From 54a6855ddfb4b47b91b8fe2c184bbca3dbc2884d Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 11 Aug 2020 14:00:21 +0200
Subject: [PATCH 01/13] Transmogrifier Tests: Extract Accept handling

---
 .../transmogrifier/accept_handling_test.exs   | 113 ++++++++++++++++++
 test/web/activity_pub/transmogrifier_test.exs | 102 +---------------
 2 files changed, 114 insertions(+), 101 deletions(-)
 create mode 100644 test/web/activity_pub/transmogrifier/accept_handling_test.exs

diff --git a/test/web/activity_pub/transmogrifier/accept_handling_test.exs b/test/web/activity_pub/transmogrifier/accept_handling_test.exs
new file mode 100644
index 000000000..3c4e134ff
--- /dev/null
+++ b/test/web/activity_pub/transmogrifier/accept_handling_test.exs
@@ -0,0 +1,113 @@
+# 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.Transmogrifier.AcceptHandlingTest do
+  use Pleroma.DataCase
+
+  alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.Transmogrifier
+  alias Pleroma.Web.CommonAPI
+
+  import Pleroma.Factory
+
+  test "it works for incoming accepts which were pre-accepted" do
+    follower = insert(:user)
+    followed = insert(:user)
+
+    {:ok, follower} = User.follow(follower, followed)
+    assert User.following?(follower, followed) == true
+
+    {:ok, _, _, follow_activity} = CommonAPI.follow(follower, followed)
+
+    accept_data =
+      File.read!("test/fixtures/mastodon-accept-activity.json")
+      |> Poison.decode!()
+      |> Map.put("actor", followed.ap_id)
+
+    object =
+      accept_data["object"]
+      |> Map.put("actor", follower.ap_id)
+      |> Map.put("id", follow_activity.data["id"])
+
+    accept_data = Map.put(accept_data, "object", object)
+
+    {:ok, activity} = Transmogrifier.handle_incoming(accept_data)
+    refute activity.local
+
+    assert activity.data["object"] == follow_activity.data["id"]
+
+    assert activity.data["id"] == accept_data["id"]
+
+    follower = User.get_cached_by_id(follower.id)
+
+    assert User.following?(follower, followed) == true
+  end
+
+  test "it works for incoming accepts which were orphaned" do
+    follower = insert(:user)
+    followed = insert(:user, locked: true)
+
+    {:ok, _, _, follow_activity} = CommonAPI.follow(follower, followed)
+
+    accept_data =
+      File.read!("test/fixtures/mastodon-accept-activity.json")
+      |> Poison.decode!()
+      |> Map.put("actor", followed.ap_id)
+
+    accept_data =
+      Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
+
+    {:ok, activity} = Transmogrifier.handle_incoming(accept_data)
+    assert activity.data["object"] == follow_activity.data["id"]
+
+    follower = User.get_cached_by_id(follower.id)
+
+    assert User.following?(follower, followed) == true
+  end
+
+  test "it works for incoming accepts which are referenced by IRI only" do
+    follower = insert(:user)
+    followed = insert(:user, locked: true)
+
+    {:ok, _, _, follow_activity} = CommonAPI.follow(follower, followed)
+
+    accept_data =
+      File.read!("test/fixtures/mastodon-accept-activity.json")
+      |> Poison.decode!()
+      |> Map.put("actor", followed.ap_id)
+      |> Map.put("object", follow_activity.data["id"])
+
+    {:ok, activity} = Transmogrifier.handle_incoming(accept_data)
+    assert activity.data["object"] == follow_activity.data["id"]
+
+    follower = User.get_cached_by_id(follower.id)
+
+    assert User.following?(follower, followed) == true
+
+    follower = User.get_by_id(follower.id)
+    assert follower.following_count == 1
+
+    followed = User.get_by_id(followed.id)
+    assert followed.follower_count == 1
+  end
+
+  test "it fails for incoming accepts which cannot be correlated" do
+    follower = insert(:user)
+    followed = insert(:user, locked: true)
+
+    accept_data =
+      File.read!("test/fixtures/mastodon-accept-activity.json")
+      |> Poison.decode!()
+      |> Map.put("actor", followed.ap_id)
+
+    accept_data =
+      Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
+
+    :error = Transmogrifier.handle_incoming(accept_data)
+
+    follower = User.get_cached_by_id(follower.id)
+
+    refute User.following?(follower, followed) == true
+  end
+end
diff --git a/test/web/activity_pub/transmogrifier_test.exs b/test/web/activity_pub/transmogrifier_test.exs
index 6dd9a3fec..52b4178bf 100644
--- a/test/web/activity_pub/transmogrifier_test.exs
+++ b/test/web/activity_pub/transmogrifier_test.exs
@@ -359,7 +359,7 @@ test "it strips internal reactions" do
       refute Map.has_key?(object_data, "reaction_count")
     end
 
-    test "it works for incomming unfollows with an existing follow" do
+    test "it works for incoming unfollows with an existing follow" do
       user = insert(:user)
 
       follow_data =
@@ -403,106 +403,6 @@ test "it works for incoming follows to locked account" do
       assert [^pending_follower] = User.get_follow_requests(user)
     end
 
-    test "it works for incoming accepts which were pre-accepted" do
-      follower = insert(:user)
-      followed = insert(:user)
-
-      {:ok, follower} = User.follow(follower, followed)
-      assert User.following?(follower, followed) == true
-
-      {:ok, _, _, follow_activity} = CommonAPI.follow(follower, followed)
-
-      accept_data =
-        File.read!("test/fixtures/mastodon-accept-activity.json")
-        |> Poison.decode!()
-        |> Map.put("actor", followed.ap_id)
-
-      object =
-        accept_data["object"]
-        |> Map.put("actor", follower.ap_id)
-        |> Map.put("id", follow_activity.data["id"])
-
-      accept_data = Map.put(accept_data, "object", object)
-
-      {:ok, activity} = Transmogrifier.handle_incoming(accept_data)
-      refute activity.local
-
-      assert activity.data["object"] == follow_activity.data["id"]
-
-      assert activity.data["id"] == accept_data["id"]
-
-      follower = User.get_cached_by_id(follower.id)
-
-      assert User.following?(follower, followed) == true
-    end
-
-    test "it works for incoming accepts which were orphaned" do
-      follower = insert(:user)
-      followed = insert(:user, locked: true)
-
-      {:ok, _, _, follow_activity} = CommonAPI.follow(follower, followed)
-
-      accept_data =
-        File.read!("test/fixtures/mastodon-accept-activity.json")
-        |> Poison.decode!()
-        |> Map.put("actor", followed.ap_id)
-
-      accept_data =
-        Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
-
-      {:ok, activity} = Transmogrifier.handle_incoming(accept_data)
-      assert activity.data["object"] == follow_activity.data["id"]
-
-      follower = User.get_cached_by_id(follower.id)
-
-      assert User.following?(follower, followed) == true
-    end
-
-    test "it works for incoming accepts which are referenced by IRI only" do
-      follower = insert(:user)
-      followed = insert(:user, locked: true)
-
-      {:ok, _, _, follow_activity} = CommonAPI.follow(follower, followed)
-
-      accept_data =
-        File.read!("test/fixtures/mastodon-accept-activity.json")
-        |> Poison.decode!()
-        |> Map.put("actor", followed.ap_id)
-        |> Map.put("object", follow_activity.data["id"])
-
-      {:ok, activity} = Transmogrifier.handle_incoming(accept_data)
-      assert activity.data["object"] == follow_activity.data["id"]
-
-      follower = User.get_cached_by_id(follower.id)
-
-      assert User.following?(follower, followed) == true
-
-      follower = User.get_by_id(follower.id)
-      assert follower.following_count == 1
-
-      followed = User.get_by_id(followed.id)
-      assert followed.follower_count == 1
-    end
-
-    test "it fails for incoming accepts which cannot be correlated" do
-      follower = insert(:user)
-      followed = insert(:user, locked: true)
-
-      accept_data =
-        File.read!("test/fixtures/mastodon-accept-activity.json")
-        |> Poison.decode!()
-        |> Map.put("actor", followed.ap_id)
-
-      accept_data =
-        Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
-
-      :error = Transmogrifier.handle_incoming(accept_data)
-
-      follower = User.get_cached_by_id(follower.id)
-
-      refute User.following?(follower, followed) == true
-    end
-
     test "it fails for incoming rejects which cannot be correlated" do
       follower = insert(:user)
       followed = insert(:user, locked: true)

