Windows TAP Interface

WindowsTap.cs

using Microsoft.Win32;
using System;
using System.Diagnostics;
using System.IO;
using System.IO.Ports;
using System.Runtime.InteropServices;

namespace WindowsTapSpace
{

    //change this in app.manifest
    /* <requestedExecutionLevel level="requireAdministrator" uiAccess="false" /> */

    class WindowsTapTest
    {

        //
        private const uint METHOD_BUFFERED = 0;
        private const uint FILE_ANY_ACCESS = 0;
        private const uint FILE_DEVICE_UNKNOWN = 0x00000022;
        private const int FILE_ATTRIBUTE_SYSTEM = 0x4;
        private const int FILE_FLAG_OVERLAPPED = 0x40000000;

        //
        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        static extern IntPtr CreateFile(
            string filename,
            [MarshalAs(UnmanagedType.U4)]FileAccess fileaccess,
            [MarshalAs(UnmanagedType.U4)]FileShare fileshare,
            int securityattributes,
            [MarshalAs(UnmanagedType.U4)]FileMode creationdisposition,
            int flags,
            IntPtr template);

        //
        [DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
        static extern bool DeviceIoControl(IntPtr hDevice, uint dwIoControlCode,
            IntPtr lpInBuffer, uint nInBufferSize,
            IntPtr lpOutBuffer, uint nOutBufferSize,
            out int lpBytesReturned, IntPtr lpOverlapped);
        
        //
        private static uint CTL_CODE(uint DeviceType, uint Function, uint Method, uint Access)
        {
            return ((DeviceType << 16) | (Access << 14) | (Function << 2) | Method);
        }

        //
        static uint TAP_WIN_CONTROL_CODE(uint request, uint method)
        {
            return CTL_CODE(FILE_DEVICE_UNKNOWN, request, method, FILE_ANY_ACCESS);
        }
        
        static string GetDeviceGuid()
        {
            const string AdapterKey = "SYSTEM\\CurrentControlSet\\Control\\Class\\{4D36E972-E325-11CE-BFC1-08002BE10318}";
            
            RegistryKey regAdapters = Registry.LocalMachine.OpenSubKey(AdapterKey);

            string[] keyNames = regAdapters.GetSubKeyNames();
            string devGuid = "";
            foreach (string x in keyNames)
            {
                try
                {
                    RegistryKey regAdapter = regAdapters.OpenSubKey(x);
                    object id = regAdapter.GetValue("ComponentId");
                    if (id != null && id.ToString() == "tap0801") devGuid = regAdapter.GetValue("NetCfgInstanceId").ToString();
                    if (id != null && id.ToString() == "tap0901") devGuid = regAdapter.GetValue("NetCfgInstanceId").ToString();
                }
                catch (Exception ex)
                {

                }
            }
            Console.WriteLine("devGuid=" + devGuid);
            return devGuid;
        }

        static string HumanName(string guid)
        {
            const string ConnectionKey = "SYSTEM\\CurrentControlSet\\Control\\Network\\{4D36E972-E325-11CE-BFC1-08002BE10318}";
            if (guid != "")
            {
                RegistryKey regConnection = Registry.LocalMachine.OpenSubKey(ConnectionKey + "\\" + guid + "\\Connection");
                object id = regConnection.GetValue("Name");
                if (id != null) return id.ToString();
            }
            return "";
        }

        static FileStream Tap;

