Fix conflicts in docker-compose.yml

Cargo.lock

@@ -4,9 +4,9 @@ version = 3
 
 [[package]]
 name = "activitystreams"
-version = "0.7.0-alpha.10"
+version = "0.7.0-alpha.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fe7ceed015dfca322d3bcec3653909c77557e7e57df72e98cb8806e2c93cc919"
+checksum = "3a5da1d857ec9ca65ef8d0469cdd64e7b93b59d6cad26f1444bf84b62f3eadd4"
 dependencies = [
  "chrono",
  "mime",

api_tests/src/post.spec.ts

@@ -22,6 +22,7 @@ import {
   searchForUser,
   banPersonFromSite,
   searchPostLocal,
+  followCommunity,
   banPersonFromCommunity,
 } from './shared';
 import { PostView, CommunityView } from 'lemmy-js-client';
@@ -169,35 +170,38 @@ test('Sticky a post', async () => {
 });
 
 test('Lock a post', async () => {
+  await followCommunity(alpha, true, betaCommunity.community.id);
   let postRes = await createPost(alpha, betaCommunity.community.id);
 
   // Lock the post
-  let lockedPostRes = await lockPost(alpha, true, postRes.post_view.post);
+  let searchBeta = await searchPost(beta, postRes.post_view.post);
+  let betaPost1 = searchBeta.posts[0];
+  let lockedPostRes = await lockPost(beta, true, betaPost1.post);
   expect(lockedPostRes.post_view.post.locked).toBe(true);
 
-  // Make sure that post is locked on beta
+  // Make sure that post is locked on alpha
-  let searchBeta = await searchPostLocal(beta, postRes.post_view.post);
+  let searchAlpha = await searchPostLocal(alpha, postRes.post_view.post);
-  let betaPost1 = searchBeta.posts[0];
+  let alphaPost1 = searchAlpha.posts[0];
-  expect(betaPost1.post.locked).toBe(true);
+  expect(alphaPost1.post.locked).toBe(true);
 
   // Try to make a new comment there, on alpha
-  let comment: any = await createComment(alpha, postRes.post_view.post.id);
+  let comment: any = await createComment(alpha, alphaPost1.post.id);
   expect(comment['error']).toBe('locked');
 
   // Unlock a post
-  let unlockedPost = await lockPost(alpha, false, postRes.post_view.post);
+  let unlockedPost = await lockPost(beta, false, betaPost1.post);
   expect(unlockedPost.post_view.post.locked).toBe(false);
 
-  // Make sure that post is unlocked on beta
+  // Make sure that post is unlocked on alpha
-  let searchBeta2 = await searchPost(beta, postRes.post_view.post);
+  let searchAlpha2 = await searchPostLocal(alpha, postRes.post_view.post);
-  let betaPost2 = searchBeta2.posts[0];
+  let alphaPost2 = searchAlpha2.posts[0];
-  expect(betaPost2.community.local).toBe(true);
+  expect(alphaPost2.community.local).toBe(false);
-  expect(betaPost2.creator.local).toBe(false);
+  expect(alphaPost2.creator.local).toBe(true);
-  expect(betaPost2.post.locked).toBe(false);
+  expect(alphaPost2.post.locked).toBe(false);
 
-  // Try to create a new comment, on beta
+  // Try to create a new comment, on alpha
-  let commentBeta = await createComment(beta, betaPost2.post.id);
+  let commentAlpha = await createComment(alpha, alphaPost1.post.id);
-  expect(commentBeta).toBeDefined();
+  expect(commentAlpha).toBeDefined();
 });
 
 test('Delete a post', async () => {

crates/api/src/community.rs

@@ -15,7 +15,9 @@ use lemmy_apub::{
   generate_inbox_url,
   generate_shared_inbox_url,
   ActorType,
+  CommunityType,
   EndpointType,
+  UserType,
 };
 use lemmy_db_queries::{
   diesel_option_overwrite_to_url,
@@ -34,7 +36,7 @@ use lemmy_db_queries::{
 };
 use lemmy_db_schema::{
   naive_now,
-  source::{comment::Comment, community::*, moderator::*, post::Post, site::*},
+  source::{comment::Comment, community::*, moderator::*, person::Person, post::Post, site::*},
   PersonId,
 };
 use lemmy_db_views::comment_view::CommentQueryBuilder;
@@ -707,16 +709,16 @@ impl Perform for AddModToCommunity {
     let data: &AddModToCommunity = &self;
     let local_user_view = get_local_user_view_from_jwt(&data.auth, context.pool()).await?;
 
-    let community_moderator_form = CommunityModeratorForm {
-      community_id: data.community_id,
-      person_id: data.person_id,
-    };
-
     let community_id = data.community_id;
 
     // Verify that only mods or admins can add mod
     is_mod_or_admin(context.pool(), local_user_view.person.id, community_id).await?;
 
+    // Update in local database
+    let community_moderator_form = CommunityModeratorForm {
+      community_id: data.community_id,
+      person_id: data.person_id,
+    };
     if data.added {
       let join = move |conn: &'_ _| CommunityModerator::join(conn, &community_moderator_form);
       if blocking(context.pool(), join).await?.is_err() {
@@ -741,6 +743,28 @@ impl Perform for AddModToCommunity {
     })
     .await??;
 
+    // Send to federated instances
+    let updated_mod_id = data.person_id;
+    let updated_mod = blocking(context.pool(), move |conn| {
+      Person::read(conn, updated_mod_id)
+    })
+    .await??;
+    let community = blocking(context.pool(), move |conn| {
+      Community::read(conn, community_id)
+    })
+    .await??;
+    if data.added {
+      community
+        .send_add_mod(&local_user_view.person, updated_mod, context)
+        .await?;
+    } else {
+      community
+        .send_remove_mod(&local_user_view.person, updated_mod, context)
+        .await?;
+    }
+
+    // Note: in case a remote mod is added, this returns the old moderators list, it will only get
+    //       updated once we receive an activity from the community (like `Announce/Add/Moderator`)
     let community_id = data.community_id;
     let moderators = blocking(context.pool(), move |conn| {
       CommunityModeratorView::for_community(conn, community_id)
@@ -748,18 +772,18 @@ impl Perform for AddModToCommunity {
     .await??;
 
     let res = AddModToCommunityResponse { moderators };
-
     context.chat_server().do_send(SendCommunityRoomMessage {
       op: UserOperation::AddModToCommunity,
       response: res.clone(),
       community_id,
       websocket_id,
     });
-
     Ok(res)
   }
 }
 
+// TODO: we dont do anything for federation here, it should be updated the next time the community
+//       gets fetched. i hope we can get rid of the community creator role soon.
 #[async_trait::async_trait(?Send)]
 impl Perform for TransferCommunity {
   type Response = GetCommunityResponse;

crates/apub/Cargo.toml

@@ -17,7 +17,7 @@ lemmy_db_views_actor = { path = "../db_views_actor" }
 lemmy_api_structs = { path = "../api_structs" }
 lemmy_websocket = { path = "../websocket" }
 diesel = "1.4.5"
-activitystreams = "0.7.0-alpha.10"
+activitystreams = "0.7.0-alpha.11"
 activitystreams-ext = "0.1.0-alpha.2"
 bcrypt = "0.9.0"
 chrono = { version = "0.4.19", features = ["serde"] }

crates/apub/src/activities/mod.rs

@@ -1,2 +1,2 @@
 pub(crate) mod receive;
-pub(crate) mod send;
+pub mod send;

crates/apub/src/activities/receive/comment.rs

@@ -1,6 +1,6 @@
 use crate::{activities::receive::get_actor_as_person, objects::FromApub, ActorType, NoteExt};
 use activitystreams::{
-  activity::{ActorAndObjectRefExt, Create, Dislike, Like, Remove, Update},
+  activity::{ActorAndObjectRefExt, Create, Dislike, Like, Update},
   base::ExtendsExt,
 };
 use anyhow::Context;
@@ -23,7 +23,8 @@ pub(crate) async fn receive_create_comment(
   let note = NoteExt::from_any_base(create.object().to_owned().one().context(location_info!())?)?
     .context(location_info!())?;
 
-  let comment = Comment::from_apub(&note, context, person.actor_id(), request_counter).await?;
+  let comment =
+    Comment::from_apub(&note, context, person.actor_id(), request_counter, false).await?;
 
   let post_id = comment.post_id;
   let post = blocking(context.pool(), move |conn| Post::read(conn, post_id)).await??;
@@ -73,7 +74,8 @@ pub(crate) async fn receive_update_comment(
     .context(location_info!())?;
   let person = get_actor_as_person(&update, context, request_counter).await?;
 
-  let comment = Comment::from_apub(&note, context, person.actor_id(), request_counter).await?;
+  let comment =
+    Comment::from_apub(&note, context, person.actor_id(), request_counter, false).await?;
 
   let comment_id = comment.id;
   let post_id = comment.post_id;
@@ -228,7 +230,6 @@ pub(crate) async fn receive_delete_comment(
 
 pub(crate) async fn receive_remove_comment(
   context: &LemmyContext,
-  _remove: Remove,
   comment: Comment,
 ) -> Result<(), LemmyError> {
   let removed_comment = blocking(context.pool(), move |conn| {

crates/apub/src/activities/receive/community.rs

@@ -1,16 +1,9 @@
-use crate::{activities::receive::verify_activity_domains_valid, inbox::is_addressed_to_public};
-use activitystreams::{
-  activity::{ActorAndObjectRefExt, Delete, Remove, Undo},
-  base::{AnyBase, ExtendsExt},
-};
-use anyhow::Context;
 use lemmy_api_structs::{blocking, community::CommunityResponse};
-use lemmy_db_queries::{source::community::Community_, ApubObject};
+use lemmy_db_queries::source::community::Community_;
 use lemmy_db_schema::source::community::Community;
 use lemmy_db_views_actor::community_view::CommunityView;
-use lemmy_utils::{location_info, LemmyError};
+use lemmy_utils::LemmyError;
 use lemmy_websocket::{messages::SendCommunityRoomMessage, LemmyContext, UserOperation};
-use url::Url;
 
 pub(crate) async fn receive_delete_community(
   context: &LemmyContext,
@@ -42,23 +35,8 @@ pub(crate) async fn receive_delete_community(
 
 pub(crate) async fn receive_remove_community(
   context: &LemmyContext,
-  activity: AnyBase,
+  community: Community,
-  expected_domain: &Url,
 ) -> Result<(), LemmyError> {
-  let remove = Remove::from_any_base(activity)?.context(location_info!())?;
-  verify_activity_domains_valid(&remove, expected_domain, true)?;
-  is_addressed_to_public(&remove)?;
-
-  let community_uri = remove
-    .object()
-    .to_owned()
-    .single_xsd_any_uri()
-    .context(location_info!())?;
-  let community = blocking(context.pool(), move |conn| {
-    Community::read_from_apub_id(conn, &community_uri.into())
-  })
-  .await??;
-
   let removed_community = blocking(context.pool(), move |conn| {
     Community::update_removed(conn, community.id, true)
   })
@@ -85,16 +63,8 @@ pub(crate) async fn receive_remove_community(
 
