attempted fix

api_tests/src/private_community.spec.ts

@@ -298,6 +298,20 @@ test.only("Fetch remote content in private community", async () => {
   const comment_id = comment.comment_view.comment.id;
   expect(comment_id).toBeDefined();
 
+  // Wait for post and comment to federate
+  /*
+  console.log('a');
+  await waitUntil(
+    () => resolvePost(alpha, post.post_view.post),
+    p => p?.post?.post.id != undefined,
+  );
+  await waitUntil(
+    () => resolveComment(gamma, comment.comment_view.comment),
+    p => p?.post?.post.id != undefined,
+  );
+  */
+  console.log("b");
+
   // create gamma user and follow community
   const gammaCommunityId = (
     await resolveCommunity(gamma, community.community_view.community.actor_id)
@@ -310,23 +324,22 @@ test.only("Fetch remote content in private community", async () => {
   await approveFollower(alpha, alphaCommunityId);
 
   // now user can fetch posts and comments in community (using signed fetch), and create posts
+  // TODO: this fails because beta doesnt know if the gamma user was approved by alpha community
+  console.log(0);
   let resolvedPost = await waitUntil(
     () => resolvePost(gamma, post.post_view.post),
     p => p?.post?.post.id != undefined,
   );
-  console.log(post.post_view.post);
-  console.log(resolvedPost.post?.post);
   expect(resolvedPost.post?.post.ap_id).toBe(post.post_view.post.ap_id);
-  const resolvedComment = (
-    await resolveComment(gamma, comment.comment_view.comment)
-  ).comment;
-  expect(resolvedComment?.comment.ap_id).toBe(
+  console.log(1);
+  const resolvedComment = await waitUntil(
+    () => resolveComment(gamma, comment.comment_view.comment),
+    p => p?.post?.post.id != undefined,
+  );
+  expect(resolvedComment?.comment?.comment.ap_id).toBe(
     comment.comment_view.comment.ap_id,
   );
-
-  // TODO: this test should fail as check_has_followers_from_instance() on beta returns errors
-  //       because it doesnt know the community follower. yet for some reason the test passes???
-  fail();
+  console.log(2);
 });
 
 async function approveFollower(user: LemmyHttp, community_id: number) {

crates/apub/src/http/community.rs

@@ -6,16 +6,19 @@ use crate::{
     community_moderators::ApubCommunityModerators,
     community_outbox::ApubCommunityOutbox,
   },
+  fetcher::site_or_community_or_user::SiteOrCommunityOrUser,
   http::{check_community_fetchable, create_apub_response, create_apub_tombstone_response},
   objects::community::ApubCommunity,
 };
 use activitypub_federation::{
   config::Data,
+  fetch::object_id::ObjectId,
   traits::{Collection, Object},
 };
 use actix_web::{web, HttpRequest, HttpResponse};
 use lemmy_api_common::context::LemmyContext;
 use lemmy_db_schema::{source::community::Community, traits::ApubActor};
+use lemmy_db_views_actor::structs::CommunityFollowerView;
 use lemmy_utils::error::{LemmyErrorType, LemmyResult};
 use serde::Deserialize;
 
@@ -24,6 +27,11 @@ pub(crate) struct CommunityQuery {
   community_name: String,
 }
 
+#[derive(Deserialize)]
+pub struct CommunityIsFollowerQuery {
+  is_follower: Option<ObjectId<SiteOrCommunityOrUser>>,
+}
+
 /// Return the ActivityPub json representation of a local community over HTTP.
 #[tracing::instrument(skip_all)]
 pub(crate) async fn get_apub_community_http(
@@ -48,11 +56,26 @@ pub(crate) async fn get_apub_community_http(
 /// Returns an empty followers collection, only populating the size (for privacy).
 pub(crate) async fn get_apub_community_followers(
   info: web::Path<CommunityQuery>,
+  query: web::Query<CommunityIsFollowerQuery>,
   context: Data<LemmyContext>,
 ) -> LemmyResult<HttpResponse> {
   let community = Community::read_from_name(&mut context.pool(), &info.community_name, false)
     .await?
     .ok_or(LemmyErrorType::NotFound)?;
+  if let Some(is_follower) = &query.is_follower {
+    let instance_id = is_follower.dereference(&context).await?.instance_id();
+    let has_followers = CommunityFollowerView::check_has_followers_from_instance(
+      community.id,
+      instance_id,
+      &mut context.pool(),
+    )
+    .await;
+    return if has_followers.is_ok() {
+      Ok(HttpResponse::Ok().finish())
+    } else {
+      Ok(HttpResponse::NotFound().finish())
+    };
+  }
   check_community_fetchable(&community)?;
   let followers = ApubCommunityFollower::read_local(&community.into(), &context).await?;
   create_apub_response(&followers)

crates/apub/src/http/mod.rs

@@ -8,6 +8,7 @@ use activitypub_federation::{
   actix_web::{inbox::receive_activity, signing_actor},
   config::Data,
   protocol::context::WithContext,
+  traits::Actor,
   FEDERATION_CONTENT_TYPE,
 };
 use actix_web::{web, web::Bytes, HttpRequest, HttpResponse};
@@ -145,14 +146,30 @@ async fn check_community_content_fetchable(
     // from the fetching instance then fetching is allowed
     Private => {
       let signing_actor = signing_actor::<SiteOrCommunityOrUser>(request, None, context).await?;
-      Ok(
-        CommunityFollowerView::check_has_followers_from_instance(
-          community.id,
-          signing_actor.instance_id(),
-          &mut context.pool(),
+      if community.local {
+        Ok(
+          CommunityFollowerView::check_has_followers_from_instance(
+            community.id,
+            signing_actor.instance_id(),
+            &mut context.pool(),
+          )
+          .await?,
         )
-        .await?,
-      )
+      } else if let Some(followers_url) = community.followers_url.clone() {
+        let mut followers_url = followers_url.inner().clone();
+        followers_url
+          .query_pairs_mut()
+          .append_pair("is_follower", signing_actor.id().as_str());
+        context
+          .client()
+          .get(followers_url.as_str())
+          .send()
+          .await?
+          .error_for_status()?;
+        Ok(())
+      } else {
+        Err(LemmyErrorType::NotFound.into())
+      }
     }
   }
 }

crates/db_views_actor/src/community_follower_view.rs

@@ -232,6 +232,25 @@ impl CommunityFollowerView {
     .then_some(())
     .ok_or(diesel::NotFound)
   }
+
+  pub async fn is_follower(
+    community_id: CommunityId,
+    instance_id: InstanceId,
+    pool: &mut DbPool<'_>,
+  ) -> Result<(), Error> {
+    let conn = &mut get_conn(pool).await?;
+    select(exists(
+      action_query(community_actions::followed)
+        .inner_join(person::table.on(community_actions::person_id.eq(person::id)))
+        .filter(community_actions::community_id.eq(community_id))
+        .filter(person::instance_id.eq(instance_id))
+        .filter(community_actions::follow_state.eq(CommunityFollowerState::Accepted)),
+    ))
+    .get_result::<bool>(conn)
+    .await?
+    .then_some(())
+    .ok_or(diesel::NotFound)
+  }
 }
 
 #[cfg(test)]