WIP client close WT session

src/cowboy_http3.erl

@@ -258,6 +258,19 @@ parse1(State, Stream=#stream{id=SessionID, status=webtransport_session}, Data, I
 		{ok, drain_wt_session, Rest} ->
 			webtransport_event(State, SessionID, close_initiated),
 			parse1(State, Stream, Rest, IsFin);
+		{ok, {close_wt_session, AppCode, AppMsg}, Rest} ->
+			%% This event will be handled specially and lead
+			%% to the termination of the session process.
+			webtransport_event(State, SessionID, {closed, AppCode, AppMsg}),
+			%% Shutdown the CONNECT stream immediately.
+			%% @todo Do this in webtransport_terminate_session?
+			ConnectStreamRef = get({quicer_stream, SessionID}),
+			_ = quicer:shutdown_stream(ConnectStreamRef),
+			%% @todo Will we receive a {stream_closed,...} after that?
+			%% If any data is received past that point this is an error.
+			%% @todo Don't crash, error out properly.
+			<<>> = Rest,
+			loop(webtransport_terminate_session(State, Stream));
 		%% Ignore unknown/unhandled capsules.
 		{ok, _, Rest} ->
 			parse1(State, Stream, Rest, IsFin);
@@ -896,8 +909,13 @@ webtransport_event(State, SessionID, Event) ->
 	ok.
 
 webtransport_commands(State, SessionID, Commands) ->
-	Session = #stream{status=webtransport_session} = stream_get(State, SessionID),
-	wt_commands(State, Session, Commands).
+	case stream_get(State, SessionID) of
+		Session = #stream{status=webtransport_session} ->
+			wt_commands(State, Session, Commands);
+		%% The stream has been terminated, ignore pending commands.
+		error ->
+			State
+	end.
 
 wt_commands(State, _, []) ->
 	State;
@@ -979,6 +997,30 @@ wt_commands(State=#state{conn=Conn}, Session=#stream{id=SessionID}, [Cmd|Tail])
 		%% @todo Handle errors.
 	end.
 
+webtransport_terminate_session(State=#state{conn=Conn, http3_machine=HTTP3Machine0,
+		streams=Streams0, lingering_streams=Lingering0}, #stream{id=SessionID}) ->
+	%% Reset/abort the WT streams.
+	Streams = maps:filtermap(fun
+		(StreamID, #stream{status={webtransport_stream, StreamSessionID, _}})
+				when SessionID =:= StreamSessionID ->
+			cowboy_quicer:shutdown_stream(Conn, StreamID,
+				both, cow_http3:error_to_code(webtransport_session_gone)),
+			false;
+		(_, _) ->
+			true
+	end, Streams0),
+	%% Keep the streams in lingering state.
+	%% We only keep up to 100 streams in this state. @todo Make it configurable?
+	Terminated = maps:keys(Streams0) -- maps:keys(Streams),
+	Lingering = lists:sublist(Terminated ++ Lingering0, 100),
+	%% Update the HTTP3 state machine.
+	HTTP3Machine = cow_http3_machine:close_webtransport_session(SessionID, HTTP3Machine0),
+	State#state{
+		http3_machine=HTTP3Machine,
+		streams=Streams,
+		lingering_streams=Lingering
+	}.
+
 reset_stream(State0=#state{conn=Conn, http3_machine=HTTP3Machine0},
 		Stream=#stream{id=StreamID}, Error) ->
 	Reason = case Error of
@@ -1048,6 +1090,7 @@ terminate_stream(State=#state{streams=Streams0, children=Children0},
 	stream_linger(State#state{streams=Streams, children=Children}, StreamID).
 
 %% We must dereference the stream state when WebTransport is in use.
+%% @todo Do this here or in cowboy_webtransport?
 terminate_stream_handler(State, StreamID, Reason,
 		{cowboy_webtransport, #{stream_state := StreamState}}) ->
 	terminate_stream_handler(State, StreamID, Reason, StreamState);
@@ -1151,6 +1194,18 @@ stream_new(State=#state{http3_machine=HTTP3Machine0, streams=Streams},
 	Stream = #stream{id=StreamID, status=Status},
 	State#state{http3_machine=HTTP3Machine, streams=Streams#{StreamID => Stream}}.
 
+%% @todo Special handling WT session?
+%%
+%% cowboy_stream:init as normal
+%% upgrade/switch_protocol to cowboy_webtransport
+%% - WT handler can stop via command
+%% - WT process can crash/exit
+%% - Client can send capsule on CONNECT stream to close
+%% - Client can terminate CONNECT stream (gracefully/abruptly)
+%% - Server can close the connection (gracefully/abruptly)
+%% - Client can close the connection (gracefully/abruptly)
+%%   Note that GOAWAY must not stop the WT session
+
 %% Stream closed message for a local (write-only) unidi stream.
 stream_closed(State=#state{local_control_id=StreamID}, StreamID, _) ->
 	stream_closed1(State, StreamID);

src/cowboy_quicer.erl

@@ -179,6 +179,7 @@ shutdown_stream(_Conn, StreamID, Dir, ErrorCode) ->
 	_ = quicer:shutdown_stream(StreamRef, shutdown_flag(Dir), ErrorCode, infinity),
 	ok.
 
