I am publishing a small #ActivityPub / #fediverse project: https://fietkau.software/webfinger_canary and @canary

Marcus Rohrmoser 🌻

Hi @julian,
but how do you (they)? The actor just doesn't know the handle domain. Strictly spoken not eve the local part but there seems to be consensus to use the preferredUserName. Serious question.

Julian Fietkau

@mro You do a WebFinger request on the AP host domain, and its response will give you a subject with the correct handle domain. See for example this account: https://toot.kif.rocks/@team and its WebFinger response: https://toot.kif.rocks/.well-known/webfinger?resource=acct:[email protected] This is a Mastodon split-domain setup.

The process is described here: https://www.w3.org/community/reports/socialcg/CG-FINAL-apwf-20240608/#reverse-discovery (step 4 is important for this)

Marcus Rohrmoser 🌻

Hi @julian,
the document is a report from @evanprodromou mid 2024, not a standard and not part of #AP. And at step 4 it reads "4. Optionally:". But it proposes a solution - thanks for bearing with me. So the #rfc7033 subject: "acct:[email protected]" would be it.

Feels hacky, IMO the profile should be explicit about the handle just like the way round #webfinger is explicit about the actor id.

Julian Fietkau

@mro There is a suggested FEP to include the WebFinger resource in the actor document: https://codeberg.org/fediverse/fep/src/branch/main/fep/2c59/fep-2c59.md But I have not seen it implemented anywhere. In the meantime, the hacky approach works and is reasonably popular.

I don't want to push you into supporting something you don't want to support. Just keep in mind that your software is showing different account handles than Mastodon for some users.

Do you want me to add Seppo to the overview table anyway?

Marcus Rohrmoser 🌻

Hi @julian,
a pity @silverpill doesn't use https://www.w3.org/TR/xmlschema-2/#anyURI and doesn't keep the acct:[email protected] from https://www.rfc-editor.org/rfc/rfc7565.html.

And yes, I'd be happy if you add #Seppo!

Julian Fietkau

@mro I see now that you were active in the discussion thread: https://socialhub.activitypub.rocks/t/fep-2c59-discovery-of-a-webfinger-address-from-an-activitypub-actor/3813 my bad for retreading ground you already know.

@silverpill

silverpill

@mro @julian Could you elaborate? Where should I use anyURI?

silverpill

@mro Is it related to me trying to follow Seppo actor?

I just received a Create(Note) where Note doesn't have attributedTo property (but is has actor property, which should be used only on activities afaik).

Osma A

This may look like a nerdy nitpick when it is positioned as discussion of subdomains. However, the lack of a widely accepted split-domain solution also makes it impossible to implement an ActivityPub endpoint which would use user handles matching their email addresses (email works by MX records, missing from ActivityPub and WebFinger), as well as hosting multiple domains on one server.

@takahe tried this. It exposes a lot of issues in other servers.

@julian @canary

Julian Fietkau

@osma Indeed! I have collected the information I could find about various server implementations at https://correct.webfinger-canary.fietkau.software/#implementation-status. @takahe remains the gold standard, although everyone is held back by several popular servers using handles to identify actors rather than AP IDs. Decoupling handles from database schemas would open up a lot of things, like user name and domain changes over time.

Caesar

@julian @canary thanks for this great document and tool!

I have two questions.

1. In a few places you link to a SocialCG document (https://www.w3.org/community/reports/socialcg/CG-FINAL-apwf-20240608/) but it's 404 now. Do you have an up to date link?

2. You mention several times that Mastodon allows users to use a different webfinger domain from the host domain. I can't find any documentation. As a user, how would I configure this?

Julian Fietkau

@caesar

1. Uhhh... that's the official published report URL that's 404'ing, that's probably not good. Maybe @w3c accidentally moved some files around? @evan do you know what's going on? In the meantime, here's a mirror: https://swicg.github.io/activitypub-webfinger/

2. For Mastodon, this is currently a server-level setting. See the "Docs" link in https://correct.webfinger-canary.fietkau.software/#implementation-status for more details. I would love to see this grow into a user setting to let people change handles! But that's far future for Mastodon, if ever.

Caesar

@julian thanks! And unfortunately that's the answer I expected about Mastodon, though I briefly got my hopes up that I might be able to use my own domain without self-hosting