From 8f9fbc86c0dcf307b87b38d218b36df2f9f35a7f Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 11 Aug 2020 14:02:09 +0200
Subject: [PATCH 02/13] Transmogrifier: Small readability changes.

---
 lib/pleroma/web/activity_pub/transmogrifier.ex              | 6 ++++--
 test/web/activity_pub/transmogrifier/undo_handling_test.exs | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 2f04cc6ff..fe016e720 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -661,7 +661,8 @@ def handle_incoming(
       )
       when type in ~w{Update Block Follow} do
     with {:ok, %User{}} <- ObjectValidator.fetch_actor(data),
-         {:ok, activity, _} <- Pipeline.common_pipeline(data, local: false) do
+         {:ok, activity, _} <-
+           Pipeline.common_pipeline(data, local: false) do
       {:ok, activity}
     end
   end
@@ -670,7 +671,8 @@ def handle_incoming(
         %{"type" => "Delete"} = data,
         _options
       ) do
-    with {:ok, activity, _} <- Pipeline.common_pipeline(data, local: false) do
+    with {:ok, activity, _} <-
+           Pipeline.common_pipeline(data, local: false) do
       {:ok, activity}
     else
       {:error, {:validate_object, _}} = e ->
diff --git a/test/web/activity_pub/transmogrifier/undo_handling_test.exs b/test/web/activity_pub/transmogrifier/undo_handling_test.exs
index 01dd6c370..8683f7135 100644
--- a/test/web/activity_pub/transmogrifier/undo_handling_test.exs
+++ b/test/web/activity_pub/transmogrifier/undo_handling_test.exs
@@ -130,7 +130,7 @@ test "it works for incoming unannounces with an existing notice" do
              "http://mastodon.example.org/users/admin/statuses/99542391527669785/activity"
   end
 
-  test "it works for incomming unfollows with an existing follow" do
+  test "it works for incoming unfollows with an existing follow" do
     user = insert(:user)
 
     follow_data =

From f1a0c10b17ff20a5ebbd070dc38aaedf82f8fe2e Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 11 Aug 2020 15:13:07 +0200
Subject: [PATCH 03/13] AcceptValidator: Add basic validator with tests.

---
 lib/pleroma/web/activity_pub/builder.ex       | 13 ++++++
 .../web/activity_pub/object_validator.ex      | 11 +++++
 .../object_validators/accept_validator.ex     | 42 ++++++++++++++++++
 .../accept_validation_test.exs                | 44 +++++++++++++++++++
 4 files changed, 110 insertions(+)
 create mode 100644 lib/pleroma/web/activity_pub/object_validators/accept_validator.ex
 create mode 100644 test/web/activity_pub/object_validators/accept_validation_test.exs

diff --git a/lib/pleroma/web/activity_pub/builder.ex b/lib/pleroma/web/activity_pub/builder.ex
index 1b4c421b8..e1f88e6cc 100644
--- a/lib/pleroma/web/activity_pub/builder.ex
+++ b/lib/pleroma/web/activity_pub/builder.ex
@@ -14,6 +14,19 @@ defmodule Pleroma.Web.ActivityPub.Builder do
 
   require Pleroma.Constants
 
+  @spec accept(User.t(), Activity.t()) :: {:ok, map(), keyword()}
+  def accept(actor, accepted_activity) do
+    data = %{
+      "id" => Utils.generate_activity_id(),
+      "actor" => actor.ap_id,
+      "type" => "Accept",
+      "object" => accepted_activity.data["id"],
+      "to" => [accepted_activity.actor]
+    }
+
+    {:ok, data, []}
+  end
+
   @spec follow(User.t(), User.t()) :: {:ok, map(), keyword()}
   def follow(follower, followed) do
     data = %{
diff --git a/lib/pleroma/web/activity_pub/object_validator.ex b/lib/pleroma/web/activity_pub/object_validator.ex
index e1114a44d..d9dd2bc30 100644
--- a/lib/pleroma/web/activity_pub/object_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validator.ex
@@ -13,6 +13,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
   alias Pleroma.EctoType.ActivityPub.ObjectValidators
   alias Pleroma.Object
   alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.ObjectValidators.AcceptValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.AnnounceValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.AnswerValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.BlockValidator
@@ -30,6 +31,16 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
   @spec validate(map(), keyword()) :: {:ok, map(), keyword()} | {:error, any()}
   def validate(object, meta)
 
+  def validate(%{"type" => "Accept"} = object, meta) do
+    with {:ok, object} <-
+           object
+           |> AcceptValidator.cast_and_validate()
+           |> Ecto.Changeset.apply_action(:insert) do
+      object = stringify_keys(object)
+      {:ok, object, meta}
+    end
+  end
+
   def validate(%{"type" => "Follow"} = object, meta) do
     with {:ok, object} <-
            object
diff --git a/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex b/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex
new file mode 100644
index 000000000..b81e078e3
--- /dev/null
+++ b/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex
@@ -0,0 +1,42 @@
+# 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.ObjectValidators.AcceptValidator do
+  use Ecto.Schema
+
+  alias Pleroma.EctoType.ActivityPub.ObjectValidators
+
+  import Ecto.Changeset
+  import Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations
+
+  @primary_key false
+
+  embedded_schema do
+    field(:id, ObjectValidators.ObjectID, primary_key: true)
+    field(:type, :string)
+    field(:object, ObjectValidators.ObjectID)
+    field(:actor, ObjectValidators.ObjectID)
+    field(:to, ObjectValidators.Recipients, default: [])
+    field(:cc, ObjectValidators.Recipients, default: [])
+  end
+
+  def cast_data(data) do
+    %__MODULE__{}
+    |> cast(data, __schema__(:fields))
+  end
+
+  def validate_data(cng) do
+    cng
+    |> validate_required([:id, :type, :actor, :to, :cc, :object])
+    |> validate_inclusion(:type, ["Accept"])
+    |> validate_actor_presence()
+    |> validate_object_presence()
+  end
+
+  def cast_and_validate(data) do
+    data
+    |> cast_data
+    |> validate_data
+  end
+end
diff --git a/test/web/activity_pub/object_validators/accept_validation_test.exs b/test/web/activity_pub/object_validators/accept_validation_test.exs
new file mode 100644
index 000000000..7f5dc14af
--- /dev/null
+++ b/test/web/activity_pub/object_validators/accept_validation_test.exs
@@ -0,0 +1,44 @@
+# 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.ObjectValidators.AcceptValidationTest do
+  use Pleroma.DataCase
+  alias Pleroma.Web.ActivityPub.Builder
+  alias Pleroma.Web.ActivityPub.Pipeline
+  alias Pleroma.Web.ActivityPub.ObjectValidator
+
+  import Pleroma.Factory
+
+  setup do
+    follower = insert(:user)
+    followed = insert(:user, local: false)
+
+    {:ok, follow_data, _} = Builder.follow(follower, followed)
+    {:ok, follow_activity, _} = Pipeline.common_pipeline(follow_data, local: true)
+
+    {:ok, accept_data, _} = Builder.accept(followed, follow_activity)
+
+    %{accept_data: accept_data, followed: followed}
+  end
+
+  test "it validates a basic 'accept'", %{accept_data: accept_data} do
+    assert {:ok, _, _} = ObjectValidator.validate(accept_data, [])
+  end
+
+  test "it fails when the actor doesn't exist", %{accept_data: accept_data} do
+    accept_data =
+      accept_data
+      |> Map.put("actor", "https://gensokyo.2hu/users/raymoo")
+
+    assert {:error, _} = ObjectValidator.validate(accept_data, [])
+  end
+
+  test "it fails when the accepted activity doesn't exist", %{accept_data: accept_data} do
+    accept_data =
+      accept_data
+      |> Map.put("object", "https://gensokyo.2hu/users/raymoo/follows/1")
+
+    assert {:error, _} = ObjectValidator.validate(accept_data, [])
+  end
+end

