Add a cowboy_http_req:upgrade_reply/3 function and use it for websockets

This function doesn't try to add any additional header besides the
Connection: Upgrade header. It also doesn't accept a body.

It should be used for the intermediate reply to an upgrade process,
before the real reply is sent (if any, for example when using TLS).

src/cowboy_http_req.erl

@@ -38,7 +38,8 @@
 
 -export([
 	reply/2, reply/3, reply/4,
-	chunked_reply/2, chunked_reply/3, chunk/2
+	chunked_reply/2, chunked_reply/3, chunk/2,
+	upgrade_reply/3
 ]). %% Response API.
 
 -export([
@@ -374,6 +375,17 @@ 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">>]).
 
+%% @doc Send an upgrade reply.
+-spec upgrade_reply(http_status(), http_headers(), #http_req{})
+	-> {ok, #http_req{}}.
+upgrade_reply(Status, Headers, Req=#http_req{socket=Socket, transport=Transport,
+		resp_state=waiting}) ->
+	Head = response_head(Status, Headers, [
+		{<<"Connection">>, <<"Upgrade">>}
+	]),
+	Transport:send(Socket, Head),
+	{ok, Req#http_req{resp_state=done}}.
+
 %% Misc API.
 
 %% @doc Compact the request data by removing all non-system information.

src/cowboy_http_websocket.erl

@@ -170,13 +170,12 @@ websocket_handshake(State=#state{version=0, origin=Origin,
 		transport=Transport, raw_host=Host, port=Port,
 		raw_path=Path, raw_qs=QS}, HandlerState) ->
 	Location = hixie76_location(Transport:name(), Host, Port, Path, QS),
-	{ok, Req2} = cowboy_http_req:reply(
+	{ok, Req2} = cowboy_http_req:upgrade_reply(
 		<<"101 WebSocket Protocol Handshake">>,
-		[{<<"Connection">>, <<"Upgrade">>},
-		 {<<"Upgrade">>, <<"WebSocket">>},
+		[{<<"Upgrade">>, <<"WebSocket">>},
 		 {<<"Sec-Websocket-Location">>, Location},
 		 {<<"Sec-Websocket-Origin">>, Origin}],
-		[], Req#http_req{resp_state=waiting}),
+		Req#http_req{resp_state=waiting}),
 	%% We replied with a proper response. Proxies should be happy enough,
 	%% we can now read the 8 last bytes of the challenge keys and send
 	%% the challenge response directly to the socket.
@@ -187,12 +186,11 @@ websocket_handshake(State=#state{version=0, origin=Origin,
 		Req3, HandlerState, <<>>);
 websocket_handshake(State=#state{challenge=Challenge},
 		Req=#http_req{transport=Transport}, HandlerState) ->
-	{ok, Req2} = cowboy_http_req:reply(
-		<<"101 Switching Protocols">>,
-		[{<<"Connection">>, <<"Upgrade">>},
-		 {<<"Upgrade">>, <<"websocket">>},
+	{ok, Req2} = cowboy_http_req:upgrade_reply(
+		101,
+		[{<<"Upgrade">>, <<"websocket">>},
 		 {<<"Sec-Websocket-Accept">>, Challenge}],
-		[], Req#http_req{resp_state=waiting}),
+		Req#http_req{resp_state=waiting}),
 	handler_before_loop(State#state{messages=Transport:messages()},
 		Req2, HandlerState, <<>>).