Fix loop handler keepalive race condition

Previously if a loop handler received the timeout message from a
previous request on the same connection the socket would be set to
{active, once} incorrectly - when a socket packet was already in the
message queue. This second packet would not be added to the buffer
before a Handler:info/3 call if a user message was in the message
queue before both socket packets.

src/cowboy_handler.erl

@@ -211,7 +211,7 @@ handler_loop(Req, State=#state{loop_buffer_size=NbBytes,
 			handler_after_loop(Req, State, Handler, HandlerState,
 				{normal, timeout});
 		{timeout, OlderTRef, ?MODULE} when is_reference(OlderTRef) ->
-			handler_before_loop(Req, State, Handler, HandlerState);
+			handler_loop(Req, State, Handler, HandlerState);
 		Message ->
 			%% We set the socket back to {active, false} mode in case
 			%% the handler is going to call recv. We also flush any
@@ -280,8 +280,14 @@ handler_after_loop(Req, State, Handler, HandlerState, Reason) ->
 -spec terminate_request(Req, #state{}, module(), any(),
 	{normal, timeout | shutdown} | {error, atom()}) ->
 	{ok, Req, cowboy_middleware:env()} when Req::cowboy_req:req().
-terminate_request(Req, #state{env=Env}, Handler, HandlerState, Reason) ->
+terminate_request(Req, #state{env=Env, loop_timeout_ref=TRef},
+		Handler, HandlerState, Reason) ->
 	HandlerRes = handler_terminate(Req, Handler, HandlerState, Reason),
+	_ = case TRef of
+		undefined -> ignore;
+		TRef -> erlang:cancel_timer(TRef)
+	end,
+	flush_timeouts(),
 	{ok, Req, [{result, HandlerRes}|Env]}.
 
 -spec handler_terminate(cowboy_req:req(), module(), any(),
@@ -299,3 +305,12 @@ handler_terminate(Req, Handler, HandlerState, Reason) ->
 			{terminate_reason, Reason}
 		])
 	end.
+
+-spec flush_timeouts() -> ok.
+flush_timeouts() ->
+	receive
+		{timeout, TRef, ?MODULE} when is_reference(TRef) ->
+			flush_timeouts()
+	after 0 ->
+		ok
+	end.

test/http_SUITE.erl

@@ -47,6 +47,7 @@
 -export([http10_hostless/1]).
 -export([keepalive_max/1]).
 -export([keepalive_nl/1]).
+-export([keepalive_stream_loop/1]).
 -export([multipart/1]).
 -export([nc_rand/1]).
 -export([nc_zero/1]).
@@ -132,6 +133,7 @@ groups() ->
 		http10_hostless,
 		keepalive_max,
 		keepalive_nl,
+		keepalive_stream_loop,
 		multipart,
 		nc_rand,
 		nc_zero,
@@ -407,6 +409,7 @@ init_dispatch(Config) ->
 			{"/rest_expires", rest_expires, []},
 			{"/rest_empty_resource", rest_empty_resource, []},
 			{"/loop_recv", http_loop_recv, []},
+			{"/loop_stream_recv", http_loop_stream_recv, []},
 			{"/loop_timeout", http_loop_timeout, []},
 			{"/", http_handler, []}
 		]}
@@ -725,6 +728,27 @@ keepalive_nl_loop(Client, URL, N) ->
 	ok = Transport:send(Socket, <<"\r\n">>), %% empty line
 	keepalive_nl_loop(Client3, URL, N - 1).
 
+keepalive_stream_loop(Config) ->
+	Client = ?config(client, Config),
+	Transport = ?config(transport, Config),
+	{ok, Client2} = cowboy_client:connect(
+		Transport, "localhost", ?config(port, Config), Client),
+	keepalive_stream_loop(Client2, 10).
+
+keepalive_stream_loop(Client, 0) ->
+	{error, closed} = cowboy_client:response(Client),
+	ok;
+keepalive_stream_loop(Client, N) ->
+	{ok, _} = cowboy_client:raw_request("POST /loop_stream_recv HTTP/1.1\r\n"
+		"Host: localhost\r\n"
+		"Connection: keepalive\r\n"
+		"Transfer-Encoding: chunked\r\n\r\n", Client),
+	_ = [{ok, _} = cowboy_client:raw_request(<<"4\r\n",Id:32,"\r\n">>, Client) ||
+		Id <- lists:seq(1, 250)],
+	{ok, _} = cowboy_client:raw_request(<<"0\r\n\r\n">>, Client),
+	{ok, 200, _, _} = cowboy_client:response(Client),
+	keepalive_stream_loop(Client, N-1).
+
 multipart(Config) ->
 	Client = ?config(client, Config),
 	Body = <<

test/http_SUITE_data/http_loop_stream_recv.erl

@@ -0,0 +1,41 @@
+%% Feel free to use, reuse and abuse the code in this file.
+
+-module(http_loop_stream_recv).
+-export([init/3]).
+-export([info/3]).
+-export([terminate/3]).
+
+init({_, http}, Req, _) ->
+	receive after 100 -> ok end,
+	self() ! stream,
+	{loop, Req, 1, 100}.
+
+info(stream, Req, Id) ->
+	case stream_next(Req) of
+		{ok, Id, Req2} ->
+			info(stream, Req2, Id+1);
+		{done, Req2} ->
+			{ok, Req3} = cowboy_req:reply(200, Req2),
+			{ok, Req3, Id}
+	end.
+
+terminate({normal, shutdown}, _, _) ->
+	ok.
+
+stream_next(Req) ->
+	stream_next(<<>>, Req).
+
+stream_next(Buffer, Req) ->
+	case cowboy_req:stream_body(Req) of
+		{ok, Packet, Req2} ->
+			case <<Buffer/binary, Packet/binary>> of
+				<<Id:32>> ->
+					{ok, Id, Req2};
+				Buffer2 when byte_size(Buffer2) < 4 ->
+					stream_next(Buffer2, Req2);
+				_InvalidBuffer ->
+					{error, invalid_chunk}
+			end;
+		Other ->
+			Other
+	end.