OpenSSL::Timestamp::Request#to_der

static VALUE
ossl_ts_req_to_der(VALUE self)
{
    TS_REQ *req;
    TS_MSG_IMPRINT *mi;
    X509_ALGOR *algo;
    const ASN1_OBJECT *obj;
    ASN1_OCTET_STRING *hashed_msg;

    GetTSRequest(self, req);
    mi = TS_REQ_get_msg_imprint(req);

    algo = TS_MSG_IMPRINT_get_algo(mi);
    X509_ALGOR_get0(&obj, NULL, NULL, algo);
    if (OBJ_obj2nid(obj) == NID_undef)
        ossl_raise(eTimestampError, "Message imprint missing algorithm");

    hashed_msg = TS_MSG_IMPRINT_get_msg(mi);
    if (!ASN1_STRING_length(hashed_msg))
        ossl_raise(eTimestampError, "Message imprint missing hashed message");

    return asn1_to_der((void *)req, (int (*)(void *, unsigned char **))i2d_TS_REQ);
}