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Add permessage-deflate approx max option #120

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Add permessage-deflate approx max option #120

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65 changes: 49 additions & 16 deletions src/cow_ws.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -47,7 +47,9 @@

%% LZ77 sliding window size limits.
server_max_window_bits => 8..15,
client_max_window_bits => 8..15
client_max_window_bits => 8..15,

approx_max => nil() | integer()
}.
-export_type([deflate_opts/0]).

Expand Down Expand Up @@ -148,7 +150,8 @@ negotiate_permessage_deflate1(Params, Extensions, Opts) ->
deflate => Deflate,
deflate_takeover => maps:get(server_context_takeover, Negotiated),
inflate => Inflate,
inflate_takeover => maps:get(client_context_takeover, Negotiated)}}
inflate_takeover => maps:get(client_context_takeover, Negotiated),
approx_max => maps:get(approx_max, Opts, nil)}}
end.

negotiate_params([], Negotiated, RespParams) ->
Expand Down Expand Up @@ -297,7 +300,8 @@ negotiate_x_webkit_deflate_frame(_Params, Extensions, Opts) ->
deflate => Deflate,
deflate_takeover => takeover,
inflate => Inflate,
inflate_takeover => takeover}}.
inflate_takeover => takeover,
approx_max => maps:get(approx_max, Opts, nil)}}.

%% @doc Validate the negotiated permessage-deflate extension.

Expand All @@ -319,7 +323,8 @@ validate_permessage_deflate(Params, Extensions, Opts) ->
deflate => Deflate,
deflate_takeover => ClientTakeOver,
inflate => Inflate,
inflate_takeover => ServerTakeOver}}
inflate_takeover => ServerTakeOver,
approx_max => maps:get(approx_max, Opts, nil)}}
end
end.

Expand Down Expand Up @@ -443,7 +448,7 @@ frag_state(_, 1, _, FragState) -> FragState.
| {ok, close_code(), binary(), utf8_state(), binary()}
| {more, binary(), utf8_state()}
| {more, close_code(), binary(), utf8_state()}
| {error, badframe | badencoding}.
| {error, badframe | badencoding | overflow}.
%% Empty last frame of compressed message.
parse_payload(Data, _, Utf8State, _, _, 0, {fin, _, << 1:1, 0:2 >>},
#{inflate := Inflate, inflate_takeover := TakeOver}, _) ->
Expand All @@ -455,16 +460,26 @@ parse_payload(Data, _, Utf8State, _, _, 0, {fin, _, << 1:1, 0:2 >>},
{ok, <<>>, Utf8State, Data};
%% Compressed fragmented frame.
parse_payload(Data, MaskKey, Utf8State, ParsedLen, Type, Len, FragState = {_, _, << 1:1, 0:2 >>},
#{inflate := Inflate, inflate_takeover := TakeOver}, _) ->
#{inflate := Inflate, inflate_takeover := TakeOver, approx_max := ApproxMax}, _) ->
{Data2, Rest, Eof} = split_payload(Data, Len),
Payload = inflate_frame(unmask(Data2, MaskKey, ParsedLen), Inflate, TakeOver, FragState, Eof),
validate_payload(Payload, Rest, Utf8State, ParsedLen, Type, FragState, Eof);
Result = inflate_frame(unmask(Data2, MaskKey, ParsedLen), Inflate, TakeOver, FragState, ApproxMax, Eof),
case Result of
{error, _} ->
Result;
{ok, Payload} ->
validate_payload(Payload, Rest, Utf8State, ParsedLen, Type, FragState, Eof)
end;
%% Compressed frame.
parse_payload(Data, MaskKey, Utf8State, ParsedLen, Type, Len, FragState,
#{inflate := Inflate, inflate_takeover := TakeOver}, << 1:1, 0:2 >>) when Type =:= text; Type =:= binary ->
#{inflate := Inflate, inflate_takeover := TakeOver, approx_max := ApproxMax}, << 1:1, 0:2 >>) when Type =:= text; Type =:= binary ->
{Data2, Rest, Eof} = split_payload(Data, Len),
Payload = inflate_frame(unmask(Data2, MaskKey, ParsedLen), Inflate, TakeOver, FragState, Eof),
validate_payload(Payload, Rest, Utf8State, ParsedLen, Type, FragState, Eof);
Result = inflate_frame(unmask(Data2, MaskKey, ParsedLen), Inflate, TakeOver, FragState, ApproxMax, Eof),
case Result of
{error, _} ->
Result;
{ok, Payload} ->
validate_payload(Payload, Rest, Utf8State, ParsedLen, Type, FragState, Eof)
end;
%% Empty frame.
parse_payload(Data, _, Utf8State, 0, _, 0, _, _, _)
when Utf8State =:= 0; Utf8State =:= undefined ->
Expand Down Expand Up @@ -541,16 +556,34 @@ mask(<< O:8 >>, MaskKey, Acc) ->
T = O bxor MaskKey2,
<< Acc/binary, T:8 >>.

inflate_frame(Data, Inflate, TakeOver, FragState, true)
safe_inflate(ApproxMax, Inflate, {continue, Data}, Acc) ->
Overflow = iolist_size(Acc) + iolist_size(Data) > ApproxMax,
if
Overflow ->
{error, overflow};
true ->
safe_inflate(ApproxMax, Inflate, zlib:safeInflate(Inflate, []), [Acc, Data])
end;
safe_inflate(_A, _I, {finished, Data}, Acc) ->
{ok, iolist_to_binary([Acc, Data])}.

inflate_dispatch(Data, Inflate, ApproxMax) ->
Data2 = << Data/binary, 0, 0, 255, 255 >>,
case ApproxMax of
nil -> {ok, iolist_to_binary(zlib:inflate(Inflate, Data2))};
_ -> safe_inflate(ApproxMax, Inflate, zlib:safeInflate(Inflate, Data2), [])
end.

inflate_frame(Data, Inflate, TakeOver, FragState, ApproxMax, true)
when FragState =:= undefined; element(1, FragState) =:= fin ->
Data2 = zlib:inflate(Inflate, << Data/binary, 0, 0, 255, 255 >>),
Result = inflate_dispatch(Data, Inflate, ApproxMax),
case TakeOver of
no_takeover -> zlib:inflateReset(Inflate);
takeover -> ok
end,
iolist_to_binary(Data2);
inflate_frame(Data, Inflate, _T, _F, _E) ->
iolist_to_binary(zlib:inflate(Inflate, Data)).
Result;
inflate_frame(Data, Inflate, _T, _F, ApproxMax, _E) ->
inflate_dispatch(Data, Inflate, ApproxMax).

%% The Utf8State variable can be set to 'undefined' to disable the validation.
validate_payload(Payload, _, undefined, _, _, _, false) ->
Expand Down