[Libwebsockets] External poll and listener usage

Vitaliy Aleksandrov vitalik.voip at gmail.com
Fri Feb 10 09:41:59 CET 2017


Thanks for the detailed explanation. Will stick to master branch and its
CONTEXT_PORT_NO_LISTEN_SERVER.

On Thu, Feb 9, 2017 at 7:21 PM, Andy Green <andy at warmcat.com> wrote:

>
>
> On February 9, 2017 11:54:10 PM GMT+08:00, Vitaliy Aleksandrov <
> vitalik.voip at gmail.com> wrote:
> >Hello, libwesockets community.
> >
> >I'm planning to use libwesockets to add WS support to an existing
> >server
> >application with its existing event loop (poll) and listening socket.
> >External poll integration looks quite simple and test server provided
> >with
> >sources is a good example. As I've already mentioned my server accepts
> >clients connections itself.
> >*lws_adopt_socket()* does the job and lws successfully adopts provided
> >fd.
>
> Great.
>
> >Since I don't use lws internal listener I wanted to turn it off and
> >found
> >two lws context options: CONTEXT_PORT_NO_LISTEN
> >and CONTEXT_PORT_NO_LISTEN_SERVER (not in 2.1 stable).
>
> Right.
>
> >Documentation about mentioned options is not clear for me. I
> >tried CONTEXT_PORT_NO_LISTEN_SERVER with the latest master branch
> >and CONTEXT_PORT_NO_LISTEN with the 2.1 stable and in both cases my
> >test
> >HTTP (not ws yet) server didn't start internal listener and took
> >provided
> >client's fd without any problems. So what is the real difference
> >between
> >them for a WS server?
>
> As you saw CONTEXT_PORT_NO_LISTEN used to be the only constant to kill
> listening, it also directly implied you want to kill listening because you
> are being a client.
>
> With the adoption apis though, that implication about client mode for the
> context is no longer necessarily true.  As in your case, you may have
> external listening and then an adoption step, you want to suppress internal
> listening for that reason and you are being a server.
>
> So CONTEXT_PORT_NO_LISTEN was left alone for backwards compatibility, and
> CONTEXT_PORT_NO_LISTEN_SERVER added that shares the listen suppression, but
> does not trigger the other client-related changes.  If you got to the point
> of adopting ssl-wrapped connections, you would trip over these
> client-related behaviour changes otherwise.
>
> So CONTEXT_PORT_NO_LISTEN_SERVER is the one you want for your case.
>
> -Andy
>
> >Best regards,
> >Vitaliy
>
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