récupérer l'addresse MAC d'une interface Wifi

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#include <sys/ioctl.h>
#include <net/if.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
 
char *get_mac_address (char const *iface);
 
int main (void)
{
   char *address = get_mac_address ("eth1");
   if (address != NULL)
   {
      puts (address);
      free (address), address = NULL;
   }
   return EXIT_SUCCESS;
}
 
char *get_mac_address (char const *iface)
{
   char *hwaddr = calloc (18, sizeof *hwaddr);
   if (hwaddr != NULL)
   {
      int fd = socket (AF_INET, SOCK_DGRAM, 0);
      if (fd != -1)
      {
         struct ifreq ifr;
         strncpy (ifr.ifr_name, iface, IFNAMSIZ);
 
         if (ioctl (fd, SIOCGIFFLAGS, &ifr) == 0)
         {
            if (ioctl (fd, SIOCGIFHWADDR, &ifr) == 0)
            {
               char buf[8];
               memcpy (buf, ifr.ifr_hwaddr.sa_data, 8);
 
               snprintf (hwaddr, 18, "%02X:%02X:%02X:%02X:%02X:%02X",
                         (buf[0] & 0xFF), (buf[1] & 0xFF), (buf[2] & 0xFF),
                         (buf[3] & 0xFF), (buf[4] & 0xFF), (buf[5] & 0xFF));
            }
            else
            {
               perror ("ioctl(SIOCGIFHWADDR)");
            }
         }
         else
         {
            perror ("ioctl(SIOCGIFFLAGS)");
         }
      }
      else
      {
         perror ("socket() error");
      }
   }
   return hwaddr;
}