Add API auth Plug

2 files changed, 27 insertions, 0 deletions

diff --git a/lib/matrix_app_service/auth_plug.ex b/lib/matrix_app_service/auth_plug.ex
new file mode 100644
index 0000000..0768caa
--- /dev/null
+++ b/lib/matrix_app_service/auth_plug.ex
@@ -0,0 +1,26 @@
+defmodule MatrixAppService.AuthPlug do
+  @behaviour Plug
+  import Plug.Conn
+  require Logger
+
+  @impl Plug
+  def init(_opts) do
+    Application.fetch_env!(:matrix_app_service, :homeserver_token)
+  end
+
+  @impl Plug
+  def call(%Plug.Conn{params: %{"access_token" => hs_token}} = conn, config_hs_token)
+      when hs_token == config_hs_token do
+    conn
+  end
+
+  def call(conn, _config_hs_token) do
+    Logger.warn("Received invalid homeserver token")
+
+    conn
+    |> put_status(:unauthorized)
+    |> Phoenix.Controller.put_view(MatrixAppServiceWeb.ErrorView)
+    |> Phoenix.Controller.render("401.json")
+    |> halt
+  end
+end
diff --git a/lib/matrix_app_service/phoenix/router.ex b/lib/matrix_app_service/phoenix/router.ex
index 4ab6bf2..a5458d2 100644
--- a/lib/matrix_app_service/phoenix/router.ex
+++ b/lib/matrix_app_service/phoenix/router.ex
@@ -3,6 +3,7 @@ defmodule MatrixAppService.Phoenix.Router do
     quote do
       pipeline :matrix_api do
         plug :accepts, ["json"]
+        plug MatrixAppService.AuthPlug
       end
 
       path = Application.compile_env(:matrix_app_service, :path, "/")