matrix.to permalinks don't work for self-hosted instance

[TheLastProject]

Description

Since 9b8e127, share buttons link to matrix.to. However, for self-hosted instances that don't communicate with riot.im, this makes the shared links useless as users cannot connect with them. It may even be considered a security risk, because users may try to log in on one of the links shown at matrix.to, leaking their credentials for the private instance.

Steps to reproduce

• Click share in a self-hosted Riot-web connected to a self-hosted Matrix
• Notice the link is formatted like https://matrix.to/#/!usfAvrMVqltHkpWfgW:example.com?via=example.com
• Send the matrix.to link to someone
• Notice that they can never join with any of the options because they link to Riot.im, which our server doesn't federate with

Describe how what happens differs from what you expected.

The link should, well, work. And the old link before this change would work on self-hosted instances.

Log: not sent

Version information

• Platform: Web

For the web app:

• Browser: Firefox 64.0.2
• OS: macOS
• URL: Riot-web 0.17.8

[jryans]

Note that if you paste the matrix.to link in a Matrix room and the receiver clicks it in Riot, then their Riot should just navigate to the room, rather than displaying the client chooser UI.

[turt2live]

Also you can type /goto https://matrix.to/... and it'll work

[TheLastProject]

Sure, in those situations it works, but it doesn't in other situations, such as people sharing a link to a colleague over email, because matrix.to itself will point to the wrong location. Especially for non-technical users this behaviour is very confusing.

[lampholder]

Options:

• allow self-hosted riot instances' share UX to use a configurable link root (i.e. let https://riot.coolbrand.horse generate https://riot.coolbrand.horse/#/room/!whatever:coolbrand.horse links instead of https://matrix.to ones
• enhance matrix.to (and riot) to play more nicely with self-hosted riots (I'm not sure what this would look like)