From 8b1e8bec2ffcb3a73eea93015d73b44c4996baff Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 11 Aug 2020 15:32:00 +0200
Subject: [PATCH 04/13] AcceptValidation: Codify accept rules.

---
 .../object_validators/accept_validator.ex        | 16 +++++++++++++++-
 .../object_validators/accept_validation_test.exs | 11 +++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex b/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex
index b81e078e3..6d0fa669a 100644
--- a/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex
@@ -6,6 +6,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.AcceptValidator do
   use Ecto.Schema
 
   alias Pleroma.EctoType.ActivityPub.ObjectValidators
+  alias Pleroma.Activity
 
   import Ecto.Changeset
   import Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations
@@ -31,7 +32,8 @@ def validate_data(cng) do
     |> validate_required([:id, :type, :actor, :to, :cc, :object])
     |> validate_inclusion(:type, ["Accept"])
     |> validate_actor_presence()
-    |> validate_object_presence()
+    |> validate_object_presence(allowed_types: ["Follow"])
+    |> validate_accept_rights()
   end
 
   def cast_and_validate(data) do
@@ -39,4 +41,16 @@ def cast_and_validate(data) do
     |> cast_data
     |> validate_data
   end
+
+  def validate_accept_rights(cng) do
+    with object_id when is_binary(object_id) <- get_field(cng, :object),
+         %Activity{data: %{"object" => followed_actor}} <- Activity.get_by_ap_id(object_id),
+         true <- followed_actor == get_field(cng, :actor) do
+      cng
+    else
+      _e ->
+        cng
+        |> add_error(:actor, "can't accept the given activity")
+    end
+  end
 end
diff --git a/test/web/activity_pub/object_validators/accept_validation_test.exs b/test/web/activity_pub/object_validators/accept_validation_test.exs
index 7f5dc14af..2d5d18046 100644
--- a/test/web/activity_pub/object_validators/accept_validation_test.exs
+++ b/test/web/activity_pub/object_validators/accept_validation_test.exs
@@ -41,4 +41,15 @@ test "it fails when the accepted activity doesn't exist", %{accept_data: accept_
 
     assert {:error, _} = ObjectValidator.validate(accept_data, [])
   end
+
+  test "for an accepted follow, it only validates if the actor of the accept is the followed actor",
+       %{accept_data: accept_data} do
+    stranger = insert(:user)
+
+    accept_data =
+      accept_data
+      |> Map.put("actor", stranger.ap_id)
+
+    assert {:error, _} = ObjectValidator.validate(accept_data, [])
+  end
 end

From da3f9b9988d2cee4baa6018e6450b2d6027e1ce3 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 11 Aug 2020 15:41:19 +0200
Subject: [PATCH 05/13] Transmogrifier: Remove handling of orphaned accepts

This was a Mastodon 2.3 issue and has been fixed for a long time.
According to fediverse.networks, less than one percent of servers
still run a version this old or older.
---
 .../web/activity_pub/transmogrifier.ex        | 18 +--------------
 .../transmogrifier/accept_handling_test.exs   | 22 -------------------
 2 files changed, 1 insertion(+), 39 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index fe016e720..5ea97e9b7 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -391,27 +391,11 @@ defp fix_content(%{"mediaType" => "text/markdown", "content" => content} = objec
 
   defp fix_content(object), do: object
 
-  defp mastodon_follow_hack(%{"id" => id, "actor" => follower_id}, followed) do
-    with true <- id =~ "follows",
-         %User{local: true} = follower <- User.get_cached_by_ap_id(follower_id),
-         %Activity{} = activity <- Utils.fetch_latest_follow(follower, followed) do
-      {:ok, activity}
-    else
-      _ -> {:error, nil}
-    end
-  end
-
-  defp mastodon_follow_hack(_, _), do: {:error, nil}
-
-  defp get_follow_activity(follow_object, followed) do
+  defp get_follow_activity(follow_object, _followed) do
     with object_id when not is_nil(object_id) <- Utils.get_ap_id(follow_object),
          {_, %Activity{} = activity} <- {:activity, Activity.get_by_ap_id(object_id)} do
       {:ok, activity}
     else
-      # Can't find the activity. This might a Mastodon 2.3 "Accept"
-      {:activity, nil} ->
-        mastodon_follow_hack(follow_object, followed)
-
       _ ->
         {:error, nil}
     end
diff --git a/test/web/activity_pub/transmogrifier/accept_handling_test.exs b/test/web/activity_pub/transmogrifier/accept_handling_test.exs
index 3c4e134ff..bc4cc227d 100644
--- a/test/web/activity_pub/transmogrifier/accept_handling_test.exs
+++ b/test/web/activity_pub/transmogrifier/accept_handling_test.exs
@@ -44,28 +44,6 @@ test "it works for incoming accepts which were pre-accepted" do
     assert User.following?(follower, followed) == true
   end
 
-  test "it works for incoming accepts which were orphaned" do
-    follower = insert(:user)
-    followed = insert(:user, locked: true)
-
-    {:ok, _, _, follow_activity} = CommonAPI.follow(follower, followed)
-
-    accept_data =
-      File.read!("test/fixtures/mastodon-accept-activity.json")
-      |> Poison.decode!()
-      |> Map.put("actor", followed.ap_id)
-
-    accept_data =
-      Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
-
-    {:ok, activity} = Transmogrifier.handle_incoming(accept_data)
-    assert activity.data["object"] == follow_activity.data["id"]
-
-    follower = User.get_cached_by_id(follower.id)
-
-    assert User.following?(follower, followed) == true
-  end
-
   test "it works for incoming accepts which are referenced by IRI only" do
     follower = insert(:user)
     followed = insert(:user, locked: true)

From 3f6d50111e57a942ecc24d4aa7cdbec23b95dfec Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 11 Aug 2020 16:07:42 +0200
Subject: [PATCH 06/13] Linter fixes.

