How to tell who disconnect ws?

[poor1017]

Hi @uNetworkingAB

Thank you for your project!

I want to know how to tell who disconnect ws in .close? Server or client?

In .close = [this](auto *ws, int code, std::string_view message) {
I can only get code, but the value 1000 can not identify the one who disconnect.

Thank you.

[uNetworkingAB]

Code 1006 is reserved for the library. It cannot be sent over the wire so getting that code in close handler means it originated from the library itself.

[poor1017]

Thank you for your reply!

It means if I got a 1000, then the connection is closed by client?

Thank you!

[uNetworkingAB]

Yes and you can also see this if you look at WireShark or similar tcpdump

[poor1017]

Thank you!

[poor1017]

Hi @uNetworkingAB

I got a 1006, maybe this is caused by fire wall or VPN.

How to prove this?(ws is closed by client side fire wall or VPN)

Thank you!

[poor1017]

Hi @uNetworkingAB

Here is the back trace for 1006:

#0  operator()<uWS::WebSocket<false, true, ai_speech::SocketData> > (
    __closure=0x7fffe8052010, ws=0x7fffe8052870, code=1006, message="")
    at /root/Workstation/web/tts-ws-service/src/websocket/server.cc:298
#1  0x00005555555ad360 in std::__invoke_impl<void, ai_speech::Batman::Work(int, std::shared_ptr<BS::thread_pool>, std::shared_ptr<ai_speech::UuidManager>)::<lambda(auto:39*, int, std::string_view)>&, uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> > >(std::__invoke_other, struct {...} &) (__f=...)
    at /usr/include/c++/10/bits/invoke.h:60
#2  0x00005555555acd4f in std::__invoke<ai_speech::Batman::Work(int, std::shared_ptr<BS::thread_pool>, std::shared_ptr<ai_speech::UuidManager>)::<lambda(auto:39*, int, std::string_view)>&, uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> > >(struct {...} &)
    (__fn=...) at /usr/include/c++/10/bits/invoke.h:95
#3  0x00005555555ac710 in std::invoke<ai_speech::Batman::Work(int, std::shared_ptr<BS::thread_pool>, std::shared_ptr<ai_speech::UuidManager>)::<lambda(auto:39*, int, std::string_view)>&, uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> > >(struct {...} &) (
    __fn=...) at /usr/include/c++/10/functional:88
#4  0x00005555555abfe0 in ofats::any_detail::handler_traits<void, uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> > >::small_handler<ai_speech::Batman::Work(int, std::shared_ptr<BS::thread_pool>, std::shared_ptr<ai_speech::UuidManager>)::<lambda(auto:39*, in--Type <RET> for more, q to quit, c to continue without paging--
t, std::string_view)> >::call(ofats::any_detail::storage &, uWS::WebSocket<false, true, ai_speech::SocketData> *, int, std::basic_string_view<char, std::char_traits<char> >) (s=..., args#0=0x7fffe8052870, args#1=1006, args#2="")
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/MoveOnlyFunction.h:133
#5  0x00005555555d7e46 in ofats::any_detail::any_invocable_impl<void, false, uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> > >::call (this=0x7fffe8052010, 
    args#0=0x7fffe8052870, args#1=1006, args#2="")
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/MoveOnlyFunction.h:247
#6  0x00005555555ca4a7 in ofats::any_invocable<void (uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >)>::operator()(uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >) (this=0x7fffe8052010, 
    args#0=0x7fffe8052870, args#1=1006, args#2="")
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/MoveOnlyFunction.h:354
#7  0x00005555555bf1c2 in uWS::TemplatedApp<false>::ws<ai_speech::SocketData>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, uWS::TemplatedApp<false>::WebSocketBehavior<ai_speech::SocketData>&&)::{lambda(uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >)#5}::operator()(uWS::WebSocket<false, true, ai_spe--Type <RET> for more, q to quit, c to continue without paging--
ech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >)
    (this=0x7fffe8052010, ws=0x7fffe8052870, code=1006, message="")
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/App.h:379
#8  0x000055555560c4b7 in std::__invoke_impl<void, uWS::TemplatedApp<false>::ws<ai_speech::SocketData>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, uWS::TemplatedApp<false>::WebSocketBehavior<ai_speech::SocketData>&&)::{lambda(uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >)#5}&, uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> > >(std::__invoke_other, uWS::TemplatedApp<false>::ws<ai_speech::SocketData>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, uWS::TemplatedApp<false>::WebSocketBehavior<ai_speech::SocketData>&&)::{lambda(uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >)#5}&, uWS::WebSocket<false, true, ai_speech::SocketData>*&&, int&&, std::basic_string_view<char, std::char_traits<char> >&&) (__f=...) at /usr/include/c++/10/bits/invoke.h:60
