/* Allocate a new netlink message with the default maximum payload size. */
struct nl_msg *nlmsg_alloc(void)
{
/* Whole page will store nl_msg + nlmsghdr + genlmsghdr + payload */
const int page_sz = getpagesize();
struct nl_msg *nm;
struct nlmsghdr *nlh;
/* Netlink message */
nm = (struct nl_msg *) malloc(page_sz);
if (!nm)
goto fail;
/* Netlink message header pointer */
nlh = (struct nlmsghdr *) ((char *) nm + sizeof(struct nl_msg));
/* Initialize */
memset(nm, 0, page_sz);
nm->nm_size = page_sz;
nm->nm_src.nl_family = AF_NETLINK;
nm->nm_src.nl_pid = getpid();
nm->nm_dst.nl_family = AF_NETLINK;
nm->nm_dst.nl_pid = 0; /* Kernel */
/* Initialize and add to netlink message */
nlh->nlmsg_len = NLMSG_HDRLEN;
nm->nm_nlh = nlh;
/* Add to reference count and return nl_msg */
nlmsg_get(nm);
return nm;
fail:
return NULL;
}
static int request_single_cb(struct nl_msg *msg, void *arg)
{
struct nl_msg **dest = arg;
if (!*dest) {
nlmsg_get(msg);
*dest = msg;
}
return NL_SKIP;
}
