MRF.StealEmojiPolicy: New Policy

Inspired by https://git.pleroma.social/moonman/emoji-stealer-mrf/-/blob/master/steal_emoji_policy.ex

test/support/http_request_mock.ex

@@ -1291,6 +1291,10 @@ defmodule HttpRequestMock do
      }}
   end
 
+  def get("https://example.org/emoji/firedfox.png", _, _, _) do
+    {:ok, %Tesla.Env{status: 200, body: File.read!("test/fixtures/image.jpg")}}
+  end
+
   def get("https://skippers-bin.com/users/7v1w1r8ce6", _, _, _) do
     {:ok, %Tesla.Env{status: 200, body: File.read!("test/fixtures/tesla_mock/sjw.json")}}
   end

test/web/activity_pub/mrf/steal_emoji_policy_test.exs

@@ -0,0 +1,64 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.MRF.StealEmojiPolicyTest do
+  use Pleroma.DataCase
+
+  alias Pleroma.Config
+  alias Pleroma.Web.ActivityPub.MRF.StealEmojiPolicy
+
+  setup_all do
+    Tesla.Mock.mock_global(fn env -> apply(HttpRequestMock, :request, [env]) end)
+    :ok
+  end
+
+  setup do
+    clear_config(:mrf_steal_emoji)
+
+    emoji_path = Path.join(Config.get([:instance, :static_dir]), "emoji/stolen")
+    File.rm_rf!(emoji_path)
+    File.mkdir!(emoji_path)
+
+    Pleroma.Emoji.reload()
+  end
+
+  test "does nothing by default" do
+    installed_emoji = Pleroma.Emoji.get_all() |> Enum.map(fn {k, _} -> k end)
+    refute "firedfox" in installed_emoji
+
+    message = %{
+      "type" => "Create",
+      "object" => %{
+        "emoji" => [{"firedfox", "https://example.org/emoji/firedfox.png"}],
+        "actor" => "https://example.org/users/admin"
+      }
+    }
+
+    assert {:ok, message} == StealEmojiPolicy.filter(message)
+
+    installed_emoji = Pleroma.Emoji.get_all() |> Enum.map(fn {k, _} -> k end)
+    refute "firedfox" in installed_emoji
+  end
+
+  test "Steals emoji on unknown shortcode from allowed remote host" do
+    installed_emoji = Pleroma.Emoji.get_all() |> Enum.map(fn {k, _} -> k end)
+    refute "firedfox" in installed_emoji
+
+    message = %{
+      "type" => "Create",
+      "object" => %{
+        "emoji" => [{"firedfox", "https://example.org/emoji/firedfox.png"}],
+        "actor" => "https://example.org/users/admin"
+      }
+    }
+
+    Config.put([:mrf_steal_emoji, :hosts], ["example.org"])
+    Config.put([:mrf_steal_emoji, :size_limit], 284_468)
+
+    assert {:ok, message} == StealEmojiPolicy.filter(message)
+
+    installed_emoji = Pleroma.Emoji.get_all() |> Enum.map(fn {k, _} -> k end)
+    assert "firedfox" in installed_emoji
+  end
+end