diff --git a/src/mtp_abridged.erl b/src/mtp_abridged.erl
index 165b9c0..2c059b0 100644
--- a/src/mtp_abridged.erl
+++ b/src/mtp_abridged.erl
@@ -56,7 +56,7 @@ try_decode_packet_len(Len, LenStripped, Data, St) ->
             {incomplete, St#st{buffer = Data}}
     end.
 
--spec encode_packet(binary(), codec()) -> iodata().
+-spec encode_packet(binary(), codec()) -> {iodata(), codec()}.
 encode_packet(Bin, St) ->
     Size = byte_size(Bin),
     Len = Size div 4,
diff --git a/src/mtp_codec.erl b/src/mtp_codec.erl
index 58c60af..a670e5d 100644
--- a/src/mtp_codec.erl
+++ b/src/mtp_codec.erl
@@ -19,8 +19,9 @@
 -export_type([codec/0]).
 
 -type state() :: any().
--type crypto_codec() :: mtb_aes_cbc
-                      | mtp_obfuscated.
+-type crypto_codec() :: mtp_aes_cbc
+                      | mtp_obfuscated
+                      | mtp_noop_codec.
 -type packet_codec() :: mtp_abridged
                       | mtp_full
                       | mtp_intermediate
@@ -58,6 +59,7 @@ decompose(#codec{crypto_mod = CryptoMod, crypto_state = CryptoState,
 
 
 %% try_decode_packet(Inner) |> try_decode_packet(Outer)
+-spec try_decode_packet(binary(), codec()) -> {ok, binary(), codec()} | {incomplete, codec()}.
 try_decode_packet(Bin, #codec{crypto_mod = CryptoMod,
                               crypto_state = CryptoSt,
                               packet_mod = PacketMod,
@@ -80,6 +82,7 @@ try_decode_packet(Bin, #codec{crypto_mod = CryptoMod,
     end.
 
 %% encode_packet(Outer) |> encode_packet(Inner)
+-spec encode_packet(iodata(), codec()) -> {iodata(), codec()}.
 encode_packet(Bin, #codec{packet_mod = PacketMod,
                           packet_state = PacketSt,
                           crypto_mod = CryptoMod,
diff --git a/src/mtp_down_conn.erl b/src/mtp_down_conn.erl
index 85d717b..eea9ffb 100644
--- a/src/mtp_down_conn.erl
+++ b/src/mtp_down_conn.erl
@@ -92,14 +92,9 @@ handle_cast(shutdown, State) ->
 handle_info({tcp, Sock, Data}, #state{sock = Sock} = S) ->
     mtp_metric:count_inc([?APP, received, bytes], byte_size(Data), #{labels => [downstream]}),
     mtp_metric:histogram_observe([?APP, tracker_packet_size, bytes], byte_size(Data), #{labels => [downstream]}),
-    case handle_downstream_data(Data, S) of
-        {ok, S1} ->
-            ok = inet:setopts(Sock, [{active, once}]),
-            {noreply, S1};
-        {error, Reason} ->
-            lager:error("Error sending tunnelled data to in socket: ~p", [Reason]),
-            {stop, normal, S}
-    end;
+    {ok, S1} = handle_downstream_data(Data, S),
+    ok = inet:setopts(Sock, [{active, once}]),
+    {noreply, S1};
 handle_info({tcp_closed, Sock}, #state{sock = Sock} = State) ->
     {stop, normal, State};
 handle_info({tcp_error, Sock, Reason}, #state{sock = Sock} = State) ->
diff --git a/src/mtp_handler.erl b/src/mtp_handler.erl
index 3539db7..aa721d2 100644
--- a/src/mtp_handler.erl
+++ b/src/mtp_handler.erl
@@ -44,7 +44,7 @@
          transport :: transport(),
          codec :: mtp_codec:codec() | undefined,
 
-         down :: mtp_down_conn:handle(),
+         down :: mtp_down_conn:handle() | undefined,
          dc_id :: integer(),
 
          ad_tag :: binary(),
@@ -88,7 +88,7 @@ ranch_init({Ref, Transport, Opts}) ->
                     {buffer, BufSize}
                    ]),
             gen_server:enter_loop(?MODULE, [], State);
-        error ->
+        {stop, error} ->
             exit(normal)
     end.
 
@@ -114,7 +114,7 @@ init({Socket, Transport, [Name, Secret, Tag]}) ->
         {error, Reason} ->
             mtp_metric:count_inc([?APP, in_connection_closed, total], 1, #{labels => [Name]}),
             lager:info("Can't read peername: ~p", [Reason]),
-            error
+            {stop, error}
     end.
 
 handle_call(_Request, _From, State) ->
@@ -123,13 +123,8 @@ handle_call(_Request, _From, State) ->
 
 handle_cast({proxy_ans, Down, Data}, #state{down = Down} = S) ->
     %% telegram server -> proxy
-    case up_send(Data, S) of
-        {ok, S1} ->
-            maybe_check_health(bump_timer(S1));
-        {error, Reason} ->
-            lager:error("Error sending tunnelled data to in socket: ~p", [Reason]),
-            {stop, normal, S}
-    end;
+    {ok, S1} = up_send(Data, S),
+    maybe_check_health(bump_timer(S1));
 handle_cast({close_ext, Down}, #state{down = Down, sock = USock, transport = UTrans} = S) ->
     lager:debug("asked to close connection by downstream"),
     ok = UTrans:close(USock),
diff --git a/src/mtp_intermediate.erl b/src/mtp_intermediate.erl
index 3e31698..df5e9ad 100644
--- a/src/mtp_intermediate.erl
+++ b/src/mtp_intermediate.erl
@@ -63,7 +63,7 @@ try_decode_packet_len(Len, Data, #int_st{padding = Pad} = St) ->
             {incomplete, St#int_st{buffer = Data}}
     end.
 
--spec encode_packet(iodata(), codec()) -> iodata().
+-spec encode_packet(iodata(), codec()) -> {iodata(), codec()}.
 encode_packet(Data, #int_st{padding = Pad} = St) ->
     Size = iolist_size(Data),
     Packet = case Pad of
diff --git a/src/mtp_secure.erl b/src/mtp_secure.erl
index 696fac8..77d7ea2 100644
--- a/src/mtp_secure.erl
+++ b/src/mtp_secure.erl
@@ -24,6 +24,6 @@ new() ->
 try_decode_packet(Data, St) ->
     mtp_intermediate:try_decode_packet(Data, St).
 
--spec encode_packet(iodata(), codec()) -> iodata().
+-spec encode_packet(iodata(), codec()) -> {iodata(), codec()}.
 encode_packet(Data, St) ->
     mtp_intermediate:encode_packet(Data, St).