 pub(crate) async fn receive_undo_delete_community(
   context: &LemmyContext,
-  undo: Undo,
   community: Community,
-  expected_domain: &Url,
 ) -> Result<(), LemmyError> {
-  is_addressed_to_public(&undo)?;
-  let inner = undo.object().to_owned().one().context(location_info!())?;
-  let delete = Delete::from_any_base(inner)?.context(location_info!())?;
-  verify_activity_domains_valid(&delete, expected_domain, true)?;
-  is_addressed_to_public(&delete)?;
-
   let deleted_community = blocking(context.pool(), move |conn| {
     Community::update_deleted(conn, community.id, false)
   })
@@ -121,26 +91,8 @@ pub(crate) async fn receive_undo_delete_community(
 
 pub(crate) async fn receive_undo_remove_community(
   context: &LemmyContext,
-  undo: Undo,
+  community: Community,
-  expected_domain: &Url,
 ) -> Result<(), LemmyError> {
-  is_addressed_to_public(&undo)?;
-
-  let inner = undo.object().to_owned().one().context(location_info!())?;
-  let remove = Remove::from_any_base(inner)?.context(location_info!())?;
-  verify_activity_domains_valid(&remove, &expected_domain, true)?;
-  is_addressed_to_public(&remove)?;
-
-  let community_uri = remove
-    .object()
-    .to_owned()
-    .single_xsd_any_uri()
-    .context(location_info!())?;
-  let community = blocking(context.pool(), move |conn| {
-    Community::read_from_apub_id(conn, &community_uri.into())
-  })
-  .await??;
-
   let removed_community = blocking(context.pool(), move |conn| {
     Community::update_removed(conn, community.id, false)
   })

crates/apub/src/activities/receive/post.rs

@@ -1,12 +1,24 @@
-use crate::{activities::receive::get_actor_as_person, objects::FromApub, ActorType, PageExt};
+use crate::{
+  activities::receive::get_actor_as_person,
+  inbox::receive_for_community::verify_mod_activity,
+  objects::FromApub,
+  ActorType,
+  PageExt,
+};
 use activitystreams::{
-  activity::{Create, Dislike, Like, Remove, Update},
+  activity::{Announce, Create, Dislike, Like, Update},
   prelude::*,
 };
 use anyhow::Context;
 use lemmy_api_structs::{blocking, post::PostResponse};
-use lemmy_db_queries::{source::post::Post_, Likeable};
+use lemmy_db_queries::{source::post::Post_, ApubObject, Crud, Likeable};
-use lemmy_db_schema::source::post::{Post, PostLike, PostLikeForm};
+use lemmy_db_schema::{
+  source::{
+    community::Community,
+    post::{Post, PostLike, PostLikeForm},
+  },
+  DbUrl,
+};
 use lemmy_db_views::post_view::PostView;
 use lemmy_utils::{location_info, LemmyError};
 use lemmy_websocket::{messages::SendPost, LemmyContext, UserOperation};
@@ -20,7 +32,7 @@ pub(crate) async fn receive_create_post(
   let page = PageExt::from_any_base(create.object().to_owned().one().context(location_info!())?)?
     .context(location_info!())?;
 
-  let post = Post::from_apub(&page, context, person.actor_id(), request_counter).await?;
+  let post = Post::from_apub(&page, context, person.actor_id(), request_counter, false).await?;
 
   // Refetch the view
   let post_id = post.id;
@@ -42,6 +54,7 @@ pub(crate) async fn receive_create_post(
 
 pub(crate) async fn receive_update_post(
   update: Update,
+  announce: Option<Announce>,
   context: &LemmyContext,
   request_counter: &mut i32,
 ) -> Result<(), LemmyError> {
@@ -49,7 +62,40 @@ pub(crate) async fn receive_update_post(
   let page = PageExt::from_any_base(update.object().to_owned().one().context(location_info!())?)?
     .context(location_info!())?;
 
-  let post = Post::from_apub(&page, context, person.actor_id(), request_counter).await?;
+  let post_id: DbUrl = page
+    .id_unchecked()
+    .context(location_info!())?
+    .to_owned()
+    .into();
+  let old_post = blocking(context.pool(), move |conn| {
+    Post::read_from_apub_id(conn, &post_id)
+  })
+  .await??;
+
+  // If sticked or locked state was changed, make sure the actor is a mod
+  let stickied = page.ext_one.stickied.context(location_info!())?;
+  let locked = !page.ext_one.comments_enabled.context(location_info!())?;
+  let mut mod_action_allowed = false;
+  if stickied != old_post.stickied || locked != old_post.locked {
+    let community = blocking(context.pool(), move |conn| {
+      Community::read(conn, old_post.community_id)
+    })
+    .await??;
+    // Only check mod status if the community is local, otherwise we trust that it was sent correctly.
+    if community.local {
+      verify_mod_activity(&update, announce, &community, context).await?;
+    }
+    mod_action_allowed = true;
+  }
+
+  let post = Post::from_apub(
+    &page,
+    context,
+    person.actor_id(),
+    request_counter,
+    mod_action_allowed,
+  )
+  .await?;
 
   let post_id = post.id;
   // Refetch the view
@@ -173,7 +219,6 @@ pub(crate) async fn receive_delete_post(
 
 pub(crate) async fn receive_remove_post(
   context: &LemmyContext,
-  _remove: Remove,
   post: Post,
 ) -> Result<(), LemmyError> {
   let removed_post = blocking(context.pool(), move |conn| {

crates/apub/src/activities/receive/private_message.rs

@@ -39,7 +39,7 @@ pub(crate) async fn receive_create_private_message(
   .context(location_info!())?;
 
   let private_message =
-    PrivateMessage::from_apub(&note, context, expected_domain, request_counter).await?;
+    PrivateMessage::from_apub(&note, context, expected_domain, request_counter, false).await?;
 
   let message = blocking(&context.pool(), move |conn| {
     PrivateMessageView::read(conn, private_message.id)
@@ -85,7 +85,7 @@ pub(crate) async fn receive_update_private_message(
   let note = NoteExt::from_any_base(object)?.context(location_info!())?;
 
   let private_message =
-    PrivateMessage::from_apub(&note, context, expected_domain, request_counter).await?;
+    PrivateMessage::from_apub(&note, context, expected_domain, request_counter, false).await?;
 
   let private_message_id = private_message.id;
   let message = blocking(&context.pool(), move |conn| {

crates/apub/src/activities/send/community.rs

@@ -1,20 +1,24 @@
 use crate::{
   activities::send::generate_activity_id,
-  activity_queue::{send_activity_single_dest, send_to_community_followers},
+  activity_queue::{send_activity_single_dest, send_to_community, send_to_community_followers},
   check_is_apub_id_valid,
   extensions::context::lemmy_context,
   fetcher::person::get_or_fetch_and_upsert_person,
+  generate_moderators_url,
   insert_activity,
   ActorType,
+  CommunityType,
 };
 use activitystreams::{
   activity::{
-    kind::{AcceptType, AnnounceType, DeleteType, LikeType, RemoveType, UndoType},
+    kind::{AcceptType, AddType, AnnounceType, DeleteType, LikeType, RemoveType, UndoType},
     Accept,
     ActorAndObjectRefExt,
+    Add,
     Announce,
     Delete,
     Follow,
+    OptTargetRefExt,
     Remove,
     Undo,
   },
@@ -26,7 +30,7 @@ use anyhow::Context;
 use itertools::Itertools;
 use lemmy_api_structs::blocking;
 use lemmy_db_queries::DbPool;
-use lemmy_db_schema::source::community::Community;
+use lemmy_db_schema::source::{community::Community, person::Person};
 use lemmy_db_views_actor::community_follower_view::CommunityFollowerView;
 use lemmy_utils::{location_info, settings::structs::Settings, LemmyError};
 use lemmy_websocket::LemmyContext;
@@ -54,23 +58,10 @@ impl ActorType for Community {
       .unwrap_or_else(|| self.inbox_url.to_owned())
       .into()
   }
+}
 
-  async fn send_follow(
+#[async_trait::async_trait(?Send)]
-    &self,
+impl CommunityType for Community {
-    _follow_actor_id: &Url,
-    _context: &LemmyContext,
-  ) -> Result<(), LemmyError> {
-    unimplemented!()
-  }
-
-  async fn send_unfollow(
-    &self,
-    _follow_actor_id: &Url,
-    _context: &LemmyContext,
-  ) -> Result<(), LemmyError> {
-    unimplemented!()
-  }
-
   /// As a local community, accept the follow request from a remote person.
   async fn send_accept_follow(
     &self,
@@ -211,4 +202,46 @@ impl ActorType for Community {
 
     Ok(inboxes)
   }
+
+  async fn send_add_mod(
+    &self,
+    actor: &Person,
+    added_mod: Person,
+    context: &LemmyContext,
+  ) -> Result<(), LemmyError> {
+    let mut add = Add::new(
+      actor.actor_id.clone().into_inner(),
+      added_mod.actor_id.into_inner(),
+    );
+    add
+      .set_many_contexts(lemmy_context()?)
+      .set_id(generate_activity_id(AddType::Add)?)
+      .set_to(public())
+      .set_many_ccs(vec![self.actor_id()])
+      .set_target(generate_moderators_url(&self.actor_id)?.into_inner());
+
+    send_to_community(add, actor, self, context).await?;
+    Ok(())
+  }
+
+  async fn send_remove_mod(
+    &self,
+    actor: &Person,
+    removed_mod: Person,
+    context: &LemmyContext,
+  ) -> Result<(), LemmyError> {
+    let mut remove = Remove::new(
+      actor.actor_id.clone().into_inner(),
+      removed_mod.actor_id.into_inner(),
+    );
+    remove
+      .set_many_contexts(lemmy_context()?)
+      .set_id(generate_activity_id(RemoveType::Remove)?)
+      .set_to(public())
+      .set_many_ccs(vec![self.actor_id()])
+      .set_target(generate_moderators_url(&self.actor_id)?.into_inner());
+
+    send_to_community(remove, &actor, self, context).await?;
+    Ok(())
+  }
 }

crates/apub/src/activities/send/person.rs

@@ -3,6 +3,7 @@ use crate::{
   activity_queue::send_activity_single_dest,
   extensions::context::lemmy_context,
   ActorType,
+  UserType,
 };
 use activitystreams::{
   activity::{
@@ -10,11 +11,11 @@ use activitystreams::{
     Follow,
     Undo,
   },
-  base::{AnyBase, BaseExt, ExtendsExt},
+  base::{BaseExt, ExtendsExt},
   object::ObjectExt,
 };
 use lemmy_api_structs::blocking;
-use lemmy_db_queries::{ApubObject, DbPool, Followable};
+use lemmy_db_queries::{ApubObject, Followable};
 use lemmy_db_schema::source::{
   community::{Community, CommunityFollower, CommunityFollowerForm},
   person::Person,
@@ -47,7 +48,10 @@ impl ActorType for Person {
       .unwrap_or_else(|| self.inbox_url.to_owned())
       .into()
   }
+}
 