#9  0x00005555556063eb in std::__invoke<uWS::TemplatedApp<false>::ws<ai_speech::SocketData>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, uWS::TemplatedApp<false>::WebSocketBehavior<ai_speech::SocketData>&&)::{lambda(uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >)#5}&, uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> --Type <RET> for more, q to quit, c to continue without paging--
> >(uWS::TemplatedApp<false>::ws<ai_speech::SocketData>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, uWS::TemplatedApp<false>::WebSocketBehavior<ai_speech::SocketData>&&)::{lambda(uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >)#5}&, (std::__invoke_result&&)...) (__fn=...)
    at /usr/include/c++/10/bits/invoke.h:95
#10 0x00005555555fd53e in std::invoke<uWS::TemplatedApp<false>::ws<ai_speech::SocketData>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, uWS::TemplatedApp<false>::WebSocketBehavior<ai_speech::SocketData>&&)::{lambda(uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >)#5}&, uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> > >(uWS::TemplatedApp<false>::ws<ai_speech::SocketData>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, uWS::TemplatedApp<false>::WebSocketBehavior<ai_speech::SocketData>&&)::{lambda(uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >)#5}&, (std::invoke_result&&)...) (__fn=...)
    at /usr/include/c++/10/functional:88
#11 0x00005555555f3f62 in ofats::any_detail::handler_traits<void, uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> > >::large_handler<uWS::TemplatedApp<false>::ws<ai_speech::SocketData>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, uWS::TemplatedApp<false>::WebSocketBehavior<ai_speech::SocketData>&&)::{--Type <RET> for more, q to quit, c to continue without paging--
lambda(uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >)#5}>::call(ofats::any_detail::storage&, uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >) (s=..., args#0=0x7fffe8052870, args#1=1006, 
    args#2="")
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/MoveOnlyFunction.h:152
#12 0x00005555555d7e46 in ofats::any_detail::any_invocable_impl<void, false, uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> > >::call (this=0x7fffe8006a18, 
    args#0=0x7fffe8052870, args#1=1006, args#2="")
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/MoveOnlyFunction.h:247
#13 0x00005555555ca4a7 in ofats::any_invocable<void (uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >)>::operator()(uWS::WebSocket<false, true, ai_speech::SocketData>*, int, std::basic_string_view<char, std::char_traits<char> >) (this=0x7fffe8006a18, 
    args#0=0x7fffe8052870, args#1=1006, args#2="")
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/MoveOnlyFunction.h:354
#14 0x00005555555d7239 in uWS::WebSocketContext<false, true, ai_speech::SocketData>::init()::{lambda(auto:1*, int, void*)#1}::operator()<us_socket_t>(us_socket_t*, int, void*) const (this=0x0, s=0x7fffe8052870, code=0, reason=0x0)
--Type <RET> for more, q to quit, c to continue without paging--
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/WebSocketContext.h:273
#15 0x00005555555f28a0 in uWS::WebSocketContext<false, true, ai_speech::SocketData>::init()::{lambda(auto:1*, int, void*)#1}::_FUN<us_socket_t>(us_socket_t*, int, void*) ()
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/WebSocketContext.h:254
#16 0x0000555555690e8b in us_socket_close (ssl=0, s=0x7fffe8052870, code=0, 
    reason=0x0)
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/uSockets/src/socket.c:130
#17 0x00005555555d754b in uWS::WebSocketContext<false, true, ai_speech::SocketData>::init()::{lambda(auto:1*)#4}::operator()<us_socket_t>(us_socket_t*) const (
    this=0x0, s=0x7fffe8052870)
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/WebSocketContext.h:376
#18 0x00005555555f3a06 in uWS::WebSocketContext<false, true, ai_speech::SocketData>::init()::{lambda(auto:1*)#4}::_FUN<us_socket_t>(us_socket_t*) ()
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/WebSocketContext.h:373
#19 0x00005555556908c5 in us_internal_dispatch_ready_poll (p=0x7fffe8052870, 
    error=0, events=1)
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/uSockets--Type <RET> for more, q to quit, c to continue without paging--
/src/loop.c:343
#20 0x0000555555694c82 in poll_cb (p=0x7fffe80529a0, status=0, events=1)
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/uSockets/src/eventing/libuv.c:26
#21 0x00007ffff71cb1ed in uv.io_poll ()
   from /usr/local/lib/x86_64-linux-gnu/libuv.so.1
#22 0x00007ffff71b8516 in uv_run ()
   from /usr/local/lib/x86_64-linux-gnu/libuv.so.1
#23 0x0000555555695295 in us_loop_run (loop=0x7fffe8000b90)
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/uSockets/src/eventing/libuv.c:188
#24 0x00005555555b2472 in uWS::Loop::run (this=0x7fffe8000b90)
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/Loop.h:182
#25 0x00005555555b248f in uWS::run ()
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/Loop.h:199
#26 0x00005555555c02fd in uWS::TemplatedApp<false>::run (this=0x7fffe8005520)
    at /root/Workstation/web/tts-ws-service/src/third_party/uWebSockets/src/App.h:571

