Added `force_login` authentication option (previously applied by default).

lib/pleroma/web/controller_helper.ex

@@ -5,6 +5,11 @@
 defmodule Pleroma.Web.ControllerHelper do
   use Pleroma.Web, :controller
 
+  # As in MastoAPI, per https://api.rubyonrails.org/classes/ActiveModel/Type/Boolean.html
+  @falsy_param_values [false, 0, "0", "f", "F", "false", "FALSE", "off", "OFF"]
+  def truthy_param?(nil), do: nil
+  def truthy_param?(value), do: value not in @falsy_param_values
+
   def oauth_scopes(params, default) do
     # Note: `scopes` is used by Mastodon — supporting it but sticking to
     # OAuth's standard `scope` wherever we control it

lib/pleroma/web/oauth/oauth_controller.ex

@@ -8,6 +8,7 @@ defmodule Pleroma.Web.OAuth.OAuthController do
   alias Pleroma.Repo
   alias Pleroma.User
   alias Pleroma.Web.Auth.Authenticator
+  alias Pleroma.Web.ControllerHelper
   alias Pleroma.Web.OAuth.App
   alias Pleroma.Web.OAuth.Authorization
   alias Pleroma.Web.OAuth.Token
@@ -19,7 +20,28 @@ defmodule Pleroma.Web.OAuth.OAuthController do
 
   action_fallback(Pleroma.Web.OAuth.FallbackController)
 
-  def authorize(conn, params) do
+  def authorize(%{assigns: %{token: %Token{} = token}} = conn, params) do
+    if ControllerHelper.truthy_param?(params["force_login"]) do
+      do_authorize(conn, params)
+    else
+      redirect_uri =
+        if is_binary(params["redirect_uri"]) do
+          params["redirect_uri"]
+        else
+          app = Repo.preload(token, :app).app
+
+          app.redirect_uris
+          |> String.split()
+          |> Enum.at(0)
+        end
+
+      redirect(conn, external: redirect_uri(conn, redirect_uri))
+    end
+  end
+
+  def authorize(conn, params), do: do_authorize(conn, params)
+
+  defp do_authorize(conn, params) do
     app = Repo.get_by(App, client_id: params["client_id"])
     available_scopes = (app && app.scopes) || []
     scopes = oauth_scopes(params, nil) || available_scopes
@@ -51,13 +73,7 @@ def create_authorization(conn, %{
          {:missing_scopes, false} <- {:missing_scopes, scopes == []},
          {:auth_active, true} <- {:auth_active, User.auth_active?(user)},
          {:ok, auth} <- Authorization.create_authorization(app, user, scopes) do
-      redirect_uri =
+      redirect_uri = redirect_uri(conn, redirect_uri)
-        if redirect_uri == "." do
-          # Special case: Local MastodonFE
-          mastodon_api_url(conn, :login)
-        else
-          redirect_uri
-        end
 
       cond do
         redirect_uri == "urn:ietf:wg:oauth:2.0:oob" ->
@@ -221,4 +237,9 @@ defp get_app_from_request(conn, params) do
       nil
     end
   end
+
+  # Special case: Local MastodonFE
+  defp redirect_uri(conn, "."), do: mastodon_api_url(conn, :index, [])
+
+  defp redirect_uri(_conn, redirect_uri), do: redirect_uri
 end

lib/pleroma/web/router.ex

@@ -5,6 +5,11 @@
 defmodule Pleroma.Web.Router do
   use Pleroma.Web, :router
 
+  pipeline :oauth do
+    plug(:fetch_session)
+    plug(Pleroma.Plugs.OAuthPlug)
+  end
+
   pipeline :api do
     plug(:accepts, ["json"])
     plug(:fetch_session)
@@ -105,10 +110,6 @@ defmodule Pleroma.Web.Router do
     plug(:accepts, ["json", "xml"])
   end
 
-  pipeline :oauth do
-    plug(:accepts, ["html", "json"])
-  end
-
   pipeline :pleroma_api do
     plug(:accepts, ["html", "json"])
   end
@@ -200,7 +201,11 @@ defmodule Pleroma.Web.Router do
   end
 
   scope "/oauth", Pleroma.Web.OAuth do
+    scope [] do
+      pipe_through(:oauth)
       get("/authorize", OAuthController, :authorize)
+    end
+
     post("/authorize", OAuthController, :create_authorization)
     post("/token", OAuthController, :token_exchange)
     post("/revoke", OAuthController, :token_revoke)