Add chunked reply support.

Send the status line and headers using
cowboy_http_req:chunked_reply/3, and
individual chunks with cowboy_http_req:chunk/2.

include/http.hrl

@@ -65,5 +65,5 @@
 	buffer     = <<>>      :: binary(),
 
 	%% Response.
-	resp_state = locked    :: locked | waiting | done
+	resp_state = locked    :: locked | waiting | chunks | done
 }).

src/cowboy_http_protocol.erl

@@ -198,9 +198,9 @@ handler_terminate(HandlerState, Req=#http_req{buffer=Buffer},
 	HandlerRes = (catch Handler:terminate(
 		Req#http_req{resp_state=locked}, HandlerState)),
 	BodyRes = ensure_body_processed(Req),
-	ensure_response(Req, State),
-	case {HandlerRes, BodyRes, State#state.connection} of
-		{ok, ok, keepalive} ->
+	RespRes = ensure_response(Req, State),
+	case {HandlerRes, BodyRes, RespRes, State#state.connection} of
+		{ok, ok, ok, keepalive} ->
 			?MODULE:parse_request(State#state{buffer=Buffer});
 		_Closed ->
 			terminate(State)
@@ -223,7 +223,12 @@ ensure_response(#http_req{resp_state=done}, _State) ->
 %% No response has been sent but everything apparently went fine.
 %% Reply with 204 No Content to indicate this.
 ensure_response(#http_req{resp_state=waiting}, State) ->
-	error_response(204, State).
+	error_response(204, State);
+%% Close the chunked reply.
+ensure_response(#http_req{socket=Socket, transport=Transport,
+		resp_state=chunks}, _State) ->
+	Transport:send(Socket, <<"0\r\n\r\n">>),
+	close.
 
 -spec error_response(Code::http_status(), State::#state{}) -> ok.
 error_response(Code, #state{socket=Socket,

src/cowboy_http_req.erl

@@ -30,7 +30,7 @@
 ]). %% Request Body API.
 
 -export([
-	reply/4
+	reply/4, chunked_reply/3, chunk/2
 ]). %% Response API.
 
 -include("include/http.hrl").
@@ -192,6 +192,22 @@ reply(Code, Headers, Body, Req=#http_req{socket=Socket,
 	Transport:send(Socket, [Head, Body]),
 	{ok, Req#http_req{resp_state=done}}.
 
+-spec chunked_reply(Code::http_status(), Headers::http_headers(),
+	Req::#http_req{}) -> {ok, Req::#http_req{}}.
+chunked_reply(Code, Headers, Req=#http_req{socket=Socket, transport=Transport,
+		resp_state=waiting}) ->
+	Head = response_head(Code, Headers, [
+		{<<"Connection">>, <<"close">>},
+		{<<"Transfer-Encoding">>, <<"chunked">>}
+	]),
+	Transport:send(Socket, Head),
+	{ok, Req#http_req{resp_state=chunks}}.
+
+-spec chunk(Data::iodata(), Req::#http_req{}) -> ok.
+chunk(Data, #http_req{socket=Socket, transport=Transport, resp_state=chunks}) ->
+	Transport:send(Socket, [integer_to_list(iolist_size(Data), 16),
+		<<"\r\n">>, Data, <<"\r\n">>]).
+
 %% Internal.
 
 -spec parse_qs(Qs::binary()) -> list({Name::binary(), Value::binary() | true}).

test/chunked_handler.erl

@@ -0,0 +1,17 @@
+%% Feel free to use, reuse and abuse the code in this file.
+
+-module(chunked_handler).
+-behaviour(cowboy_http_handler).
+-export([init/3, handle/2, terminate/2]).
+
+init({_Transport, http}, Req, _Opts) ->
+	{ok, Req, undefined}.
+
+handle(Req, State) ->
+	{ok, Req2} = cowboy_http_req:chunked_reply(200, [], Req),
+	cowboy_http_req:chunk("chunked_handler\r\n", Req2),
+	cowboy_http_req:chunk("works fine!", Req2),
+	{ok, Req2, State}.
+
+terminate(_Req, _State) ->
+	ok.

test/http_SUITE.erl

@@ -18,7 +18,7 @@
 
 -export([all/0, groups/0, init_per_suite/1, end_per_suite/1,
 	init_per_group/2, end_per_group/2]). %% ct.
--export([headers_dupe/1, headers_huge/1,
+-export([chunked_response/1, headers_dupe/1, headers_huge/1,
 	nc_rand/1, pipeline/1, raw/1]). %% http.
 -export([http_200/1, http_404/1, websocket/1]). %% http and https.
 
@@ -29,7 +29,7 @@ all() ->
 
 groups() ->
 	BaseTests = [http_200, http_404],
-	[{http, [], [headers_dupe, headers_huge,
+	[{http, [], [chunked_response, headers_dupe, headers_huge,
 		nc_rand, pipeline, raw, websocket] ++ BaseTests},
 	{https, [], BaseTests}].
 
@@ -79,6 +79,7 @@ end_per_group(https, _Config) ->
 init_http_dispatch() ->
 	[
 		{[<<"localhost">>], [
+			{[<<"chunked_response">>], chunked_handler, []},
 			{[<<"websocket">>], websocket_handler, []},
 			{[<<"headers">>, <<"dupe">>], http_handler,
 				[{headers, [{<<"Connection">>, <<"close">>}]}]},
@@ -91,6 +92,10 @@ init_https_dispatch() ->
 
 %% http.
 
+chunked_response(Config) ->
+	{ok, {{"HTTP/1.1", 200, "OK"}, _Headers, "chunked_handler\r\nworks fine!"}} =
+		httpc:request(build_url("/chunked_response", Config)).
+
 headers_dupe(Config) ->
 	{port, Port} = lists:keyfind(port, 1, Config),
 	{ok, Socket} = gen_tcp:connect("localhost", Port,