federator: don't federate anything other than Note objects to OStatus

lib/pleroma/web/federator/federator.ex

@@ -7,6 +7,7 @@ defmodule Pleroma.Web.Federator do
   alias Pleroma.Web.ActivityPub.Relay
   alias Pleroma.Web.ActivityPub.Transmogrifier
   alias Pleroma.Web.ActivityPub.Utils
+  alias Pleroma.Web.OStatus
   require Logger
 
   @websub Application.get_env(:pleroma, :websub)
@@ -63,11 +64,13 @@ defmodule Pleroma.Web.Federator do
       {:ok, actor} = WebFinger.ensure_keys_present(actor)
 
       if ActivityPub.is_public?(activity) do
-        Logger.info(fn -> "Sending #{activity.data["id"]} out via WebSub" end)
-        Websub.publish(Pleroma.Web.OStatus.feed_path(actor), actor, activity)
+        if OStatus.is_representable?(activity) do
+          Logger.info(fn -> "Sending #{activity.data["id"]} out via WebSub" end)
+          Websub.publish(Pleroma.Web.OStatus.feed_path(actor), actor, activity)
 
-        Logger.info(fn -> "Sending #{activity.data["id"]} out via Salmon" end)
-        Pleroma.Web.Salmon.publish(actor, activity)
+          Logger.info(fn -> "Sending #{activity.data["id"]} out via Salmon" end)
+          Pleroma.Web.Salmon.publish(actor, activity)
+        end
 
         if Keyword.get(Application.get_env(:pleroma, :instance), :allow_relay) do
           Logger.info(fn -> "Relaying #{activity.data["id"]} out" end)

lib/pleroma/web/ostatus/ostatus.ex

@@ -11,6 +11,21 @@ defmodule Pleroma.Web.OStatus do
   alias Pleroma.Web.OStatus.{FollowHandler, UnfollowHandler, NoteHandler, DeleteHandler}
   alias Pleroma.Web.ActivityPub.Transmogrifier
 
+  def is_representable?(%Activity{data: data}) do
+    object = Object.normalize(data["object"])
+
+    cond do
+      is_nil(object) ->
+        false
+
+      object.data["type"] == "Note" ->
+        true
+
+      true ->
+        false
+    end
+  end
+
   def feed_path(user) do
     "#{user.ap_id}/feed.atom"
   end