        [STAThread]
        static void Main(string[] args)
        {
            //tap ioctls
            uint TAP_WIN_IOCTL_GET_MAC = TAP_WIN_CONTROL_CODE(1, METHOD_BUFFERED);
            uint TAP_WIN_IOCTL_GET_VERSION = TAP_WIN_CONTROL_CODE(2, METHOD_BUFFERED);
            uint TAP_WIN_IOCTL_GET_MTU = TAP_WIN_CONTROL_CODE(3, METHOD_BUFFERED);
            uint TAP_WIN_IOCTL_GET_INFO = TAP_WIN_CONTROL_CODE(4, METHOD_BUFFERED);
            uint TAP_WIN_IOCTL_CONFIG_POINT_TO_POINT = TAP_WIN_CONTROL_CODE(5, METHOD_BUFFERED);
            uint TAP_WIN_IOCTL_SET_MEDIA_STATUS = TAP_WIN_CONTROL_CODE(6, METHOD_BUFFERED);
            uint TAP_WIN_IOCTL_CONFIG_DHCP_MASQ = TAP_WIN_CONTROL_CODE(7, METHOD_BUFFERED);
            uint TAP_WIN_IOCTL_GET_LOG_LINE = TAP_WIN_CONTROL_CODE(8, METHOD_BUFFERED);
            uint TAP_WIN_IOCTL_CONFIG_DHCP_SET_OPT = TAP_WIN_CONTROL_CODE(9, METHOD_BUFFERED);
            uint TAP_WIN_IOCTL_CONFIG_TUN = TAP_WIN_CONTROL_CODE(10, METHOD_BUFFERED);
            
            //get first tap interface
            const string UsermodeDeviceSpace = "\\\\.\\Global\\";
            string devGuid = GetDeviceGuid();
            Console.WriteLine("interface-human-name=" + HumanName(devGuid));

            //create handle to tap interface
            IntPtr ptr = CreateFile(UsermodeDeviceSpace + devGuid + ".tap", FileAccess.ReadWrite, FileShare.ReadWrite, 0, FileMode.Open, FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED, IntPtr.Zero);
            
            //create stream to tap interface
            Tap = new FileStream(ptr, FileAccess.ReadWrite, true, 4096, true);
            
            //create buffer to read packets from tap interface
            byte[] buf = new byte[4096];

            //set tap interface up
            int len;
            IntPtr pstatus = Marshal.AllocHGlobal(4);
            Marshal.WriteInt32(pstatus, 1);
            DeviceIoControl(ptr, TAP_WIN_IOCTL_SET_MEDIA_STATUS, pstatus, 4, pstatus, 4, out len, IntPtr.Zero);
            
            //configure ipv4 of tap interface
            string arg = "interface ip set address \"" + HumanName(devGuid) + "\" dhcp";
            Console.WriteLine(arg);
            Process p = new Process();
            ProcessStartInfo psi = new ProcessStartInfo("netsh", arg);
            p.StartInfo = psi;
            p.Start();

            //configure ipv6 of tap interface
            string arg2 = "interface ipv6 set address \"" + HumanName(devGuid) + "\" 2001::6969 advertise=enabled";
            Console.WriteLine(arg2);
            Process p2 = new Process();
            ProcessStartInfo psi2 = new ProcessStartInfo("netsh", arg2);
            p2.StartInfo = psi2;
            p2.Start();
            
            //serial connection to embedded system
            System.IO.Ports.SerialPort serial_port = new System.IO.Ports.SerialPort();
            serial_port.PortName = "COM1";
            serial_port.BaudRate = 115200;
            serial_port.DataReceived += port_DataReceived;
            serial_port.Open();

            while (true)
            {
                //async read from windows network kernel
                int BytesRead = Tap.Read(buf, 0, buf.Length);
                Console.WriteLine("from-windows=" + BytesRead + "=>" + BitConverter.ToString(buf, 0, BytesRead));
                //write to serial connected in embedded system
                serial_port.Write(buf, 0, BytesRead);
            }
        }

        //read from serial connected in embedded system
        static void port_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
        {
            SerialPort sp = (SerialPort)sender;
            string indata = sp.ReadExisting();
            byte[] bin_from_stm32 = System.Text.Encoding.ASCII.GetBytes(indata);
            Console.WriteLine("from-embedded=" + bin_from_stm32.Length + "=>" + BitConverter.ToString(bin_from_stm32, 0, bin_from_stm32.Length));
            //mininum valid packet size for windows kernel
            if (bin_from_stm32.Length >= 20)
            {
                //async write to windows network kernel
                Tap.Write(bin_from_stm32, 0, bin_from_stm32.Length);
            }
        }
        
    }
}