MSC2398: proposal to allow mxc:// in the "a" tag within messages

[eras]

Currently message events (m.room.message) can contain formatted data in its formatted_body field, if the format of the message is org.matrix.custom.html. This is a proposal to allow the mxc:// schema to appear also for a tags in addition to just img tags currently permitted (in fact, required).

Rendered: https://github.com/eras/matrix-doc/blob/MSC2398-mxc-for-a-tags/proposals/2398-allow-mxc-within-message-links.md

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SCT:

Implementation: Not required. Feature appears to be self-contained enough to make sense as-is. ~TravisR

~~FCP tickyboxes~~

[turt2live]

@eras also slightly annoying, but the proposal needs to be signed off so we can merge it: https://github.com/matrix-org/matrix-doc/blob/master/CONTRIBUTING.rst#sign-off

[eras]

Updated.

Changes:

• Added note about alternatives per @KitsuneRal 's comment
• Removed changes to instant_messaging.rst per @turt2live 's comment
• Added a Signed Off -line to the commit message per @turt2live 's comment

[eras]

So it came to me that an implementation should be careful when implementing this.

In particular, when a web-based client opens a HTML document from the same domain as the Matrix API, the document can probably use JavaScript to make requests with the user's credentials.

[ShadowJonathan]

@eras i believe those thoughts would be best served under the "Security Considerations" header in the proposal :+1:

[turt2live]

sorry this got stuck :(

@mscbot fcp merge

[mscbot]

Team member @mscbot has proposed to merge this. The next step is review by the rest of the tagged people:

• [ ] @dbkr
• [x] @uhoreg
• [x] @turt2live
• [x] @ara4n
• [x] @anoadragon453
• [x] @richvdh
• [ ] @erikjohnston
• [x] @KitsuneRal

Concerns:

• ~~add explicit text about transforming mxc link to https~~
• How do you implement this on web clients with MSC3916

Once at least 75% of reviewers approve (and there are no outstanding concerns), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for information about what commands tagged team members can give me.

[dbkr]

@mscbot concern add explicit text about transforming mxc link to https

[dbkr]

@mscbot resolve add explicit text about transforming mxc link to https

[mscbot]

:bell: This is now entering its final comment period, as per the review above. :bell:

[erikjohnston]

@mscbot concern How do you implement this on web clients with MSC3916

Sorry, but sounds like we need to double check the above before we can land this. Hopefully someone can just confirm its possible. c.f. https://github.com/matrix-org/matrix-spec-proposals/pull/2398#discussion_r1450863444

[mscbot]

The final comment period, with a disposition to merge, as per the review above, is now complete.

[turt2live]

(FCP is not complete because there are outstanding concerns - see https://github.com/matrix-org/mscbot-python/issues/3 )

[turt2live]

The outstanding concern on this does not appear easily resolved - I'm cancelling FCP or returning this MSC back to its pre-FCP state (whichever the bot lets me do) pending further work in the area of media linking. It feels like changes may be required that would warrant a new FCP call anyways.

@mscbot fcp cancel

[mscbot]

This proposal is not in FCP nor has had FCP proposed.