BIO_should_read
int ret = BIO_socket_wait(fd, BIO_should_read(bio), max_time);
conn->tx_need_rx = BIO_should_read(conn->ssl_bio);
conn->tx_need_rx = BIO_should_read(conn->ssl_bio);
if (BIO_should_read(bio))
else if (BIO_should_read(bio))
if (ret <= 0 && BIO_should_read(next))
if (BIO_should_read(c_bio))
if (BIO_should_read(c_bio))
if (BIO_should_read(s_bio))
if (BIO_should_read(s_bio))
if (ret <= 0 && BIO_should_read(next))