From c871518ca0789ff3397ef4dcfc4fbcbc640e1440 Mon Sep 17 00:00:00 2001
From: lucus <lixin9311@gmail.com>
Date: Sun, 25 Dec 2016 17:35:25 +0900
Subject: [PATCH] Add windows support. To use it on windows, you need a tap
 driver, or just install OpenVPN.

---
 syscalls_other.go   |   2 +-
 syscalls_windows.go | 171 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 172 insertions(+), 1 deletion(-)
 create mode 100644 syscalls_windows.go

diff --git a/syscalls_other.go b/syscalls_other.go
index 96d1d63..ab3b9e5 100644
--- a/syscalls_other.go
+++ b/syscalls_other.go
@@ -1,4 +1,4 @@
-// +build !linux,!darwin
+// +build !linux,!darwin,!windows
 
 package water
 
diff --git a/syscalls_windows.go b/syscalls_windows.go
new file mode 100644
index 0000000..140ab88
--- /dev/null
+++ b/syscalls_windows.go
@@ -0,0 +1,171 @@
+// +build windows
+
+// To use it with windows, you need a tap driver installed on windows.
+// https://github.com/OpenVPN/tap-windows6
+// or just install OpenVPN
+// https://github.com/OpenVPN/openvpn
+package water
+
+import (
+	"errors"
+	"net"
+	"os"
+	"syscall"
+
+	"golang.org/x/sys/windows/registry"
+)
+
+var (
+	IfceNameNotFound  = errors.New("Failed to find the name of interface.")
+	TapDeviceNotFound = errors.New("Failed to find the tap device in registry.")
+	// Device Control Codes
+	tap_win_ioctl_get_mac             = tap_control_code(1, 0)
+	tap_win_ioctl_get_version         = tap_control_code(2, 0)
+	tap_win_ioctl_get_mtu             = tap_control_code(3, 0)
+	tap_win_ioctl_get_info            = tap_control_code(4, 0)
+	tap_ioctl_config_point_to_point   = tap_control_code(5, 0)
+	tap_ioctl_set_media_status        = tap_control_code(6, 0)
+	tap_win_ioctl_config_dhcp_masq    = tap_control_code(7, 0)
+	tap_win_ioctl_get_log_line        = tap_control_code(8, 0)
+	tap_win_ioctl_config_dhcp_set_opt = tap_control_code(9, 0)
+	tap_ioctl_config_tun              = tap_control_code(10, 0)
+	// w32 api
+	file_device_unknown = uint32(0x00000022)
+)
+
+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)
+}
+
+// getdeviceid finds out a TAP device from registry, it requires privileged right.
+func getdeviceid() (string, error) {
+	// TAP driver key location
+	regkey := `SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}`
+	k, err := registry.OpenKey(registry.LOCAL_MACHINE, regkey, registry.ALL_ACCESS)
+	if err != nil {
+		return "", err
+	}
+	defer k.Close()
+	// read all subkeys
+	keys, err := k.ReadSubKeyNames(-1)
+	if err != nil {
+		return "", err
+	}
+	// find the one with ComponentId == "tap0901"
+	for _, v := range keys {
+		key, err := registry.OpenKey(registry.LOCAL_MACHINE, regkey+"\\"+v, registry.ALL_ACCESS)
+		if err != nil {
+			continue
+		}
+		val, _, err := key.GetStringValue("ComponentId")
+		if err != nil {
+			goto next
+		}
+		if val == "tap0901" {
+			val, _, err = key.GetStringValue("NetCfgInstanceId")
+			if err != nil {
+				goto next
+			}
+			key.Close()
+			return val, nil
+		}
+	next:
+		key.Close()
+	}
+	return "", TapDeviceNotFound
+}
+
+// openDev find and open an interface.
+func openDev(isTAP bool) (ifce *Interface, err error) {
+	// ifName won't work
+	// find the device in registrym you need privileged right.
+	deviceid, err := getdeviceid()
+	if err != nil {
+		return nil, err
+	}
+	path := "\\\\.\\Global\\" + deviceid + ".tap"
+	pathp, err := syscall.UTF16PtrFromString(path)
+	if err != nil {
+		return nil, err
+	}
+	// type Handle uintptr
+	file, err := syscall.CreateFile(pathp, syscall.GENERIC_READ|syscall.GENERIC_WRITE, uint32(syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE), nil, syscall.OPEN_EXISTING, syscall.FILE_ATTRIBUTE_SYSTEM, 0)
+	// if err hanppens, close the interface.
+	defer func() {
+		if err != nil {
+			syscall.Close(file)
+		}
+		if err := recover(); err != nil {
+			syscall.Close(file)
+		}
+	}()
+	if err != nil {
+		return nil, err
+	}
+	var bytesReturned uint32
+	rdbbuf := make([]byte, syscall.MAXIMUM_REPARSE_DATA_BUFFER_SIZE)
+
+	//TUN
+	if !isTAP {
+		code2 := []byte{0x0a, 0x03, 0x00, 0x01, 0x0a, 0x03, 0x00, 0x00, 0xff, 0xff, 0xff, 0x00}
+		err = syscall.DeviceIoControl(file, tap_ioctl_config_tun, &code2[0], uint32(12), &rdbbuf[0], uint32(len(rdbbuf)), &bytesReturned, nil)
+		if err != nil {
+			return
+		}
+	}
+
+	// find the mac address of tap device, use this to find the name of interface
+	mac := make([]byte, 6)
+	err = syscall.DeviceIoControl(file, tap_win_ioctl_get_mac, &mac[0], uint32(len(mac)), &mac[0], uint32(len(mac)), &bytesReturned, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	fd := os.NewFile(uintptr(file), path)
+	ifce = &Interface{isTAP: isTAP, ReadWriteCloser: fd}
+
+	// bring up device.
+	code := []byte{0x01, 0x00, 0x00, 0x00}
+	err = syscall.DeviceIoControl(file, tap_ioctl_set_media_status, &code[0], uint32(4), &rdbbuf[0], uint32(len(rdbbuf)), &bytesReturned, nil)
+	if err != nil {
+		return
+	}
+	// find the name of tap interface(u need it to set the ip or other command)
+	hwaddr_equal := func(a net.HardwareAddr, b []byte) bool {
+		for i := 0; i < 6; i++ {
+			if a[i] != b[i] {
+				return false
+			}
+		}
+		return true
+	}
+
+	ifces, err := net.Interfaces()
+	if err != nil {
+		return
+	}
+
+	for _, v := range ifces {
+		if hwaddr_equal(v.HardwareAddr[:6], mac[:6]) {
+			ifce.name = v.Name
+			return
+		}
+	}
+
+	err = IfceNameNotFound
+	return
+}
+
+func newTAP(ifName string) (ifce *Interface, err error) {
+	// ifName won't work
+	return openDev(true)
+}
+
+func newTUN(ifName string) (ifce *Interface, err error) {
+	// ifName won't work
+	return openDev(false)
+}