nlmsg_reserve_data
out_hdr = nlmsg_reserve_data(nw, NLMSG_ALIGN(hdr->nlmsg_len), char);
void *next_hdr = nlmsg_reserve_data(nw, sz, void);
struct nlattr *nla = nlmsg_reserve_data(nw, nla_orig->nla_len, struct nlattr);
dst_payload = nlmsg_reserve_data(nw, NLMSG_ALIGN(copy_len), char);
if (nlmsg_reserve_data(&nw, alloc_len, void *) == NULL) {
errmsg = nlmsg_reserve_data(nw, payload_len, struct nlmsgerr);
struct nlattr *nla = nlmsg_reserve_data(nw, sizeof(struct nlattr), struct nlattr);
struct nlattr *nla = nlmsg_reserve_data(nw, sz, struct nlattr);
struct nlattr *nla = nlmsg_reserve_data(nw, nla_len, struct nlattr);
struct nlattr *nla = nlmsg_reserve_data(nw, nla_len, struct nlattr);
struct nlattr *nla = nlmsg_reserve_data(nw, nla_len, struct nlattr);