linux獲取指定網口的MAC

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <net/if.h>
#include <assert.h>

int obtain_mac(const char *ifname, unsigned char *mac, int len)
{
    int sk = -1, ret = 0;
    struct ifreq ifreq;

    assert(ifname);
    assert(mac);
    assert(len >= 6);

    sk = socket(AF_INET, SOCK_STREAM, 0);
    if (sk < 0)
    {
        perror("socket");
        ret--;
        goto OUT;
    }

    strcpy(ifreq.ifr_name, ifname);
    if (ioctl(sk, SIOCGIFHWADDR, &ifreq) < 0)
    {
        perror("ioctl");
        ret--;
        goto OUT;
    }
    memcpy(mac, (unsigned char *)ifreq.ifr_hwaddr.sa_data, 6);

OUT:
    if (sk >= 0)
        close(sk);
    return ret;
}

int main(int argc, char **argv)
{
    unsigned char mac[12];

    if (obtain_mac(argv[1], mac, sizeof(mac)) < 0)
        return -1;

    printf("%02X:%02X:%02X:%02X:%02X:%02X\n", 
           mac[0],
           mac[1],
           mac[2],
           mac[3],
           mac[4],
           mac[5]
           );

    return 0;
}