OpenSSL::ASN1::Constructive#to_der

static VALUE
ossl_asn1cons_to_der(VALUE self)
{
    VALUE ary, str;
    long i;
    int indef_len;

    indef_len = RTEST(ossl_asn1_get_indefinite_length(self));
    ary = rb_convert_type(ossl_asn1_get_value(self), T_ARRAY, "Array", "to_a");
    str = rb_str_new(NULL, 0);
    for (i = 0; i < RARRAY_LEN(ary); i++) {
        VALUE item = RARRAY_AREF(ary, i);

        if (indef_len && rb_obj_is_kind_of(item, cASN1EndOfContent)) {
            if (i != RARRAY_LEN(ary) - 1)
                ossl_raise(eASN1Error, "illegal EOC octets in value");

            /*
             * EOC is not really part of the content, but we required to add one
             * at the end in the past.
             */
            break;
        }

        item = ossl_to_der_if_possible(item);
        StringValue(item);
        rb_str_append(str, item);
    }

    return to_der_internal(self, 1, indef_len, str);
}