Handle unexpected continuation frames (#33)

Author: bfolkens

lib/mint/web_socket/frame.ex

@@ -431,6 +431,10 @@ defmodule Mint.WebSocket.Frame do
     {:close, code, reason}
   end
 
+  def translate(continuation()) do
+    {:error, :unexpected_continuation}
+  end
+
   @doc """
   Emits frames for any finalized fragments and stores any unfinalized fragments
   in the `:fragment` key in the websocket data structure

test/mint/web_socket/frame_test.exs

@@ -9,4 +9,9 @@ defmodule Mint.WebSocket.FrameTest do
 
     assert ping(fin?: true) |> is_fin()
   end
+
+  test "incomplete frames should return error" do
+    assert {:error, :unexpected_continuation} =
+             translate({:continuation, <<0x0::size(3)>>, nil, "hello", true})
+  end
 end