/* Fetch the inteface configuration from the kernel. */
static int
if_fetch(char *ifname, struct interface *ife)
{
  struct ifreq ifr;

  memset((char *) ife, 0, sizeof(struct interface));
  strcpy(ife->name, ifname);

  strcpy(ifr.ifr_name, ifname);
  if (ioctl(skfd, SIOCGIFFLAGS, &ifr) < 0) return(-1);
  ife->flags = ifr.ifr_flags;

  strcpy(ifr.ifr_name, ifname);
  if (ioctl(skfd, SIOCGIFADDR, &ifr) < 0) {
	memset(&ife->addr, 0, sizeof(struct sockaddr));
  } else ife->addr = ifr.ifr_addr;

  strcpy(ifr.ifr_name, ifname);

  if (ioctl(skfd, SIOCGIFHWADDR, &ifr) < 0) {
	memset(ife->hwaddr, 0, 32);
  } else memcpy(ife->hwaddr,ifr.ifr_hwaddr.sa_data,8);

  ife->type=ifr.ifr_hwaddr.sa_family;

  strcpy(ifr.ifr_name, ifname);
  if (ioctl(skfd, SIOCGIFMETRIC, &ifr) < 0) {
	ife->metric = 0;
  } else ife->metric = ifr.ifr_metric;

  strcpy(ifr.ifr_name, ifname);
  if (ioctl(skfd, SIOCGIFMTU, &ifr) < 0) {
	ife->mtu = 0;
  } else ife->mtu = ifr.ifr_mtu;

  strcpy(ifr.ifr_name, ifname);
  if (ioctl(skfd, SIOCGIFMAP, &ifr) < 0) {
	memset(&ife->map, 0, sizeof(struct ifmap));
  } else memcpy(&ife->map,&ifr.ifr_map,sizeof(struct ifmap));

  strcpy(ifr.ifr_name, ifname);
  if (ioctl(skfd, SIOCGIFDSTADDR, &ifr) < 0) {
	memset(&ife->dstaddr, 0, sizeof(struct sockaddr));
  } else ife->dstaddr = ifr.ifr_dstaddr;

  strcpy(ifr.ifr_name, ifname);
  if (ioctl(skfd, SIOCGIFBRDADDR, &ifr) < 0) {
	memset(&ife->broadaddr, 0, sizeof(struct sockaddr));
  } else ife->broadaddr = ifr.ifr_broadaddr;

  strcpy(ifr.ifr_name, ifname);
  if (ioctl(skfd, SIOCGIFNETMASK, &ifr) < 0) {
	memset(&ife->netmask, 0, sizeof(struct sockaddr));
  } else ife->netmask = ifr.ifr_netmask;

  strcpy(ifr.ifr_name, ifname);
  if (ioctl(skfd, SIOCGIFMAP, &ifr) < 0) {
  	memset(&ife->map, 0, sizeof(struct ifmap));
  }
  else ife->map = ifr.ifr_map;

  if_getstats(ifname,ife);
  return(0);
}


static void
if_print(char *ifname)
{
  char buff[1024];
  struct interface ife;
  struct ifconf ifc;
  struct ifreq *ifr;
  int i;

  if (ifname == (char *)NULL) {
	ifc.ifc_len = sizeof(buff);
	ifc.ifc_buf = buff;
	if (ioctl(skfd, SIOCGIFCONF, &ifc) < 0) {
		fprintf(stderr, "SIOCGIFCONF: %s\n", strerror(errno));
		return;
	}

	ifr = ifc.ifc_req;
	for (i = ifc.ifc_len / sizeof(struct ifreq); --i >= 0; ifr++) {
		if (if_fetch(ifr->ifr_name, &ife) < 0) {
			fprintf(stderr, "%s: unknown interface.\n",
							ifr->ifr_name);
			continue;
		}

		if (((ife.flags & IFF_UP) == 0) && !opt_a) continue;
		ife_print(&ife);
	}
  } else {
	if (if_fetch(ifname, &ife) < 0)
		fprintf(stderr, "%s: unknown interface.\n", ifname);
	  else ife_print(&ife);
  }
}