---
 .../web/activity_pub/object_validators/accept_validator.ex     | 2 +-
 .../activity_pub/object_validators/accept_validation_test.exs  | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex b/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex
index 6d0fa669a..fd75f4b6e 100644
--- a/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex
@@ -5,8 +5,8 @@
 defmodule Pleroma.Web.ActivityPub.ObjectValidators.AcceptValidator do
   use Ecto.Schema
 
-  alias Pleroma.EctoType.ActivityPub.ObjectValidators
   alias Pleroma.Activity
+  alias Pleroma.EctoType.ActivityPub.ObjectValidators
 
   import Ecto.Changeset
   import Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations
diff --git a/test/web/activity_pub/object_validators/accept_validation_test.exs b/test/web/activity_pub/object_validators/accept_validation_test.exs
index 2d5d18046..d6111ba41 100644
--- a/test/web/activity_pub/object_validators/accept_validation_test.exs
+++ b/test/web/activity_pub/object_validators/accept_validation_test.exs
@@ -4,9 +4,10 @@
 
 defmodule Pleroma.Web.ActivityPub.ObjectValidators.AcceptValidationTest do
   use Pleroma.DataCase
+
   alias Pleroma.Web.ActivityPub.Builder
-  alias Pleroma.Web.ActivityPub.Pipeline
   alias Pleroma.Web.ActivityPub.ObjectValidator
+  alias Pleroma.Web.ActivityPub.Pipeline
 
   import Pleroma.Factory
 

From 9dda13bfa193be8ab5d9b2c117f7a50aaba451e1 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 11 Aug 2020 16:22:15 +0200
Subject: [PATCH 07/13] Transmogrifier Test: Remove mastodon hack test.

---
 test/web/activity_pub/transmogrifier_test.exs | 26 -------------------
 1 file changed, 26 deletions(-)

diff --git a/test/web/activity_pub/transmogrifier_test.exs b/test/web/activity_pub/transmogrifier_test.exs
index 52b4178bf..13da864d1 100644
--- a/test/web/activity_pub/transmogrifier_test.exs
+++ b/test/web/activity_pub/transmogrifier_test.exs
@@ -422,32 +422,6 @@ test "it fails for incoming rejects which cannot be correlated" do
       refute User.following?(follower, followed) == true
     end
 
-    test "it works for incoming rejects which are orphaned" do
-      follower = insert(:user)
-      followed = insert(:user, locked: true)
-
-      {:ok, follower} = User.follow(follower, followed)
-      {:ok, _, _, _follow_activity} = CommonAPI.follow(follower, followed)
-
-      assert User.following?(follower, followed) == true
-
-      reject_data =
-        File.read!("test/fixtures/mastodon-reject-activity.json")
-        |> Poison.decode!()
-        |> Map.put("actor", followed.ap_id)
-
-      reject_data =
-        Map.put(reject_data, "object", Map.put(reject_data["object"], "actor", follower.ap_id))
-
-      {:ok, activity} = Transmogrifier.handle_incoming(reject_data)
-      refute activity.local
-      assert activity.data["id"] == reject_data["id"]
-
-      follower = User.get_cached_by_id(follower.id)
-
-      assert User.following?(follower, followed) == false
-    end
-
     test "it works for incoming rejects which are referenced by IRI only" do
       follower = insert(:user)
       followed = insert(:user, locked: true)

From f988d82e463d2c08fa2cc22dc6ee733ee8668671 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 11 Aug 2020 17:26:01 +0200
Subject: [PATCH 08/13] Transmogrifier: Handle accepts with the pipeline

---
 lib/pleroma/web/activity_pub/side_effects.ex  | 28 ++++++++++++++++
 .../web/activity_pub/transmogrifier.ex        | 32 +------------------
 .../transmogrifier/accept_handling_test.exs   |  2 +-
 3 files changed, 30 insertions(+), 32 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/side_effects.ex b/lib/pleroma/web/activity_pub/side_effects.ex
index 5104d38ee..3ba7eaf9e 100644
--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@@ -21,9 +21,37 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
   alias Pleroma.Web.Push
   alias Pleroma.Web.Streamer
   alias Pleroma.Workers.BackgroundWorker
+  alias Pleroma.FollowingRelationship
 
   def handle(object, meta \\ [])
 
+  # Task this handles
+  # - Follows
+  # - Sends a notification
+  def handle(
+        %{
+          data: %{
+            "actor" => actor,
+            "type" => "Accept",
+            "object" => follow_activity_id
+          }
+        } = object,
+        meta
+      ) do
+    with %Activity{actor: follower_id} = follow_activity <-
+           Activity.get_by_ap_id(follow_activity_id),
+         %User{} = followed <- User.get_cached_by_ap_id(actor),
+         %User{} = follower <- User.get_cached_by_ap_id(follower_id),
+         {:ok, follow_activity} <- Utils.update_follow_state_for_all(follow_activity, "accept"),
+         {:ok, _relationship} <- FollowingRelationship.update(follower, followed, :follow_accept) do
+      Notification.update_notification_type(followed, follow_activity)
+      User.update_follower_count(followed)
+      User.update_following_count(follower)
+    end
+
+    {:ok, object, meta}
+  end
+
   # Tasks this handle
   # - Follows if possible
   # - Sends a notification
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 5ea97e9b7..24da1ef9c 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -11,7 +11,6 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   alias Pleroma.EctoType.ActivityPub.ObjectValidators
   alias Pleroma.FollowingRelationship
   alias Pleroma.Maps
-  alias Pleroma.Notification
   alias Pleroma.Object
   alias Pleroma.Object.Containment
   alias Pleroma.Repo
@@ -535,35 +534,6 @@ def handle_incoming(
     end
   end
 
-  def handle_incoming(
-        %{"type" => "Accept", "object" => follow_object, "actor" => _actor, "id" => id} = data,
-        _options
-      ) do
-    with actor <- Containment.get_actor(data),
-         {:ok, %User{} = followed} <- User.get_or_fetch_by_ap_id(actor),
-         {:ok, follow_activity} <- get_follow_activity(follow_object, followed),
-         {:ok, follow_activity} <- Utils.update_follow_state_for_all(follow_activity, "accept"),
-         %User{local: true} = follower <- User.get_cached_by_ap_id(follow_activity.data["actor"]),
-         {:ok, _relationship} <- FollowingRelationship.update(follower, followed, :follow_accept) do
-      User.update_follower_count(followed)
-      User.update_following_count(follower)
-
-      Notification.update_notification_type(followed, follow_activity)
-
-      ActivityPub.accept(%{
-        to: follow_activity.data["to"],
-        type: "Accept",
-        actor: followed,
-        object: follow_activity.data["id"],
-        local: false,
-        activity_id: id
-      })
-    else
-      _e ->
-        :error
-    end
-  end
-
   def handle_incoming(
         %{"type" => "Reject", "object" => follow_object, "actor" => _actor, "id" => id} = data,
         _options
@@ -643,7 +613,7 @@ def handle_incoming(
         %{"type" => type} = data,
         _options
       )
-      when type in ~w{Update Block Follow} do
+      when type in ~w{Update Block Follow Accept} do
     with {:ok, %User{}} <- ObjectValidator.fetch_actor(data),
          {:ok, activity, _} <-
            Pipeline.common_pipeline(data, local: false) do
diff --git a/test/web/activity_pub/transmogrifier/accept_handling_test.exs b/test/web/activity_pub/transmogrifier/accept_handling_test.exs
index bc4cc227d..77d468f5c 100644
--- a/test/web/activity_pub/transmogrifier/accept_handling_test.exs
+++ b/test/web/activity_pub/transmogrifier/accept_handling_test.exs
@@ -82,7 +82,7 @@ test "it fails for incoming accepts which cannot be correlated" do
     accept_data =
       Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
 
