Re: [Xen-devel] [PATCH][Take 3] VNC authentification

[Masami Watanabe <masami.watanabe@xxxxxxxxxxxxxx>]

Hi all,

My understanding of main_loop of vl.c was insufficient. 
I have improved the point to have set the handler doubly.
The protocol of protocol 3.3 and (UltraVNC's ?)3.4 did not actually
need the response of the authentification type from the client.
Therefore, protocol_authtype operated without being called.

I will post the take 4 patch after this.

The patch has limited  RFB protocol to 3.3 and 3.4.
I also think that it should support 3.8 without being support 3.3 in
the future.

However, Leaving like non authetification is not good.
You will think the patch to be provisional action till then.

Another.
ill the RFB protocol still keep evolving in the future?


Best regards,
Watanabe


On Tue, 03 Oct 2006 13:49:37 -0500, Anthony Liguori wrote:
> Daniel P. Berrange wrote:
> > On Tue, Oct 03, 2006 at 12:56:31PM -0500, Anthony Liguori wrote:
> >   
> >> Masami Watanabe wrote:
> >>     
> >>> +static int vnc_auth(VncState *vs)
> >>> +{
> >>> +    extern char vncpasswd[64];
> >>> +    extern unsigned char challenge[AUTHCHALLENGESIZE];
> >>> +
> >>> +    if (*vncpasswd == '\0') {
> >>> + /* AuthType is None */
> >>> + vnc_write_u32(vs, 1);
> >>> + vnc_flush(vs);
> >>> + vnc_read_when(vs, protocol_client_init, 1);
> >>> +    } else {
> >>> + /* AuthType is VncAuth */
> >>> + vnc_write_u32(vs, 2);
> >>> + vnc_flush(vs);
> >>> +
> >>> + /* Read AuthType */
> >>> + vnc_read_when(vs, protocol_authtype, 1);
> >>>  
> >>>       
> >> As I mentioned before, you cannot have to vnc_read_when()'s execution 
> >> path without returning the the mainloop.
> >>
> >> protocol_authtype() cannot possibly be invoked.  If the code is working 
> >> now, it's pure luck.
> >>     
> >
> > Yeah, the impl of protocol_authtype() in there is a no-op too - it should
> > be rejecting auth types which aren't supported, even if it was being 
> > invoked.
> > With the code as it is, protocol_authtype never runs & the server starts
> > doing VNCAuth regardless of what the client says it wants to do, which is
> > clearly not correct.
> >   
> 
> Another thing to keep in mind, is that the reason I did 3.3 instead of 
> 3.8 is that I knew there was only one auth type we would be supporting.  
> If we do support multiple auth types, we really ought to move to using 
> the 3.8 protocol since that provides a negotiation mechanism.
> 
> Regards,
> 
> Anthony Liguori
> 
> > Dan.
> >   
> 


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