thepraandClaude Opus 5.5
8f4d6cbdf9
tools/pasture/run.sh starts PrivaPub, GoToSocial and Mongo on one podman network behind Caddy's internal CA, and interop.sh drives both through their own client APIs: follows (one to a locked account), posts, CW, replies, likes, boosts, DMs, edits, deletes and unfollow. All 25 checks pass, three fresh runs in a row. - Federation:AcceptAnyCertificate joins the two test-network switches; startup refuses all three in Production. - WebFinger falls back to http only when AllowPlainHttp is on. - A bootstrap logger, so a failure before the host is built is no longer silent. - P4 is ticked in the roadmap, with what has not been run live (Lemmy, a Mastodon circle member). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB
134 lines
7.7 KiB
Markdown
134 lines
7.7 KiB
Markdown
# Federation
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PrivaPub is an ActivityPub server written in C#. This document follows
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[FEP-67ff](https://codeberg.org/fediverse/fep/src/branch/main/fep/67ff/fep-67ff.md) and describes how it federates.
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## Supported federation protocols and standards
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- [ActivityPub](https://www.w3.org/TR/activitypub/) (server-to-server)
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- [WebFinger](https://webfinger.net/)
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- [HTTP Signatures](https://datatracker.ietf.org/doc/html/draft-cavage-http-signatures), `rsa-sha256` / `hs2019` with RSA keys
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- [NodeInfo](https://nodeinfo.diaspora.software/) 2.0 and 2.1
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## Tested against
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- **GoToSocial 0.22.1, end to end.** It runs in a private network on the workstation (`tools/pasture/`) and is driven
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through its own client API. Checked both ways:
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- follows, including to a locked account;
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- public posts with a content warning;
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- replies with notifications;
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- likes and boosts;
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- direct messages;
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- edits and deletes;
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- unfollow.
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- **Mastodon, Misskey, Lemmy and PeerTube, by unit tests only.** The tests feed the parser documents written in each
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server's shape. No live exchange with any of them has run yet.
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## Supported FEPs
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- [FEP-67ff: FEDERATION.md](https://codeberg.org/fediverse/fep/src/branch/main/fep/67ff/fep-67ff.md)
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- [FEP-f1d5: NodeInfo in Fediverse Software](https://codeberg.org/fediverse/fep/src/branch/main/fep/f1d5/fep-f1d5.md)
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- [FEP-2c59: Discovery of a WebFinger address from an ActivityPub actor](https://codeberg.org/fediverse/fep/src/branch/main/fep/2c59/fep-2c59.md)
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Planned: FEP-1b12 (communities), FEP-8fcf (followers synchronisation), FEP-5feb (`indexable`), FEP-7628 (Move),
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FEP-044f (quotes).
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## Actors
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Every account is an *avatar*: one private login can own several, and they are deliberately unlinkable. Nothing in an
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actor document, a collection, NodeInfo or a delivery relates two avatars of the same login.
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| Thing | Address |
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| Actor (Person, Group, Application) | `/peasants/{name}` (`/users/{name}` redirects) |
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| Inbox | `/peasants/{name}/mouth` |
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| Outbox | `/peasants/{name}/anus` |
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| Shared inbox | `/human-centipede` |
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| Followers / following | `/peasants/{name}/groupies`, `/peasants/{name}/stalking` |
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| Objects | `/peasants/{name}/scribbles/{id}` |
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| Activities | `/peasants/{name}/grunts/{id}` |
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| Direct-message context | `/peasants/{name}/whispers/{id}` |
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| Profile and post pages | `/@{name}`, `/@{name}/{id}` |
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The names are the project's own and are stable; resolve actors through WebFinger, not by guessing a path.
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- The key is `{actor}#main-key`, RSA 2048, served as SPKI PEM with `owner` set to the actor.
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- `published` on an actor is truncated to the day. `indexable` is `false`.
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- The instance actor is `/peasants/privapub` (type `Application`). It signs every fetch PrivaPub makes, so no avatar's key
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is used to read another server's content.
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## Groups
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A group is either a **community** or a **circle**.