-    :error = Transmogrifier.handle_incoming(accept_data)
+    {:error, _} = Transmogrifier.handle_incoming(accept_data)
 
     follower = User.get_cached_by_id(follower.id)
 

From 25bfee0d12d6ee096bba169089cc57c91efd7bc3 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 11 Aug 2020 17:43:16 +0200
Subject: [PATCH 09/13] ActivityPub: Remove ActivityPub.accept

Switch to the pipeline in CommonAPI and SideEffects
---
 lib/pleroma/web/activity_pub/activity_pub.ex |  5 -----
 lib/pleroma/web/activity_pub/side_effects.ex | 15 +++------------
 lib/pleroma/web/common_api/common_api.ex     | 13 ++-----------
 3 files changed, 5 insertions(+), 28 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index fe62673dc..6dd94119b 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -285,11 +285,6 @@ def listen(%{to: to, actor: actor, context: context, object: object} = params) d
     end
   end
 
-  @spec accept(map()) :: {:ok, Activity.t()} | {:error, any()}
-  def accept(params) do
-    accept_or_reject("Accept", params)
-  end
-
   @spec reject(map()) :: {:ok, Activity.t()} | {:error, any()}
   def reject(params) do
     accept_or_reject("Reject", params)
diff --git a/lib/pleroma/web/activity_pub/side_effects.ex b/lib/pleroma/web/activity_pub/side_effects.ex
index 3ba7eaf9e..4228041e7 100644
--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@@ -16,6 +16,7 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
   alias Pleroma.Repo
   alias Pleroma.User
   alias Pleroma.Web.ActivityPub.ActivityPub
+  alias Pleroma.Web.ActivityPub.Builder
   alias Pleroma.Web.ActivityPub.Pipeline
   alias Pleroma.Web.ActivityPub.Utils
   alias Pleroma.Web.Push
@@ -72,18 +73,8 @@ def handle(
          {_, {:ok, _}, _, _} <-
            {:following, User.follow(follower, followed, :follow_pending), follower, followed} do
       if followed.local && !followed.locked do
-        Utils.update_follow_state_for_all(object, "accept")
-        FollowingRelationship.update(follower, followed, :follow_accept)
-        User.update_follower_count(followed)
-        User.update_following_count(follower)
-
-        %{
-          to: [following_user],
-          actor: followed,
-          object: follow_id,
-          local: true
-        }
-        |> ActivityPub.accept()
+        {:ok, accept_data, _} = Builder.accept(followed, object)
+        {:ok, _activity, _} = Pipeline.common_pipeline(accept_data, local: true)
       end
     else
       {:following, {:error, _}, follower, followed} ->
diff --git a/lib/pleroma/web/common_api/common_api.ex b/lib/pleroma/web/common_api/common_api.ex
index c08e0ffeb..7b08c19a8 100644
--- a/lib/pleroma/web/common_api/common_api.ex
+++ b/lib/pleroma/web/common_api/common_api.ex
@@ -122,17 +122,8 @@ def unfollow(follower, unfollowed) do
 
   def accept_follow_request(follower, followed) do
     with %Activity{} = follow_activity <- Utils.fetch_latest_follow(follower, followed),
-         {:ok, follower} <- User.follow(follower, followed),
-         {:ok, follow_activity} <- Utils.update_follow_state_for_all(follow_activity, "accept"),
-         {:ok, _relationship} <- FollowingRelationship.update(follower, followed, :follow_accept),
-         {:ok, _activity} <-
-           ActivityPub.accept(%{
-             to: [follower.ap_id],
-             actor: followed,
-             object: follow_activity.data["id"],
-             type: "Accept"
-           }) do
-      Notification.update_notification_type(followed, follow_activity)
+         {:ok, accept_data, _} <- Builder.accept(followed, follow_activity),
+         {:ok, _activity, _} <- Pipeline.common_pipeline(accept_data, local: true) do
       {:ok, follower}
     end
   end

From 500576dcb623bdc29193e3b372837c581e151755 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 11 Aug 2020 19:22:14 +0200
Subject: [PATCH 10/13] Linting fixes.

---
 lib/pleroma/web/activity_pub/side_effects.ex | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/pleroma/web/activity_pub/side_effects.ex b/lib/pleroma/web/activity_pub/side_effects.ex
index 4228041e7..e1fa75e1c 100644
--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@@ -22,7 +22,6 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
   alias Pleroma.Web.Push
   alias Pleroma.Web.Streamer
   alias Pleroma.Workers.BackgroundWorker
-  alias Pleroma.FollowingRelationship
 
   def handle(object, meta \\ [])
 

From 62f7cca9a1e3f6c6685094eb3618876d4b6ca3a7 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Wed, 12 Aug 2020 13:39:54 +0200
Subject: [PATCH 11/13] Transmogrifier Tests: Extract rejections.

---
 .../transmogrifier/follow_handling_test.exs   | 19 +++++
 .../transmogrifier/reject_handling_test.exs   | 67 +++++++++++++++++
 test/web/activity_pub/transmogrifier_test.exs | 72 -------------------
 3 files changed, 86 insertions(+), 72 deletions(-)
 create mode 100644 test/web/activity_pub/transmogrifier/reject_handling_test.exs

