From 297a2c7d3f2f4e79d05ed799e7bb20ed27b35a9c Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Mon, 19 Feb 2018 17:37:45 +0100
Subject: [PATCH] Ignore duplicate create activities.

---
 .../web/activity_pub/activity_pub_controller.ex      |  2 +-
 lib/pleroma/web/activity_pub/transmogrifier.ex       |  4 +++-
 test/web/activity_pub/transmogrifier_test.exs        | 12 ++++++++++++
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/activity_pub_controller.ex b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
index 1a6d7ec7a..835e8bd9d 100644
--- a/lib/pleroma/web/activity_pub/activity_pub_controller.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
@@ -25,7 +25,7 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubController do
   # TODO: Ensure that this inbox is a recipient of the message
   def inbox(%{assigns: %{valid_signature: true}} = conn, params) do
     # File.write("/tmp/incoming.json", Poison.encode!(params))
-    Logger.info(Poison.encode!(params, [pretty: 2]))
+    # Logger.info(Poison.encode!(params, [pretty: 2]))
     with {:ok, _user} <- ap_enabled_actor(params["actor"]),
          nil <- Activity.get_by_ap_id(params["id"]),
          {:ok, activity} <- Transmogrifier.handle_incoming(params) do
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 075250aa5..e53957fbf 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -37,7 +37,8 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   # - tags
   # - emoji
   def handle_incoming(%{"type" => "Create", "object" => %{"type" => "Note"} = object} = data) do
-    with %User{} = user <- User.get_or_fetch_by_ap_id(data["actor"]) do
+    with nil <- Activity.get_create_activity_by_object_ap_id(object["id"]),
+         %User{} = user <- User.get_or_fetch_by_ap_id(data["actor"]) do
       object = fix_object(data["object"])
       params = %{
         to: data["to"],
@@ -54,6 +55,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
 
       ActivityPub.create(params)
     else
+      %Activity{} = activity -> {:ok, activity}
       _e -> :error
     end
   end
diff --git a/test/web/activity_pub/transmogrifier_test.exs b/test/web/activity_pub/transmogrifier_test.exs
index 45e284157..11c6bbe1c 100644
--- a/test/web/activity_pub/transmogrifier_test.exs
+++ b/test/web/activity_pub/transmogrifier_test.exs
@@ -10,6 +10,18 @@ defmodule Pleroma.Web.ActivityPub.TransmogrifierTest do
   alias Pleroma.Web.CommonAPI
 
   describe "handle_incoming" do
+    test "it ignores an incoming notice if we already have it" do
+      activity = insert(:note_activity)
+
+      data = File.read!("test/fixtures/mastodon-post-activity.json")
+      |> Poison.decode!
+      |> Map.put("object", activity.data["object"])
+
+      {:ok, returned_activity} = Transmogrifier.handle_incoming(data)
+
+      assert activity == returned_activity
+    end
+
     test "it works for incoming notices" do
       data = File.read!("test/fixtures/mastodon-post-activity.json") |> Poison.decode!