c语言库函数获取mac地址

int GetHostMac( UCHAR *NetMac, UCHAR ucEthNo)
{
 struct ifreq ifreq;
    int sock, i;

 if(NetMac == NULL)
  return -1;
 
       if(ucEthNo == 0)
        sprintf(ifreq.ifr_name, "eth0");
       else if(ucEthNo == 1)
     sprintf(ifreq.ifr_name, "eth1");
 else
  return -2;
 
       if((sock=socket(AF_INET,SOCK_STREAM,0))<0)
     return -3;
   
       if(ioctl(sock,SIOCGIFHWADDR,&ifreq)<0)
        return -4;
   
 for(i = 0; i < 6; i++)
  NetMac[i] = (UCHAR)ifreq.ifr_hwaddr.sa_data[i];
 
        return 0;
}