newah
const struct newah *ahp;
struct newah ah;
ahp = (struct newah *)(mtod(m, char *) + off);
struct newah *ah;
M_REGION_GET(ah, struct newah *, m, skip, rplen);
m_copydata(m, skip + offsetof(struct newah, ah_seq),
struct newah *ah;
ah = (struct newah *)(mtod(mi, char *) + roff);