+#[async_trait::async_trait(?Send)]
+impl UserType for Person {
   /// As a given local person, send out a follow request to a remote community.
   async fn send_follow(
     &self,
@@ -110,40 +114,4 @@ impl ActorType for Person {
     send_activity_single_dest(undo, self, community.inbox_url.into(), context).await?;
     Ok(())
   }
-
-  async fn send_accept_follow(
-    &self,
-    _follow: Follow,
-    _context: &LemmyContext,
-  ) -> Result<(), LemmyError> {
-    unimplemented!()
-  }
-
-  async fn send_delete(&self, _context: &LemmyContext) -> Result<(), LemmyError> {
-    unimplemented!()
-  }
-
-  async fn send_undo_delete(&self, _context: &LemmyContext) -> Result<(), LemmyError> {
-    unimplemented!()
-  }
-
-  async fn send_remove(&self, _context: &LemmyContext) -> Result<(), LemmyError> {
-    unimplemented!()
-  }
-
-  async fn send_undo_remove(&self, _context: &LemmyContext) -> Result<(), LemmyError> {
-    unimplemented!()
-  }
-
-  async fn send_announce(
-    &self,
-    _activity: AnyBase,
-    _context: &LemmyContext,
-  ) -> Result<(), LemmyError> {
-    unimplemented!()
-  }
-
-  async fn get_follower_inboxes(&self, _pool: &DbPool) -> Result<Vec<Url>, LemmyError> {
-    unimplemented!()
-  }
 }

crates/apub/src/activity_queue.rs

@@ -3,6 +3,7 @@ use crate::{
   extensions::signatures::sign_and_send,
   insert_activity,
   ActorType,
+  CommunityType,
   APUB_JSON_CONTENT_TYPE,
 };
 use activitystreams::{

crates/apub/src/extensions/context.rs

@@ -11,7 +11,8 @@ pub(crate) fn lemmy_context() -> Result<Vec<AnyBase>, LemmyError> {
     "comments_enabled": {
       "kind": "sc:Boolean",
       "id": "pt:commentsEnabled"
-    }
+    },
+    "moderators": "as:moderators"
   }))?;
   Ok(vec![AnyBase::from(context()), context_ext])
 }

crates/apub/src/extensions/group_extensions.rs

@@ -2,6 +2,7 @@ use activitystreams::unparsed::UnparsedMutExt;
 use activitystreams_ext::UnparsedExtension;
 use lemmy_utils::LemmyError;
 use serde::{Deserialize, Serialize};
+use url::Url;
 
 /// Activitystreams extension to allow (de)serializing additional Community field
 /// `sensitive` (called 'nsfw' in Lemmy).
@@ -9,12 +10,14 @@ use serde::{Deserialize, Serialize};
 #[serde(rename_all = "camelCase")]
 pub struct GroupExtension {
   pub sensitive: Option<bool>,
+  pub moderators: Option<Url>,
 }
 
 impl GroupExtension {
-  pub fn new(sensitive: bool) -> Result<GroupExtension, LemmyError> {
+  pub fn new(sensitive: bool, moderators_url: Url) -> Result<GroupExtension, LemmyError> {
     Ok(GroupExtension {
       sensitive: Some(sensitive),
+      moderators: Some(moderators_url),
     })
   }
 }
@@ -28,11 +31,13 @@ where
   fn try_from_unparsed(unparsed_mut: &mut U) -> Result<Self, Self::Error> {
     Ok(GroupExtension {
       sensitive: unparsed_mut.remove("sensitive")?,
+      moderators: unparsed_mut.remove("moderators")?,
     })
   }
 
   fn try_into_unparsed(self, unparsed_mut: &mut U) -> Result<(), Self::Error> {
     unparsed_mut.insert("sensitive", self.sensitive)?;
+    unparsed_mut.insert("moderators", self.moderators)?;
     Ok(())
   }
 }

crates/apub/src/fetcher/community.rs

@@ -1,10 +1,5 @@
 use crate::{
-  fetcher::{
+  fetcher::{fetch::fetch_remote_object, is_deleted, should_refetch_actor},
-    fetch::fetch_remote_object,
-    get_or_fetch_and_upsert_person,
-    is_deleted,
-    should_refetch_actor,
-  },
   inbox::person_inbox::receive_announce,
   objects::FromApub,
   GroupExt,
@@ -12,13 +7,12 @@ use crate::{
 use activitystreams::{
   actor::ApActorExt,
   collection::{CollectionExt, OrderedCollection},
-  object::ObjectExt,
 };
 use anyhow::Context;
 use diesel::result::Error::NotFound;
 use lemmy_api_structs::blocking;
-use lemmy_db_queries::{source::community::Community_, ApubObject, Joinable};
+use lemmy_db_queries::{source::community::Community_, ApubObject};
-use lemmy_db_schema::source::community::{Community, CommunityModerator, CommunityModeratorForm};
+use lemmy_db_schema::source::community::Community;
 use lemmy_utils::{location_info, LemmyError};
 use lemmy_websocket::LemmyContext;
 use log::debug;
@@ -77,42 +71,14 @@ async fn fetch_remote_community(
   }
 
   let group = group?;
-  let community =
+  let community = Community::from_apub(
-    Community::from_apub(&group, context, apub_id.to_owned(), recursion_counter).await?;
+    &group,
-
+    context,
-  // Also add the community moderators too
+    apub_id.to_owned(),
-  let attributed_to = group.inner.attributed_to().context(location_info!())?;
+    recursion_counter,
-  let creator_and_moderator_uris: Vec<&Url> = attributed_to
+    false,
-    .as_many()
+  )
-    .context(location_info!())?
+  .await?;
-    .iter()
-    .map(|a| a.as_xsd_any_uri().context(""))
-    .collect::<Result<Vec<&Url>, anyhow::Error>>()?;
-
-  let mut creator_and_moderators = Vec::new();
-
-  for uri in creator_and_moderator_uris {
-    let c_or_m = get_or_fetch_and_upsert_person(uri, context, recursion_counter).await?;
-
-    creator_and_moderators.push(c_or_m);
-  }
-
-  // TODO: need to make this work to update mods of existing communities
-  if old_community.is_none() {
-    let community_id = community.id;
-    blocking(context.pool(), move |conn| {
-      for mod_ in creator_and_moderators {
-        let community_moderator_form = CommunityModeratorForm {
-          community_id,
-          person_id: mod_.id,
-        };
-
-        CommunityModerator::join(conn, &community_moderator_form)?;
-      }
-      Ok(()) as Result<(), LemmyError>
-    })
-    .await??;
-  }
 
   // only fetch outbox for new communities, otherwise this can create an infinite loop
   if old_community.is_none() {
@@ -143,3 +109,27 @@ async fn fetch_community_outbox(
 
   Ok(())
 }
+
+pub(crate) async fn fetch_community_mods(
+  context: &LemmyContext,
+  group: &GroupExt,
+  recursion_counter: &mut i32,
+) -> Result<Vec<Url>, LemmyError> {
+  if let Some(mods_url) = &group.ext_one.moderators {
+    let mods =
+      fetch_remote_object::<OrderedCollection>(context.client(), mods_url, recursion_counter)
+        .await?;
+    let mods = mods
+      .items()
+      .map(|i| i.as_many())
+      .flatten()
+      .context(location_info!())?
+      .iter()
+      .filter_map(|i| i.as_xsd_any_uri())
+      .map(|u| u.to_owned())
+      .collect();
+    Ok(mods)
+  } else {
+    Ok(vec![])
+  }
+}

crates/apub/src/fetcher/objects.rs

@@ -30,7 +30,14 @@ pub(crate) async fn get_or_fetch_and_insert_post(
       debug!("Fetching and creating remote post: {}", post_ap_id);
       let page =
         fetch_remote_object::<PageExt>(context.client(), post_ap_id, recursion_counter).await?;
-      let post = Post::from_apub(&page, context, post_ap_id.to_owned(), recursion_counter).await?;
+      let post = Post::from_apub(
+        &page,
+        context,
+        post_ap_id.to_owned(),
+        recursion_counter,
+        false,
+      )
+      .await?;
 
       Ok(post)
     }
@@ -67,6 +74,7 @@ pub(crate) async fn get_or_fetch_and_insert_comment(
         context,
         comment_ap_id.to_owned(),
         recursion_counter,
+        false,
       )
       .await?;
 

crates/apub/src/fetcher/person.rs

@@ -46,8 +46,14 @@ pub(crate) async fn get_or_fetch_and_upsert_person(
         return Ok(u);
       }
 
-      let person =
+      let person = Person::from_apub(
-        Person::from_apub(&person?, context, apub_id.to_owned(), recursion_counter).await?;
+        &person?,
+        context,
+        apub_id.to_owned(),
+        recursion_counter,
+        false,
+      )
+      .await?;
 
       let person_id = person.id;
       blocking(context.pool(), move |conn| {
@@ -63,8 +69,14 @@ pub(crate) async fn get_or_fetch_and_upsert_person(
       let person =
         fetch_remote_object::<PersonExt>(context.client(), apub_id, recursion_counter).await?;
 
-      let person =
+      let person = Person::from_apub(
-        Person::from_apub(&person, context, apub_id.to_owned(), recursion_counter).await?;
+        &person,
+        context,
+        apub_id.to_owned(),
+        recursion_counter,
+        false,
+      )
+      .await?;
 
       Ok(person)
     }

crates/apub/src/fetcher/search.rs

@@ -147,13 +147,13 @@ async fn build_response(
       ];
     }
     SearchAcceptedObjects::Page(p) => {
-      let p = Post::from_apub(&p, context, query_url, recursion_counter).await?;
+      let p = Post::from_apub(&p, context, query_url, recursion_counter, false).await?;
 
       response.posts =
         vec![blocking(context.pool(), move |conn| PostView::read(conn, p.id, None)).await??];
     }
     SearchAcceptedObjects::Comment(c) => {
-      let c = Comment::from_apub(&c, context, query_url, recursion_counter).await?;
+      let c = Comment::from_apub(&c, context, query_url, recursion_counter, false).await?;
 
       response.comments = vec![
         blocking(context.pool(), move |conn| {

crates/apub/src/http/comment.rs

@@ -12,12 +12,12 @@ use lemmy_websocket::LemmyContext;
 use serde::Deserialize;
 
 #[derive(Deserialize)]
-pub struct CommentQuery {
+pub(crate) struct CommentQuery {
   comment_id: String,
 }
 
 /// Return the ActivityPub json representation of a local comment over HTTP.
-pub async fn get_apub_comment(
+pub(crate) async fn get_apub_comment(
   info: Path<CommentQuery>,
   context: web::Data<LemmyContext>,
 ) -> Result<HttpResponse<Body>, LemmyError> {

crates/apub/src/http/community.rs

@@ -1,5 +1,6 @@
 use crate::{
   extensions::context::lemmy_context,
+  generate_moderators_url,
   http::{create_apub_response, create_apub_tombstone_response},
   objects::ToApub,
   ActorType,
@@ -7,23 +8,27 @@ use crate::{
 use activitystreams::{
   base::{AnyBase, BaseExt},
   collection::{CollectionExt, OrderedCollection, UnorderedCollection},
+  url::Url,
 };
 use actix_web::{body::Body, web, HttpResponse};
 use lemmy_api_structs::blocking;
 use lemmy_db_queries::source::{activity::Activity_, community::Community_};
 use lemmy_db_schema::source::{activity::Activity, community::Community};
-use lemmy_db_views_actor::community_follower_view::CommunityFollowerView;
+use lemmy_db_views_actor::{
+  community_follower_view::CommunityFollowerView,
+  community_moderator_view::CommunityModeratorView,
+};
 use lemmy_utils::LemmyError;
 use lemmy_websocket::LemmyContext;
 use serde::Deserialize;
 
 #[derive(Deserialize)]
-pub struct CommunityQuery {
+pub(crate) struct CommunityQuery {
   community_name: String,
 }
 
