ADFS 2.0 - How to know on the STS which RP sent you there

Question

We are trying to configure and develop a solution to properly brand the login site accordingly to where the user is coming from. The users are coming from relying parties, but they all use the same login site (STS).

Is there any way I can set a property from the RP that will be accessible from the STS? The wtrealm property is changed once it passes through the ADFS webservice. The RU parameter of the wctx is relative to the site it is redirected to, so it wont help.

I just need the STS to be aware of where the user is coming from, that way I add the necessary style sheets necessary.

Answer 1

Ended up baking an additional parameter into the query string via the ADFS webservice. Just edited the global.asax file and added the necessary parameter from there, then told the STS to pick up on this variable.