Re: [Qemu-devel] Re: [RFC 0/7]: Add VNC connect/disconnect events

["Daniel P. Berrange" <berrange@redhat.com>]

On Tue, Jan 12, 2010 at 04:28:46PM -0600, Anthony Liguori wrote:
> On 01/12/2010 03:28 PM, Luiz Capitulino wrote:
> >On Mon, 11 Jan 2010 13:55:19 +0000
> >"Daniel P. Berrange"<berrange@redhat.com>  wrote:
> >
> >   
> >>So perhaps we should declare that the lifecycle is
> >>
> >>   -  CONNECT       (provide IP / port details)
> >>   -  AUTHENTICATED (provide IP / port details + authenticated ID details
> >>                     eg x509 dname, or SASL usernsmae)
> >>   -  DISCONNECT    (provide IP / port details)
> >>
> >>
> >>Obviously AUTHENTICATED may be optional if the client goes away
> >>immedaitely before trying auth. The AUTHENTICATED event probably
> >>also ought to allow for an indication of success vs failure so
> >>the app can see failed login attempts
> >>     
> >  I'm having an issue with the reporting of failure.
> >
> >  Turns out we can have a few error conditions on login and they are
> >auth mechanism dependent. Also, as I'm not familiar with the code,
> >it's not always easy to get the ID information on failures.
> >
> >  So, what is simple to do is to have an event called VNC_AUTHENTICATION,
> >it will have a 'authenticated' key which can be true or false. If it's true
> >authentication has been successful and ID information is available,
> >otherwise authentication has failed and only IP/port info is available.
> >
> >  Of course that CONNECT and DISCONNECT events are also provided.
> >   
> 
> It might be worthwhile looking at the events that gtk-vnc supports.
> 
> |	VNC_CONNECTED,    <-  client has connected
> 	VNC_INITIALIZED,<- initialized is completed
> 	VNC_DISCONNECTED,<- client has disconnected
> 	VNC_AUTH_FAILURE,  <- authorization has failed
> 	VNC_AUTH_UNSUPPORTED,<- authorization has failed (could not 
> 	negotiate an auth type)
> 
> Initialized can provide you all of the credential information.  I think 
> it's stronger than AUTHENTICATED because authentication alone does not 
> imply that a session is active.  Initialized tells a listener that at the 
> moment this is received, the VNC session is active.  If I'm a management 
> tool, that's the thing I'm likely interested in.

That is a good point, and if we have the three events at time of 'connect',
'initialized' and 'disconnected', then if a mgmt app sees a 'disconnect' but
no 'initialized' event, it knows the authentication was unsuccessful so do
not need an explicit flag for that.

Daniel
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