+
+const (
+	METHOD_BUFFERED = 0
+	ComponentID     = "tap0901" // tap0801
+)
+
+func ctl_code(device_type, function, method, access uint32) uint32 {
+	return (device_type << 16) | (access << 14) | (function << 2) | method
+}
+
+func TAP_CONTROL_CODE(request, method uint32) uint32 {
+	return ctl_code(file_device_unknown, request, method, 0)
+}
+
+var (
+	errIfceNameNotFound = errors.New("Failed to find the name of interface")
+
+	TAP_IOCTL_GET_MAC               = TAP_CONTROL_CODE(1, METHOD_BUFFERED)
+	TAP_IOCTL_GET_VERSION           = TAP_CONTROL_CODE(2, METHOD_BUFFERED)
+	TAP_IOCTL_GET_MTU               = TAP_CONTROL_CODE(3, METHOD_BUFFERED)
+	TAP_IOCTL_GET_INFO              = TAP_CONTROL_CODE(4, METHOD_BUFFERED)
+	TAP_IOCTL_CONFIG_POINT_TO_POINT = TAP_CONTROL_CODE(5, METHOD_BUFFERED)
+	TAP_IOCTL_SET_MEDIA_STATUS      = TAP_CONTROL_CODE(6, METHOD_BUFFERED)
+	TAP_IOCTL_CONFIG_DHCP_MASQ      = TAP_CONTROL_CODE(7, METHOD_BUFFERED)
+	TAP_IOCTL_GET_LOG_LINE          = TAP_CONTROL_CODE(8, METHOD_BUFFERED)
+	TAP_IOCTL_CONFIG_DHCP_SET_OPT   = TAP_CONTROL_CODE(9, METHOD_BUFFERED)
+	TAP_IOCTL_CONFIG_TUN            = TAP_CONTROL_CODE(10, METHOD_BUFFERED)
+
+	file_device_unknown = uint32(0x00000022)
+	nCreateEvent,
+	nResetEvent,
+	nGetOverlappedResult uintptr
+)
+
+func init() {
+	k32, err := windows.LoadLibrary("kernel32.dll")
+	if err != nil {
+		panic("LoadLibrary " + err.Error())
+	}
+	defer windows.FreeLibrary(k32)
+	nCreateEvent = getProcAddr(k32, "CreateEventW")
+	nResetEvent = getProcAddr(k32, "ResetEvent")
+	nGetOverlappedResult = getProcAddr(k32, "GetOverlappedResult")
+}
+
+/* implementation of the read/write/closer interface */
+
+func getProcAddr(lib windows.Handle, name string) uintptr {
+	addr, err := windows.GetProcAddress(lib, name)
+	if err != nil {
+		panic(name + " " + err.Error())
+	}
+	return addr
+}
+
+func resetEvent(h windows.Handle) error {
+	r, _, err := syscall.Syscall(nResetEvent, 1, uintptr(h), 0, 0)
+	if r == 0 {
+		return err
+	}
+	return nil
+}
+
+func getOverlappedResult(h windows.Handle, overlapped *windows.Overlapped) (int, error) {
+	var n int
+	r, _, err := syscall.Syscall6(
+		nGetOverlappedResult,
+		4,
+		uintptr(h),
+		uintptr(unsafe.Pointer(overlapped)),
+		uintptr(unsafe.Pointer(&n)), 1, 0, 0)
+
+	if r == 0 {
+		return n, err
+	}
+	return n, nil
+}
+
+func newOverlapped() (*windows.Overlapped, error) {
+	var overlapped windows.Overlapped
+	r, _, err := syscall.Syscall6(nCreateEvent, 4, 0, 1, 0, 0, 0, 0)
+	if r == 0 {
+		return nil, err
+	}
+	overlapped.HEvent = windows.Handle(r)
+	return &overlapped, nil
+}
+
+func (f *NativeTUN) Events() chan TUNEvent {
+	return f.events
+}
+
+func (f *NativeTUN) Close() error {
+	return windows.Close(f.fd)
+}
+
+func (f *NativeTUN) Write(b []byte) (int, error) {
+	f.wl.Lock()
+	defer f.wl.Unlock()
+
+	if err := resetEvent(f.wo.HEvent); err != nil {
+		return 0, err
+	}
+	var n uint32
+	err := windows.WriteFile(f.fd, b, &n, f.wo)
+	if err != nil && err != windows.ERROR_IO_PENDING {
+		return int(n), err
+	}
+	return getOverlappedResult(f.fd, f.wo)
+}
+
+func (f *NativeTUN) Read(b []byte) (int, error) {
