Redirect to the referer url after mastofe authorization

lib/pleroma/web/mastodon_api/mastodon_api_controller.ex

@@ -1091,9 +1091,7 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPIController do
   end
 
   def index(%{assigns: %{user: user}} = conn, _params) do
-    token =
-      conn
-      |> get_session(:oauth_token)
+    token = get_session(conn, :oauth_token)
 
     if user && token do
       mastodon_emoji = mastodonized_emoji()
@@ -1194,6 +1192,7 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPIController do
       |> render("index.html", %{initial_state: initial_state, flavour: flavour})
     else
       conn
+      |> put_session(:return_to, conn.request_path)
       |> redirect(to: "/web/login")
     end
   end
@@ -1278,12 +1277,20 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPIController do
           scope: Enum.join(app.scopes, " ")
         )
 
-      conn
-      |> redirect(to: path)
+      redirect(conn, to: path)
     end
   end
 
-  defp local_mastodon_root_path(conn), do: mastodon_api_path(conn, :index, ["getting-started"])
+  defp local_mastodon_root_path(conn) do
+    case get_session(conn, :return_to) do
+      nil ->
+        mastodon_api_path(conn, :index, ["getting-started"])
+
+      return_to ->
+        delete_session(conn, :return_to)
+        return_to
+    end
+  end
 
   defp get_or_make_app do
     find_attrs = %{client_name: @local_mastodon_name, redirect_uris: "."}

test/support/factory.ex

@@ -240,6 +240,16 @@ defmodule Pleroma.Factory do
     }
   end
 
+  def oauth_authorization_factory do
+    %Pleroma.Web.OAuth.Authorization{
+      token: :crypto.strong_rand_bytes(32) |> Base.url_encode64(padding: false),
+      scopes: ["read", "write", "follow", "push"],
+      valid_until: NaiveDateTime.add(NaiveDateTime.utc_now(), 60 * 10),
+      user: build(:user),
+      app: build(:oauth_app)
+    }
+  end
+
   def push_subscription_factory do
     %Pleroma.Web.Push.Subscription{
       user: build(:user),

test/web/mastodon_api/mastodon_api_controller_test.exs

@@ -2340,4 +2340,71 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPIControllerTest do
     refute acc_one == acc_two
     assert acc_two == acc_three
   end
+
+  describe "index/2 redirections" do
+    setup %{conn: conn} do
+      session_opts = [
+        store: :cookie,
+        key: "_test",
+        signing_salt: "cooldude"
+      ]
+
+      conn =
+        conn
+        |> Plug.Session.call(Plug.Session.init(session_opts))
+        |> fetch_session()
+
+      test_path = "/web/statuses/test"
+      %{conn: conn, path: test_path}
+    end
+
+    test "redirects not logged-in users to the login page", %{conn: conn, path: path} do
+      conn = get(conn, path)
+
+      assert conn.status == 302
+      assert redirected_to(conn) == "/web/login"
+    end
+
+    test "does not redirect logged in users to the login page", %{conn: conn, path: path} do
+      token = insert(:oauth_token)
+
+      conn =
+        conn
+        |> assign(:user, token.user)
+        |> put_session(:oauth_token, token.token)
+        |> get(path)
+
+      assert conn.status == 200
+    end
+
+    test "saves referer path to session", %{conn: conn, path: path} do
+      conn = get(conn, path)
+      return_to = Plug.Conn.get_session(conn, :return_to)
+
+      assert return_to == path
+    end
+
+    test "redirects to the saved path after log in", %{conn: conn, path: path} do
+      app = insert(:oauth_app, client_name: "Mastodon-Local", redirect_uris: ".")
+      auth = insert(:oauth_authorization, app: app)
+
+      conn =
+        conn
+        |> put_session(:return_to, path)
+        |> get("/web/login", %{code: auth.token})
+
+      assert conn.status == 302
+      assert redirected_to(conn) == path
+    end
+
+    test "redirects to the getting-started page when referer is not present", %{conn: conn} do
+      app = insert(:oauth_app, client_name: "Mastodon-Local", redirect_uris: ".")
+      auth = insert(:oauth_authorization, app: app)
+
+      conn = get(conn, "/web/login", %{code: auth.token})
+
+      assert conn.status == 302
+      assert redirected_to(conn) == "/web/getting-started"
+    end
+  end
 end