Apache Shib SP and target URL rewrite

[Peter Schober]

* Jan Vilhuber <JVilhuber at absolute.com> [2017-03-09 11:33]:
> So how can I get the assertion (or at least attributes from the
> assertion) down to my webapp? Is there an 'internal session hook'? I
> looked at various assertion export options and none were all that
> great :-/ It's entirely plausible I add some local cgi script that
> looks at cgi environment variable and somehow passes that on to an
> external service, but that still leaves me wondering which internal
> call I can use for that. I'll go back to the docs and read some
> more, but if you have advice, I'd much appreciate it (and I
> appreciate it so far; boy do I feel dumb now that I missed this was
> a redirection, not an internal call).

Not sure what you're looking for. The Shib exposes selected elements
from the assertion via environment variables or request headers.
So anything that can get at e.g. REMOTE_ADDR as as by Apache httpd can
get attributes or NameIDs from the SAML assertion. The wiki covers
access to that data for many difference platforms/APIs.
https://wiki.shibboleth.net/confluence/display/SHIB2/NativeSPAttributeAccess#NativeSPAttributeAccess-Tool-SpecificExamples

If your own code referenced in the Shib SP's sessionHook in a place
that's covered by the Shib session (anywhere, if sessions are created
with / as the cookie path, which should be the default) you'll also
have full access to those enviroment variables there, and can redirect
(or stop people in their tracks) as desired.

So there seems to be a more fundamental misunderstanding in how one
interfaces with the Shibboleth SP software, possibly preserved due to
complete lack of technical details on how you're intending to access
the data.
-peter