/*
 * Copyright (c) 2012 Tristan Le Guern <tleguern@bouledef.eu>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
/*#include <strsafe.h>*/
#include "tuntap.h"

// DDK macros
#define CTL_CODE(DeviceType, Function, Method, Access) \
  (((DeviceType) << 16) | ((Access) << 14) | ((Function) << 2) | (Method))
#define FILE_DEVICE_UNKNOWN 0x00000022
#define FILE_ANY_ACCESS 0x00000000
#define METHOD_BUFFERED 0

/* From OpenVPN tap driver, common.h */
#define TAP_CONTROL_CODE(request, method) \
  CTL_CODE(FILE_DEVICE_UNKNOWN, request, method, FILE_ANY_ACCESS)
#define TAP_IOCTL_GET_MAC TAP_CONTROL_CODE(1, METHOD_BUFFERED)
#define TAP_IOCTL_GET_VERSION TAP_CONTROL_CODE(2, METHOD_BUFFERED)
#define TAP_IOCTL_GET_MTU TAP_CONTROL_CODE(3, METHOD_BUFFERED)
#define TAP_IOCTL_GET_INFO TAP_CONTROL_CODE(4, METHOD_BUFFERED)
#define TAP_IOCTL_CONFIG_POINT_TO_POINT TAP_CONTROL_CODE(5, METHOD_BUFFERED)
#define TAP_IOCTL_SET_MEDIA_STATUS TAP_CONTROL_CODE(6, METHOD_BUFFERED)
#define TAP_IOCTL_CONFIG_DHCP_MASQ TAP_CONTROL_CODE(7, METHOD_BUFFERED)
#define TAP_IOCTL_GET_LOG_LINE TAP_CONTROL_CODE(8, METHOD_BUFFERED)
#define TAP_IOCTL_CONFIG_DHCP_SET_OPT TAP_CONTROL_CODE(9, METHOD_BUFFERED)
#define TAP_IOCTL_CONFIG_TUN TAP_CONTROL_CODE(10, METHOD_BUFFERED)

/* Windows registry crap */
#define MAX_KEY_LENGTH 255
#define MAX_VALUE_NAME 16383
#define NETWORK_ADAPTERS                                                 \
  "SYSTEM\\CurrentControlSet\\Control\\Class\\{4D36E972-E325-11CE-BFC1-" \
  "08002BE10318}"
#define ETHER_ADDR_LEN 6

/* From OpenVPN tap driver, proto.h */
typedef unsigned long IPADDR;

/* This one is from Fabien Pichot, in the tNETacle source code */
static LPWSTR
formated_error(LPWSTR pMessage, DWORD m, ...)
{
  LPWSTR pBuffer = NULL;

  va_list args = NULL;
  va_start(args, m);

  FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER,
                pMessage, m, 0, (LPSTR)&pBuffer, 0, &args);

  va_end(args);

  return pBuffer;
}

/* TODO: Rework to be more generic and allow arbitrary key modification (MTU and
 * stuff) */
static char *
reg_query(char *key_name)
{
  HKEY adapters, adapter;
  DWORD i, ret, len;
  char *deviceid = NULL;
  DWORD sub_keys = 0;

  ret =
      RegOpenKeyEx(HKEY_LOCAL_MACHINE, TEXT(key_name), 0, KEY_READ, &adapters);
  if(ret != ERROR_SUCCESS)
  {
    tuntap_log(TUNTAP_LOG_ERR, (const char *)formated_error(L"%1%0", ret));
    return NULL;
  }

  ret = RegQueryInfoKey(adapters, NULL, NULL, NULL, &sub_keys, NULL, NULL, NULL,
                        NULL, NULL, NULL, NULL);
  if(ret != ERROR_SUCCESS)
  {
    tuntap_log(TUNTAP_LOG_ERR, (const char *)formated_error(L"%1%0", ret));
    return NULL;
  }

  if(sub_keys <= 0)
  {
    tuntap_log(TUNTAP_LOG_DEBUG, "Wrong registry key");
    return NULL;
  }

  /* Walk througt all adapters */
  for(i = 0; i < sub_keys; i++)
  {
    char new_key[MAX_KEY_LENGTH];
    char data[256];
    TCHAR key[MAX_KEY_LENGTH];
    DWORD keylen = MAX_KEY_LENGTH;

    /* Get the adapter key name */
    ret = RegEnumKeyEx(adapters, i, key, &keylen, NULL, NULL, NULL, NULL);
    if(ret != ERROR_SUCCESS)
    {
      continue;
    }

    /* Append it to NETWORK_ADAPTERS and open it */
    snprintf(new_key, sizeof new_key, "%s\\%s", key_name, key);
    ret =
        RegOpenKeyEx(HKEY_LOCAL_MACHINE, TEXT(new_key), 0, KEY_READ, &adapter);
    if(ret != ERROR_SUCCESS)
    {
      continue;
    }