Specially, in WebSocketContext.h, I see:
"Handle FIN, HTTP does not support half-closed sockets, so simply close"
then, I got a 1006.

Is this a reasonable flow?

Looking forward for your reply.

Thank you!

[uNetworkingAB]

Ah, okay let me clarify:

1006

1006 is a reserved value and MUST NOT be set as a status code in a
Close control frame by an endpoint. It is designated for use in
applications expecting a status code to indicate that the
connection was closed abnormally, e.g., without sending or
receiving a Close control frame.

So in your case you get TCP FIN either from the OS or the client (no way to tell) and that causes the lib to emit 1006. Essentially you have a broken connection or a broken client in some way - the client should not send TCP FIN before a WebSocket Close frame. So in your case it can be anything. Hard to tell. But any reliable app shouldn't care - from its perspective you just need to handle it.

For debugging - now that's up to you.

[poor1017]

@uNetworkingAB

Yes, you're right.

The websocket framework used by the C++ client is mongoose. This C++ client does not wait for a response after excuting the close connection operation.

However, I tested with the python client (which calls the websockets package) and found that the python client will wait for the server's response after closing the connection.

So, I need NOT to care about this 1006 caused by mongoose client?

Looking for your reply!
Thank you!

[uNetworkingAB]

Probably more likely that you are using mongoose wrong - it looks like a well used client and very low level. So wouldn't be a shock if you just haven't got the shutdown procedure correct. In any case, a server should handle all cases correctly.

[poor1017]

Hi @uNetworkingAB

Do you mean I'm not using the server or the client correctly? But whether it is uwebsocket or mongoose, I use the example code for testing.

As you said, "In any case, a server should handle all cases correctly.", how can I handle this 1006 case correctly?

[uNetworkingAB]

I don't provide generic tutorials for websockets. You need to read up on whatever you need to handle your problems. I can only give you info regarding uws itself.