+	f.rl.Lock()
+	defer f.rl.Unlock()
+
+	if err := resetEvent(f.ro.HEvent); err != nil {
+		return 0, err
+	}
+	var done uint32
+	err := windows.ReadFile(f.fd, b, &done, f.ro)
+	if err != nil && err != windows.ERROR_IO_PENDING {
+		return int(done), err
+	}
+	return getOverlappedResult(f.fd, f.ro)
+}
+
+func getdeviceid(
+	targetComponentId string,
+	targetDeviceName string,
+) (deviceid string, err error) {
+
+	getName := func(instanceId string) (string, error) {
+		path := fmt.Sprintf(
+			`SYSTEM\CurrentControlSet\Control\Network\{4D36E972-E325-11CE-BFC1-08002BE10318}\%s\Connection`,
+			instanceId,
+		)
+
+		key, err := registry.OpenKey(
+			registry.LOCAL_MACHINE,
+			path,
+			registry.READ,
+		)
+
+		if err != nil {
+			return "", err
+		}
+		defer key.Close()
+
+		val, _, err := key.GetStringValue("Name")
+		key.Close()
+		return val, err
+	}
+
+	getInstanceId := func(keyName string) (string, string, error) {
+		path := fmt.Sprintf(
+			`SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}\%s`,
+			keyName,
+		)
+
+		key, err := registry.OpenKey(
+			registry.LOCAL_MACHINE,
+			path,
+			registry.READ,
+		)
+
+		if err != nil {
+			return "", "", err
+		}
+		defer key.Close()
+
+		componentId, _, err := key.GetStringValue("ComponentId")
+		if err != nil {
+			return "", "", err
+		}
+
+		instanceId, _, err := key.GetStringValue("NetCfgInstanceId")
+
+		return componentId, instanceId, err
+	}
+
+	// find list of all network devices
+
+	k, err := registry.OpenKey(
+		registry.LOCAL_MACHINE,
+		`SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}`,
+		registry.READ,
+	)
+
+	if err != nil {
+		return "", fmt.Errorf("Failed to open the adapter registry, TAP driver may be not installed, %v", err)
+	}
+
+	defer k.Close()
+
+	keys, err := k.ReadSubKeyNames(-1)
+
+	if err != nil {
+		return "", err
+	}
+
+	// look for matching component id and name
+
+	var componentFound bool
+
+	for _, v := range keys {
+
+		componentId, instanceId, err := getInstanceId(v)
+		if err != nil || componentId != targetComponentId {
+			continue
+		}
+
+		componentFound = true
+
+		deviceName, err := getName(instanceId)
+		if err != nil || deviceName != targetDeviceName {
+			continue
+		}
+
+		return instanceId, nil
+	}
+
+	// provide a descriptive error message
+
+	if componentFound {
+		return "", fmt.Errorf("Unable to find tun/tap device with name = %s", targetDeviceName)
+	}
+
+	return "", fmt.Errorf(
+		"Unable to find device in registry with ComponentId = %s, is tap-windows installed?",
+		targetComponentId,
+	)
+}
+
+// setStatus is used to bring up or bring down the interface
+func setStatus(fd windows.Handle, status bool) error {
+	var code [4]byte
+	if status {
+		binary.LittleEndian.PutUint32(code[:], 1)
+	}
+
+	var bytesReturned uint32
+	rdbbuf := make([]byte, windows.MAXIMUM_REPARSE_DATA_BUFFER_SIZE)
+	return windows.DeviceIoControl(
+		fd,
+		TAP_IOCTL_SET_MEDIA_STATUS,
+		&code[0],
+		uint32(4),
+		&rdbbuf[0],
+		uint32(len(rdbbuf)),
+		&bytesReturned,
+		nil,
+	)
+}
+
+/* When operating in TUN mode we must assign an ip address & subnet to the device.