 /// Return the ActivityPub json representation of a local community over HTTP.
-pub async fn get_apub_community_http(
+pub(crate) async fn get_apub_community_http(
   info: web::Path<CommunityQuery>,
   context: web::Data<LemmyContext>,
 ) -> Result<HttpResponse<Body>, LemmyError> {
@@ -42,7 +47,7 @@ pub async fn get_apub_community_http(
 }
 
 /// Returns an empty followers collection, only populating the size (for privacy).
-pub async fn get_apub_community_followers(
+pub(crate) async fn get_apub_community_followers(
   info: web::Path<CommunityQuery>,
   context: web::Data<LemmyContext>,
 ) -> Result<HttpResponse<Body>, LemmyError> {
@@ -67,7 +72,7 @@ pub async fn get_apub_community_followers(
 
 /// Returns the community outbox, which is populated by a maximum of 20 posts (but no other
 /// activites like votes or comments).
-pub async fn get_apub_community_outbox(
+pub(crate) async fn get_apub_community_outbox(
   info: web::Path<CommunityQuery>,
   context: web::Data<LemmyContext>,
 ) -> Result<HttpResponse<Body>, LemmyError> {
@@ -96,7 +101,7 @@ pub async fn get_apub_community_outbox(
   Ok(create_apub_response(&collection))
 }
 
-pub async fn get_apub_community_inbox(
+pub(crate) async fn get_apub_community_inbox(
   info: web::Path<CommunityQuery>,
   context: web::Data<LemmyContext>,
 ) -> Result<HttpResponse<Body>, LemmyError> {
@@ -107,7 +112,39 @@ pub async fn get_apub_community_inbox(
 
   let mut collection = OrderedCollection::new();
   collection
-    .set_id(format!("{}/inbox", community.actor_id).parse()?)
+    .set_id(community.inbox_url.into())
+    .set_many_contexts(lemmy_context()?);
+  Ok(create_apub_response(&collection))
+}
+
+pub(crate) async fn get_apub_community_moderators(
+  info: web::Path<CommunityQuery>,
+  context: web::Data<LemmyContext>,
+) -> Result<HttpResponse<Body>, LemmyError> {
+  let community = blocking(context.pool(), move |conn| {
+    Community::read_from_name(&conn, &info.community_name)
+  })
+  .await??;
+
+  // The attributed to, is an ordered vector with the creator actor_ids first,
+  // then the rest of the moderators
+  // TODO Technically the instance admins can mod the community, but lets
+  // ignore that for now
+  let cid = community.id;
+  let moderators = blocking(context.pool(), move |conn| {
+    CommunityModeratorView::for_community(&conn, cid)
+  })
+  .await??;
+
+  let moderators: Vec<Url> = moderators
+    .into_iter()
+    .map(|m| m.moderator.actor_id.into_inner())
+    .collect();
+  let mut collection = OrderedCollection::new();
+  collection
+    .set_id(generate_moderators_url(&community.actor_id)?.into())
+    .set_total_items(moderators.len() as u64)
+    .set_many_items(moderators)
     .set_many_contexts(lemmy_context()?);
   Ok(create_apub_response(&collection))
 }

crates/apub/src/http/mod.rs

@@ -42,7 +42,7 @@ pub struct CommunityQuery {
 }
 
 /// Return the ActivityPub json representation of a local community over HTTP.
-pub async fn get_activity(
+pub(crate) async fn get_activity(
   info: web::Path<CommunityQuery>,
   context: web::Data<LemmyContext>,
 ) -> Result<HttpResponse<Body>, LemmyError> {

crates/apub/src/http/person.rs

@@ -23,7 +23,7 @@ pub struct PersonQuery {
 }
 
 /// Return the ActivityPub json representation of a local person over HTTP.
-pub async fn get_apub_person_http(
+pub(crate) async fn get_apub_person_http(
   info: web::Path<PersonQuery>,
   context: web::Data<LemmyContext>,
 ) -> Result<HttpResponse<Body>, LemmyError> {
@@ -43,7 +43,7 @@ pub async fn get_apub_person_http(
   }
 }
 
-pub async fn get_apub_person_outbox(
+pub(crate) async fn get_apub_person_outbox(
   info: web::Path<PersonQuery>,
   context: web::Data<LemmyContext>,
 ) -> Result<HttpResponse<Body>, LemmyError> {
@@ -61,7 +61,7 @@ pub async fn get_apub_person_outbox(
   Ok(create_apub_response(&collection))
 }
 
-pub async fn get_apub_person_inbox(
+pub(crate) async fn get_apub_person_inbox(
   info: web::Path<PersonQuery>,
   context: web::Data<LemmyContext>,
 ) -> Result<HttpResponse<Body>, LemmyError> {
@@ -72,7 +72,7 @@ pub async fn get_apub_person_inbox(
 
   let mut collection = OrderedCollection::new();
   collection
-    .set_id(format!("{}/inbox", person.actor_id.into_inner()).parse()?)
+    .set_id(person.inbox_url.into())
     .set_many_contexts(lemmy_context()?);
   Ok(create_apub_response(&collection))
 }

crates/apub/src/http/post.rs

@@ -12,12 +12,12 @@ use lemmy_websocket::LemmyContext;
 use serde::Deserialize;
 
 #[derive(Deserialize)]
-pub struct PostQuery {
+pub(crate) struct PostQuery {
   post_id: String,
 }
 
 /// Return the ActivityPub json representation of a local post over HTTP.
-pub async fn get_apub_post(
+pub(crate) async fn get_apub_post(
   info: web::Path<PostQuery>,
   context: web::Data<LemmyContext>,
 ) -> Result<HttpResponse<Body>, LemmyError> {

crates/apub/src/inbox/community_inbox.rs

@@ -6,18 +6,21 @@ use crate::{
     get_activity_to_and_cc,
     inbox_verify_http_signature,
     is_activity_already_known,
-    is_addressed_to_public,
     receive_for_community::{
+      receive_add_for_community,
       receive_create_for_community,
       receive_delete_for_community,
       receive_dislike_for_community,
       receive_like_for_community,
+      receive_remove_for_community,
       receive_undo_for_community,
       receive_update_for_community,
     },
+    verify_is_addressed_to_public,
   },
   insert_activity,
   ActorType,
+  CommunityType,
 };
 use activitystreams::{
   activity::{kind::FollowType, ActorAndObject, Follow, Undo},
@@ -54,7 +57,8 @@ pub enum CommunityValidTypes {
   Like,    // upvote post or comment
   Dislike, // downvote post or comment
   Delete,  // post or comment deleted by creator
-  Remove,  // post or comment removed by mod or admin
+  Remove,  // post or comment removed by mod or admin, or mod removed from community
+  Add,     // mod added to community
 }
 
 pub type CommunityAcceptedActivities = ActorAndObject<CommunityValidTypes>;
@@ -148,7 +152,8 @@ pub(crate) async fn community_receive_message(
       true
     }
     CommunityValidTypes::Update => {
-      receive_update_for_community(context, any_base.clone(), &actor_url, request_counter).await?;
+      receive_update_for_community(context, any_base.clone(), None, &actor_url, request_counter)
+        .await?;
       true
     }
     CommunityValidTypes::Like => {
@@ -160,19 +165,22 @@ pub(crate) async fn community_receive_message(
       true
     }
     CommunityValidTypes::Delete => {
-      receive_delete_for_community(context, any_base.clone(), &actor_url).await?;
+      receive_delete_for_community(context, any_base.clone(), None, &actor_url).await?;
+      true
+    }
+    CommunityValidTypes::Add => {
+      receive_add_for_community(context, any_base.clone(), None, request_counter).await?;
       true
     }
     CommunityValidTypes::Remove => {
-      // TODO: we dont support remote mods, so this is ignored for now
+      receive_remove_for_community(context, any_base.clone(), None, request_counter).await?;
-      //receive_remove_for_community(context, any_base.clone(), &person_url).await?
+      true
-      false
     }
   };
 
   if do_announce {
     // Check again that the activity is public, just to be sure
-    is_addressed_to_public(&activity)?;
+    verify_is_addressed_to_public(&activity)?;
     to_community
       .send_announce(activity.into_any_base()?, context)
       .await?;
@@ -224,7 +232,7 @@ async fn handle_undo(
     handle_undo_follow(any_base, actor_url, to_community, &context).await?;
     Ok(false)
   } else {
-    receive_undo_for_community(context, any_base, &actor_url, request_counter).await?;
+    receive_undo_for_community(context, any_base, None, &actor_url, request_counter).await?;
     Ok(true)
   }
 }

crates/apub/src/inbox/mod.rs

@@ -27,7 +27,7 @@ use url::Url;
 
 pub mod community_inbox;
 pub mod person_inbox;
-mod receive_for_community;
+pub(crate) mod receive_for_community;
 pub mod shared_inbox;
 
 pub(crate) fn get_activity_id<T, Kind>(activity: &T, creator_uri: &Url) -> Result<Url, LemmyError>
@@ -84,7 +84,7 @@ where
   to_and_cc
 }
 
-pub(crate) fn is_addressed_to_public<T, Kind>(activity: &T) -> Result<(), LemmyError>
+pub(crate) fn verify_is_addressed_to_public<T, Kind>(activity: &T) -> Result<(), LemmyError>
 where
   T: AsBase<Kind> + AsObject<Kind> + ActorAndObjectRefExt,
 {

crates/apub/src/inbox/person_inbox.rs

@@ -26,8 +26,8 @@ use crate::{
     is_activity_already_known,
     is_addressed_to_community_followers,
     is_addressed_to_local_person,
-    is_addressed_to_public,
     receive_for_community::{
+      receive_add_for_community,
       receive_create_for_community,
       receive_delete_for_community,
       receive_dislike_for_community,
@@ -36,12 +36,13 @@ use crate::{
       receive_undo_for_community,
       receive_update_for_community,
     },
+    verify_is_addressed_to_public,
   },
   insert_activity,
   ActorType,
 };
 use activitystreams::{
-  activity::{Accept, ActorAndObject, Announce, Create, Delete, Follow, Undo, Update},
+  activity::{Accept, ActorAndObject, Announce, Create, Delete, Follow, Remove, Undo, Update},
   base::AnyBase,
   prelude::*,
 };
@@ -165,7 +166,7 @@ pub(crate) async fn person_receive_message(
       receive_delete(context, any_base, &actor_url, request_counter).await?
     }
     PersonValidTypes::Undo => receive_undo(context, any_base, &actor_url, request_counter).await?,
-    PersonValidTypes::Remove => receive_remove_community(&context, any_base, &actor_url).await?,
+    PersonValidTypes::Remove => receive_remove(context, any_base, &actor_url).await?,
   };
 
   // TODO: would be logical to move websocket notification code here
@@ -252,6 +253,7 @@ enum AnnouncableActivities {
   Delete,
   Remove,
   Undo,
+  Add,
 }
 
