Files
SocialPub/PrivaPub/Federation/Outbox/GroupDistributor.cs
T
thepraandClaude Opus 5.5 a5d9a89445 Communities follow FEP-1b12, circles federate to their members only
Communities:
- a post addressed to a community (to, cc or audience) is accepted
  according to its posting policy - followers, anyone, or moderators -
  and GroupDistributor announces the whole activity with `audience` to
  the community's followers, plus the object for new posts so Mastodon
  shows them; updates and deletes of community content are announced too;
- top-level posts are Pages with a name (the title, or a headline from
  the text); /flock counts members, /wardens lists moderators;
- a Mastodon client posts into a community by mentioning it, or into a
  remote group, which sets `audience`;
- an Announce of an activity from a remote group a persona follows (Lemmy)
  is followed through: the object is fetched from its own origin, kept with
  its AudienceURI, and fanned out to the group's local followers; updates
  are applied in place and deletes checked against the origin.

Circles stop being local-only: an undiscoverable Group actor whose follows
are all requests the owner approves; posts addressed to the circle and its
/flock and delivered to members' own inboxes, never announced, never
public; a remote member's post into the circle is accepted from members
only. SignedFetchAuthorizer serves circle posts and collections only to a
signed request from a member or a member server's instance actor - 404 for
anyone else. Circles never surface in search, lookups, mentions, account
ids or profile pages.

Federation:SecureMode requires a valid signature on every GET under
/peasants except the instance actor. Group forms take a posting policy.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB
2026-10-01 12:30:57 +02:00

49 lines
1.6 KiB
C#

using PrivaPub.Federation.Actors;
using PrivaPub.Federation.Rendering;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json.Nodes;
namespace PrivaPub.Federation.Outbox
{
public interface IGroupDistributor
{
Task Announce(LocalActor group, JsonObject activity, string objectUri, bool isNewPost, CancellationToken token);
}
public class GroupDistributor : IGroupDistributor
{
readonly IDeliveryService _delivery;
public GroupDistributor(IDeliveryService delivery)
{
_delivery = delivery;
}
public async Task Announce(LocalActor group, JsonObject activity, string objectUri, bool isNewPost, CancellationToken token)
{
if (group is not { IsCircle: false, Kind: Models.Federation.LocalActorKind.Group })
return;
var embedded = (JsonObject)activity.DeepClone();
embedded.Remove("@context");
embedded["audience"] ??= group.Uri;
var key = Convert.ToHexStringLower(SHA256.HashData(Encoding.UTF8.GetBytes(activity["id"]?.GetValue<string>() ?? embedded.ToJsonString())))[..24];
var announce = new JsonObject
{
["@context"] = ActivityPubRenderer.Context(),
["id"] = group.ActivityUri($"announce-{key}"),
["type"] = "Announce",
["actor"] = group.Uri,
["to"] = new JsonArray(ActivityPubRenderer.Public),
["cc"] = new JsonArray(group.Followers),
["audience"] = group.Uri,
["object"] = embedded
};
await _delivery.EnqueueToFollowers(group, announce, token);
if (isNewPost && !string.IsNullOrEmpty(objectUri))
await _delivery.EnqueueToFollowers(group, ActivityPubRenderer.Announce(group, objectUri, $"announce-object-{key}"), token);
}
}
}