Fake TLS protocol

* pretends being TLS1.3 + http2
* mtp_handler state-machine refactored

test/mtp_prop_gen.erl

@@ -7,6 +7,7 @@
          packet_4b/0,
          stream_16b/0,
          packet_16b/0,
+         binary/2,
          key/0,
          iv/0,
          secret/0,
@@ -33,6 +34,14 @@ packet_16b() ->
 stream_16b() ->
     proper_types:list(packet_16b()).
 
+%% Binary of size between Min and Max
+binary(Min, Max) when Min < Max ->
+    TailSize = Max - Min,
+    ?LET({First, Tail}, {proper_types:binary(Min),
+                         proper_types:resize(TailSize,
+                                             proper_types:list(proper_types:byte()))},
+         iolist_to_binary([First | Tail])).
+
 %% 32-byte encryption key: `binary()`
 key() ->
     proper_types:binary(32).

test/mtp_test_client.erl

@@ -31,7 +31,7 @@ connect(Host, Port, Seed, Secret, DcId, Protocol) ->
     ok = gen_tcp:send(Sock, Header),
     PacketLayer = Protocol:new(),
     Codec = mtp_codec:new(mtp_obfuscated, CryptoLayer,
-                          Protocol, PacketLayer),
+                          Protocol, PacketLayer, false, undefined, 25 * 1024 * 1024),
     #client{sock = Sock,
             codec = Codec}.
 

test/mtp_test_middle_server.erl

@@ -118,10 +118,8 @@ wait_nonce(info, {tcp, _Sock, TcpData},
     {DecKey, DecIv} = mtp_down_conn:get_middle_key(Args#{purpose => <<"CLIENT">>}),
     {EncKey, EncIv} = mtp_down_conn:get_middle_key(Args#{purpose => <<"SERVER">>}),
     %% Add encryption layer to codec
-    {_, _, PacketMod, PacketState} = mtp_codec:decompose(Codec2),
     CryptoState = mtp_aes_cbc:new(EncKey, EncIv, DecKey, DecIv, 16),
-    Codec3 = mtp_codec:new(mtp_aes_cbc, CryptoState,
-                           PacketMod, PacketState),
+    Codec3 = mtp_codec:replace(crypto, mtp_aes_cbc, CryptoState, Codec2),
 
     {next_state, wait_handshake,
      activate(S1#hs_state{codec = Codec3,

test/prop_mtp_fake_tls.erl

@@ -0,0 +1,62 @@
+%% @doc property-based tests for mtp_fake_tls
+-module(prop_mtp_fake_tls).
+-include_lib("proper/include/proper.hrl").
+-include_lib("stdlib/include/assert.hrl").
+
+-export([prop_codec_small/1, prop_codec_big/1, prop_stream/1]).
+
+prop_codec_small(doc) ->
+    "Tests that any binary below 65535 bytes can be encoded and decoded back as single frame".
+
+prop_codec_small() ->
+    ?FORALL(Bin, mtp_prop_gen:binary(8, 65535), codec_small(Bin)).
+
+codec_small(Bin) ->
+    %% fake_tls can split big packets to multiple TLS frames of 64kb
+    Codec = mtp_fake_tls:new(),
+    {Data, Codec1} = mtp_fake_tls:encode_packet(Bin, Codec),
+    {ok, Decoded, <<>>, _} = mtp_fake_tls:try_decode_packet(iolist_to_binary(Data), Codec1),
+    Decoded == Bin.
+
+
+prop_codec_big(doc) ->
+    "Tests that big binaries will be split to multiple chunks".
+
+prop_codec_big() ->
+    ?FORALL(Bin, mtp_prop_gen:binary(65536, 75000), codec_big(Bin)).
+
+codec_big(Bin) ->
+    Codec = mtp_fake_tls:new(),
+    {Data, Codec1} = mtp_fake_tls:encode_packet(Bin, Codec),
+    Chunks = decode_stream(iolist_to_binary(Data), Codec1, []),
+    ?assert(length(Chunks) > 1),
+    ?assertEqual(Bin, iolist_to_binary(Chunks)),
+    true.
+    
+
+prop_stream(doc) ->
+    "Tests that set of packets of size below 65535b can be encoded and decoded back".
+
+prop_stream() ->
+    ?FORALL(Stream, proper_types:list(mtp_prop_gen:binary(8, 20000)),
+           codec_stream(Stream)).
+
+codec_stream(Stream) ->
+    Codec = mtp_fake_tls:new(),
+    {BinStream, Codec1} =
+        lists:foldl(
+          fun(Bin, {Acc, Codec1}) ->
+                  {Data, Codec2} = mtp_fake_tls:encode_packet(Bin, Codec1),
+                  {<<Acc/binary, (iolist_to_binary(Data))/binary>>,
+                   Codec2}
+          end, {<<>>, Codec}, Stream),
+    DecodedStream = decode_stream(BinStream, Codec1, []),
+    Stream == DecodedStream.
+
+decode_stream(BinStream, Codec, Acc) ->
+    case mtp_fake_tls:try_decode_packet(BinStream, Codec) of
+        {incomplete, _} ->
+            lists:reverse(Acc);
+        {ok, DecPacket, Tail, Codec1} ->
+            decode_stream(Tail, Codec1, [DecPacket | Acc])
+    end.