isnst_add_to_portal_list
iportal = isnst_add_to_portal_list(&sa, &isns_all_portals);
jportal = isnst_add_to_portal_list(&iportal->portal_addr, t2);
iportal = isnst_add_to_portal_list(
isnst_add_to_portal_list(struct sockaddr_storage *sa, avl_tree_t *portal_list);