Mine

struct libnet_ether_addr *libnet_get_hwaddr(libnet_t *l){    /* This implementation is not-reentrant. */    static struct libnet_ether_addr *mac;    ULONG IoCtlBufferLength = (sizeof(PACKET_OID_DATA) + sizeof(ULONG) - 1);	PPACKET_OID_DATA OidData;	int i = 0;	if (l == NULL)    {        return (NULL);    }	if (l->device == NULL)    {        if (libnet_select_device(l) == -1)        {            snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,                    "%s(): can't figure out a device to use\n", __func__);            return (NULL);        }    }    mac = (struct libnet_ether_addr *)calloc(1,sizeof(struct libnet_ether_addr));	if (mac == NULL)	{		snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,                    "%s(): calloc error\n", __func__);		return (NULL);	}    OidData = (struct _PACKET_OID_DATA *) malloc(IoCtlBufferLength);	if (OidData == NULL)	{	     snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,				 "%s(): OidData is NULL\n", __func__);	    return(NULL);	}	if (l->link_type == DLT_IEEE802)	{		OidData->Oid = OID_802_5_CURRENT_ADDRESS;	}	else	{		OidData->Oid = OID_802_3_CURRENT_ADDRESS;	}	OidData->Length = 6;	if((PacketRequest(l->lpAdapter, FALSE, OidData)) == FALSE)	{		memset(mac, 0, 6);	}	else	{		for (i = 0; i < 6; i++)		{			mac->ether_addr_octet[i] = OidData->Data[i];		}	}        free(OidData);	return(mac);}