Getting query string from LUA in action context


We have a project that does some calculations on HAproxy and modifies request headers with LUA before passing it to backends. This is done in action context (core.register_action(“action”, {“http-req”}, function (txn) … end)); Some calculations are based on arguments passed on query string. Is there a way to access query string or it’s parsed arguments from action context? I only see HTTP.req_set_query() function, but not req_get_query().
It looks like it’s not implemented. I don’t see anything related to it in a source code (hlua.c:req_get_).
Do you have any plans on implementing this? Or may be I’m doing something wrong?