In a SAS stored process, is there a way to identify the server which called it via ajax

Question

I have a public Stored process (STP) in which I would like to be able to identify which page is calling it, via ajax.

The STP is momentarily set to run with a guest account and is thus public.

I thought to do it by inserting a secret Key in the STP variables.
But that key can be changed by users in the url.

Is there a method to identify that without leaving the possibility to users to change it?

Maybe there is a reserved STP variable that tells the origin of the request (like the server name or ip or something identifiable)?
But I could not find any among those:

_debug
_grafloc
_htcook
_htua
_program
_reqmeth
_rmtaddr
_rmthost
_srvname
_srvport
_url
_userlocale
_username
_version

http://support.sas.com/rnd/itech/doc9/dev_guide/stprocess/reserved.html

Answer 1

Changing my answer as I was previously incorrect. You CAN get this information (via _htrefer) but it requires a configuration change to your SAS server. As per documentation:

_HTREFER: Specifies the address of the referring page. This variable is not set by default but can be enabled in the params.config file.

It's worth noting that no method can ever be 100% reliable as end users can always manipulate their requests.