BIO_set_fd
BIO_set_fd(ret, fd, close_flag);
BIO_set_fd(ret, fd, close_flag);
BIO_set_fd(ret, fd, close_flag);
BIO_set_fd(bio, fd, BIO_NOCLOSE);
BIO_set_fd(bio, fd, BIO_NOCLOSE);
BIO_set_fd(bio, fd, BIO_NOCLOSE);
BIO_set_fd(ocsp->ocsp_cbio, sock->sock_fd, BIO_NOCLOSE);