Ref T5685. Currently we just 403 on an invalid token, but we can be a little more helpful.
The issues here are:
- If we do redirect you on this page and something goes wrong, you might get stuck in a redirect loop.
- If we don't redirect you, copy/pasting the link to someone (or reloading the page) gives them a pretty confusing result, since the link doesn't work any more. Prior to this diff, they get a 403.
To mitigate this, do a little better than a bare 403: give them a link to auth and generate a new URI for the file.
If this is still confusing, the next best thing I can come up with is something like this:
- Put some modulous of the timestamp in the URI.
- If the current time is within 2 seconds of the generation time, show this dialog.
- Otherwise, redirect.
That seems like it would be okay, but I worry that "2" has to be small (so links you copy/paste -> chat -> click still work) and a small value means that a small amount of clock skew breaks things. We could use the database clock, but ehhh.
Other ideas:
- Put a hash of the remote IP in the URI, redirect if it doesn't match. Fails for companies behind a NAT gateway but should work in a lot of other cases.
- Just redirect always, there's no reason it should ever loop and browsers don't really do anything bad when there's a loop (they'll show an error after too many redirects).
I'm leaning toward letting this stabilize in the wild for a bit, then trying "always redirect".
