Add Wintun support (#289)

wintun/device.go

@@ -0,0 +1,23 @@
+//go:build windows
+
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
+ */
+
+//NOTE: this file was forked from https://git.zx2c4.com/wireguard-go/tree/tun/tun.go?id=851efb1bb65555e0f765a3361c8eb5ac47435b19
+
+package wintun
+
+import (
+	"os"
+)
+
+type Device interface {
+	File() *os.File                 // returns the file descriptor of the device
+	Read([]byte, int) (int, error)  // read a packet from the device (without any additional headers)
+	Write([]byte, int) (int, error) // writes a packet to the device (without any additional headers)
+	Flush() error                   // flush all previous writes to the device
+	Name() (string, error)          // fetches and returns the current name
+	Close() error                   // stops the device and closes the event channel
+}