+ *
+ */
+func setTUN(fd windows.Handle, network string) error {
+	var bytesReturned uint32
+	rdbbuf := make([]byte, windows.MAXIMUM_REPARSE_DATA_BUFFER_SIZE)
+	localIP, remoteNet, err := net.ParseCIDR(network)
+
+	if err != nil {
+		return fmt.Errorf("Failed to parse network CIDR in config, %v", err)
+	}
+
+	if localIP.To4() == nil {
+		return fmt.Errorf("Provided network(%s) is not a valid IPv4 address", network)
+	}
+
+	var param [12]byte
+
+	copy(param[0:4], localIP.To4())
+	copy(param[4:8], remoteNet.IP.To4())
+	copy(param[8:12], remoteNet.Mask)
+
+	return windows.DeviceIoControl(
+		fd,
+		TAP_IOCTL_CONFIG_TUN,
+		&param[0],
+		uint32(12),
+		&rdbbuf[0],
+		uint32(len(rdbbuf)),
+		&bytesReturned,
+		nil,
+	)
+}
+
+func (tun *NativeTUN) MTU() (int, error) {
+	var mtu [4]byte
+	var bytesReturned uint32
+	err := windows.DeviceIoControl(
+		tun.fd,
+		TAP_IOCTL_GET_MTU,
+		&mtu[0],
+		uint32(len(mtu)),
+		&mtu[0],
+		uint32(len(mtu)),
+		&bytesReturned,
+		nil,
+	)
+	val := binary.LittleEndian.Uint32(mtu[:])
+	return int(val), err
+}
+
+func (tun *NativeTUN) Name() string {
+	return tun.name
+}
+
+func CreateTUN(name string) (TUNDevice, error) {
+
+	// find the device in registry.
+
+	deviceid, err := getdeviceid(ComponentID, name)
+	if err != nil {
+		return nil, err
+	}
+	path := "\\\\.\\Global\\" + deviceid + ".tap"
+	pathp, err := windows.UTF16PtrFromString(path)
+	if err != nil {
+		return nil, err
+	}
+
+	// create TUN device
+
+	handle, err := windows.CreateFile(
+		pathp,
+		windows.GENERIC_READ|windows.GENERIC_WRITE,
+		0,
+		nil,
+		windows.OPEN_EXISTING,
+		windows.FILE_ATTRIBUTE_SYSTEM|windows.FILE_FLAG_OVERLAPPED,
+		0,
+	)
+
+	if err != nil {
+		return nil, err
+	}
+
+	ro, err := newOverlapped()
+	if err != nil {
+		windows.Close(handle)
+		return nil, err
+	}
+
+	wo, err := newOverlapped()
+	if err != nil {
+		windows.Close(handle)
+		return nil, err
+	}
+
+	tun := &NativeTUN{
+		fd:     handle,
+		name:   name,
+		ro:     ro,
+		wo:     wo,
+		events: make(chan TUNEvent, 5),
+	}
+
+	// find addresses of interface
+	// TODO: fix this hack, the question is how
+
+	inter, err := net.InterfaceByName(name)
+	if err != nil {
+		windows.Close(handle)
+		return nil, err
+	}
+
+	addrs, err := inter.Addrs()
+	if err != nil {
+		windows.Close(handle)
+		return nil, err
+	}
+
+	var ip net.IP
+	for _, addr := range addrs {
+		ip = func() net.IP {
+			switch v := addr.(type) {
+			case *net.IPNet:
+				return v.IP.To4()
+			case *net.IPAddr:
+				return v.IP.To4()
+			}
+			return nil
+		}()
+		if ip != nil {
+			break
+		}
+	}
+
+	if ip == nil {
+		windows.Close(handle)
+		return nil, errors.New("No IPv4 address found for interface")
+	}
+
+	// bring up device.
+
+	if err := setStatus(handle, true); err != nil {
+		windows.Close(handle)
+		return nil, err
+	}
+
+	// set tun mode
+
+	mask := ip.String() + "/0"
+	if err := setTUN(handle, mask); err != nil {
+		windows.Close(handle)
+		return nil, err
+	}
+
+	// start listener
+
+	go func(native *NativeTUN, ifname string) {
+		// TODO: Fix this very niave implementation
+		var (
+			statusUp  bool
+			statusMTU int
+		)
+
+		for ; ; time.Sleep(time.Second) {
+			intr, err := net.InterfaceByName(name)
+			if err != nil {
+				// TODO: handle
+				return
+			}
+
+			// Up / Down event
+			up := (intr.Flags & net.FlagUp) != 0
+			if up != statusUp && up {
+				native.events <- TUNEventUp
+			}
+			if up != statusUp && !up {
+				native.events <- TUNEventDown
+			}
+			statusUp = up
+
+			// MTU changes
+			if intr.MTU != statusMTU {
+				native.events <- TUNEventMTUUpdate
+			}
+			statusMTU = intr.MTU
+		}
+	}(tun, name)
+
+	return tun, nil
+}