accept_add
return (accept_add(control_fd, control_accept, NULL));
accept_add(af_global->ldp_session_socket, session_accept, NULL);
int accept_add(int, void (*)(int, short, void *), void *);
int accept_add (int, void (*)(int, short, void *), void *arg);
if (accept_add(_this->sock, pptpd_io_event, _this) != 0) {