ng_l2cap_clt_hdr_t
(NG_L2CAP_MTU_MAXIMUM - sizeof(ng_l2cap_clt_hdr_t))
m = ng_l2cap_prepend(m, sizeof(ng_l2cap_clt_hdr_t));
mtod(m, ng_l2cap_clt_hdr_t *)->psm =
ng_l2cap_clt_hdr_t c_h;
ng_l2cap_clt_hdr_t *clt_hdr = NULL;
clt_hdr = mtod(m, ng_l2cap_clt_hdr_t *);