+%% @todo Are these flags correct for what we want?
 shutdown_flag(both) -> ?QUIC_STREAM_SHUTDOWN_FLAG_ABORT;
 shutdown_flag(receiving) -> ?QUIC_STREAM_SHUTDOWN_FLAG_ABORT_RECEIVE.
 

src/cowboy_webtransport.erl

@@ -27,7 +27,6 @@
 
 -export([upgrade/4]).
 -export([upgrade/5]).
--export([terminate/3]).
 
 -type opts() :: #{
 	%% @todo
@@ -127,6 +126,8 @@ loop(State=#state{parent=Parent%, timeout_ref=TRef
 	receive
 		%% @todo Parent to filter messages? Nothing?
 		%% @todo Can there be groups of events?
+		{'$webtransport_event', Event={closed, _, _}} ->
+			terminate(State, HandlerState, Event);
 		{'$webtransport_event', Event} ->
 			handler_call(State, HandlerState, webtransport_handle, Event);
 		%% Timeouts.
@@ -213,22 +214,16 @@ commands([Command={close, _, _}|Tail], State, _, Acc) ->
 %% @todo set_options (to increase number of streams? data amounts? or a flow command?)
 %% @todo shutdown_reason if useful.
 
-terminate(State=#state{req=Req}, HandlerState, Reason) ->
-		%cowboy_stream:terminate(StreamID, Reason, StreamState)
-%% @todo This terminate is at the connection level.
-%	handler_terminate(State, HandlerState, Reason),
+terminate(State, HandlerState, Reason) ->
+	handler_terminate(State, HandlerState, Reason),
 %	case Shutdown of
 %		normal -> exit(normal);
 %		_ -> exit({shutdown, Shutdown})
 %	end.
-%	exit(normal).
-%handler_terminate(#state{handler=Handler, req=Req}, HandlerState, Reason) ->
-%	cowboy_handler:terminate(Reason, Req, HandlerState, Handler).
-	%% @todo I think we must call terminate ourselves.
-	{ok, Req, Reason}.
-
-
+	exit(normal).
 
+handler_terminate(#state{handler=Handler, req=Req}, HandlerState, Reason) ->
+	cowboy_handler:terminate(Reason, Req, HandlerState, Handler).
 
 
 

test/draft_h3_webtransport_SUITE.erl

@@ -431,7 +431,30 @@ drain_wt_session_continue_server(Config) ->
 
 %% @todo connect_stream_closed_cleanly_client
 %% @todo connect_stream_closed_abruptly_client
-%% @todo close_wt_session_client
+
+close_wt_session_client(Config) ->
+	doc("The WT client can close a single session. (draft_webtrans_http3 4.6)"),
+	%% Connect to the WebTransport server.
+	#{
+		conn := Conn,
+		connect_stream_ref := ConnectStreamRef,
+		session_id := SessionID
+	} = do_webtransport_connect(Config),
+	%% Send the CLOSE_WEBTRANSPORT_SESSION capsule on the CONNECT stream.
+	{ok, _} = quicer:send(ConnectStreamRef,
+		cow_capsule:close_wt_session(0, <<>>),
+		?QUIC_SEND_FLAG_FIN),
+	%% Normally we should also stop reading but in order to detect
+	%% that the server stops the stream we must not otherwise the
+	%% stream will be de facto closed on our end.
+	%%
+	%% The recipient must close or reset the stream in response.
+	receive
+		{quic, stream_closed, ConnectStreamRef, _} ->
+			ok
+	after 1000 ->
+		error({timeout, waiting_for_stream_closed})
+	end.
 
 close_wt_session_server(Config) ->
 	doc("The WT server can close a single session. (draft_webtrans_http3 4.6)"),

test/handlers/wt_echo_h.erl

@@ -7,6 +7,7 @@
 -export([init/2]).
 -export([webtransport_handle/2]).
 -export([webtransport_info/2]).
+-export([terminate/3]).
 
 init(Req0, _) ->
 	Req = case cowboy_req:parse_header(<<"wt-available-protocols">>, Req0) of
@@ -83,3 +84,7 @@ webtransport_handle(Event, Streams) ->
 webtransport_info({try_again, Event}, Streams) ->
 	ct:pal("try_again ~p", [Event]),
 	webtransport_handle(Event, Streams).
+
+terminate(Reason, Req, State) ->
+	ct:pal("terminate ~p ~p ~p", [Reason, Req, State]),
+	ok.