Restrict attribute values based on SP entity?

[Peter Schober]

* Brian Mathis <brian.mathis at gmail.com> [2016-11-15 17:56]:
> I need to restrict entity1 to only send "abc", while entity2 can only
> send "xyz", and be scalable up to entity3, 4, etc...

If you need it to scale I guess you're left with handling that within
application code. Unless you consider regularly adding to the
attribute-policy.xml and potentially restarting shibd to be
sufficiently scalable.
As to getting it right: If you supplied examples it would be easier to
say what's wrong.
Either way, you will have to mess with that rule:
  <afp:AttributeRule attributeID="*" permitAny="true"/>
otherwise everything else you do will be futile, IIRC.
-peter