tlv_check
static int tlv_check(const void *, size_t, const struct tlvhdr *,
if (tlv_check(mdu, sizeof(*mdu), &mdu->mdu_tlv,
if (tlv_check(mdu, sizeof(*mdu), &mdu->mdu_tlv,
if (tlv_check(du, sizeof(*du), &du->ldu_tlv_actor,