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https://issues.apache.org/jira/browse/GUACAMOLE-1196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17906232#comment-17906232
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Nick Couchman commented on GUACAMOLE-1196:
------------------------------------------
Okay, I think I've found how this works in clients that work without causing
the crash - there's actually an encoding flag that is exchanged between client
and server that sets this capability [1]:
{quote}
#define rfbEncodingNewFBSize 0xFFFFFF21
{quote}
And possibly one other one, though it's unclear to me at the moment what the
difference between the two is:
{quote}
#define rfbEncodingExtDesktopSize 0xFFFFFECC
{quote}
The client sends both of these through, which I see in my packet capture from
guacd to the VNC server. What I suspect is happening is that, somewhere along
the way, the server is or should return a message with the encodings that it
agrees are valid, which may not include the new FB size. I'm wondering, at this
point, if we're forcibly sending the resize command before libvncclient can
receive that initial update from the server indicating what features it will
allow, and this is causing the server to drop the connection? I would think the
exchange of handling actual encodings would be done internally within
libvncclient, and wouldn't be something that a user of that API like guacd
would have to worry about.
> Add auto resize to VNC sessions
> -------------------------------
>
> Key: GUACAMOLE-1196
> URL: https://issues.apache.org/jira/browse/GUACAMOLE-1196
> Project: Guacamole
> Issue Type: Improvement
> Components: Documentation, VNC
> Reporter: Markus Bonet
> Assignee: Nick Couchman
> Priority: Minor
> Fix For: 1.6.0
>
>
> As discussed on the mailing list:
> {quote}
> I'm running a TigerVNC session on the server where Guacamole is installed. If
> I connect with the TigerVNC viewer there is this nice feature that the remote
> desktop is automatically resized if the viewer window is resized, like this
> if offered with RDP already.
> Is there a configuration how to achieve this with a Guacamole session as well
> for my VNC connection?
> {quote}
> Historically, this could not be done without corresponding support within
> libvncclient. This should now be possible through handling the required
> message type ({{SetDesktopSize}}):
> {quote}
> Unfortunately my team had to come up with a home baked solution for this
> about 2 years ago. But it involved hacking up libvnc.
> BUT, I think it is feasible to submit a feature request for it because now
> libvnc recently tagged a new version that includes the message type that
> guacamole needs to do this:
> Tag: https://github.com/LibVNC/libvncserver/releases/tag/LibVNCServer-0.9.13
> New message:
> https://github.com/rfbproto/rfbproto/blob/master/rfbproto.rst#setdesktopsize
> {quote}
> See:
> [http://apache-guacamole-general-user-mailing-list.2363388.n4.nabble.com/Auto-resize-of-VNC-sessions-td9511.html]
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