class OpenSSL::Timestamp::Factory

static VALUE
ossl_tsfac_create_ts(VALUE self, VALUE key, VALUE certificate, VALUE request)
{
    VALUE serial_number, def_policy_id, gen_time, additional_certs, allowed_digests;
    VALUE str;
    STACK_OF(X509) *inter_certs;
    VALUE tsresp, ret = Qnil;
    EVP_PKEY *sign_key;
    X509 *tsa_cert;
    TS_REQ *req;
    TS_RESP *response = NULL;
    TS_RESP_CTX *ctx = NULL;
    BIO *req_bio;
    ASN1_INTEGER *asn1_serial = NULL;
    ASN1_OBJECT *def_policy_id_obj = NULL;
    long lgen_time;
    const char * err_msg = NULL;
    int status = 0;

    tsresp = NewTSResponse(cTimestampResponse);
    tsa_cert = GetX509CertPtr(certificate);
    sign_key = GetPrivPKeyPtr(key);
    GetTSRequest(request, req);

    gen_time = ossl_tsfac_get_gen_time(self);
    if (!rb_obj_is_instance_of(gen_time, rb_cTime)) {
        err_msg = "@gen_time must be a Time.";
        goto end;
    }
    lgen_time = NUM2LONG(rb_funcall(gen_time, rb_intern("to_i"), 0));

    serial_number = ossl_tsfac_get_serial_number(self);
    if (NIL_P(serial_number)) {
        err_msg = "@serial_number must be set.";
        goto end;
    }
    asn1_serial = num_to_asn1integer(serial_number, NULL);

    def_policy_id = ossl_tsfac_get_default_policy_id(self);
    if (NIL_P(def_policy_id) && !TS_REQ_get_policy_id(req)) {
        err_msg = "No policy id in the request and no default policy set";
        goto end;
    }
    if (!NIL_P(def_policy_id) && !TS_REQ_get_policy_id(req)) {
        def_policy_id_obj = (ASN1_OBJECT*)rb_protect(obj_to_asn1obj_i, (VALUE)def_policy_id, &status);
        if (status)
            goto end;
    }

    if (!(ctx = TS_RESP_CTX_new())) {
        err_msg = "Memory allocation failed.";
        goto end;
    }

    TS_RESP_CTX_set_serial_cb(ctx, ossl_tsfac_serial_cb, &asn1_serial);
    if (!TS_RESP_CTX_set_signer_cert(ctx, tsa_cert)) {
        err_msg = "Certificate does not contain the timestamping extension";
        goto end;
    }

    additional_certs = ossl_tsfac_get_additional_certs(self);
    if (rb_obj_is_kind_of(additional_certs, rb_cArray)) {
        inter_certs = ossl_protect_x509_ary2sk(additional_certs, &status);
        if (status)
                goto end;

        /* this dups the sk_X509 and ups each cert's ref count */
        TS_RESP_CTX_set_certs(ctx, inter_certs);
        sk_X509_pop_free(inter_certs, X509_free);
    }

    TS_RESP_CTX_set_signer_key(ctx, sign_key);
    if (!NIL_P(def_policy_id) && !TS_REQ_get_policy_id(req))
        TS_RESP_CTX_set_def_policy(ctx, def_policy_id_obj);
    if (TS_REQ_get_policy_id(req))
        TS_RESP_CTX_set_def_policy(ctx, TS_REQ_get_policy_id(req));
    TS_RESP_CTX_set_time_cb(ctx, ossl_tsfac_time_cb, &lgen_time);

    allowed_digests = ossl_tsfac_get_allowed_digests(self);
    if (rb_obj_is_kind_of(allowed_digests, rb_cArray)) {
        int i;
        VALUE rbmd;
        const EVP_MD *md;

        for (i = 0; i < RARRAY_LEN(allowed_digests); i++) {
            rbmd = rb_ary_entry(allowed_digests, i);
            md = (const EVP_MD *)rb_protect(ossl_evp_get_digestbyname_i, rbmd, &status);
            if (status)
                goto end;
            TS_RESP_CTX_add_md(ctx, md);
        }
    }

    str = rb_protect(ossl_to_der, request, &status);
    if (status)
        goto end;

    req_bio = (BIO*)rb_protect(ossl_obj2bio_i, (VALUE)&str, &status);
    if (status)
        goto end;

    response = TS_RESP_create_response(ctx, req_bio);
    BIO_free(req_bio);

    if (!response) {
        err_msg = "Error during response generation";
        goto end;
    }

    /* bad responses aren't exceptional, but openssl still sets error
     * information. */
    ossl_clear_error();

    SetTSResponse(tsresp, response);
    ret = tsresp;

end:
    ASN1_INTEGER_free(asn1_serial);
    ASN1_OBJECT_free(def_policy_id_obj);
    TS_RESP_CTX_free(ctx);
    if (err_msg)
        rb_exc_raise(ossl_make_error(eTimestampError, rb_str_new_cstr(err_msg)));
    if (status)
        rb_jump_tag(status);
    return ret;
}