[sr-dev] WebSocket (RFC 6455) and draft-ibc-sipcore-sip-websocket on Kamailio

[Peter Dunkley]

Hi,

One of the things I need to be able to do from the WebSocket module is to
cleanly close TCP/TLS connections when I receive/send a Close() frame.

Is there an easy way to do this from a Kamailio module?

Regards,

Peter

> Hello,
>
> On 6/15/12 11:33 AM, Peter Dunkley wrote:
>> Hi Daniel,
>>
>> Thanks for the encouragement.
>>
>> I could do with a guide here.  I think there is only a few hours work
>> left to finish off the handshake and basic module stuff. After that I
>> think the next step needs to be:
>> - Getting the module to register with core to receive WS frames (which
>> may arrive over TCP or TLS)
>> - Giving the module/core the ability to "change" the connection the
>> handshake came in on from SIP/HTTP to WS (so that new messages go
>> straight to the handler in the new module)
>> - In the module adding handling for Close, Ping, and Pong
>> - To do the handling for Ping the module needs to be able to send WS
>> frames out (over TCP or TLS)
>> - In the module "printing" received binary and text frames (which will
>> contain SIP requests)
>>
>> The bits I need help with here the most are the registering the module
>> to receive the WS frames and sending WS frames (over TCP or TLS), and
>> adding the ability for the module/core to "upgrade" the connection
>> from SIP/HTTP to WS after successful handshake.
>
> I think of doing it like:
> - when WS handshake is completed, mark the tcp connection as being WS
> from the module (a new flag or so)
> - then in the TCP read function (iirc, tcp_read.{c,h} in core) if the
> connection is marked WS, then execute a callback that is registered by
> the module
> - this is pretty much how http and msrp work, but there the detection is
> on the content, not on the socket type. HTTP is using so called no-SIP
> content callback, while MSRP is using a dedicated core event
>
> For sending, using tcp_send(...) (looking at msrp module will give the
> right directions) should do it -- the function takes the tcp connection
> as parameter as well as the outgoing buffer and encrypts the content if
> actually is over TLS. The send operation may become transparent as soon
> as the algorithm for finding the connection can grep on WS/WSS protocol.
>
> Cheers,
> Daniel
>
>>
> --
> Daniel-Constantin Mierla - http://www.asipto.com
> http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
> Kamailio Advanced Training, Seattle, USA, Sep 23-26, 2012 -
> http://asipto.com/u/katu
> Kamailio Practical Workshop, Netherlands, Sep 10-12, 2012 -
> http://asipto.com/u/kpw
>
>


-- 
Peter Dunkley
Technical Director
Crocodile RCS Ltd