Reading/Writing OpenVPN's TUN/TAP Device under Windows using Python.

tun-ping-win.py

import _winreg as reg
import win32file


adapter_key = r'SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}'


def get_device_guid():
    with reg.OpenKey(reg.HKEY_LOCAL_MACHINE, adapter_key) as adapters:
        try:
            for i in xrange(10000):
                key_name = reg.EnumKey(adapters, i)
                with reg.OpenKey(adapters, key_name) as adapter:
                    try:
                        component_id = reg.QueryValueEx(adapter, 'ComponentId')[0]
                        if component_id == 'tap0801':
                            return reg.QueryValueEx(adapter, 'NetCfgInstanceId')[0]
                    except WindowsError, err:
                        pass
        except WindowsError, err:
            pass

def CTL_CODE(device_type, function, method, access):
    return (device_type << 16) | (access << 14) | (function << 2) | method;

def TAP_CONTROL_CODE(request, method):
    return CTL_CODE(34, request, method, 0)

TAP_IOCTL_CONFIG_POINT_TO_POINT = TAP_CONTROL_CODE(5, 0)
TAP_IOCTL_SET_MEDIA_STATUS = TAP_CONTROL_CODE(6, 0)
TAP_IOCTL_CONFIG_TUN = TAP_CONTROL_CODE(10, 0)


if __name__ == '__main__':
    guid = get_device_guid()
    handle = win32file.CreateFile(r'\\.\Global\%s.tap' % guid,
                                  win32file.GENERIC_READ | win32file.GENERIC_WRITE,
                                  win32file.FILE_SHARE_READ | win32file.FILE_SHARE_WRITE,
                                  None, win32file.OPEN_EXISTING,
                                  win32file.FILE_ATTRIBUTE_SYSTEM, # | win32file.FILE_FLAG_OVERLAPPED,
                                  None)
    print(handle.handle)
    if False:
        win32file.DeviceIoControl(handle, TAP_IOCTL_CONFIG_POINT_TO_POINT,
                                  '\xc0\xa8\x11\x01\xc0\xa8\x11\x10', None);
    else:
        win32file.DeviceIoControl(handle, TAP_IOCTL_SET_MEDIA_STATUS, '\x01\x00\x00\x00', None)
        win32file.DeviceIoControl(handle, TAP_IOCTL_CONFIG_TUN,
                                  '\x0a\x03\x00\x01\x0a\x03\x00\x00\xff\xff\xff\x00', None)
    while True:
        l, p = win32file.ReadFile(handle, 2000)
        q = p[:12] + p[16:20] + p[12:16] + p[20:]
        win32file.WriteFile(handle, q)
        print(p, q)
    win32file.CloseHandle(handle)

In my computer, adapter_key hasnot a string key "tap0801" named ComponentId, just has a "tap0901", so, what I can do?

On my Win7, it is also tap0901. So just change the ID with the one you create.

Is there way get devie by name?

Is there way get devie by name?

Yes, the devices in control panel can be found in the Windows Registry.
I have a JNI impl here, you may copy and modify the code, the project is under MIT license.

And you can also refer to the codes in OpenVPN project, tun.c, it not only searches through the adapters with a name in control panel, but also those taps only having a GUID.

(Answer for anyone who might come here through a search engine)