eap_chap
RADIUS_PACKET *, struct eap_chap *);
req = eap_recv_mschap(self, req, pkt, (struct eap_chap *)eap);
RADIUS_PACKET *pkt, struct eap_chap *chap)
struct eap_chap chap;
eapsiz = offsetof(struct eap_chap, chap.value[respsiz - 1]);