OpenSSL::X509::Request#to_der

static VALUE
ossl_x509req_to_der(VALUE self)
{
    X509_REQ *req;
    VALUE str;
    long len;
    unsigned char *p;

    GetX509Req(self, req);
    if ((len = i2d_X509_REQ(req, NULL)) <= 0)
        ossl_raise(eX509ReqError, NULL);
    str = rb_str_new(0, len);
    p = (unsigned char *)RSTRING_PTR(str);
    if (i2d_X509_REQ(req, &p) <= 0)
        ossl_raise(eX509ReqError, NULL);
    ossl_str_adjust(str, p);

    return str;
}