/*
 * Copyright (c) 2018 Alastair Roy Poole <netstar@gmail.com>
 *
 * 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.
 */

#if defined(__MacOS__) || defined(__FreeBSD__) || defined(__DragonFly__)
static void
_freebsd_generic_network_status(uint64_t *in,
                                uint64_t *out)
{
   struct ifmibdata *ifmd;
   size_t len;
   int i, count;
   len = sizeof(count);

   if (sysctlbyname("net.link.generic.system.ifcount", &count, &len, NULL, 0) == -1)
     return;

   ifmd = malloc(sizeof(struct ifmibdata));
   if (!ifmd)
     return;

   for (i = 1; i <= count; i++) {
        int mib[] = {
           CTL_NET, PF_LINK, NETLINK_GENERIC, IFMIB_IFDATA, i, IFDATA_GENERAL
        };
        len = sizeof(*ifmd);
        if (sysctl(mib, 6, ifmd, &len, NULL, 0) < 0) continue;
        if (!strcmp(ifmd->ifmd_name, "lo0"))
          continue;
        *in += ifmd->ifmd_data.ifi_ibytes;
        *out += ifmd->ifmd_data.ifi_obytes;
     }
   free(ifmd);
}

#endif

#if defined(__OpenBSD__)
static void
_openbsd_generic_network_status(uint64_t *in,
                                uint64_t *out)
{
   struct ifaddrs *interfaces, *ifa;

   if (getifaddrs(&interfaces) < 0)
     return;

   int sock = socket(AF_INET, SOCK_STREAM, 0);
   if (sock < 0)
     return;

   for (ifa = interfaces; ifa; ifa = ifa->ifa_next) {
        struct ifreq ifreq;
        struct if_data if_data;

        // TBC: Interfaces can have multiple addresses.
        // Using this netmask check we should be obtaining
        // the overall interface data across addresses.

        if (ifa->ifa_netmask != 0) continue;

        ifreq.ifr_data = (void *)&if_data;
        strncpy(ifreq.ifr_name, ifa->ifa_name, IFNAMSIZ - 1);
        if (ioctl(sock, SIOCGIFDATA, &ifreq) < 0)
          return;

        const struct if_data *ifi = &if_data;
        if (!LINK_STATE_IS_UP(ifi->ifi_link_state))
          continue;

        if (ifi->ifi_type == IFT_ETHER ||
            ifi->ifi_type == IFT_FASTETHER ||
            ifi->ifi_type == IFT_GIGABITETHERNET ||
            ifi->ifi_type == IFT_IEEE80211)
          {
             if (ifi->ifi_ibytes)
               *in += ifi->ifi_ibytes;

             if (ifi->ifi_obytes)
               *out += ifi->ifi_obytes;
          }
     }
   close(sock);
}

#endif

#if defined(__linux__)
static void
_linux_generic_network_status(uint64_t *in,
                              uint64_t *out)
{
   FILE *f;
   char buf[4096], dummy_s[256];
   unsigned long int tmp_in, tmp_out, dummy;

   f = fopen("/proc/net/dev", "r");
   if (!f) return;

   while (fgets(buf, sizeof(buf), f))
     {
        if (17 == sscanf(buf, "%s %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu "
                         "%lu %lu %lu %lu %lu\n", dummy_s, &tmp_in, &dummy,
                         &dummy, &dummy, &dummy, &dummy, &dummy, &dummy,
                         &tmp_out, &dummy, &dummy, &dummy, &dummy, &dummy,
                         &dummy, &dummy))
          {
             *in += tmp_in;
             *out += tmp_out;
          }
     }

   fclose(f);
}

#endif

void
system_network_transfer_get(network_t *usage)
{
   uint64_t first_in = 0, first_out = 0;
   uint64_t last_in = 0, last_out = 0;
#if defined(__linux__)
   _linux_generic_network_status(&first_in, &first_out);
   usleep(1000000);
   _linux_generic_network_status(&last_in, &last_out);
#elif defined(__OpenBSD__)
   _openbsd_generic_network_status(&first_in, &first_out);
   usleep(1000000);
   _openbsd_generic_network_status(&last_in, &last_out);
#elif defined(__MacOS__) || defined(__FreeBSD__) || defined(__DragonFly__)
   _freebsd_generic_network_status(&first_in, &first_out);
   usleep(1000000);
   _freebsd_generic_network_status(&last_in, &last_out);
#endif
   usage->incoming = last_in - first_in;
   usage->outgoing = last_out - first_out;
}