How to block subsequent steps if user isn't logged in?

[gremo]

In the middle of my flow I'm asking the user to login:

1. The flow uses allowRedirectAfterSubmit
2. "Step 3" will ask to login or register. After login, I redirect the user to the URL of the step 3.
3. "Step 3" is skipped when the user is already logged in

This seems to work. But how to "block" subsequent steps if user is not logged in?

[gremo]

@craue still relevant as I use you bundle in some projects. Any help?