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- A **community** follows [FEP-1b12](https://codeberg.org/fediverse/fep/src/branch/main/fep/1b12/fep-1b12.md). Posts
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addressed to it (in `to`, `cc` or `audience`) are accepted according to its posting policy (followers, anyone, or
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moderators only) and the group `Announce`s the whole activity, with `audience` set, to its followers. A new post is
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also announced as an object so Mastodon shows it. Updates and deletes of community content are announced too. A
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top-level post is a `Page` with a `name`. Members are counted at `/flock`; moderators are listed at `/wardens`, which
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the actor's `attributedTo` points to, with `postingRestrictedToMods` as Lemmy expects. A mention of a community posts into it.
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- A **circle** is private. Its actor is not discoverable and every follow is a request. Its posts are addressed to the
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circle and its members collection, delivered to each member's own inbox and never announced. They are served only
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to a signed request from a member, or from the instance actor of a member's server; anyone else gets 404. A
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Mastodon member's replies reach only the people they mention.
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- Announces from **remote** groups (Lemmy communities) are followed through to the activity: the object is fetched
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from its own origin, never taken from the announce.
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## Activities
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Received:
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| Activity | Effect |
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| `Follow` | follows an avatar or community; `Accept` is sent unless the community approves members by hand |
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| `Accept{Follow}`, `Reject{Follow}` | completes or ends a follow an avatar requested |
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| `Undo{Follow, Like, Announce}` | reverses it |
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| `Create{Note, Article, Page, Question, …}` | stored when a local avatar follows the author, is addressed or mentioned, when it replies to a local post, or when it is addressed to a community the author follows; a public parent is fetched to complete the thread |
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| `Update{Note}` | replaces the content; the previous version is kept |
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| `Update{Person}` | refetches the actor |
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| `Like` | counted and notified, on posts the liker could see |
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| `Announce` | counted and notified for local posts; shown to followers of the announcer, with the original refetched from its origin |
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| `Delete` | deletes the object, or the actor and its follows |
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| `Flag` | becomes a report for this server's moderators |
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Sent: `Follow`, `Undo{Follow}`, `Create{Note}`, `Update{Note}`, `Update{Person}`, `Delete{Tombstone}`, `Accept{Follow}`,
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`Reject{Follow}`, `Like`, `Announce` and their `Undo`, `Flag`. A deleted post answers 410 with a `Tombstone`.
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- **Attachments** are `Document`s with `mediaType`, `name` (alt text), `blurhash`, `focalPoint`, `width` and `height`.
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Uploaded files have all metadata removed.
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- **Pinned posts** are the actor's `featured` collection (`/trophies`); `featuredTags` is `/tattoos`.
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- **Blocks are never sent.** A blocked account is sent `Reject{Follow}` if it followed, and is unfollowed.
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- **Reports** are sent as `Flag` by the instance actor, never by the reporting account.
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A `Create`'s `Note` carries Mastodon's `content`, `contentMap`, `summary` and `sensitive`, plus `Mention` and `Hashtag`
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tags. A post's title becomes `name` and is also the first, bold line of `content`, because Mastodon does not show
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`name`. A content warning without its own text uses the title, or "Content warning".
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Visibility is expressed in `to`/`cc` the way Mastodon does it: public, unlisted, followers-only and direct. Inbound
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followers-only posts are recognised by the author's own `followers` collection.
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## Local-only posts
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Posts with a location (shown to nearby users of this server) never leave the server, in any form.
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## Security rules a peer will notice
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- **Signatures.** Inbox POSTs must be signed over `(request-target)`, `host`, `digest` and `date` (or `(created)`). The
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date may be at most one hour old and fifteen minutes ahead. A bad signature gets 401, malformed input 400, an accepted
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activity 202, too many requests 429. Activities are processed after the 202.
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- **Origins.** An actor document is accepted only from the address it names as its `id`. A key only if its actor lists
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it with `owner` set to the actor and on the actor's origin. An activity's `id`, and any object it creates, updates or
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deletes, must be on its actor's origin. An embedded object from another origin is fetched from that origin.
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- **Fetching.** All fetches are signed by the instance actor. They go only to public addresses, follow at most three
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redirects and read at most 1 MB.
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- **HTML.** Received HTML is sanitised to Mastodon's allowlist.
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- **Delivery.** Failed deliveries are retried with Mastodon's backoff (16 attempts). A host that keeps failing is paused,
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starting at an hour and growing to a week.
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## Known limitations
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- Polls and custom emoji are not implemented.
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- Remote media is fetched through this server's proxy when a local client displays it.
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- Collections expose counts, not members.
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- Only `rsa-sha256`-style keys are verified. RFC 9421 signatures are planned.
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