diff --git a/test/web/activity_pub/transmogrifier/follow_handling_test.exs b/test/web/activity_pub/transmogrifier/follow_handling_test.exs
index 17e764ca1..757d90941 100644
--- a/test/web/activity_pub/transmogrifier/follow_handling_test.exs
+++ b/test/web/activity_pub/transmogrifier/follow_handling_test.exs
@@ -185,5 +185,24 @@ test "it works for incoming follow requests from hubzilla" do
       assert data["id"] == "https://hubzilla.example.org/channel/kaniini#follows/2"
       assert User.following?(User.get_cached_by_ap_id(data["actor"]), user)
     end
+
+    test "it works for incoming follows to locked account" do
+      pending_follower = insert(:user, ap_id: "http://mastodon.example.org/users/admin")
+      user = insert(:user, locked: true)
+
+      data =
+        File.read!("test/fixtures/mastodon-follow-activity.json")
+        |> Poison.decode!()
+        |> Map.put("object", user.ap_id)
+
+      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+      assert data["type"] == "Follow"
+      assert data["object"] == user.ap_id
+      assert data["state"] == "pending"
+      assert data["actor"] == "http://mastodon.example.org/users/admin"
+
+      assert [^pending_follower] = User.get_follow_requests(user)
+    end
   end
 end
diff --git a/test/web/activity_pub/transmogrifier/reject_handling_test.exs b/test/web/activity_pub/transmogrifier/reject_handling_test.exs
new file mode 100644
index 000000000..5e5248641
--- /dev/null
+++ b/test/web/activity_pub/transmogrifier/reject_handling_test.exs
@@ -0,0 +1,67 @@
+# 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.Transmogrifier.RejectHandlingTest do
+  use Pleroma.DataCase
+
+  alias Pleroma.Activity
+  alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.Transmogrifier
+  alias Pleroma.Web.CommonAPI
+
+  import Pleroma.Factory
+
+  test "it fails for incoming rejects which cannot be correlated" do
+    follower = insert(:user)
+    followed = insert(:user, locked: true)
+
+    accept_data =
+      File.read!("test/fixtures/mastodon-reject-activity.json")
+      |> Poison.decode!()
+      |> Map.put("actor", followed.ap_id)
+
+    accept_data =
+      Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
+
+    :error = Transmogrifier.handle_incoming(accept_data)
+
+    follower = User.get_cached_by_id(follower.id)
+
+    refute User.following?(follower, followed) == true
+  end
+
+  test "it works for incoming rejects which are referenced by IRI only" do
+    follower = insert(:user)
+    followed = insert(:user, locked: true)
+
+    {:ok, follower} = User.follow(follower, followed)
+    {:ok, _, _, follow_activity} = CommonAPI.follow(follower, followed)
+
+    assert User.following?(follower, followed) == true
+
+    reject_data =
+      File.read!("test/fixtures/mastodon-reject-activity.json")
+      |> Poison.decode!()
+      |> Map.put("actor", followed.ap_id)
+      |> Map.put("object", follow_activity.data["id"])
+
+    {:ok, %Activity{data: _}} = Transmogrifier.handle_incoming(reject_data)
+
+    follower = User.get_cached_by_id(follower.id)
+
+    assert User.following?(follower, followed) == false
+  end
+
+  test "it rejects activities without a valid ID" do
+    user = insert(:user)
+
+    data =
+      File.read!("test/fixtures/mastodon-follow-activity.json")
+      |> Poison.decode!()
+      |> Map.put("object", user.ap_id)
+      |> Map.put("id", "")
+
+    :error = Transmogrifier.handle_incoming(data)
+  end
+end
diff --git a/test/web/activity_pub/transmogrifier_test.exs b/test/web/activity_pub/transmogrifier_test.exs
index 13da864d1..0dd4e6e47 100644
--- a/test/web/activity_pub/transmogrifier_test.exs
+++ b/test/web/activity_pub/transmogrifier_test.exs
@@ -384,78 +384,6 @@ test "it works for incoming unfollows with an existing follow" do
       refute User.following?(User.get_cached_by_ap_id(data["actor"]), user)
     end
 
-    test "it works for incoming follows to locked account" do
-      pending_follower = insert(:user, ap_id: "http://mastodon.example.org/users/admin")
-      user = insert(:user, locked: true)
-
-      data =
-        File.read!("test/fixtures/mastodon-follow-activity.json")
-        |> Poison.decode!()
-        |> Map.put("object", user.ap_id)
-
-      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
-
-      assert data["type"] == "Follow"
-      assert data["object"] == user.ap_id
-      assert data["state"] == "pending"
-      assert data["actor"] == "http://mastodon.example.org/users/admin"
-
-      assert [^pending_follower] = User.get_follow_requests(user)
-    end
-
-    test "it fails for incoming rejects which cannot be correlated" do
-      follower = insert(:user)
-      followed = insert(:user, locked: true)
-
-      accept_data =
-        File.read!("test/fixtures/mastodon-reject-activity.json")
-        |> Poison.decode!()
-        |> Map.put("actor", followed.ap_id)
-
-      accept_data =
-        Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
-
-      :error = Transmogrifier.handle_incoming(accept_data)
-
-      follower = User.get_cached_by_id(follower.id)
-
-      refute User.following?(follower, followed) == true
-    end
-
-    test "it works for incoming rejects which are referenced by IRI only" do
-      follower = insert(:user)
-      followed = insert(:user, locked: true)
-
-      {:ok, follower} = User.follow(follower, followed)
-      {:ok, _, _, follow_activity} = CommonAPI.follow(follower, followed)
-
-      assert User.following?(follower, followed) == true
-
-      reject_data =
-        File.read!("test/fixtures/mastodon-reject-activity.json")
-        |> Poison.decode!()
-        |> Map.put("actor", followed.ap_id)
-        |> Map.put("object", follow_activity.data["id"])
-
-      {:ok, %Activity{data: _}} = Transmogrifier.handle_incoming(reject_data)
-
-      follower = User.get_cached_by_id(follower.id)
-
-      assert User.following?(follower, followed) == false
-    end
-
-    test "it rejects activities without a valid ID" do
-      user = insert(:user)
-
-      data =
-        File.read!("test/fixtures/mastodon-follow-activity.json")
-        |> Poison.decode!()
-        |> Map.put("object", user.ap_id)
-        |> Map.put("id", "")
-
-      :error = Transmogrifier.handle_incoming(data)
-    end
-
     test "skip converting the content when it is nil" do
       object_id = "https://peertube.social/videos/watch/278d2b7c-0f38-4aaa-afe6-9ecc0c4a34fe"
 

From 7224bf309ef38a80898d7e560e96fbc2895737be Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Wed, 12 Aug 2020 14:48:51 +0200
Subject: [PATCH 12/13] Transmogrifier: Move Rejects to the Pipeline

---
 lib/pleroma/web/activity_pub/builder.ex       | 19 +++++--
 .../web/activity_pub/object_validator.ex      |  7 ++-
 ...alidator.ex => accept_reject_validator.ex} | 10 ++--
 lib/pleroma/web/activity_pub/side_effects.ex  | 24 ++++++++
 .../web/activity_pub/transmogrifier.ex        | 38 +------------
 .../reject_validation_test.exs                | 56 +++++++++++++++++++
 .../transmogrifier/reject_handling_test.exs   |  2 +-
 7 files changed, 105 insertions(+), 51 deletions(-)
 rename lib/pleroma/web/activity_pub/object_validators/{accept_validator.ex => accept_reject_validator.ex} (82%)
 create mode 100644 test/web/activity_pub/object_validators/reject_validation_test.exs

diff --git a/lib/pleroma/web/activity_pub/builder.ex b/lib/pleroma/web/activity_pub/builder.ex
index e1f88e6cc..f2392ce79 100644
--- a/lib/pleroma/web/activity_pub/builder.ex
+++ b/lib/pleroma/web/activity_pub/builder.ex
@@ -14,19 +14,28 @@ defmodule Pleroma.Web.ActivityPub.Builder do
 
   require Pleroma.Constants
 
-  @spec accept(User.t(), Activity.t()) :: {:ok, map(), keyword()}
-  def accept(actor, accepted_activity) do
+  def accept_or_reject(actor, activity, type) do
     data = %{
       "id" => Utils.generate_activity_id(),
       "actor" => actor.ap_id,
-      "type" => "Accept",
-      "object" => accepted_activity.data["id"],
-      "to" => [accepted_activity.actor]
+      "type" => type,
+      "object" => activity.data["id"],
+      "to" => [activity.actor]
     }
 
     {:ok, data, []}
   end
 
+  @spec reject(User.t(), Activity.t()) :: {:ok, map(), keyword()}
+  def reject(actor, rejected_activity) do
+    accept_or_reject(actor, rejected_activity, "Reject")
+  end
+
+  @spec accept(User.t(), Activity.t()) :: {:ok, map(), keyword()}
+  def accept(actor, accepted_activity) do
+    accept_or_reject(actor, accepted_activity, "Accept")
+  end
+
   @spec follow(User.t(), User.t()) :: {:ok, map(), keyword()}
   def follow(follower, followed) do
     data = %{
diff --git a/lib/pleroma/web/activity_pub/object_validator.ex b/lib/pleroma/web/activity_pub/object_validator.ex
index d9dd2bc30..3f1dffe2b 100644
--- a/lib/pleroma/web/activity_pub/object_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validator.ex
@@ -13,7 +13,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
   alias Pleroma.EctoType.ActivityPub.ObjectValidators
   alias Pleroma.Object
   alias Pleroma.User
-  alias Pleroma.Web.ActivityPub.ObjectValidators.AcceptValidator
+  alias Pleroma.Web.ActivityPub.ObjectValidators.AcceptRejectValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.AnnounceValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.AnswerValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.BlockValidator
@@ -31,10 +31,11 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
   @spec validate(map(), keyword()) :: {:ok, map(), keyword()} | {:error, any()}
   def validate(object, meta)
 
