[Libwebsockets] v2.0 crashes

Andrejs Hanins andrejs.hanins at ubnt.com
Fri May 13 13:25:43 CEST 2016



On 05/13/2016 01:22 PM, Andy Green wrote:
>
>
> On 05/13/2016 05:36 PM, Andrejs Hanins wrote:
>> Andy,
>>
>> On 05/12/2016 10:01 PM, Andy Green wrote:
>>>> Well, still bad. With current master I can establish client connection
>>>> only once. After it is disconnected I try to establish it again, but
>>>> never get any callback back.
>>>> I will investigate tomorrow in more details. Just to let you know - it
>>>> was absolutely rock solid with 1.7.5, never had any single problem with
>>>> LWS.
>>> Well, v2.0 test client has no problems making multiple connections.
>>>
>>> V2.0 is v1.7 with some patches.
>>>
>>> There's nothing I can do about 'bad', 'crash', except wonder about the code I can't see.
>> I figured it out why reconnects didn't work for me - I was passing two protocols for vhost creation,
>> as a result failed connection attempts were notified by LWS_CALLBACK_CLIENT_CONNECTION_ERROR
>> for the _first_ protocol (that is Http, array index 0), but my code was expecting to get all WS-related
>> callbacks from the _second_ protocol (array index 1). After I removed Http protocol from the vhost
>> creation everything started to work fine and no more crashes. So patch is good, thank you Andy!
>
> Good... there are some things that happen before the protocol is negotiated with the ws or http server.  Since you may have multiple ws protocols listed, there's no way before negotiation to make a sensible choice, so they just go on the first one.  Which at least one way or the other, can always be counted on to be there; there's no requirement to have any second protocol.
>
> Likewise some things are global.
>
>> But I noticed, that SSL_library_init is called twice - first from lws_context_init_ssl_library when I create a
>> ctx, then from lws_context_init_client_ssl when I call lws_init_vhost_client_ssl.
>
> Yes... it's not right.
>
>> If I remove LWS_SERVER_OPTION_DO_SSL_GLOBAL_INIT from ctx creation, then something breaks
>> internally, incoming/outgoing connections don't work any more and I get the following logs:
>
> No you want that.
>
>> LWS:  forbidding on uri sanitation
>> LWS: error on reading from skt : 131
>> LWS: SSL connect error 336031996: error:140770FC:lib(20):func(119):reason(252)
>>
>> So it looks like in order for the SSL to work it needs to be initialized in ctx, but then it is
>> initialized again due to lws_init_vhost_client_ssl. It doesn't look to be causing any
>> problems, but initializing SSL more than once doesn't look right to me.
>
> Yes it's not needed any more, since after 1.7 the SSL global init got cleaned up and always occurs at context creation time now.
>
> I pushed a patch on master removing the duplicated init from lws_context_init_client_ssl().
The patch works fine, thanks.

Still, each creation of ctx calls SSL_library_init. In my code I need to recreate the ctx when network configuration
changes, so SSL_library_init still might be called several times for one process. Do you think this is a problem from SSL library design
point of view?

Are you going to release 2.0.2 soon? If not, I need to stick to some master branch git hash.
>
> -Andy
>
>>> -Andy
>>>
>>




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