Send path to IDP (referer_url)

[Michael Schwartz]

Shib Gurus,

We have a use case where it would be really handy to have the 
referer_url available to the IDP. We are setting up an Apache proxy, 
where each folder proxies to a different backend application. For 
example:
    /idpA --> http://192.168.0.1
    /idpB --> http://192.168.0.2

Our SAML IDP is an Asimba SAML proxy, which is providing the discovery 
service. It would be really convenient if we could use the path of the 
requested URI to automatically route the request to the respective 
backend IDP.

Using the EntityID is not an option, because we only have one SAML SP 
for the Apache proxy.

Is there any way to pass the path information in an HTTP header to the 
IDP, or any other feasible solution?

Thanks in advance!!!

- Mike