-  def validate(%{"type" => "Accept"} = object, meta) do
+  def validate(%{"type" => type} = object, meta)
+      when type in ~w[Accept Reject] do
     with {:ok, object} <-
            object
-           |> AcceptValidator.cast_and_validate()
+           |> AcceptRejectValidator.cast_and_validate()
            |> Ecto.Changeset.apply_action(:insert) do
       object = stringify_keys(object)
       {:ok, object, meta}
diff --git a/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex b/lib/pleroma/web/activity_pub/object_validators/accept_reject_validator.ex
similarity index 82%
rename from lib/pleroma/web/activity_pub/object_validators/accept_validator.ex
rename to lib/pleroma/web/activity_pub/object_validators/accept_reject_validator.ex
index fd75f4b6e..179beda58 100644
--- a/lib/pleroma/web/activity_pub/object_validators/accept_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/accept_reject_validator.ex
@@ -2,7 +2,7 @@
 # Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
 # SPDX-License-Identifier: AGPL-3.0-only
 
-defmodule Pleroma.Web.ActivityPub.ObjectValidators.AcceptValidator do
+defmodule Pleroma.Web.ActivityPub.ObjectValidators.AcceptRejectValidator do
   use Ecto.Schema
 
   alias Pleroma.Activity
@@ -30,10 +30,10 @@ def cast_data(data) do
   def validate_data(cng) do
     cng
     |> validate_required([:id, :type, :actor, :to, :cc, :object])
-    |> validate_inclusion(:type, ["Accept"])
+    |> validate_inclusion(:type, ["Accept", "Reject"])
     |> validate_actor_presence()
     |> validate_object_presence(allowed_types: ["Follow"])
-    |> validate_accept_rights()
+    |> validate_accept_reject_rights()
   end
 
   def cast_and_validate(data) do
@@ -42,7 +42,7 @@ def cast_and_validate(data) do
     |> validate_data
   end
 
-  def validate_accept_rights(cng) do
+  def validate_accept_reject_rights(cng) do
     with object_id when is_binary(object_id) <- get_field(cng, :object),
          %Activity{data: %{"object" => followed_actor}} <- Activity.get_by_ap_id(object_id),
          true <- followed_actor == get_field(cng, :actor) do
@@ -50,7 +50,7 @@ def validate_accept_rights(cng) do
     else
       _e ->
         cng
-        |> add_error(:actor, "can't accept the given activity")
+        |> add_error(:actor, "can't accept or reject the given activity")
     end
   end
 end
diff --git a/lib/pleroma/web/activity_pub/side_effects.ex b/lib/pleroma/web/activity_pub/side_effects.ex
index e1fa75e1c..a4ad12d53 100644
--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@@ -52,6 +52,30 @@ def handle(
     {:ok, object, meta}
   end
 
+  # Task this handles
+  # - Rejects all existing follow activities for this person
+  # - Updates the follow state
+  def handle(
+        %{
+          data: %{
+            "actor" => actor,
+            "type" => "Reject",
+            "object" => follow_activity_id
+          }
+        } = object,
+        meta
+      ) do
+    with %Activity{actor: follower_id} = follow_activity <-
+           Activity.get_by_ap_id(follow_activity_id),
+         %User{} = followed <- User.get_cached_by_ap_id(actor),
+         %User{} = follower <- User.get_cached_by_ap_id(follower_id),
+         {:ok, _follow_activity} <- Utils.update_follow_state_for_all(follow_activity, "reject") do
+      FollowingRelationship.update(follower, followed, :follow_reject)
+    end
+
+    {:ok, object, meta}
+  end
+
   # Tasks this handle
   # - Follows if possible
   # - Sends a notification
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 24da1ef9c..544f3f3b6 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -9,7 +9,6 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   alias Pleroma.Activity
   alias Pleroma.EarmarkRenderer
   alias Pleroma.EctoType.ActivityPub.ObjectValidators
-  alias Pleroma.FollowingRelationship
   alias Pleroma.Maps
   alias Pleroma.Object
   alias Pleroma.Object.Containment
@@ -390,16 +389,6 @@ defp fix_content(%{"mediaType" => "text/markdown", "content" => content} = objec
 
   defp fix_content(object), do: object
 
-  defp get_follow_activity(follow_object, _followed) do
-    with object_id when not is_nil(object_id) <- Utils.get_ap_id(follow_object),
-         {_, %Activity{} = activity} <- {:activity, Activity.get_by_ap_id(object_id)} do
-      {:ok, activity}
-    else
-      _ ->
-        {:error, nil}
-    end
-  end
-
   # Reduce the object list to find the reported user.
   defp get_reported(objects) do
     Enum.reduce_while(objects, nil, fn ap_id, _ ->
@@ -534,31 +523,6 @@ def handle_incoming(
     end
   end
 
