Merge branch 'feature/mrf-subchain' into 'develop'

MRF: subchain policy

See merge request pleroma/pleroma!1233

CHANGELOG.md

@@ -49,6 +49,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - OAuth: added job to clean expired access tokens
 - MRF: Support for rejecting reports from specific instances (`mrf_simple`)
 - MRF: Support for stripping avatars and banner images from specific instances (`mrf_simple`)
+- MRF: Support for running subchains.
 
 ### Changed
 - **Breaking:** Configuration: move from Pleroma.Mailer to Pleroma.Emails.Mailer

config/config.exs

@@ -326,6 +326,8 @@ config :pleroma, :mrf_keyword,
   federated_timeline_removal: [],
   replace: []
 
+config :pleroma, :mrf_subchain, match_actor: %{}
+
 config :pleroma, :rich_media, enabled: true
 
 config :pleroma, :media_proxy,

docs/config.md

@@ -86,6 +86,7 @@ config :pleroma, Pleroma.Emails.Mailer,
   * `Pleroma.Web.ActivityPub.MRF.NoOpPolicy`: Doesn’t modify activities (default)
   * `Pleroma.Web.ActivityPub.MRF.DropPolicy`: Drops all activities. It generally doesn’t makes sense to use in production
   * `Pleroma.Web.ActivityPub.MRF.SimplePolicy`: Restrict the visibility of activities from certains instances (See ``:mrf_simple`` section)
+  * `Pleroma.Web.ActivityPub.MRF.SubchainPolicy`: Selectively runs other MRF policies when messages match (see ``:mrf_subchain`` section)
   * `Pleroma.Web.ActivityPub.MRF.RejectNonPublic`: Drops posts with non-public visibility settings (See ``:mrf_rejectnonpublic`` section)
   * `Pleroma.Web.ActivityPub.MRF.EnsureRePrepended`: Rewrites posts to ensure that replies to posts with subjects do not have an identical subject and instead begin with re:.
 * `public`: Makes the client API in authentificated mode-only except for user-profiles. Useful for disabling the Local Timeline and The Whole Known Network.
@@ -229,6 +230,21 @@ relates to mascots on the mastodon frontend
 * `avatar_removal`: List of instances to strip avatars from
 * `banner_removal`: List of instances to strip banners from
 
+## :mrf_subchain
+This policy processes messages through an alternate pipeline when a given message matches certain criteria.
+All criteria are configured as a map of regular expressions to lists of policy modules.
+
+* `match_actor`: Matches a series of regular expressions against the actor field.
+
+Example:
+
+```
+config :pleroma, :mrf_subchain,
+  match_actor: %{
+    ~r/https:\/\/example.com/s => [Pleroma.Web.ActivityPub.MRF.DropPolicy]
+  }
+```
+
 ## :mrf_rejectnonpublic
 * `allow_followersonly`: whether to allow followers-only posts
 * `allow_direct`: whether to allow direct messages

lib/pleroma/web/activity_pub/mrf.ex

@@ -5,8 +5,8 @@
 defmodule Pleroma.Web.ActivityPub.MRF do
   @callback filter(Map.t()) :: {:ok | :reject, Map.t()}
 
-  def filter(object) do
-    get_policies()
+  def filter(policies, %{} = object) do
+    policies
     |> Enum.reduce({:ok, object}, fn
       policy, {:ok, object} ->
         policy.filter(object)
@@ -16,6 +16,8 @@ defmodule Pleroma.Web.ActivityPub.MRF do
     end)
   end
 
+  def filter(%{} = object), do: get_policies() |> filter(object)
+
   def get_policies do
     Pleroma.Config.get([:instance, :rewrite_policy], []) |> get_policies()
   end

lib/pleroma/web/activity_pub/mrf/subchain_policy.ex

@@ -0,0 +1,40 @@
+# 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.SubchainPolicy do
+  alias Pleroma.Config
+  alias Pleroma.Web.ActivityPub.MRF
+
+  require Logger
+
+  @behaviour MRF
+
+  defp lookup_subchain(actor) do
+    with matches <- Config.get([:mrf_subchain, :match_actor]),
+         {match, subchain} <- Enum.find(matches, fn {k, _v} -> String.match?(actor, k) end) do
+      {:ok, match, subchain}
+    else
+      _e -> {:error, :notfound}
+    end
+  end
+
+  @impl true
+  def filter(%{"actor" => actor} = message) do
+    with {:ok, match, subchain} <- lookup_subchain(actor) do
+      Logger.debug(
+        "[SubchainPolicy] Matched #{actor} against #{inspect(match)} with subchain #{
+          inspect(subchain)
+        }"
+      )
+
+      subchain
+      |> MRF.filter(message)
+    else
+      _e -> {:ok, message}
+    end
+  end
+
+  @impl true
+  def filter(message), do: {:ok, message}
+end

test/web/activity_pub/mrf/subchain_policy_test.exs

@@ -0,0 +1,32 @@
+# 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.SubchainPolicyTest do
+  use Pleroma.DataCase
+
+  alias Pleroma.Web.ActivityPub.MRF.DropPolicy
+  alias Pleroma.Web.ActivityPub.MRF.SubchainPolicy
+
+  @message %{
+    "actor" => "https://banned.com",
+    "type" => "Create",
+    "object" => %{"content" => "hi"}
+  }
+
+  test "it matches and processes subchains when the actor matches a configured target" do
+    Pleroma.Config.put([:mrf_subchain, :match_actor], %{
+      ~r/^https:\/\/banned.com/s => [DropPolicy]
+    })
+
+    {:reject, _} = SubchainPolicy.filter(@message)
+  end
+
+  test "it doesn't match and process subchains when the actor doesn't match a configured target" do
+    Pleroma.Config.put([:mrf_subchain, :match_actor], %{
+      ~r/^https:\/\/borked.com/s => [DropPolicy]
+    })
+
+    {:ok, _message} = SubchainPolicy.filter(@message)
+  end
+end