Add keyword policy

2 files changed, 102 insertions, 0 deletions

diff --git a/lib/pleroma/web/activity_pub/mrf/keyword_policy.ex b/lib/pleroma/web/activity_pub/mrf/keyword_policy.ex
new file mode 100644
index 000000000..6e2673e9c
--- /dev/null
+++ b/lib/pleroma/web/activity_pub/mrf/keyword_policy.ex
@@ -0,0 +1,74 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.MRF.KeywordPolicy do
+  @behaviour Pleroma.Web.ActivityPub.MRF
+  defp string_matches?(string, pattern) when is_binary(pattern) do
+    String.contains?(string, pattern)
+  end
+
+  defp string_matches?(string, pattern) do
+    String.match?(string, pattern)
+  end
+
+  defp check_reject(%{"object" => %{"content" => content}} = message) do
+    if Enum.any?(Pleroma.Config.get([:mrf_keyword, :reject]), fn pattern ->
+         string_matches?(content, pattern)
+       end) do
+      {:reject, nil}
+    else
+      {:ok, message}
+    end
+  end
+
+  defp check_ftl_removal(%{"to" => to, "object" => %{"content" => content}} = message) do
+    if "https://www.w3.org/ns/activitystreams#Public" in to and
+         Enum.any?(Pleroma.Config.get([:mrf_keyword, :ftl_removal]), fn pattern ->
+           string_matches?(content, pattern)
+         end) do
+      to = List.delete(to, "https://www.w3.org/ns/activitystreams#Public")
+      cc = ["https://www.w3.org/ns/activitystreams#Public" | [message["cc"] || []]]
+
+      message =
+        message
+        |> Map.put("to", to)
+        |> Map.put("cc", cc)
+
+      IO.inspect(message)
+      {:ok, message}
+    else
+      {:ok, message}
+    end
+  end
+
+  defp check_replace(%{"object" => %{"content" => content}} = message) do
+    content =
+      Enum.reduce(Pleroma.Config.get([:mrf_keyword, :replace]), content, fn {pattern, replacement},
+                                                                            acc ->
+        String.replace(acc, pattern, replacement)
+      end)
+
+    {:ok, put_in(message["object"]["content"], content)}
+  end
+
+  @impl true
+  def filter(%{"object" => %{"content" => nil}} = message) do
+    {:ok, message}
+  end
+
+  @impl true
+  def filter(%{"type" => "Create", "object" => %{"content" => _content}} = message) do
+    with {:ok, message} <- check_reject(message),
+         {:ok, message} <- check_ftl_removal(message),
+         {:ok, message} <- check_replace(message) do
+      {:ok, message}
+    else
+      _e ->
+        {:reject, nil}
+    end
+  end
+
+  @impl true
+  def filter(message), do: {:ok, message}
+end
diff --git a/lib/pleroma/web/nodeinfo/nodeinfo_controller.ex b/lib/pleroma/web/nodeinfo/nodeinfo_controller.ex
index 21694a5ee..7c24d4761 100644
--- a/lib/pleroma/web/nodeinfo/nodeinfo_controller.ex
+++ b/lib/pleroma/web/nodeinfo/nodeinfo_controller.ex
@@ -44,6 +44,33 @@ defmodule Pleroma.Web.Nodeinfo.NodeinfoController do
       Application.get_env(:pleroma, :mrf_simple)
       |> Enum.into(%{})
 
+    # This horror is needed to convert regex sigils to strings
+    mrf_keyword =
+      Application.get_env(:pleroma, :mrf_keyword)
+      |> Enum.map(fn {key, value} ->
+        {key,
+         Enum.map(value, fn
+           {pattern, replacement} ->
+             %{
+               "pattern" =>
+                 if not is_binary(pattern) do
+                   inspect(pattern)
+                 else
+                   pattern
+                 end,
+               "replacement" => replacement
+             }
+
+           pattern ->
+             if not is_binary(pattern) do
+               inspect(pattern)
+             else
+               pattern
+             end
+         end)}
+      end)
+      |> Enum.into(%{})
+
     mrf_policies =
       MRF.get_policies()
       |> Enum.map(fn policy -> to_string(policy) |> String.split(".") |> List.last() end)
@@ -73,6 +100,7 @@ defmodule Pleroma.Web.Nodeinfo.NodeinfoController do
         %{
           mrf_policies: mrf_policies,
           mrf_simple: mrf_simple,
+          mrf_keyword: mrf_keyword,
           mrf_user_allowlist: mrf_user_allowlist,
           quarantined_instances: quarantined
         }