Limit TLS record size to 2^14

See rfc8446#section-5.1

src/mtp_fake_tls.erl

@@ -33,7 +33,8 @@
          extensions :: [{non_neg_integer(), any()}]
         }).
 
--define(MAX_PACKET_SIZE, 65535).      % sizeof(uint16) - 1
+-define(MAX_IN_PACKET_SIZE, 65535).      % sizeof(uint16) - 1
+-define(MAX_OUT_PACKET_SIZE, 16384).     % 2^14 https://tools.ietf.org/html/rfc8446#section-5.1
 
 -define(TLS_10_VERSION, 3, 1).
 -define(TLS_12_VERSION, 3, 3).
@@ -184,7 +185,7 @@ try_decode_packet(<<?TLS_REC_CHANGE_CIPHER, ?TLS_12_VERSION, Size:16/unsigned-bi
                     _Data:Size/binary, Tail/binary>>, St) ->
     %% "Change cipher" are ignored
     try_decode_packet(Tail, St);
-try_decode_packet(Bin, St) when byte_size(Bin) =< (?MAX_PACKET_SIZE + 5) ->  % 5 is ?TLS_12_DATA + Size:16 size
+try_decode_packet(Bin, St) when byte_size(Bin) =< (?MAX_IN_PACKET_SIZE + 5) ->  % 5 is ?TLS_12_DATA + Size:16 size
     {incomplete, St};
 try_decode_packet(Bin, _St) ->
     error({protocol_error, tls_max_size, byte_size(Bin)}).
@@ -207,9 +208,9 @@ decode_all(Bin, Acc, St0) ->
 encode_packet(Bin, St) ->
     {encode_as_frames(Bin), St}.
 
-encode_as_frames(Bin) when byte_size(Bin) =< ?MAX_PACKET_SIZE ->
+encode_as_frames(Bin) when byte_size(Bin) =< ?MAX_OUT_PACKET_SIZE ->
     as_tls_data_frame(Bin);
-encode_as_frames(<<Chunk:?MAX_PACKET_SIZE/binary, Tail/binary>>) ->
+encode_as_frames(<<Chunk:?MAX_OUT_PACKET_SIZE/binary, Tail/binary>>) ->
     [as_tls_data_frame(Chunk) | encode_as_frames(Tail)].
 
 as_tls_data_frame(Bin) ->

test/prop_mtp_codec.erl

@@ -167,9 +167,9 @@ prop_tls_big_stream() ->
     ?FORALL({Key, Iv, Stream}, tls_big_stream_arg_set(), tls_obfuscated_secure_stream(Key, Iv, Stream)).
 
 tls_big_stream_arg_set() ->
-    %% Packets more than 64kb but less than 512kb
-    Min = 64 * 1024 + 10,
-    Max = 512 * 1024,
+    %% Packets more than 2^14b but less than 128kb
+    Min = 16 * 1024 + 10,
+    Max = 128 * 1024,
     proper_types:tuple(
       [mtp_prop_gen:key(),
        mtp_prop_gen:iv(),

test/prop_mtp_fake_tls.erl

@@ -9,10 +9,10 @@ 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)).
+    ?FORALL(Bin, mtp_prop_gen:binary(8, 16 * 1024), codec_small(Bin)).
 
 codec_small(Bin) ->
-    %% fake_tls can split big packets to multiple TLS frames of 64kb
+    %% fake_tls can split big packets to multiple TLS frames of 2^14b
     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),
@@ -23,7 +23,7 @@ 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)).
+    ?FORALL(Bin, mtp_prop_gen:binary(16 * 1024, 65535), codec_big(Bin)).
 
 codec_big(Bin) ->
     Codec = mtp_fake_tls:new(),
@@ -35,10 +35,10 @@ codec_big(Bin) ->
     
 
 prop_stream(doc) ->
-    "Tests that set of packets of size below 65535b can be encoded and decoded back".
+    "Tests that set of packets of size below 2^14b can be encoded and decoded back".
 
 prop_stream() ->
-    ?FORALL(Stream, proper_types:list(mtp_prop_gen:binary(8, 20000)),
+    ?FORALL(Stream, proper_types:list(mtp_prop_gen:binary(8, 16000)),
            codec_stream(Stream)).
 
 codec_stream(Stream) ->