From a013becc66b50db038c1f7f3539040b4482bba18 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= Date: Sun, 6 Jan 2013 19:49:01 +0100 Subject: Add protection against slowloris vulnerability This changes the behavior of the `timeout` protocol option to mean "Time in which the full request line and headers must be received". The default of 5s should be fine for all normal uses. This change has no noticeable impact on performance and is thus enabled by default for everyone. It can be disabled by setting `timeout` to `infinity` although that is definitely not encouraged. Inspired by the contribution from @naryl on github. --- src/cowboy_protocol.erl | 56 +++++++++++++++++++++++++++++++++++-------------- 1 file changed, 40 insertions(+), 16 deletions(-) (limited to 'src/cowboy_protocol.erl') diff --git a/src/cowboy_protocol.erl b/src/cowboy_protocol.erl index b82fa2b..48c0b00 100644 --- a/src/cowboy_protocol.erl +++ b/src/cowboy_protocol.erl @@ -38,8 +38,8 @@ %% not available at this point. %%
onresponse
Optional fun that allows replacing a response %% sent by the application.
-%%
timeout
Time in milliseconds before an idle -%% connection is closed. Defaults to 5000 milliseconds.
+%%
timeout
Time in milliseconds a client has to send the +%% full request line and headers. Defaults to 5000 milliseconds.
%% %% %% Note that there is no need to monitor these processes when using Cowboy as @@ -74,7 +74,8 @@ max_header_name_length :: non_neg_integer(), max_header_value_length :: non_neg_integer(), max_headers :: non_neg_integer(), - timeout :: timeout() + timeout :: timeout(), + until :: non_neg_integer() | infinity }). %% API. @@ -116,7 +117,15 @@ init(ListenerPid, Socket, Transport, Opts) -> max_request_line_length=MaxRequestLineLength, max_header_name_length=MaxHeaderNameLength, max_header_value_length=MaxHeaderValueLength, max_headers=MaxHeaders, - timeout=Timeout, onrequest=OnRequest, onresponse=OnResponse}, 0). + onrequest=OnRequest, onresponse=OnResponse, + timeout=Timeout, until=until(Timeout)}, 0). + +-spec until(timeout()) -> non_neg_integer() | infinity. +until(infinity) -> + infinity; +until(Timeout) -> + {Me, S, Mi} = os:timestamp(), + Me * 1000000000 + S * 1000 + Mi div 1000 + Timeout. %% Request parsing. %% @@ -125,10 +134,24 @@ init(ListenerPid, Socket, Transport, Opts) -> %% right after the header parsing is finished and the code becomes %% more interesting past that point. +-spec recv(inet:socket(), module(), non_neg_integer() | infinity) + -> {ok, binary()} | {error, closed | timeout | atom()}. +recv(Socket, Transport, infinity) -> + Transport:recv(Socket, 0, infinity); +recv(Socket, Transport, Until) -> + {Me, S, Mi} = os:timestamp(), + Now = Me * 1000000000 + S * 1000 + Mi div 1000, + Timeout = Until - Now, + if Timeout < 0 -> + {error, timeout}; + true -> + Transport:recv(Socket, 0, Timeout) + end. + -spec wait_request(binary(), #state{}, non_neg_integer()) -> ok. wait_request(Buffer, State=#state{socket=Socket, transport=Transport, - timeout=Timeout}, ReqEmpty) -> - case Transport:recv(Socket, 0, Timeout) of + until=Until}, ReqEmpty) -> + case recv(Socket, Transport, Until) of {ok, Data} -> parse_request(<< Buffer/binary, Data/binary >>, State, ReqEmpty); {error, _} -> @@ -219,8 +242,8 @@ wait_header(_, State=#state{max_headers=MaxHeaders}, _, _, _, _, _, Headers) when length(Headers) >= MaxHeaders -> error_terminate(400, State); wait_header(Buffer, State=#state{socket=Socket, transport=Transport, - timeout=Timeout}, M, P, Q, F, V, H) -> - case Transport:recv(Socket, 0, Timeout) of + until=Until}, M, P, Q, F, V, H) -> + case recv(Socket, Transport, Until) of {ok, Data} -> parse_header(<< Buffer/binary, Data/binary >>, State, M, P, Q, F, V, H); @@ -291,9 +314,9 @@ parse_hd_name_ws(<< C, Rest/bits >>, S, M, P, Q, F, V, H, Name) -> end. wait_hd_before_value(Buffer, State=#state{ - socket=Socket, transport=Transport, timeout=Timeout}, + socket=Socket, transport=Transport, until=Until}, M, P, Q, F, V, H, N) -> - case Transport:recv(Socket, 0, Timeout) of + case recv(Socket, Transport, Until) of {ok, Data} -> parse_hd_before_value(<< Buffer/binary, Data/binary >>, State, M, P, Q, F, V, H, N); @@ -323,9 +346,9 @@ parse_hd_before_value(Buffer, State=#state{ %% to change the other arguments' position and trigger costy %% operations for no reasons. wait_hd_value(_, State=#state{ - socket=Socket, transport=Transport, timeout=Timeout}, + socket=Socket, transport=Transport, until=Until}, M, P, Q, F, V, H, N, SoFar) -> - case Transport:recv(Socket, 0, Timeout) of + case recv(Socket, Transport, Until) of {ok, Data} -> parse_hd_value(Data, State, M, P, Q, F, V, H, N, SoFar); {error, timeout} -> @@ -338,9 +361,9 @@ wait_hd_value(_, State=#state{ %% to check for multilines allows us to avoid a few tests in %% the critical path, but forces us to have a special function. wait_hd_value_nl(_, State=#state{ - socket=Socket, transport=Transport, timeout=Timeout}, + socket=Socket, transport=Transport, until=Until}, M, P, Q, F, V, Headers, Name, SoFar) -> - case Transport:recv(Socket, 0, Timeout) of + case recv(Socket, Transport, Until) of {ok, << C, Data/bits >>} when C =:= $\s; C =:= $\t -> parse_hd_value(Data, State, M, P, Q, F, V, Headers, Name, SoFar); {ok, Data} -> @@ -492,7 +515,8 @@ resume(State, Env, Tail, Module, Function, Args) -> end. -spec next_request(cowboy_req:req(), #state{}, any()) -> ok. -next_request(Req, State=#state{req_keepalive=Keepalive}, HandlerRes) -> +next_request(Req, State=#state{req_keepalive=Keepalive, timeout=Timeout}, + HandlerRes) -> cowboy_req:ensure_response(Req, 204), {BodyRes, [Buffer, Connection]} = case cowboy_req:skip_body(Req) of {ok, Req2} -> {ok, cowboy_req:get([buffer, connection], Req2)}; @@ -503,7 +527,7 @@ next_request(Req, State=#state{req_keepalive=Keepalive}, HandlerRes) -> case {HandlerRes, BodyRes, Connection} of {ok, ok, keepalive} -> ?MODULE:parse_request(Buffer, State#state{ - req_keepalive=Keepalive + 1}, 0); + req_keepalive=Keepalive + 1, until=until(Timeout)}, 0); _Closed -> terminate(State) end. -- cgit v1.2.3