Do not prevent login if .well-known response is invalid

[p12tic]

The current code results in confusing behavior under the following circumstances:

• Homeserver is guessed correctly from the Matrix ID

• The server returns invalid (e.g. HTTP 200 with empty body) response for .well-known data

The user will be presented with "Autodiscovery failed. Received malformed response" message even though all details are entered correctly. Login button will not work. The only workaround is to edit the home server field a few times so that homeserverChanged() and checkHomeserverVersion() would be invoked.

This is not optimal, especially because autodiscovery based on .well-known is optional. The solution is to always invoke checkHomeserverVersion() even when autodiscovery fails due to any reason.

checkHomeserverVersion() will check the home server against required Matrix API endpoints. If this fails, user will be presented with error messages instructing to check home server URL. Accordingly, allowing to continue in case of failed autodiscovery does not reduce clarity of errors presented to the user.

[deepbluev7]

The Matrix specification is quite explicit, that the user should be provided with an error message, if .well-known discovery fails in those cases and enter the homeserver url themselves: https://spec.matrix.org/latest/client-server-api/#server-discovery . I'm a bit concerned, that just dropping that error information will lead to even more misconfigured homeservers. In both of these cases the homeserver is misconfigured, since it provides a .well-known with invalid content. If this is very widespread, then working around that in Nheko would make sense, but so far those servers seem to be in the minority?

Do you know why those servers return an empty body with a HTTP 200?

And as you said, the .well-known should be optional, but then you need to manually enter the homeserver address, which should still work.

[p12tic]

Thanks for feedback. I agree. I will think of a way to keep error message in case autodiscovery fails.

[p12tic]

Do you know why those servers return an empty body with a HTTP 200?

I don't know, probably misconfiguration.

And as you said, the .well-known should be optional, but then you need to manually enter the homeserver address, which should still work.

Just one data point, in my particular case homeserver address was guessed correctly. Putting @username:homeserver into matrix ID correctly guessed homeserver as the home server. This is what was the most confusing - if home server was guessed incorrectly, then I would have edited it and allowed to login. Now there was nothing to edit and I managed to log in only after I looked into the source code.

[deepbluev7]

Just one data point, in my particular case homeserver address was guessed correctly. Putting @username:homeserver into matrix ID correctly guessed homeserver as the home server. This is what was the most confusing - if home server was guessed incorrectly, then I would have edited it and allowed to login. Now there was nothing to edit and I managed to log in only after I looked into the source code.

Okay, that makes a bit more sense to me now. You basically get prompted to enter a value, that was correctly guessed, which is confusing. I guess it does make sense to continue in that case, since the user will just enter the same value anyway, but maybe it should instead be a prompt like "The server is misconfigured, but example.com might be your homeserver. Continue with the login?"?