timespecsub(&t, &(s->in_last_read), &td);
if (timespeccmp(&td, &(s->out_ttl), >=)) {
/* TODO: Maybe configurable expiry character. */
timespecsub(&t, &(s->in_last_read), &td);
if (timespeccmp(&td, &(s->out_ttl), >=)) {
/* TODO: Maybe configurable expiry character. */