ar_spa
uint8_t ar_spa[]; /* sender protocol address */
memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
memcpy(&srv_ip, ar_spa(ah), sizeof(srv_ip));
memcpy(ar_spa(ah), sip, ah->ar_pln);
memcpy(&isaddr, ar_spa(ah), sizeof(isaddr));
memmove(ar_spa(ap), (char *) &ii->ii_ipaddr, 4);