Getting MAC addresses

listmacaddrs.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <ifaddrs.h>

#ifdef AF_LINK
#   include <net/if_dl.h>
unsigned char *get_ptr(struct ifaddrs *ifaptr) {
    if (((ifaptr)->ifa_addr)->sa_family == AF_LINK) {
        return (unsigned char *)LLADDR((struct sockaddr_dl *)(ifaptr)->ifa_addr);
    }
    return NULL;
}
#endif
#ifdef AF_PACKET
#   include <netpacket/packet.h>
unsigned char *get_ptr(struct ifaddrs *ifaptr) {
    if (((ifaptr)->ifa_addr)->sa_family == AF_PACKET) {
        return (unsigned char *)((struct sockaddr_ll*)ifaptr->ifa_addr)->sll_addr;
    }
    return NULL;
}
#endif

int listmacaddrs(void) {
    struct ifaddrs *ifap, *ifaptr;
    unsigned char *ptr;

    if (getifaddrs(&ifap) == 0) {
        for (ifaptr = ifap; ifaptr != NULL; ifaptr = (ifaptr)->ifa_next) {
            ptr = get_ptr(ifaptr);
            if (ptr != NULL) {
                printf("%s: %02x:%02x:%02x:%02x:%02x:%02x\n",
                                    (ifaptr)->ifa_name,
                                    *ptr, *(ptr + 1), *(ptr + 2), *(ptr + 3), *(ptr + 4), *(ptr + 5));
            }
        }
        freeifaddrs(ifap);
        return 1;
    } else {
        return 0;
    }
}

extern int
main(int argc, char* argv[]) {
    return listmacaddrs();
}