Redirect after logout about drupalauth HOT 7 OPEN

This code is golden. Now I have managed to successfully do a SLO initiated from 
the SP, logging out from all SPs and IdP and returning to SP where it was 
initiated. This should be included in the project.

With these changes, it logs out from the SP but not from the IdP site, while 
the browser remains on the SP (what I want). Without these changes, it logs out 
from both but the browser goes to the IdP (what I do not want). Both sites are 
Drupal 7 sites. Is there a way to get logged out from both with the browser 
remaining on the SP?

"unset($_SESSION['uid']);" often causes a warning: "Undefined variable: 
_SESSION in sspmod_drupalauth_Auth_Source_External->logout() ...". Check if set:

if (isset($_SESSION['uid'])) {
   unset($_SESSION['uid']);
}

Yesterday, I wrote (in #2): "With these changes, it logs out from the SP but 
not from the IdP site, while the browser remains on the SP." Having considered 
it, I think this is the required behaviour as more SPs can be linked to the 
same IdP, therefore it would be bad to log out from the IdP too.

For me it logs out from the IdP also and sends the logout request to all active 
SPs. I think that's how it's supposed to work, if user would logout only from 
one SP, it would be easy to forget another SP active. If the user doesn't want 
to logout from IdP he can just close the browser window of the SP, leaving the 
IdP and all other SPs active.

Re #5: How do you reach that? Did you change the code further? 

The above code worked for us.  After applying the code, when I logout from an 
SP, I get logged out from Drupal and all the other SPs. Thanks a lot for the 
code.

We also needed IDP initated logout support; i.e. whenever I logout from Drupal, 
I should get logged out from all the other SPs.  I have extended the above code 
to add support for IDP initiated logout.  I have attached a patch that contains 
the changes for drupalauth SimpleSAMLPHP module.

Instead of changing the drupalauth4ssp Drupal module, I have added the 
necessary Drupal code in a custom module.  This code is inside the second 
attachment.

Thanks,
Adnan