to_der

static VALUE
ossl_ocspcid_to_der(VALUE self)
{
    OCSP_CERTID *id;
    VALUE str;
    long len;
    unsigned char *p;

    GetOCSPCertId(self, id);
    if ((len = i2d_OCSP_CERTID(id, NULL)) <= 0)
        ossl_raise(eOCSPError, NULL);
    str = rb_str_new(0, len);
    p = (unsigned char *)RSTRING_PTR(str);
    if (i2d_OCSP_CERTID(id, &p) <= 0)
        ossl_raise(eOCSPError, NULL);
    ossl_str_adjust(str, p);

    return str;
}