oid=

static VALUE
ossl_x509ext_set_oid(VALUE self, VALUE oid)
{
    X509_EXTENSION *ext;
    ASN1_OBJECT *obj;
    char *s;

    s = StringValuePtr(oid);
    obj = OBJ_txt2obj(s, 0);
    if(!obj) obj = OBJ_txt2obj(s, 1);
    if(!obj) ossl_raise(eX509ExtError, NULL);
    GetX509Ext(self, ext);
    X509_EXTENSION_set_object(ext, obj);

    return oid;
}