I'm setting up a small forum for a client, and we're testing out different platforms. One rare requirement is that the forum should support SAML login from several IDPs. In our other applications this is handled through apache + shibboleth, which then passes on a few extra HTTP headers to the underlying application (i.e. REMOTE_USER, EMAIL, etc). I've so far failed to find a platform that supports this, either natively or through plugins. Any tips?