[Libwebsockets] SegFault for Websocket Server on Multiple Network Interface

Andy Green andy at warmcat.com
Sat Jul 8 12:29:59 CEST 2017



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" if 
people reached it by typing "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>> 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>>> 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.
> 
> 
> 
> 
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> 
> 



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