CTA_PROTOINFO
[CTA_PROTOINFO] = { .type = NLA_NESTED },
const struct nlattr *attr = cda[CTA_PROTOINFO];
nest_proto = nla_nest_start(skb, CTA_PROTOINFO);
if (cda[CTA_PROTOINFO]) {
if (cda[CTA_PROTOINFO]) {
nest = mnl_attr_nest_start(nlh, CTA_PROTOINFO);