    /* Check its values */
    len = sizeof data;
    ret =
        RegQueryValueEx(adapter, "ComponentId", NULL, NULL, (LPBYTE)data, &len);
    if(ret != ERROR_SUCCESS)
    {
      /* This value doesn't exist in this adaptater tree */
      goto clean;
    }
    /* If its a tap adapter, its all good */
    if(strncmp(data, "tap", 3) == 0)
    {
      DWORD type;

      len = sizeof data;
      ret = RegQueryValueEx(adapter, "NetCfgInstanceId", NULL, &type,
                            (LPBYTE)data, &len);
      if(ret != ERROR_SUCCESS)
      {
        tuntap_log(TUNTAP_LOG_INFO, (const char *)formated_error(L"%1", ret));
        goto clean;
      }
      deviceid = strdup(data);
      break;
    }
  clean:
    RegCloseKey(adapter);
  }
  RegCloseKey(adapters);
  return deviceid;
}

void
tuntap_sys_destroy(struct device *dev)
{
  (void)dev;
  return;
}

int
tuntap_start(struct device *dev, int mode, int tun)
{
  HANDLE tun_fd;
  char *deviceid;
  char buf[60];

  /* Don't re-initialise a previously started device */
  if(dev->tun_fd != TUNFD_INVALID_VALUE)
  {
    return -1;
  }

  /* Shift the persistence bit */
  if(mode & TUNTAP_MODE_PERSIST)
  {
    mode &= ~TUNTAP_MODE_PERSIST;
  }

  if(mode == TUNTAP_MODE_TUNNEL)
  {
    deviceid = reg_query(NETWORK_ADAPTERS);
    snprintf(buf, sizeof buf, "\\\\.\\Global\\%s.tap", deviceid);
    tun_fd = CreateFile(buf, GENERIC_WRITE | GENERIC_READ,
                        FILE_SHARE_READ | FILE_SHARE_WRITE, 0, OPEN_EXISTING,
                        FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED, 0);
  }
  else if(mode != TUNTAP_MODE_ETHERNET)
  {
    tuntap_log(TUNTAP_LOG_ERR, "Invalid parameter 'mode'");
    return -1;
  }

  if(tun_fd == TUNFD_INVALID_VALUE)
  {
    int errcode = GetLastError();
    tuntap_log(TUNTAP_LOG_ERR, (const char *)formated_error(L"%1%0", errcode));
    return -1;
  }

  dev->tun_fd = tun_fd;
  return 0;
}

void
tuntap_release(struct device *dev)
{
  (void)CloseHandle(dev->tun_fd);
  free(dev);
}

char *
tuntap_get_hwaddr(struct device *dev)
{
  static unsigned char hwaddr[ETHER_ADDR_LEN];
  DWORD len;

  if(DeviceIoControl(dev->tun_fd, TAP_IOCTL_GET_MAC, &hwaddr, sizeof(hwaddr),
                     &hwaddr, sizeof(hwaddr), &len, NULL)
     == 0)
  {
    int errcode = GetLastError();

    tuntap_log(TUNTAP_LOG_ERR, (const char *)formated_error(L"%1%0", errcode));
    return NULL;
  }
  else
  {
    char buf[128];

    (void)_snprintf(buf, sizeof buf,
                    "MAC address: %.2x:%.2x:%.2x:%.2x:%.2x:%.2x", hwaddr[0],
                    hwaddr[1], hwaddr[2], hwaddr[3], hwaddr[4], hwaddr[5]);
    tuntap_log(TUNTAP_LOG_DEBUG, buf);
  }
  return (char *)hwaddr;
}

int
tuntap_set_hwaddr(struct device *dev, const char *hwaddr)
{
  tuntap_log(TUNTAP_LOG_NOTICE,
             "Your system does not support tuntap_set_hwaddr()");
  return -1;
}

static int
tuntap_sys_set_updown(struct device *dev, ULONG flag)
{
  DWORD len;

  if(DeviceIoControl(dev->tun_fd, TAP_IOCTL_SET_MEDIA_STATUS, &flag,
                     sizeof(flag), &flag, sizeof(flag), &len, NULL)
     == 0)
  {
    int errcode = GetLastError();

    tuntap_log(TUNTAP_LOG_ERR, (const char *)formated_error(L"%1%0", errcode));
    return -1;
  }
  else
  {
    char buf[32];