-  def handle_incoming(
-        %{"type" => "Reject", "object" => follow_object, "actor" => _actor, "id" => id} = data,
-        _options
-      ) do
-    with actor <- Containment.get_actor(data),
-         {:ok, %User{} = followed} <- User.get_or_fetch_by_ap_id(actor),
-         {:ok, follow_activity} <- get_follow_activity(follow_object, followed),
-         {:ok, follow_activity} <- Utils.update_follow_state_for_all(follow_activity, "reject"),
-         %User{local: true} = follower <- User.get_cached_by_ap_id(follow_activity.data["actor"]),
-         {:ok, _relationship} <- FollowingRelationship.update(follower, followed, :follow_reject),
-         {:ok, activity} <-
-           ActivityPub.reject(%{
-             to: follow_activity.data["to"],
-             type: "Reject",
-             actor: followed,
-             object: follow_activity.data["id"],
-             local: false,
-             activity_id: id
-           }) do
-      {:ok, activity}
-    else
-      _e -> :error
-    end
-  end
-
   @misskey_reactions %{
     "like" => "👍",
     "love" => "❤️",
@@ -613,7 +577,7 @@ def handle_incoming(
         %{"type" => type} = data,
         _options
       )
-      when type in ~w{Update Block Follow Accept} do
+      when type in ~w{Update Block Follow Accept Reject} do
     with {:ok, %User{}} <- ObjectValidator.fetch_actor(data),
          {:ok, activity, _} <-
            Pipeline.common_pipeline(data, local: false) do
diff --git a/test/web/activity_pub/object_validators/reject_validation_test.exs b/test/web/activity_pub/object_validators/reject_validation_test.exs
new file mode 100644
index 000000000..370bb6e5c
--- /dev/null
+++ b/test/web/activity_pub/object_validators/reject_validation_test.exs
@@ -0,0 +1,56 @@
+# 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.ObjectValidators.RejectValidationTest do
+  use Pleroma.DataCase
+
+  alias Pleroma.Web.ActivityPub.Builder
+  alias Pleroma.Web.ActivityPub.ObjectValidator
+  alias Pleroma.Web.ActivityPub.Pipeline
+
+  import Pleroma.Factory
+
+  setup do
+    follower = insert(:user)
+    followed = insert(:user, local: false)
+
+    {:ok, follow_data, _} = Builder.follow(follower, followed)
+    {:ok, follow_activity, _} = Pipeline.common_pipeline(follow_data, local: true)
+
+    {:ok, reject_data, _} = Builder.reject(followed, follow_activity)
+
+    %{reject_data: reject_data, followed: followed}
+  end
+
+  test "it validates a basic 'reject'", %{reject_data: reject_data} do
+    assert {:ok, _, _} = ObjectValidator.validate(reject_data, [])
+  end
+
+  test "it fails when the actor doesn't exist", %{reject_data: reject_data} do
+    reject_data =
+      reject_data
+      |> Map.put("actor", "https://gensokyo.2hu/users/raymoo")
+
+    assert {:error, _} = ObjectValidator.validate(reject_data, [])
+  end
+
+  test "it fails when the rejected activity doesn't exist", %{reject_data: reject_data} do
+    reject_data =
+      reject_data
+      |> Map.put("object", "https://gensokyo.2hu/users/raymoo/follows/1")
+
+    assert {:error, _} = ObjectValidator.validate(reject_data, [])
+  end
+
+  test "for an rejected follow, it only validates if the actor of the reject is the followed actor",
+       %{reject_data: reject_data} do
+    stranger = insert(:user)
+
+    reject_data =
+      reject_data
+      |> Map.put("actor", stranger.ap_id)
+
+    assert {:error, _} = ObjectValidator.validate(reject_data, [])
+  end
+end
diff --git a/test/web/activity_pub/transmogrifier/reject_handling_test.exs b/test/web/activity_pub/transmogrifier/reject_handling_test.exs
index 5e5248641..7592fbe1c 100644
--- a/test/web/activity_pub/transmogrifier/reject_handling_test.exs
+++ b/test/web/activity_pub/transmogrifier/reject_handling_test.exs
@@ -24,7 +24,7 @@ test "it fails for incoming rejects which cannot be correlated" do
     accept_data =
       Map.put(accept_data, "object", Map.put(accept_data["object"], "actor", follower.ap_id))
 
-    :error = Transmogrifier.handle_incoming(accept_data)
+    {:error, _} = Transmogrifier.handle_incoming(accept_data)
 
     follower = User.get_cached_by_id(follower.id)
 

From 2e347e8286fab13075e6e39e64e56cb3ba14e7e8 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Wed, 12 Aug 2020 15:07:46 +0200
Subject: [PATCH 13/13] ActivityPub: Remove `reject`, move everything to the
 Pipeline.

---
 lib/pleroma/web/activity_pub/activity_pub.ex | 21 --------------------
 lib/pleroma/web/activity_pub/side_effects.ex | 18 +++++------------
 lib/pleroma/web/common_api/common_api.ex     | 14 ++-----------
 3 files changed, 7 insertions(+), 46 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index 6dd94119b..bde1fe708 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -285,27 +285,6 @@ def listen(%{to: to, actor: actor, context: context, object: object} = params) d
     end
   end
 
-  @spec reject(map()) :: {:ok, Activity.t()} | {:error, any()}
-  def reject(params) do
-    accept_or_reject("Reject", params)
-  end
-
-  @spec accept_or_reject(String.t(), map()) :: {:ok, Activity.t()} | {:error, any()}
-  defp accept_or_reject(type, %{to: to, actor: actor, object: object} = params) do
-    local = Map.get(params, :local, true)
-    activity_id = Map.get(params, :activity_id, nil)
-
-    data =
-      %{"to" => to, "type" => type, "actor" => actor.ap_id, "object" => object}
-      |> Maps.put_if_present("id", activity_id)
-
-    with {:ok, activity} <- insert(data, local),
-         _ <- notify_and_stream(activity),
-         :ok <- maybe_federate(activity) do
-      {:ok, activity}
-    end
-  end
-
   @spec unfollow(User.t(), User.t(), String.t() | nil, boolean()) ::
           {:ok, Activity.t()} | nil | {:error, any()}
   def unfollow(follower, followed, activity_id \\ nil, local \\ true) do
diff --git a/lib/pleroma/web/activity_pub/side_effects.ex b/lib/pleroma/web/activity_pub/side_effects.ex
index a4ad12d53..14a1da0c1 100644
--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@@ -55,6 +55,7 @@ def handle(
   # Task this handles
   # - Rejects all existing follow activities for this person
   # - Updates the follow state
+  # - Dismisses notificatios
   def handle(
         %{
           data: %{
@@ -71,6 +72,7 @@ def handle(
          %User{} = follower <- User.get_cached_by_ap_id(follower_id),
          {:ok, _follow_activity} <- Utils.update_follow_state_for_all(follow_activity, "reject") do
       FollowingRelationship.update(follower, followed, :follow_reject)
+      Notification.dismiss(follow_activity)
     end
 
     {:ok, object, meta}
@@ -100,19 +102,9 @@ def handle(
         {:ok, _activity, _} = Pipeline.common_pipeline(accept_data, local: true)
       end
     else
-      {:following, {:error, _}, follower, followed} ->
-        Utils.update_follow_state_for_all(object, "reject")
-        FollowingRelationship.update(follower, followed, :follow_reject)
-
-        if followed.local do
-          %{
-            to: [follower.ap_id],
-            actor: followed,
-            object: follow_id,
-            local: true
-          }
-          |> ActivityPub.reject()
-        end
+      {:following, {:error, _}, _follower, followed} ->
+        {:ok, reject_data, _} = Builder.reject(followed, object)
+        {:ok, _activity, _} = Pipeline.common_pipeline(reject_data, local: true)
 
       _ ->
         nil
diff --git a/lib/pleroma/web/common_api/common_api.ex b/lib/pleroma/web/common_api/common_api.ex
index 7b08c19a8..a8141b28f 100644
--- a/lib/pleroma/web/common_api/common_api.ex
+++ b/lib/pleroma/web/common_api/common_api.ex
@@ -6,9 +6,7 @@ defmodule Pleroma.Web.CommonAPI do
   alias Pleroma.Activity
   alias Pleroma.ActivityExpiration
   alias Pleroma.Conversation.Participation
-  alias Pleroma.FollowingRelationship
   alias Pleroma.Formatter
-  alias Pleroma.Notification
   alias Pleroma.Object
   alias Pleroma.ThreadMute
   alias Pleroma.User
@@ -130,16 +128,8 @@ def accept_follow_request(follower, followed) do
 
   def reject_follow_request(follower, followed) do
     with %Activity{} = follow_activity <- Utils.fetch_latest_follow(follower, followed),
-         {:ok, follow_activity} <- Utils.update_follow_state_for_all(follow_activity, "reject"),
-         {:ok, _relationship} <- FollowingRelationship.update(follower, followed, :follow_reject),
-         {:ok, _notifications} <- Notification.dismiss(follow_activity),
-         {:ok, _activity} <-
-           ActivityPub.reject(%{
-             to: [follower.ap_id],
-             actor: followed,
-             object: follow_activity.data["id"],
-             type: "Reject"
-           }) do
+         {:ok, reject_data, _} <- Builder.reject(followed, follow_activity),
+         {:ok, _activity, _} <- Pipeline.common_pipeline(reject_data, local: true) do
       {:ok, follower}
     end
   end