Mastodon API: Fix lists leaking private posts

Our previous list visibility resolver grabbed posts if either follower
collection of the user in a list who is followed is in `to` or if
follower collection of the user in a list was in `cc`. This not only
missed unlisted posts but also lead to leaking private posts when
`fix_explicit_addressing` mistakingly started putting follower collections
to `cc` (also fixed in this MR).

Reported by @kurisu@iscute.moe via a DM

1 files changed, 11 insertions, 16 deletions

diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index bd4ac6197..7eea5b447 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -466,20 +466,6 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
 
   defp restrict_tag(query, _), do: query
 
-  defp restrict_to_cc(query, recipients_to, recipients_cc) do
-    from(
-      activity in query,
-      where:
-        fragment(
-          "(?->'to' \\?| ?) or (?->'cc' \\?| ?)",
-          activity.data,
-          ^recipients_to,
-          activity.data,
-          ^recipients_cc
-        )
-    )
-  end
-
   defp restrict_recipients(query, [], _user), do: query
 
   defp restrict_recipients(query, recipients, nil) do
@@ -629,9 +615,18 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
     |> Enum.reverse()
   end
 
-  def fetch_activities_bounded(recipients_to, recipients_cc, opts \\ %{}) do
+  def fetch_activities_bounded_query(query, recipients, recipients_with_public) do
+    from(activity in query,
+      where:
+        fragment("? && ?", activity.recipients, ^recipients) or
+          (fragment("? && ?", activity.recipients, ^recipients_with_public) and
+             "https://www.w3.org/ns/activitystreams#Public" in activity.recipients)
+    )
+  end
+
+  def fetch_activities_bounded(recipients, recipients_with_public, opts \\ %{}) do
     fetch_activities_query([], opts)
-    |> restrict_to_cc(recipients_to, recipients_cc)
+    |> fetch_activities_bounded_query(recipients, recipients_with_public)
     |> Repo.all()
     |> Enum.reverse()
   end