[Libwebsockets] SegFault for Websocket Server on Multiple Network Interface

Andy Green andy at warmcat.com
Tue Jul 11 11:32:33 CEST 2017



On 07/11/2017 05:25 PM, techi eth wrote:
> Hi,
> 
> Now i am able to run both the SSL server. Thanks for input.
> Could you please check attached file & let me know i am right in using 
> libwebsocket.

I don't have time to look at users' code.  Unless I feel I owe them for 
contributions, mowing my lawn or whatever.

> I would just like to know how to stop one server listening on vhost.

I assume you want to do it dynamically... the closest you can do easily 
is reject the connection in an early callback.

If you handle the http callback, you can also have it decide to respond 
with a redirect or a 500 page or whatever.

-Andy

> Thanks
> 
> On Mon, Jul 10, 2017 at 3:27 PM, techi eth <techieth at gmail.com 
> <mailto:techieth at gmail.com>> wrote:
> 
>     I have tried test as suggested by you now I don’t see segfault
>     anymore however I am not able to connect over server.
> 
>     Could you please check attached test code & detaild lws log & give
>     me hint what is wrong in code.
> 
>     Thanks for your input.
> 
>     On Sat, Jul 8, 2017 at 4:28 PM, Andy Green <andy at warmcat.com
>     <mailto:andy at warmcat.com>> wrote:
> 
> 
> 
>         On 07/08/2017 06:51 PM, techi eth wrote:
> 
>             Thanks for your input.
>             Having two context is not right or technically complex ?
> 
>             I was running two server without SSL mode from past 1 month
>             & it is working fine with two context.
> 
> 
>         Well... if you want two contexts you better fix your segfault. 
>         You're always free to do what you prefer (and I am free to
>         ignore your problems with it).
> 
>         From:
> 
>           - the POV SNI won't work sharing port 443, because the two
>         vhosts you created by having two contexts don't know about each
>         other
> 
>           - the POV you only have one set of fds in your process, the
>         context holds a lookup table for all of them
> 
>           - the POV you only need to service (ie, wait in poll or epoll)
>         for one set of fds, not have an idle context increase your
>         service latency on handling service for an active context every time
> 
>         ...you should have one context and two vhosts.
> 
>         That's literally what the vhosts are for.  It's easy to do, and
>         from lws perspective "the right thing".
> 
>         -Andy
> 
>             On Sat, Jul 8, 2017 at 3:59 PM, Andy Green <andy at warmcat.com
>             <mailto:andy at warmcat.com> <mailto:andy at warmcat.com
>             <mailto:andy at warmcat.com>>> wrote:
> 
> 
> 
>                  On 07/08/2017 06:12 PM, techi eth wrote:
> 
>                      It is with two context.One context each for one
>             network interface.
> 
> 
>                  I can suggest you don't do that.
> 
>                  Let's leave aside how I am supposed to guess what you
>             have done to
>                  service both.
> 
>                  The network interface to bind to is an attribute of the
>             vhost, not
>                  the context.
> 
>                  By default, for compatibility lws creates you one vhost
>             called
>                  "default" when you create the context.
> 
>                  If you set the option bit
>             LWS_SERVER_OPTION_EXPLICIT_VHOSTS when you
>                  create the context, creating the context does not
>             create any vhosts.
> 
>                  Instead you can use the same lws_context_creation_info
>             struct to
>                  create as many vhosts as you want and attach them to
>             the context
>                  yourself, using
> 
>                  LWS_EXTERN LWS_VISIBLE struct lws_vhost *
>                  lws_create_vhost(struct lws_context *context,
>                                    struct lws_context_creation_info *info);
> 
>                  You can mostly re-use your existing info struct
>             contents, changing
>                  .iface and .name to reflect the vhost hostname (ie,
>             "warmcat.com <http://warmcat.com>
>                  <http://warmcat.com>" if people reached it by typing
>             "warmcat.com <http://warmcat.com>
>                  <http://warmcat.com>" in their browser).  And changing the
>                  protocols, mounts etc according to what you want to be
>             available.
> 
>                  Both can be on port 443, lws will use SNI to match the
>             hostname the
>                  client had used to reach it to decide which vhost to
>             give them.
> 
>                  Each vhost can be told to use different SSL certs and
>             keys.  Lws
>                  will sort it out.
> 
>                  So... one context.  Two vhosts.
> 
>             https://warmcat.com and https://libwebsockets.org are two
>             vhosts on
>                  the same lws server using this method.
> 
>                  -Andy
> 
> 
> 
>                      On Sat, Jul 8, 2017 at 3:31 PM, Andy Green
>             <andy at warmcat.com <mailto:andy at warmcat.com>
>                      <mailto:andy at warmcat.com <mailto:andy at warmcat.com>>
>             <mailto:andy at warmcat.com <mailto:andy at warmcat.com>
>                      <mailto:andy at warmcat.com
>             <mailto:andy at warmcat.com>>>> wrote:
> 
> 
> 
>                           On 07/08/2017 05:44 PM, techi eth wrote:
> 
>                               OpenSSL version : 1.0.2h
> 
> 
>                           Supposedly the new OpenSSL init / destroy api