 /// Takes an announce and passes the inner activity to the appropriate handler.
@@ -263,7 +265,7 @@ pub async fn receive_announce(
 ) -> Result<(), LemmyError> {
   let announce = Announce::from_any_base(activity)?.context(location_info!())?;
   verify_activity_domains_valid(&announce, &actor.actor_id(), false)?;
-  is_addressed_to_public(&announce)?;
+  verify_is_addressed_to_public(&announce)?;
 
   let kind = announce
     .object()
@@ -287,7 +289,14 @@ pub async fn receive_announce(
       receive_create_for_community(context, inner_activity, &inner_id, request_counter).await
     }
     Some(Update) => {
-      receive_update_for_community(context, inner_activity, &inner_id, request_counter).await
+      receive_update_for_community(
+        context,
+        inner_activity,
+        Some(announce),
+        &inner_id,
+        request_counter,
+      )
+      .await
     }
     Some(Like) => {
       receive_like_for_community(context, inner_activity, &inner_id, request_counter).await
@@ -295,15 +304,31 @@ pub async fn receive_announce(
     Some(Dislike) => {
       receive_dislike_for_community(context, inner_activity, &inner_id, request_counter).await
     }
-    Some(Delete) => receive_delete_for_community(context, inner_activity, &inner_id).await,
+    Some(Delete) => {
-    Some(Remove) => receive_remove_for_community(context, inner_activity, &inner_id).await,
+      receive_delete_for_community(context, inner_activity, Some(announce), &inner_id).await
+    }
+    Some(Remove) => {
+      receive_remove_for_community(context, inner_activity, Some(announce), request_counter).await
+    }
     Some(Undo) => {
-      receive_undo_for_community(context, inner_activity, &inner_id, request_counter).await
+      receive_undo_for_community(
+        context,
+        inner_activity,
+        Some(announce),
+        &inner_id,
+        request_counter,
+      )
+      .await
+    }
+    Some(Add) => {
+      receive_add_for_community(context, inner_activity, Some(announce), request_counter).await
     }
     _ => receive_unhandled_activity(inner_activity),
   }
 }
 
+/// Receive either a new private message, or a new comment mention. We distinguish them by checking
+/// whether the activity is public.
 async fn receive_create(
   context: &LemmyContext,
   activity: AnyBase,
@@ -312,13 +337,15 @@ async fn receive_create(
 ) -> Result<(), LemmyError> {
   let create = Create::from_any_base(activity)?.context(location_info!())?;
   verify_activity_domains_valid(&create, &expected_domain, true)?;
-  if is_addressed_to_public(&create).is_ok() {
+  if verify_is_addressed_to_public(&create).is_ok() {
     receive_create_comment(create, context, request_counter).await
   } else {
     receive_create_private_message(&context, create, expected_domain, request_counter).await
   }
 }
 
+/// Receive either an updated private message, or an updated comment mention. We distinguish
+/// them by checking whether the activity is public.
 async fn receive_update(
   context: &LemmyContext,
   activity: AnyBase,
@@ -327,7 +354,7 @@ async fn receive_update(
 ) -> Result<(), LemmyError> {
   let update = Update::from_any_base(activity)?.context(location_info!())?;
   verify_activity_domains_valid(&update, &expected_domain, true)?;
-  if is_addressed_to_public(&update).is_ok() {
+  if verify_is_addressed_to_public(&update).is_ok() {
     receive_update_comment(update, context, request_counter).await
   } else {
     receive_update_private_message(&context, update, expected_domain, request_counter).await
@@ -356,13 +383,31 @@ async fn receive_delete(
   }
 }
 
+async fn receive_remove(
+  context: &LemmyContext,
+  any_base: AnyBase,
+  expected_domain: &Url,
+) -> Result<(), LemmyError> {
+  let remove = Remove::from_any_base(any_base.clone())?.context(location_info!())?;
+  verify_activity_domains_valid(&remove, expected_domain, true)?;
+  let object_uri = remove
+    .object()
+    .to_owned()
+    .single_xsd_any_uri()
+    .context(location_info!())?;
+  let community = blocking(context.pool(), move |conn| {
+    Community::read_from_apub_id(conn, &object_uri.into())
+  })
+  .await??;
+  receive_remove_community(&context, community).await
+}
+
 async fn receive_undo(
   context: &LemmyContext,
   any_base: AnyBase,
   expected_domain: &Url,
   request_counter: &mut i32,
 ) -> Result<(), LemmyError> {
-  use CommunityOrPrivateMessage::*;
   let undo = Undo::from_any_base(any_base)?.context(location_info!())?;
   verify_activity_domains_valid(&undo, expected_domain, true)?;
 
@@ -377,15 +422,28 @@ async fn receive_undo(
         .to_owned()
         .single_xsd_any_uri()
         .context(location_info!())?;
+      use CommunityOrPrivateMessage::*;
       match find_community_or_private_message_by_id(context, object_uri).await? {
-        Community(c) => receive_undo_delete_community(context, undo, c, expected_domain).await,
+        Community(c) => receive_undo_delete_community(context, c).await,
         PrivateMessage(p) => {
           receive_undo_delete_private_message(context, undo, expected_domain, p, request_counter)
             .await
         }
       }
     }
-    Some("Remove") => receive_undo_remove_community(context, undo, expected_domain).await,
+    Some("Remove") => {
+      let remove = Remove::from_any_base(inner_activity)?.context(location_info!())?;
+      let object_uri = remove
+        .object()
+        .to_owned()
+        .single_xsd_any_uri()
+        .context(location_info!())?;
+      let community = blocking(context.pool(), move |conn| {
+        Community::read_from_apub_id(conn, &object_uri.into())
+      })
+      .await??;
+      receive_undo_remove_community(context, community).await
+    }
     _ => receive_unhandled_activity(undo),
   }
 }

crates/apub/src/inbox/receive_for_community.rs

@@ -31,21 +31,50 @@ use crate::{
     receive_unhandled_activity,
     verify_activity_domains_valid,
   },
-  fetcher::objects::{get_or_fetch_and_insert_comment, get_or_fetch_and_insert_post},
+  fetcher::{
+    objects::{get_or_fetch_and_insert_comment, get_or_fetch_and_insert_post},
+    person::get_or_fetch_and_upsert_person,
+  },
+  find_object_by_id,
   find_post_or_comment_by_id,
-  inbox::is_addressed_to_public,
+  generate_moderators_url,
+  inbox::verify_is_addressed_to_public,
+  ActorType,
+  CommunityType,
+  Object,
   PostOrComment,
 };
 use activitystreams::{
-  activity::{Create, Delete, Dislike, Like, Remove, Undo, Update},
+  activity::{
+    ActorAndObjectRef,
+    Add,
+    Announce,
+    Create,
+    Delete,
+    Dislike,
+    Like,
+    OptTargetRef,
+    Remove,
+    Undo,
+    Update,
+  },
   base::AnyBase,
+  object::AsObject,
   prelude::*,
 };
-use anyhow::Context;
+use anyhow::{anyhow, Context};
 use diesel::result::Error::NotFound;
 use lemmy_api_structs::blocking;
-use lemmy_db_queries::Crud;
+use lemmy_db_queries::{source::community::CommunityModerator_, ApubObject, Crud, Joinable};
-use lemmy_db_schema::source::site::Site;
+use lemmy_db_schema::{
+  source::{
+    community::{Community, CommunityModerator, CommunityModeratorForm},
+    person::Person,
+    site::Site,
+  },
+  DbUrl,
+};
+use lemmy_db_views_actor::community_view::CommunityView;
 use lemmy_utils::{location_info, LemmyError};
 use lemmy_websocket::LemmyContext;
 use strum_macros::EnumString;
@@ -69,7 +98,7 @@ pub(in crate::inbox) async fn receive_create_for_community(
 ) -> Result<(), LemmyError> {
   let create = Create::from_any_base(activity)?.context(location_info!())?;
   verify_activity_domains_valid(&create, &expected_domain, true)?;
-  is_addressed_to_public(&create)?;
+  verify_is_addressed_to_public(&create)?;
 
   let kind = create
     .object()
@@ -86,19 +115,21 @@ pub(in crate::inbox) async fn receive_create_for_community(
 pub(in crate::inbox) async fn receive_update_for_community(
   context: &LemmyContext,
   activity: AnyBase,
+  announce: Option<Announce>,
   expected_domain: &Url,
   request_counter: &mut i32,
 ) -> Result<(), LemmyError> {
   let update = Update::from_any_base(activity)?.context(location_info!())?;
-  verify_activity_domains_valid(&update, &expected_domain, true)?;
+  verify_activity_domains_valid(&update, &expected_domain, false)?;
-  is_addressed_to_public(&update)?;
+  verify_is_addressed_to_public(&update)?;
+  verify_modification_actor_instance(&update, &announce, context).await?;
 
   let kind = update
     .object()
     .as_single_kind_str()
     .and_then(|s| s.parse().ok());
   match kind {
-    Some(PageOrNote::Page) => receive_update_post(update, context, request_counter).await,
+    Some(PageOrNote::Page) => receive_update_post(update, announce, context, request_counter).await,
     Some(PageOrNote::Note) => receive_update_comment(update, context, request_counter).await,
     _ => receive_unhandled_activity(update),
   }
@@ -113,7 +144,7 @@ pub(in crate::inbox) async fn receive_like_for_community(
 ) -> Result<(), LemmyError> {
   let like = Like::from_any_base(activity)?.context(location_info!())?;
   verify_activity_domains_valid(&like, &expected_domain, false)?;
-  is_addressed_to_public(&like)?;
+  verify_is_addressed_to_public(&like)?;
 
   let object_id = like
     .object()
@@ -144,7 +175,7 @@ pub(in crate::inbox) async fn receive_dislike_for_community(
 
   let dislike = Dislike::from_any_base(activity)?.context(location_info!())?;
   verify_activity_domains_valid(&dislike, &expected_domain, false)?;
-  is_addressed_to_public(&dislike)?;
+  verify_is_addressed_to_public(&dislike)?;
 
   let object_id = dislike
     .object()
@@ -164,11 +195,13 @@ pub(in crate::inbox) async fn receive_dislike_for_community(
 pub(in crate::inbox) async fn receive_delete_for_community(
   context: &LemmyContext,
   activity: AnyBase,
+  announce: Option<Announce>,
   expected_domain: &Url,
 ) -> Result<(), LemmyError> {
   let delete = Delete::from_any_base(activity)?.context(location_info!())?;
   verify_activity_domains_valid(&delete, &expected_domain, true)?;
-  is_addressed_to_public(&delete)?;
+  verify_is_addressed_to_public(&delete)?;
+  verify_modification_actor_instance(&delete, &announce, context).await?;
 
   let object = delete
     .object()
@@ -187,39 +220,49 @@ pub(in crate::inbox) async fn receive_delete_for_community(
 /// A post or comment being removed by a mod/admin
 pub(in crate::inbox) async fn receive_remove_for_community(
   context: &LemmyContext,
-  activity: AnyBase,
+  remove_any_base: AnyBase,
-  expected_domain: &Url,
+  announce: Option<Announce>,
+  request_counter: &mut i32,
 ) -> Result<(), LemmyError> {
-  let remove = Remove::from_any_base(activity)?.context(location_info!())?;
+  let remove = Remove::from_any_base(remove_any_base.to_owned())?.context(location_info!())?;
-  verify_activity_domains_valid(&remove, &expected_domain, false)?;
+  let community = extract_community_from_cc(&remove, context).await?;
-  is_addressed_to_public(&remove)?;
 
-  let cc = remove
+  verify_mod_activity(&remove, announce, &community, context).await?;
-    .cc()
+  verify_is_addressed_to_public(&remove)?;
-    .map(|c| c.as_many())
-    .flatten()
-    .context(location_info!())?;
-  let community_id = cc
-    .first()
-    .map(|c| c.as_xsd_any_uri())
-    .flatten()
-    .context(location_info!())?;
 
