#include <sys/types.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <sys/socket.h>

#include <errno.h>
#include <stdio.h>

#define BCOPY(a, b, n)            memmove((char *)b, (char *)a, n)

char *e2str(u_char *);

main(int argc, char **argv)
{
  register char *cp;
  char *prog, *interface;
  struct ifreq ifr;
  u_char mymac[IFHWADDRLEN];
  int s;

  if (argv[0] == NULL)
    prog = "myname";
  else if ((cp = strrchr(argv[0], '/')) != NULL)
    prog = cp + 1;
  else
    prog = argv[0];

  if (argc != 2) {
    (void)fprintf(stderr, "%s: no interface supplied\n", prog);
    (void)fprintf(stderr, "usage: %s {interface}\n", prog);
    exit(1);
  }
  interface = argv[1];

  ifr.ifr_addr.sa_family = AF_INET;
  BCOPY(interface, ifr.ifr_name, sizeof(ifr.ifr_name));
  if ((s = socket(ifr.ifr_addr.sa_family, SOCK_DGRAM, 0)) < 0) {
    (void)fprintf(stderr, "%s: unable to create socket on %s: %d\n",
                  prog, interface, errno);
    exit(1);
  }
  if (ioctl(s, SIOCGIFHWADDR, &ifr) < 0) {
    (void)fprintf(stderr, "%s: unable to get ifhwaddr on %s: %d\n",
                  prog, interface, errno);
    exit(1);
  }
  BCOPY(ifr.ifr_hwaddr.sa_data, mymac, IFHWADDRLEN);
  printf("got MAC address %s for %s\n", e2str(mymac),
         interface);
  
}

char *
e2str(register u_char *e)
{
  static char str[32];

  (void)sprintf(str, "%02x:%02x:%02x:%02x:%02x:%02x",
                e[0], e[1], e[2], e[3], e[4], e[5]);
  return(str);
}