OFFSET_LENGTH
len = load_16_be(offset(buffer, OFFSET_LENGTH));
len = load_16_be(offset(buffer, OFFSET_LENGTH));
#define pkt_len_get(p) load_16_be(offset(&(p)->pkt, OFFSET_LENGTH))
#define pkt_len_set(p, v) store_16_be(v, offset(&(p)->pkt, OFFSET_LENGTH))