+  if remove.target().is_some() {
+    let remove_mod = remove
+      .object()
+      .as_single_xsd_any_uri()
+      .context(location_info!())?;
+    let remove_mod = get_or_fetch_and_upsert_person(&remove_mod, context, request_counter).await?;
+    let form = CommunityModeratorForm {
+      community_id: community.id,
+      person_id: remove_mod.id,
+    };
+    blocking(context.pool(), move |conn| {
+      CommunityModerator::leave(conn, &form)
+    })
+    .await??;
+    community.send_announce(remove_any_base, context).await?;
+    // TODO: send websocket notification about removed mod
+    Ok(())
+  }
+  // Remove a post or comment
+  else {
     let object = remove
       .object()
       .to_owned()
       .single_xsd_any_uri()
       .context(location_info!())?;
 
-  // Ensure that remove activity comes from the same domain as the community
-  remove.id(community_id.domain().context(location_info!())?)?;
-
     match find_post_or_comment_by_id(context, object).await {
-    Ok(PostOrComment::Post(p)) => receive_remove_post(context, remove, *p).await,
+      Ok(PostOrComment::Post(p)) => receive_remove_post(context, *p).await,
-    Ok(PostOrComment::Comment(c)) => receive_remove_comment(context, remove, *c).await,
+      Ok(PostOrComment::Comment(c)) => receive_remove_comment(context, *c).await,
       // if we dont have the object, no need to do anything
       Err(_) => Ok(()),
     }
+  }
 }
 
 #[derive(EnumString)]
@@ -234,12 +277,13 @@ enum UndoableActivities {
 pub(in crate::inbox) async fn receive_undo_for_community(
   context: &LemmyContext,
   activity: AnyBase,
+  announce: Option<Announce>,
   expected_domain: &Url,
   request_counter: &mut i32,
 ) -> Result<(), LemmyError> {
   let undo = Undo::from_any_base(activity)?.context(location_info!())?;
   verify_activity_domains_valid(&undo, &expected_domain.to_owned(), true)?;
-  is_addressed_to_public(&undo)?;
+  verify_is_addressed_to_public(&undo)?;
 
   use UndoableActivities::*;
   match undo
@@ -248,7 +292,9 @@ pub(in crate::inbox) async fn receive_undo_for_community(
     .and_then(|s| s.parse().ok())
   {
     Some(Delete) => receive_undo_delete_for_community(context, undo, expected_domain).await,
-    Some(Remove) => receive_undo_remove_for_community(context, undo, expected_domain).await,
+    Some(Remove) => {
+      receive_undo_remove_for_community(context, undo, announce, expected_domain).await
+    }
     Some(Like) => {
       receive_undo_like_for_community(context, undo, expected_domain, request_counter).await
     }
@@ -268,7 +314,7 @@ pub(in crate::inbox) async fn receive_undo_delete_for_community(
   let delete = Delete::from_any_base(undo.object().to_owned().one().context(location_info!())?)?
     .context(location_info!())?;
   verify_activity_domains_valid(&delete, &expected_domain, true)?;
-  is_addressed_to_public(&delete)?;
+  verify_is_addressed_to_public(&delete)?;
 
   let object = delete
     .object()
@@ -287,12 +333,14 @@ pub(in crate::inbox) async fn receive_undo_delete_for_community(
 pub(in crate::inbox) async fn receive_undo_remove_for_community(
   context: &LemmyContext,
   undo: Undo,
+  announce: Option<Announce>,
   expected_domain: &Url,
 ) -> Result<(), LemmyError> {
   let remove = Remove::from_any_base(undo.object().to_owned().one().context(location_info!())?)?
     .context(location_info!())?;
   verify_activity_domains_valid(&remove, &expected_domain, false)?;
-  is_addressed_to_public(&remove)?;
+  verify_is_addressed_to_public(&remove)?;
+  verify_undo_remove_actor_instance(&undo, &remove, &announce, context).await?;
 
   let object = remove
     .object()
@@ -317,7 +365,7 @@ pub(in crate::inbox) async fn receive_undo_like_for_community(
   let like = Like::from_any_base(undo.object().to_owned().one().context(location_info!())?)?
     .context(location_info!())?;
   verify_activity_domains_valid(&like, &expected_domain, false)?;
-  is_addressed_to_public(&like)?;
+  verify_is_addressed_to_public(&like)?;
 
   let object_id = like
     .object()
@@ -333,6 +381,50 @@ pub(in crate::inbox) async fn receive_undo_like_for_community(
   }
 }
 
+/// Add a new mod to the community (can only be done by an existing mod).
+pub(in crate::inbox) async fn receive_add_for_community(
+  context: &LemmyContext,
+  add_any_base: AnyBase,
+  announce: Option<Announce>,
+  request_counter: &mut i32,
+) -> Result<(), LemmyError> {
+  let add = Add::from_any_base(add_any_base.to_owned())?.context(location_info!())?;
+  let community = extract_community_from_cc(&add, context).await?;
+
+  verify_mod_activity(&add, announce, &community, context).await?;
+  verify_is_addressed_to_public(&add)?;
+  verify_add_remove_moderator_target(&add, &community)?;
+
+  let new_mod = add
+    .object()
+    .as_single_xsd_any_uri()
+    .context(location_info!())?;
+  let new_mod = get_or_fetch_and_upsert_person(&new_mod, context, request_counter).await?;
+
+  // If we had to refetch the community while parsing the activity, then the new mod has already
+  // been added. Skip it here as it would result in a duplicate key error.
+  let new_mod_id = new_mod.id;
+  let moderated_communities = blocking(context.pool(), move |conn| {
+    CommunityModerator::get_person_moderated_communities(conn, new_mod_id)
+  })
+  .await??;
+  if !moderated_communities.contains(&community.id) {
+    let form = CommunityModeratorForm {
+      community_id: community.id,
+      person_id: new_mod.id,
+    };
+    blocking(context.pool(), move |conn| {
+      CommunityModerator::join(conn, &form)
+    })
+    .await??;
+  }
+  if community.local {
+    community.send_announce(add_any_base, context).await?;
+  }
+  // TODO: send websocket notification about added mod
+  Ok(())
+}
+
 /// A post or comment downvote being reverted
 pub(in crate::inbox) async fn receive_undo_dislike_for_community(
   context: &LemmyContext,
@@ -343,7 +435,7 @@ pub(in crate::inbox) async fn receive_undo_dislike_for_community(
   let dislike = Dislike::from_any_base(undo.object().to_owned().one().context(location_info!())?)?
     .context(location_info!())?;
   verify_activity_domains_valid(&dislike, &expected_domain, false)?;
-  is_addressed_to_public(&dislike)?;
+  verify_is_addressed_to_public(&dislike)?;
 
   let object_id = dislike
     .object()
@@ -374,3 +466,172 @@ async fn fetch_post_or_comment_by_id(
 
   Err(NotFound.into())
 }
+
+/// Searches the activity's cc field for a Community ID, and returns the community.
+async fn extract_community_from_cc<T, Kind>(
+  activity: &T,
+  context: &LemmyContext,
+) -> Result<Community, LemmyError>
+where
+  T: AsObject<Kind>,
+{
+  let cc = activity
+    .cc()
+    .map(|c| c.as_many())
+    .flatten()
+    .context(location_info!())?;
+  let community_id = cc
+    .first()
+    .map(|c| c.as_xsd_any_uri())
+    .flatten()
+    .context(location_info!())?;
+  let community_id: DbUrl = community_id.to_owned().into();
+  let community = blocking(&context.pool(), move |conn| {
+    Community::read_from_apub_id(&conn, &community_id)
+  })
+  .await??;
+  Ok(community)
+}
+
+/// Checks that a moderation activity was sent by a user who is listed as mod for the community.
+/// This is only used in the case of remote mods, as local mod actions don't go through the
+/// community inbox.
+///
+/// This method should only be used for activities received by the community, not for activities
+/// used by community followers.
+async fn verify_actor_is_community_mod<T, Kind>(
+  activity: &T,
+  community: &Community,
+  context: &LemmyContext,
+) -> Result<(), LemmyError>
+where
+  T: ActorAndObjectRef + BaseExt<Kind>,
+{
+  let actor = activity
+    .actor()?
+    .as_single_xsd_any_uri()
+    .context(location_info!())?
+    .to_owned();
+  let actor = blocking(&context.pool(), move |conn| {
+    Person::read_from_apub_id(&conn, &actor.into())
+  })
+  .await??;
+
+  // Note: this will also return true for admins in addition to mods, but as we dont know about
+  //       remote admins, it doesnt make any difference.
+  let community_id = community.id;
+  let actor_id = actor.id;
+  let is_mod_or_admin = blocking(context.pool(), move |conn| {
+    CommunityView::is_mod_or_admin(conn, actor_id, community_id)
+  })
+  .await?;
+  if !is_mod_or_admin {
+    return Err(anyhow!("Not a mod").into());
+  }
+
+  Ok(())
+}
+
+/// This method behaves differently, depending if it is called via community inbox (activity
+/// received by community from a remote user), or via user inbox (activity received by user from
+/// community). We distinguish the cases by checking if the activity is wrapper in an announce
+/// (only true when sent from user to community).
+///
+/// In the first case, we check that the actor is listed as community mod. In the second case, we
+/// only check that the announce comes from the same domain as the activity. We trust the
+/// community's instance to have validated the inner activity correctly. We can't do this validation
+/// here, because we don't know who the instance admins are. Plus this allows for compatibility with
+/// software that uses different rules for mod actions.
+pub(crate) async fn verify_mod_activity<T, Kind>(
+  mod_action: &T,
+  announce: Option<Announce>,
+  community: &Community,
+  context: &LemmyContext,
+) -> Result<(), LemmyError>
+where
+  T: ActorAndObjectRef + BaseExt<Kind>,
+{
+  match announce {
+    None => verify_actor_is_community_mod(mod_action, community, context).await?,
+    Some(a) => verify_activity_domains_valid(&a, &community.actor_id.to_owned().into(), false)?,
+  }
+
+  Ok(())
+}
+
+/// For Add/Remove community moderator activities, check that the target field actually contains
+/// /c/community/moderators. Any different values are unsupported.
+fn verify_add_remove_moderator_target<T, Kind>(
+  activity: &T,
+  community: &Community,
+) -> Result<(), LemmyError>
+where
+  T: ActorAndObjectRef + BaseExt<Kind> + OptTargetRef,
+{
+  let target = activity
+    .target()
+    .map(|t| t.as_single_xsd_any_uri())
+    .flatten()
+    .context(location_info!())?;
+  if target != &generate_moderators_url(&community.actor_id)?.into_inner() {
+    return Err(anyhow!("Unkown target url").into());
+  }
+  Ok(())
+}
+
+/// For activities like Update, Delete or Remove, check that the actor is from the same instance
+/// as the original object itself (or is a remote mod).
+///
+/// Note: This is only needed for mod actions. Normal user actions (edit post, undo vote etc) are
+///       already verified with `expected_domain`, so this serves as an additional check.
+async fn verify_modification_actor_instance<T, Kind>(
+  activity: &T,
+  announce: &Option<Announce>,
+  context: &LemmyContext,
+) -> Result<(), LemmyError>
+where
+  T: ActorAndObjectRef + BaseExt<Kind> + AsObject<Kind>,
+{
+  let actor_id = activity
+    .actor()?
+    .to_owned()
+    .single_xsd_any_uri()
+    .context(location_info!())?;
+  let object_id = activity
+    .object()
+    .as_one()
+    .map(|o| o.id())
+    .flatten()
+    .context(location_info!())?;
+  let original_id = match find_object_by_id(context, object_id.to_owned()).await? {
+    Object::Post(p) => p.ap_id.into_inner(),
+    Object::Comment(c) => c.ap_id.into_inner(),
+    Object::Community(c) => c.actor_id(),
+    Object::Person(p) => p.actor_id(),
+    Object::PrivateMessage(p) => p.ap_id.into_inner(),
+  };
+  if actor_id.domain() != original_id.domain() {
+    let community = extract_community_from_cc(activity, context).await?;
+    verify_mod_activity(activity, announce.to_owned(), &community, context).await?;
+  }
+
+  Ok(())
+}
+
+pub(crate) async fn verify_undo_remove_actor_instance<T, Kind>(
+  undo: &Undo,
+  inner: &T,
+  announce: &Option<Announce>,
+  context: &LemmyContext,
+) -> Result<(), LemmyError>
+where
+  T: ActorAndObjectRef + BaseExt<Kind> + AsObject<Kind>,
+{
+  if announce.is_none() {
+    let community = extract_community_from_cc(undo, context).await?;
+    verify_mod_activity(undo, announce.to_owned(), &community, context).await?;
+    verify_mod_activity(inner, announce.to_owned(), &community, context).await?;
+  }
+
+  Ok(())
+}

