Closes#20084
This is the flow that this implements:
1. A logged-in user clicks "Logout".
2. If they didn't auth via SAML, just do normal logout. Otherwise:
3. Form a LogoutRequest and redirect the user to
https://idp.example.com/slo-endpoint?SAMLRequest=<LogoutRequest here>
4. The IdP validates the LogoutRequest, terminates its own user session
and redirects the user to
https://thezuliporg.example.com/complete/saml/?SAMLRequest=<LogoutResponse>
with the appropriate LogoutResponse. In case of failure, the
LogoutResponse is expected to express that.
5. Zulip validates the LogoutResponse and if the response is a success
response, it executes the regular Zulip logout and the full flow is
finished.
Adds the ability to set a SAML attribute which contains a
list of subdomains the user is allowed to access. This allows a Zulip
server with multiple organizations to filter using SAML attributes
which organization each user can access.
Cleaned up and adapted by Mateusz Mandera to fit our conventions and
needs more.
Co-authored-by: Mateusz Mandera <mateusz.mandera@zulip.com>
Instead of plumbing the idp to /complete/saml/ through redis, it's much
more natural to just figure it out from the SAMLResponse, because the
information is there.
This is also a preparatory step for adding IdP-initiated sign in, for
which it is important for /complete/saml/ to be able to figure out which
IdP the request is coming from.
There are a few outstanding issues that we expect to resolve beforce
including this in a release, but this is good checkpoint to merge.
This PR is a collaboration with Tim Abbott.
Fixes#716.