    (void)_snprintf(buf, sizeof buf, "Status: %s", flag ? "Up" : "Down");
    tuntap_log(TUNTAP_LOG_DEBUG, buf);
    return 0;
  }
}

int
tuntap_up(struct device *dev)
{
  ULONG flag;

  flag = 1;
  return tuntap_sys_set_updown(dev, flag);
}

int
tuntap_down(struct device *dev)
{
  ULONG flag;

  flag = 0;
  return tuntap_sys_set_updown(dev, flag);
}

int
tuntap_get_mtu(struct device *dev)
{
  ULONG mtu;
  DWORD len;

  if(DeviceIoControl(dev->tun_fd, TAP_IOCTL_GET_MTU, &mtu, sizeof(mtu), &mtu,
                     sizeof(mtu), &len, NULL)
     == 0)
  {
    int errcode = GetLastError();

    tuntap_log(TUNTAP_LOG_ERR, (const char *)formated_error(L"%1%0", errcode));
    return -1;
  }
  return 0;
}

int
tuntap_set_mtu(struct device *dev, int mtu)
{
  (void)dev;
  (void)mtu;
  tuntap_log(TUNTAP_LOG_NOTICE,
             "Your system does not support tuntap_set_mtu()");
  return -1;
}

int
tuntap_sys_set_ipv4(struct device *dev, t_tun_in_addr *s, uint32_t mask)
{
  IPADDR sock[3];
  DWORD len, ret;
  IPADDR ep[4];
#pragma pack(push)
#pragma pack(1)
  struct
  {
    uint8_t dhcp_opt;
    uint8_t length;
    uint32_t value[2];
  } dns;
#pragma pack(pop)

  sock[0] = s->S_un.S_addr;
  sock[2] = mask;
  sock[1] = sock[0] & sock[2];
  ret = DeviceIoControl(dev->tun_fd, TAP_IOCTL_CONFIG_TUN, &sock, sizeof(sock),
                        &sock, sizeof(sock), &len, NULL);
  ep[0] = s->S_un.S_addr;
  ep[1] = mask;
  ep[2] = (s->S_un.S_addr | ~mask)
      - (mask + 1); /* For the 10.x.0.y subnet (in a class C config), _should_
                       be 10.x.0.254 i think */
  ep[3] = 86400;    /* one day */

  ret = DeviceIoControl(dev->tun_fd, TAP_IOCTL_CONFIG_DHCP_MASQ, ep, sizeof(ep),
                        ep, sizeof(ep), &len, NULL);

  /* set DNS address to 127.0.0.1 as lokinet-client runs its own DNS resolver
   * inline */
  dns.dhcp_opt = 6;
  dns.length   = 4;
  dns.value[0] =
      htonl(0x7F000001); /* apparently this doesn't show in network properties,
                            but it works 🤷🏻‍♂️ */
  dns.value[1] = 0;

  ret = DeviceIoControl(dev->tun_fd, TAP_IOCTL_CONFIG_DHCP_SET_OPT, &dns,
                        sizeof(dns), &dns, sizeof(dns), &len, NULL);

  if(!ret)
  {
    int errcode = GetLastError();

    tuntap_log(TUNTAP_LOG_ERR, (const char *)formated_error(L"%1%0", errcode));
    return -1;
  }

  return 0;
}

int
tuntap_sys_set_ipv6(struct device *dev, t_tun_in6_addr *s, uint32_t mask)
{
  (void)dev;
  (void)s;
  (void)mask;
  tuntap_log(TUNTAP_LOG_NOTICE,
             "Your system does not support tuntap_sys_set_ipv6()");
  return -1;
}

int
tuntap_read(struct device *dev, void *buf, size_t size)
{
  DWORD len;

  if(ReadFile(dev->tun_fd, buf, (DWORD)size, &len, NULL) == 0)
  {
    int errcode = GetLastError();

    tuntap_log(TUNTAP_LOG_ERR, (const char *)formated_error(L"%1%0", errcode));
    return -1;
  }

  return 0;
}

int
tuntap_write(struct device *dev, void *buf, size_t size)
{
  DWORD len;

  if(WriteFile(dev->tun_fd, buf, (DWORD)size, &len, NULL) == 0)
  {
    int errcode = GetLastError();

    tuntap_log(TUNTAP_LOG_ERR, (const char *)formated_error(L"%1%0", errcode));
    return -1;
  }

  return 0;
}

int
tuntap_get_readable(struct device *dev)
{
  (void)dev;
  tuntap_log(TUNTAP_LOG_NOTICE,
             "Your system does not support tuntap_get_readable()");
  return -1;
}

int
tuntap_set_nonblocking(struct device *dev, int set)
{
  (void)dev;
  (void)set;
  tuntap_log(TUNTAP_LOG_NOTICE,
             "Your system does not support tuntap_set_nonblocking()");
  return -1;
}

int
tuntap_set_debug(struct device *dev, int set)
{
  (void)dev;
  (void)set;
  tuntap_log(TUNTAP_LOG_NOTICE,
             "Your system does not support tuntap_set_debug()");
  return -1;
}

int
tuntap_set_descr(struct device *dev, const char *descr)
{
  (void)dev;
  (void)descr;
  tuntap_log(TUNTAP_LOG_NOTICE,
             "Your system does not support tuntap_set_descr()");
  return -1;
}

int
tuntap_set_ifname(struct device *dev, const char *name)
{
  /* TODO: Check Windows API to know how to rename an interface */
  (void)dev;
  (void)name;
  tuntap_log(TUNTAP_LOG_NOTICE,
             "Your system does not support tuntap_set_ifname()");
  return -1;
}