crates/apub/src/inbox/shared_inbox.rs

@@ -36,6 +36,7 @@ pub enum ValidTypes {
   Undo,
   Remove,
   Announce,
+  Add,
 }
 
 // TODO: this isnt entirely correct, cause some of these receive are not ActorAndObject,

crates/apub/src/lib.rs

@@ -17,7 +17,7 @@ use crate::extensions::{
 };
 use activitystreams::{
   activity::Follow,
-  actor::{ApActor, Group, Person},
+  actor,
   base::AnyBase,
   object::{ApObject, Note, Page},
 };
@@ -31,7 +31,7 @@ use lemmy_db_schema::{
     activity::Activity,
     comment::Comment,
     community::Community,
-    person::Person as DbPerson,
+    person::{Person as DbPerson, Person},
     post::Post,
     private_message::PrivateMessage,
   },
@@ -44,9 +44,9 @@ use std::net::IpAddr;
 use url::{ParseError, Url};
 
 /// Activitystreams type for community
-type GroupExt = Ext2<ApActor<ApObject<Group>>, GroupExtension, PublicKeyExtension>;
+type GroupExt = Ext2<actor::ApActor<ApObject<actor::Group>>, GroupExtension, PublicKeyExtension>;
 /// Activitystreams type for person
-type PersonExt = Ext1<ApActor<ApObject<Person>>, PublicKeyExtension>;
+type PersonExt = Ext1<actor::ApActor<ApObject<actor::Person>>, PublicKeyExtension>;
 /// Activitystreams type for post
 type PageExt = Ext1<ApObject<Page>, PageExtension>;
 type NoteExt = ApObject<Note>;
@@ -166,38 +166,6 @@ pub trait ActorType {
   fn public_key(&self) -> Option<String>;
   fn private_key(&self) -> Option<String>;
 
-  async fn send_follow(
-    &self,
-    follow_actor_id: &Url,
-    context: &LemmyContext,
-  ) -> Result<(), LemmyError>;
-  async fn send_unfollow(
-    &self,
-    follow_actor_id: &Url,
-    context: &LemmyContext,
-  ) -> Result<(), LemmyError>;
-
-  async fn send_accept_follow(
-    &self,
-    follow: Follow,
-    context: &LemmyContext,
-  ) -> Result<(), LemmyError>;
-
-  async fn send_delete(&self, context: &LemmyContext) -> Result<(), LemmyError>;
-  async fn send_undo_delete(&self, context: &LemmyContext) -> Result<(), LemmyError>;
-
-  async fn send_remove(&self, context: &LemmyContext) -> Result<(), LemmyError>;
-  async fn send_undo_remove(&self, context: &LemmyContext) -> Result<(), LemmyError>;
-
-  async fn send_announce(
-    &self,
-    activity: AnyBase,
-    context: &LemmyContext,
-  ) -> Result<(), LemmyError>;
-
-  /// For a given community, returns the inboxes of all followers.
-  async fn get_follower_inboxes(&self, pool: &DbPool) -> Result<Vec<Url>, LemmyError>;
-
   fn get_shared_inbox_or_inbox_url(&self) -> Url;
 
   /// Outbox URL is not generally used by Lemmy, so it can be generated on the fly (but only for
@@ -221,6 +189,55 @@ pub trait ActorType {
   }
 }
 
+#[async_trait::async_trait(?Send)]
+pub trait CommunityType {
+  async fn get_follower_inboxes(&self, pool: &DbPool) -> Result<Vec<Url>, LemmyError>;
+  async fn send_accept_follow(
+    &self,
+    follow: Follow,
+    context: &LemmyContext,
+  ) -> Result<(), LemmyError>;
+
+  async fn send_delete(&self, context: &LemmyContext) -> Result<(), LemmyError>;
+  async fn send_undo_delete(&self, context: &LemmyContext) -> Result<(), LemmyError>;
+
+  async fn send_remove(&self, context: &LemmyContext) -> Result<(), LemmyError>;
+  async fn send_undo_remove(&self, context: &LemmyContext) -> Result<(), LemmyError>;
+
+  async fn send_announce(
+    &self,
+    activity: AnyBase,
+    context: &LemmyContext,
+  ) -> Result<(), LemmyError>;
+
+  async fn send_add_mod(
+    &self,
+    actor: &Person,
+    added_mod: Person,
+    context: &LemmyContext,
+  ) -> Result<(), LemmyError>;
+  async fn send_remove_mod(
+    &self,
+    actor: &Person,
+    removed_mod: Person,
+    context: &LemmyContext,
+  ) -> Result<(), LemmyError>;
+}
+
+#[async_trait::async_trait(?Send)]
+pub trait UserType {
+  async fn send_follow(
+    &self,
+    follow_actor_id: &Url,
+    context: &LemmyContext,
+  ) -> Result<(), LemmyError>;
+  async fn send_unfollow(
+    &self,
+    follow_actor_id: &Url,
+    context: &LemmyContext,
+  ) -> Result<(), LemmyError>;
+}
+
 pub enum EndpointType {
   Community,
   Person,
@@ -276,6 +293,10 @@ pub fn generate_shared_inbox_url(actor_id: &DbUrl) -> Result<DbUrl, LemmyError>
   Ok(Url::parse(&url)?.into())
 }
 
+pub(crate) fn generate_moderators_url(community_id: &DbUrl) -> Result<DbUrl, LemmyError> {
+  Ok(Url::parse(&format!("{}/moderators", community_id))?.into())
+}
+
 /// Store a sent or received activity in the database, for logging purposes. These records are not
 /// persistent.
 pub(crate) async fn insert_activity<T>(
@@ -329,6 +350,7 @@ pub(crate) async fn find_post_or_comment_by_id(
   Err(NotFound.into())
 }
 
+#[derive(Debug)]
 pub(crate) enum Object {
   Comment(Box<Comment>),
   Post(Box<Post>),

crates/apub/src/objects/comment.rs

@@ -102,9 +102,16 @@ impl FromApub for Comment {
     context: &LemmyContext,
     expected_domain: Url,
     request_counter: &mut i32,
+    mod_action_allowed: bool,
   ) -> Result<Comment, LemmyError> {
-    let comment: Comment =
+    let comment: Comment = get_object_from_apub(
-      get_object_from_apub(note, context, expected_domain, request_counter).await?;
+      note,
+      context,
+      expected_domain,
+      request_counter,
+      mod_action_allowed,
+    )
+    .await?;
 
     let post_id = comment.post_id;
     let post = blocking(context.pool(), move |conn| Post::read(conn, post_id)).await??;
@@ -131,6 +138,7 @@ impl FromApubToForm<NoteExt> for CommentForm {
     context: &LemmyContext,
     expected_domain: Url,
     request_counter: &mut i32,
+    _mod_action_allowed: bool,
   ) -> Result<CommentForm, LemmyError> {
     let creator_actor_id = &note
       .attributed_to()

crates/apub/src/objects/community.rs

@@ -1,6 +1,7 @@
 use crate::{
   extensions::{context::lemmy_context, group_extensions::GroupExtension},
-  fetcher::person::get_or_fetch_and_upsert_person,
+  fetcher::{community::fetch_community_mods, person::get_or_fetch_and_upsert_person},
+  generate_moderators_url,
   objects::{
     check_object_domain,
     create_tombstone,
@@ -23,10 +24,11 @@ use activitystreams::{
 use activitystreams_ext::Ext2;
 use anyhow::Context;
 use lemmy_api_structs::blocking;
-use lemmy_db_queries::DbPool;
+use lemmy_db_queries::{DbPool, Joinable};
 use lemmy_db_schema::{
   naive_now,
-  source::community::{Community, CommunityForm},
+  source::community::{Community, CommunityForm, CommunityModerator, CommunityModeratorForm},
+  DbUrl,
 };
 use lemmy_db_views_actor::community_moderator_view::CommunityModeratorView;
 use lemmy_utils::{
@@ -41,28 +43,13 @@ use url::Url;
 impl ToApub for Community {
   type ApubType = GroupExt;
 
-  async fn to_apub(&self, pool: &DbPool) -> Result<GroupExt, LemmyError> {
+  async fn to_apub(&self, _pool: &DbPool) -> Result<GroupExt, LemmyError> {
-    // The attributed to, is an ordered vector with the creator actor_ids first,
-    // then the rest of the moderators
-    // TODO Technically the instance admins can mod the community, but lets
-    // ignore that for now
-    let id = self.id;
-    let moderators = blocking(pool, move |conn| {
-      CommunityModeratorView::for_community(&conn, id)
-    })
-    .await??;
-    let moderators: Vec<Url> = moderators
-      .into_iter()
-      .map(|m| m.moderator.actor_id.into_inner())
-      .collect();
-
     let mut group = ApObject::new(Group::new());
     group
       .set_many_contexts(lemmy_context()?)
       .set_id(self.actor_id.to_owned().into())
       .set_name(self.title.to_owned())
-      .set_published(convert_datetime(self.published))
+      .set_published(convert_datetime(self.published));
-      .set_many_attributed_tos(moderators);
 
     if let Some(u) = self.updated.to_owned() {
       group.set_updated(convert_datetime(u));
@@ -95,7 +82,7 @@ impl ToApub for Community {
 
     Ok(Ext2::new(
       ap_actor,
-      GroupExtension::new(self.nsfw)?,
+      GroupExtension::new(self.nsfw, generate_moderators_url(&self.actor_id)?.into())?,
       self.get_public_key_ext()?,
     ))
   }
@@ -114,14 +101,64 @@ impl ToApub for Community {
 impl FromApub for Community {
   type ApubType = GroupExt;
 