>             was introduced in
>                           1.0.2g, so it shouldn't be the problem.
> 
>                               I have tried libwebsocket from master & i
>             am getting same
>                               error.I will do the setup to get the trace.
>                               Do you confirm libwebsokcet works in above
>             mentioned
>                      use case ?
> 
> 
>                           I have no idea what your use case looks like.
> 
>                           Two contexts?  One context?
> 
>                               Is their any running sample then it would
>             be good for
>                      me to test ?
> 
> 
>                           Find out the line of source and reason for the
>             segfault.  "A
>                           segfault" by itself is like saying "an error"
>             or "a
>                      problem", it can
>                           mean anything.  Related to lws, related to
>             your code,
>                      something else...
> 
>                           -Andy
> 
> 
>                               On Sat, Jul 8, 2017 at 2:51 PM, Andy Green
>                      <andy at warmcat.com <mailto:andy at warmcat.com>
>             <mailto:andy at warmcat.com <mailto:andy at warmcat.com>>
>                               <mailto:andy at warmcat.com
>             <mailto:andy at warmcat.com> <mailto:andy at warmcat.com
>             <mailto:andy at warmcat.com>>>
>                      <mailto:andy at warmcat.com <mailto:andy at warmcat.com>
>             <mailto:andy at warmcat.com <mailto:andy at warmcat.com>>
> 
>                               <mailto:andy at warmcat.com
>             <mailto:andy at warmcat.com> <mailto:andy at warmcat.com
>             <mailto:andy at warmcat.com>>>>>
> 
>                      wrote:
> 
> 
> 
>                                    On 07/08/2017 05:16 PM, techi eth wrote:
> 
>                                        I was facing segfault over below
>             use case with
>                               libwebsocket.
> 
> 
>                                    It's usually of zero use to hear
>             there is a segfault
>                               without getting
>                                    a backtrace.
> 
>                                        I have two network interface & i
>             am trying to
>                      run SSL
>                               server on
>                                        port 443 for each network
>             interface.When i run
>                               independently
>                                        each server by separate programme
>             for each it
>                      works
>                               great but
>                                        when i run both in same programme
>             one is
>                      giving segfault.
> 
> 
>                                    Is this by any remote chance with two
>             contexts?
> 
>                                    What version is your OpenSSL?
> 
>                                    -Andy
> 
>                                        Last line i am getting is
>             (inserted SSL accept
>                      into
>                               fds, trying
>                                        SSL_accept).
> 
>                                        Note : Same programme when i run
>             without SSL
>                      it works
>                               great.
> 
> 
> 
> 
>                                       
>             _______________________________________________
>                                        Libwebsockets mailing list
>             Libwebsockets at ml.libwebsockets.org
>             <mailto:Libwebsockets at ml.libwebsockets.org>
>                      <mailto:Libwebsockets at ml.libwebsockets.org
>             <mailto:Libwebsockets at ml.libwebsockets.org>>
>                               <mailto:Libwebsockets at ml.libwebsockets.org
>             <mailto:Libwebsockets at ml.libwebsockets.org>
>                      <mailto:Libwebsockets at ml.libwebsockets.org
>             <mailto:Libwebsockets at ml.libwebsockets.org>>>
>                                       
>             <mailto:Libwebsockets at ml.libwebsockets.org
>             <mailto:Libwebsockets at ml.libwebsockets.org>
>                      <mailto:Libwebsockets at ml.libwebsockets.org
>             <mailto:Libwebsockets at ml.libwebsockets.org>>
>                               <mailto:Libwebsockets at ml.libwebsockets.org
>             <mailto:Libwebsockets at ml.libwebsockets.org>
>                      <mailto:Libwebsockets at ml.libwebsockets.org
>             <mailto:Libwebsockets at ml.libwebsockets.org>>>>
>             https://libwebsockets.org/mailman/listinfo/libwebsockets
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets>
>                     
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets>>
>                                     
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets>
>                     
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets>>>
>                                                     
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets>
>                     
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets>>
>                                     
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets>
>                     
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets
>             <https://libwebsockets.org/mailman/listinfo/libwebsockets>>>>
> 
> 
> 
> 
> 
> 



More information about the Libwebsockets mailing list