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

[Daniel-Constantin Mierla]

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

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