/*
 * 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 <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/param.h>

#include <arpa/inet.h>
#include <net/if.h>
#include <net/if_types.h>
#include <netinet/if_ether.h>
#include <netinet/in.h>

#include <fcntl.h>
#include <ifaddrs.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "tuntap.h"

static int
tuntap_sys_create_dev(struct device *dev, int tun)
{
  return -1;
}

int
tuntap_sys_start(struct device *dev, int mode, int tun)
{
  struct ifreq ifr;
  struct ifaddrs *ifa;
  char name[MAXPATHLEN];
  int fd;
  char *type;

  fd = -1;

  /* Force creation of the driver if needed or let it resilient */
  if(mode & TUNTAP_MODE_PERSIST)
  {
    mode &= ~TUNTAP_MODE_PERSIST;
    /* TODO: Call tuntap_sys_create_dev() */
  }

  /* Set the mode: tun or tap */
  if(mode == TUNTAP_MODE_ETHERNET)
  {
    type = "tap";
    ifr.ifr_flags |= IFF_LINK0;
  }
  else if(mode == TUNTAP_MODE_TUNNEL)
  {
    type = "tun";
    ifr.ifr_flags &= ~IFF_LINK0;
  }
  else
  {
    tuntap_log(TUNTAP_LOG_ERR, "Invalid parameter 'mode'");
    return -1;
  }

  /* Try to use the given driver or loop throught the avaible ones */
  if(tun < TUNTAP_ID_MAX)
  {
    (void)snprintf(name, sizeof name, "/dev/%s%i", type, tun);
    fd = open(name, O_RDWR);
  }
  else if(tun == TUNTAP_ID_ANY)
  {
    for(tun = 0; tun < TUNTAP_ID_MAX; ++tun)
    {
      (void)memset(name, '\0', sizeof name);
      (void)snprintf(name, sizeof name, "/dev/%s%i", type, tun);
      if((fd = open(name, O_RDWR)) > 0)
        break;
    }
  }
  else
  {
    tuntap_log(TUNTAP_LOG_ERR, "Invalid parameter 'tun'");
    return -1;
  }
  switch(fd)
  {
    case -1:
      tuntap_log(TUNTAP_LOG_ERR, "Permission denied");
      return -1;
    case 256:
      tuntap_log(TUNTAP_LOG_ERR, "Can't find a tun entry");
      return -1;
    default:
      /* NOTREACHED */
      break;
  }

  /* Get the interface default values */
  if(ioctl(dev->ctrl_sock, SIOCGIFFLAGS, &ifr) == -1)
  {
    tuntap_log(TUNTAP_LOG_ERR, "Can't get interface values");
    return -1;
  }
  /* set interface name */
  strncpy(ifr.ifr_name, dev->if_name, sizeof(ifr.ifr_name));
  /* Set our modifications */
  if(ioctl(dev->ctrl_sock, SIOCSIFFLAGS, &ifr) == -1)
  {
    tuntap_log(TUNTAP_LOG_ERR, "Can't set interface values");
    return -1;
  }

  /* Save flags for tuntap_{up, down} */
  dev->flags = ifr.ifr_flags;

  /* Save pre-existing MAC address */
  if(mode == TUNTAP_MODE_ETHERNET && getifaddrs(&ifa) == 0)
  {
    struct ifaddrs *pifa;

    for(pifa = ifa; pifa != NULL; pifa = pifa->ifa_next)
    {
      if(strcmp(pifa->ifa_name, dev->if_name) == 0)
      {
        struct ether_addr eth_addr;

        /*
         * The MAC address is from 10 to 15.
         *
         * And yes, I know, the buffer is supposed
         * to have a size of 14 bytes.
         */
        (void)memcpy(dev->hwaddr, pifa->ifa_addr->sa_data + 10, ETHER_ADDR_LEN);

        (void)memset(&eth_addr.ether_addr_octet, 0, ETHER_ADDR_LEN);
        (void)memcpy(&eth_addr.ether_addr_octet, pifa->ifa_addr->sa_data + 10,
                     ETHER_ADDR_LEN);
        break;
      }
    }
    if(pifa == NULL)
      tuntap_log(TUNTAP_LOG_WARN, "Can't get link-layer address");
    freeifaddrs(ifa);
  }
  return fd;
}

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

int
tuntap_sys_set_hwaddr(struct device *dev, struct ether_addr *eth_addr)
{
  struct ifreq ifr;

  (void)memset(&ifr, '\0', sizeof ifr);
  (void)strlcpy(ifr.ifr_name, dev->if_name, sizeof ifr.ifr_name);
  ifr.ifr_addr.sa_len    = ETHER_ADDR_LEN;
  ifr.ifr_addr.sa_family = AF_LINK;
  (void)memcpy(ifr.ifr_addr.sa_data, eth_addr, ETHER_ADDR_LEN);
  if(ioctl(dev->ctrl_sock, SIOCSIFLLADDR, &ifr) < 0)
  {
    tuntap_log(TUNTAP_LOG_ERR, "Can't set link-layer address");
    return -1;
  }
  return 0;
}

int
tuntap_sys_set_ipv4(struct device *dev, t_tun_in_addr *s4, uint32_t bits)
{
  struct ifaliasreq ifa;
  struct ifreq ifr;
  struct sockaddr_in addr;
  struct sockaddr_in mask;

  (void)memset(&ifa, '\0', sizeof ifa);
  (void)strlcpy(ifa.ifra_name, dev->if_name, sizeof ifa.ifra_name);

  (void)memset(&ifr, '\0', sizeof ifr);
  (void)strlcpy(ifr.ifr_name, dev->if_name, sizeof ifr.ifr_name);

  /* Delete previously assigned address */
  (void)ioctl(dev->ctrl_sock, SIOCDIFADDR, &ifr);

  /*
   * Fill-in the destination address and netmask,
   * but don't care of the broadcast address
   */
  (void)memset(&addr, '\0', sizeof addr);
  addr.sin_family      = AF_INET;
  addr.sin_addr.s_addr = s4->s_addr;
  addr.sin_len         = sizeof addr;
  (void)memcpy(&ifa.ifra_addr, &addr, sizeof addr);

  (void)memset(&mask, '\0', sizeof mask);
  mask.sin_family      = AF_INET;
  mask.sin_addr.s_addr = bits;
  mask.sin_len         = sizeof mask;
  (void)memcpy(&ifa.ifra_mask, &mask, sizeof ifa.ifra_mask);

  /* Simpler than calling SIOCSIFADDR and/or SIOCSIFBRDADDR */
  if(ioctl(dev->ctrl_sock, SIOCSIFADDR, &ifa) == -1)
  {
    tuntap_log(TUNTAP_LOG_ERR, "Can't set IP/netmask");
    return -1;
  }
  return 0;
}

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