MRF Policies: Return a {:reject, reason} instead of {:reject, nil}

[akkoma] / lib / pleroma / web / activity_pub / mrf / hellthread_policy.ex

diff --git a/lib/pleroma/web/activity_pub/mrf/hellthread_policy.ex b/lib/pleroma/web/activity_pub/mrf/hellthread_policy.ex
index 4c6e612b28357025f8b436c6ea3065e1bdce6bf7..9ba07b4e38b73c4a1bffdfba131511aee90855f9 100644 (file)
--- a/lib/pleroma/web/activity_pub/mrf/hellthread_policy.ex
+++ b/lib/pleroma/web/activity_pub/mrf/hellthread_policy.ex
@@ -1,48 +1,100 @@
 # Pleroma: A lightweight social networking server
-# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.ActivityPub.MRF.HellthreadPolicy do
   alias Pleroma.User
+
+  require Pleroma.Constants
+
+  @moduledoc "Block messages with too much mentions (configurable)"
+
   @behaviour Pleroma.Web.ActivityPub.MRF
 
-  defp delist_message(message) do
+  defp delist_message(message, threshold) when threshold > 0 do
     follower_collection = User.get_cached_by_ap_id(message["actor"]).follower_address
+    to = message["to"] || []
+    cc = message["cc"] || []
+
+    follower_collection? = Enum.member?(to ++ cc, follower_collection)
 
-    message
-    |> Map.put("to", [follower_collection])
-    |> Map.put("cc", ["https://www.w3.org/ns/activitystreams#Public"])
+    message =
+      case get_recipient_count(message) do
+        {:public, recipients}
+        when follower_collection? and recipients > threshold ->
+          message
+          |> Map.put("to", [follower_collection])
+          |> Map.put("cc", [Pleroma.Constants.as_public()])
+
+        {:public, recipients} when recipients > threshold ->
+          message
+          |> Map.put("to", [])
+          |> Map.put("cc", [Pleroma.Constants.as_public()])
+
+        _ ->
+          message
+      end
+
+    {:ok, message}
   end
 
-  @impl true
-  def filter(%{"type" => "Create"} = message) do
-    delist_threshold = Pleroma.Config.get([:mrf_hellthread, :delist_threshold])
+  defp delist_message(message, _threshold), do: {:ok, message}
+
+  defp reject_message(message, threshold) when threshold > 0 do
+    with {_, recipients} <- get_recipient_count(message) do
+      if recipients > threshold do
+        {:reject, "[HellthreadPolicy] #{recipients} recipients is over the limit of #{threshold}"}
+      else
+        {:ok, message}
+      end
+    end
+  end
+
+  defp reject_message(message, _threshold), do: {:ok, message}
+
+  defp get_recipient_count(message) do
+    recipients = (message["to"] || []) ++ (message["cc"] || [])
+    follower_collection = User.get_cached_by_ap_id(message["actor"]).follower_address
+
+    if Enum.member?(recipients, Pleroma.Constants.as_public()) do
+      recipients =
+        recipients
+        |> List.delete(Pleroma.Constants.as_public())
+        |> List.delete(follower_collection)
+
+      {:public, length(recipients)}
+    else
+      recipients =
+        recipients
+        |> List.delete(follower_collection)
 
+      {:not_public, length(recipients)}
+    end
+  end
+
+  @impl true
+  def filter(%{"type" => "Create", "object" => %{"type" => object_type}} = message)
+      when object_type in ~w{Note Article} do
     reject_threshold =
       Pleroma.Config.get(
         [:mrf_hellthread, :reject_threshold],
         Pleroma.Config.get([:mrf_hellthread, :threshold])
       )
 
-    recipients = (message["to"] || []) ++ (message["cc"] || [])
-
-    cond do
-      length(recipients) > reject_threshold and reject_threshold > 0 ->
-        {:reject, nil}
-
-      length(recipients) > delist_threshold and delist_threshold > 0 ->
-        if Enum.member?(message["to"], "https://www.w3.org/ns/activitystreams#Public") or
-             Enum.member?(message["cc"], "https://www.w3.org/ns/activitystreams#Public") do
-          {:ok, delist_message(message)}
-        else
-          {:ok, message}
-        end
+    delist_threshold = Pleroma.Config.get([:mrf_hellthread, :delist_threshold])
 
-      true ->
-        {:ok, message}
+    with {:ok, message} <- reject_message(message, reject_threshold),
+         {:ok, message} <- delist_message(message, delist_threshold) do
+      {:ok, message}
+    else
+      e -> e
     end
   end
 
   @impl true
   def filter(message), do: {:ok, message}
+
+  @impl true
+  def describe,
+    do: {:ok, %{mrf_hellthread: Pleroma.Config.get(:mrf_hellthread) |> Enum.into(%{})}}
 end