Process server, port, error and warning records

lib/chronoscope/nts.ex

@@ -11,6 +11,7 @@ defmodule Chronoscope.NTS do
     case :ssl.connect(host, port, tls_options, @timeout_in_milliseconds) do
       {:ok, socket} -> perform_key_establishment(socket)
       {:error, {:tls_alert, {:handshake_failure, error}}} -> {:error, to_string(error)}
+      {:error, :timeout} -> {:error, :timeout}
       {:error, error} -> {:error, inspect(error)}
       error -> {:error, inspect(error)}
     end

lib/chronoscope/nts/key_establishment.ex

@@ -10,24 +10,37 @@ defmodule Chronoscope.NTS.KeyEstablishment do
     30 => "AEAD_AES_128_GCM_SIV"
   }
 
-  @next_protocols %{0 => "NTPv4"}
+  @next_protocols %{
+    0 => "NTPv4"
+  }
+
+  @errors %{
+    0 => "Unrecognized Critical Record",
+    1 => "Bad Request",
+    2 => "Internal Server Error"
+  }
 
   def request() do
     @next_protocol_negotiation <> @aead_algorithm_negotiation <> @end_of_message
   end
 
   def parse_response(response) do
-    {:ok, Map.update(do_parse_response(response, %{}), :cookies, 0, &length/1)}
+    response
+    |> do_parse_response(%{})
+    |> Map.update(:cookies, 0, &length/1)
+    |> then(&{:ok, &1})
   end
 
   defp do_parse_response([], acc) do
     acc
   end
 
+  # End of Message
   defp do_parse_response([0x80, 0x00, 0x00, 0x00], acc) do
     acc
   end
 
+  # NTS Next Protocol Negotiation
   defp do_parse_response([0x80, 0x01, length_high, length_low | rest], acc) do
     length = combine_octets(length_high, length_low)
     {next_protocols, remaining} = Enum.split(rest, length)
@@ -38,6 +51,24 @@ defmodule Chronoscope.NTS.KeyEstablishment do
     )
   end
 
+  # Error
+  defp do_parse_response([0x80, 0x02, 0x00, 0x02, error_high, error_low | rest], acc) do
+    error = combine_octets(error_high, error_low)
+
+    do_parse_response(
+      rest,
+      Map.put(acc, :error, Map.get(@errors, error, error))
+    )
+  end
+
+  # Warning
+  defp do_parse_response([0x80, 0x03, 0x00, 0x02, warning_high, warning_low | rest], acc) do
+    warning = combine_octets(warning_high, warning_low)
+
+    do_parse_response(rest, Map.put(acc, :warning, warning))
+  end
+
+  # AEAD Algorithm Negotiation
   defp do_parse_response([first, 0x04, length_high, length_low | rest], acc)
        when first == 0x00 or first == 0x80 do
     length = combine_octets(length_high, length_low)
@@ -49,6 +80,7 @@ defmodule Chronoscope.NTS.KeyEstablishment do
     )
   end
 
+  # New Cookie for NTPv4
   defp do_parse_response([first, 0x05, length_high, length_low | rest], acc)
        when first == 0x00 or first == 0x80 do
     length = combine_octets(length_high, length_low)
@@ -62,6 +94,23 @@ defmodule Chronoscope.NTS.KeyEstablishment do
     )
   end
 
+  # NTPv4 Server Negotiation
+  defp do_parse_response([first, 0x06, length_high, length_low | rest], acc)
+       when first == 0x00 or first == 0x80 do
+    length = combine_octets(length_high, length_low)
+    {server, remaining} = Enum.split(rest, length)
+
+    do_parse_response(remaining, Map.put(acc, :server, to_string(server)))
+  end
+
+  # NTPv4 Port Negotiation
+  defp do_parse_response([first, 0x07, 0x00, 0x02, port_high, port_low | rest], acc)
+       when first == 0x00 or first == 0x80 do
+    port = combine_octets(port_high, port_low)
+
+    do_parse_response(rest, Map.put(acc, :port, port))
+  end
+
   defp do_parse_response([_, _, length_high, length_low | rest], acc) do
     length = combine_octets(length_high, length_low)
     {_, remaining} = Enum.split(rest, length)
@@ -97,8 +146,6 @@ defmodule Chronoscope.NTS.KeyEstablishment do
     |> then(&do_parse_aead_algorithm_list(rest, [&1 | acc]))
   end
 
-  # todo parse server/port information
-
   defp combine_octets(high, low) do
     high <<< 8 ||| low
   end

lib/chronoscope_web/controllers/api/v1/nts/key_establishment_controller.ex

@@ -16,7 +16,7 @@ defmodule ChronoscopeWeb.API.V1.NTS.KeyEstablishmentController do
         ok_response(conn, %{status: :ok, configuration: configuration})
 
       {:error, error} ->
-        ok_response(conn, %{status: :error, reason: inspect(error)})
+        ok_response(conn, %{status: :error, reason: to_string(error)})
     end
   end