-  /// Converts a `Group` to `Community`.
+  /// Converts a `Group` to `Community`, inserts it into the database and updates moderators.
   async fn from_apub(
     group: &GroupExt,
     context: &LemmyContext,
     expected_domain: Url,
     request_counter: &mut i32,
+    mod_action_allowed: bool,
   ) -> Result<Community, LemmyError> {
-    get_object_from_apub(group, context, expected_domain, request_counter).await
+    let community: Community = get_object_from_apub(
+      group,
+      context,
+      expected_domain,
+      request_counter,
+      mod_action_allowed,
+    )
+    .await?;
+
+    let new_moderators = fetch_community_mods(context, group, request_counter).await?;
+    let community_id = community.id;
+    let current_moderators = blocking(context.pool(), move |conn| {
+      CommunityModeratorView::for_community(&conn, community_id)
+    })
+    .await??;
+    // Remove old mods from database which arent in the moderators collection anymore
+    for mod_user in &current_moderators {
+      if !new_moderators.contains(&&mod_user.moderator.actor_id.clone().into()) {
+        let community_moderator_form = CommunityModeratorForm {
+          community_id: mod_user.community.id,
+          person_id: mod_user.moderator.id,
+        };
+        blocking(context.pool(), move |conn| {
+          CommunityModerator::leave(conn, &community_moderator_form)
+        })
+        .await??;
+      }
+    }
+
+    // Add new mods to database which have been added to moderators collection
+    for mod_uri in new_moderators {
+      let mod_user = get_or_fetch_and_upsert_person(&mod_uri, context, request_counter).await?;
+      let current_mod_uris: Vec<DbUrl> = current_moderators
+        .clone()
+        .iter()
+        .map(|c| c.moderator.actor_id.clone())
+        .collect();
+      if !current_mod_uris.contains(&mod_user.actor_id) {
+        let community_moderator_form = CommunityModeratorForm {
+          community_id: community.id,
+          person_id: mod_user.id,
+        };
+        blocking(context.pool(), move |conn| {
+          CommunityModerator::join(conn, &community_moderator_form)
+        })
+        .await??;
+      }
+    }
+
+    Ok(community)
   }
 }
 
@@ -132,16 +169,10 @@ impl FromApubToForm<GroupExt> for CommunityForm {
     context: &LemmyContext,
     expected_domain: Url,
     request_counter: &mut i32,
+    _mod_action_allowed: bool,
   ) -> Result<Self, LemmyError> {
-    let creator_and_moderator_uris = group.inner.attributed_to().context(location_info!())?;
+    let moderator_uris = fetch_community_mods(context, group, request_counter).await?;
-    let creator_uri = creator_and_moderator_uris
+    let creator_uri = moderator_uris.first().context(location_info!())?;
-      .as_many()
-      .context(location_info!())?
-      .iter()
-      .next()
-      .context(location_info!())?
-      .as_xsd_any_uri()
-      .context(location_info!())?;
 
     let creator = get_or_fetch_and_upsert_person(creator_uri, context, request_counter).await?;
     let name = group

crates/apub/src/objects/mod.rs

@@ -45,12 +45,14 @@ pub(crate) trait FromApub {
   ///
   /// * `apub` The object to read from
   /// * `context` LemmyContext which holds DB pool, HTTP client etc
-  /// * `expected_domain` Domain where the object was received from
+  /// * `expected_domain` Domain where the object was received from. None in case of mod action.
+  /// * `mod_action_allowed` True if the object can be a mod activity, ignore `expected_domain` in this case
   async fn from_apub(
     apub: &Self::ApubType,
     context: &LemmyContext,
     expected_domain: Url,
     request_counter: &mut i32,
+    mod_action_allowed: bool,
   ) -> Result<Self, LemmyError>
   where
     Self: Sized;
@@ -63,6 +65,7 @@ pub(in crate::objects) trait FromApubToForm<ApubType> {
     context: &LemmyContext,
     expected_domain: Url,
     request_counter: &mut i32,
+    mod_action_allowed: bool,
   ) -> Result<Self, LemmyError>
   where
     Self: Sized;
@@ -132,19 +135,17 @@ where
 {
   let content = object
     .content()
-    .map(|s| s.as_single_xsd_string())
+    .map(|s| s.as_single_xsd_string().map(|s2| s2.to_string()))
-    .flatten()
+    .flatten();
-    .map(|s| s.to_string());
   if content.is_some() {
     let source = object.source().context(location_info!())?;
     let source = Object::<()>::from_any_base(source.to_owned())?.context(location_info!())?;
     check_is_markdown(source.media_type())?;
     let source_content = source
       .content()
-      .map(|s| s.as_single_xsd_string())
+      .map(|s| s.as_single_xsd_string().map(|s2| s2.to_string()))
       .flatten()
-      .context(location_info!())?
+      .context(location_info!())?;
-      .to_string();
     return Ok(Some(source_content));
   }
   Ok(None)
@@ -177,6 +178,7 @@ pub(in crate::objects) async fn get_object_from_apub<From, Kind, To, ToForm, IdT
   context: &LemmyContext,
   expected_domain: Url,
   request_counter: &mut i32,
+  is_mod_action: bool,
 ) -> Result<To, LemmyError>
 where
   From: BaseExt<Kind>,
@@ -196,7 +198,14 @@ where
   }
   // otherwise parse and insert, assuring that it comes from the right domain
   else {
-    let to_form = ToForm::from_apub(&from, context, expected_domain, request_counter).await?;
+    let to_form = ToForm::from_apub(
+      &from,
+      context,
+      expected_domain,
+      request_counter,
+      is_mod_action,
+    )
+    .await?;
 
     let to = blocking(context.pool(), move |conn| To::upsert(conn, &to_form)).await??;
     Ok(to)

crates/apub/src/objects/person.rs

@@ -93,6 +93,7 @@ impl FromApub for DbPerson {
     context: &LemmyContext,
     expected_domain: Url,
     request_counter: &mut i32,
+    mod_action_allowed: bool,
   ) -> Result<DbPerson, LemmyError> {
     let person_id = person.id_unchecked().context(location_info!())?.to_owned();
     let domain = person_id.domain().context(location_info!())?;
@@ -103,8 +104,14 @@ impl FromApub for DbPerson {
       .await??;
       Ok(person)
     } else {
-      let person_form =
+      let person_form = PersonForm::from_apub(
-        PersonForm::from_apub(person, context, expected_domain, request_counter).await?;
+        person,
+        context,
+        expected_domain,
+        request_counter,
+        mod_action_allowed,
+      )
+      .await?;
       let person = blocking(context.pool(), move |conn| {
         DbPerson::upsert(conn, &person_form)
       })
@@ -121,6 +128,7 @@ impl FromApubToForm<PersonExt> for PersonForm {
     _context: &LemmyContext,
     expected_domain: Url,
     _request_counter: &mut i32,
+    _mod_action_allowed: bool,
   ) -> Result<Self, LemmyError> {
     let avatar = match person.icon() {
       Some(any_image) => Some(

crates/apub/src/objects/post.rs

@@ -1,4 +1,5 @@
 use crate::{
+  check_is_apub_id_valid,
   extensions::{context::lemmy_context, page_extension::PageExtension},
   fetcher::person::get_or_fetch_and_upsert_person,
   objects::{
@@ -117,8 +118,16 @@ impl FromApub for Post {
     context: &LemmyContext,
     expected_domain: Url,
     request_counter: &mut i32,
+    mod_action_allowed: bool,
   ) -> Result<Post, LemmyError> {
-    let post: Post = get_object_from_apub(page, context, expected_domain, request_counter).await?;
+    let post: Post = get_object_from_apub(
+      page,
+      context,
+      expected_domain,
+      request_counter,
+      mod_action_allowed,
+    )
+    .await?;
     check_object_for_community_or_site_ban(page, post.community_id, context, request_counter)
       .await?;
     Ok(post)
@@ -132,7 +141,15 @@ impl FromApubToForm<PageExt> for PostForm {
     context: &LemmyContext,
     expected_domain: Url,
     request_counter: &mut i32,
+    mod_action_allowed: bool,
   ) -> Result<PostForm, LemmyError> {
+    let ap_id = if mod_action_allowed {
+      let id = page.id_unchecked().context(location_info!())?;
+      check_is_apub_id_valid(id)?;
+      id.to_owned().into()
+    } else {
+      check_object_domain(page, expected_domain)?
+    };
     let ext = &page.ext_one;
     let creator_actor_id = page
       .inner
@@ -179,16 +196,20 @@ impl FromApubToForm<PageExt> for PostForm {
     let name = page
       .inner
       .name()
-      .map(|s| s.map(|s2| s2.to_owned()))
       // The following is for compatibility with lemmy v0.9.9 and older
       // TODO: remove it after some time (along with the map above)
-      .or_else(|| page.inner.summary().map(|s| s.to_owned()))
+      .or_else(|| page.inner.summary())
       .context(location_info!())?
       .as_single_xsd_string()
       .context(location_info!())?
       .to_string();
     let body = get_source_markdown_value(page)?;
 
+    // TODO: expected_domain is wrong in this case, because it simply takes the domain of the actor
+    //       maybe we need to take id_unchecked() if the activity is from community to user?
+    //       why did this work before? -> i dont think it did?
+    //       -> try to make expected_domain optional and set it null if it is a mod action
+
     check_slurs(&name)?;
     let body_slurs_removed = body.map(|b| remove_slurs(&b));
     Ok(PostForm {
@@ -216,7 +237,7 @@ impl FromApubToForm<PageExt> for PostForm {
       embed_description: iframely_description,
       embed_html: iframely_html,
       thumbnail_url: pictrs_thumbnail.map(|u| u.into()),
-      ap_id: Some(check_object_domain(page, expected_domain)?),
+      ap_id: Some(ap_id),
       local: false,
     })
   }

crates/apub/src/objects/private_message.rs

@@ -77,8 +77,16 @@ impl FromApub for PrivateMessage {
     context: &LemmyContext,
     expected_domain: Url,
     request_counter: &mut i32,
+    mod_action_allowed: bool,
   ) -> Result<PrivateMessage, LemmyError> {
-    get_object_from_apub(note, context, expected_domain, request_counter).await
+    get_object_from_apub(
+      note,
+      context,
+      expected_domain,
+      request_counter,
+      mod_action_allowed,
+    )
+    .await
   }
 }
 
@@ -89,6 +97,7 @@ impl FromApubToForm<NoteExt> for PrivateMessageForm {
     context: &LemmyContext,
     expected_domain: Url,
     request_counter: &mut i32,
+    _mod_action_allowed: bool,
   ) -> Result<PrivateMessageForm, LemmyError> {
     let creator_actor_id = note
       .attributed_to()

crates/apub/src/routes.rs

@@ -5,6 +5,7 @@ use crate::{
       get_apub_community_followers,
       get_apub_community_http,
       get_apub_community_inbox,
+      get_apub_community_moderators,
       get_apub_community_outbox,
     },
     get_activity,
@@ -57,6 +58,10 @@ pub fn config(cfg: &mut web::ServiceConfig) {
             "/c/{community_name}/inbox",
             web::get().to(get_apub_community_inbox),
           )
+          .route(
+            "/c/{community_name}/moderators",
+            web::get().to(get_apub_community_moderators),
+          )
           .route("/u/{user_name}", web::get().to(get_apub_person_http))
           .route(
             "/u/{user_name}/outbox",

docker/federation/lemmy_alpha.hjson

@@ -1,4 +1,5 @@
 {
+  hostname: lemmy-alpha:8541
   port: 8541
   tls_enabled: false
   jwt_secret: changeme