gtkvncviewer does not support SSH tunnels (like vncviewer -via) [patch]

[peridot]

Almost all the servers I connect to with VNC are behind a gateway machine which I must SSH into. To use VNC, I need to use SSH port forwarding to pass my VNC connection through the gateway machine. This can be done easily from the command line, using "vncviewer -via gateway.example.com vnc-host-internal-name:23", but is currently impossible with gtkvncviewer.

Attached is a patch to add this feature. It works well, though I have not tested it with a VNC username (I have no idea what that even means; no machine I use VNC on asks for a username). The biggest pitfall is currently that servers are referred to by vnc-host-internal-name, as above; I occasionally use "vncviewer -via somehost.example.com localhost:44", and this will appear in the icon box under "localhost". It might be better to allow host specifications of the form "<email address hidden>:22/vnc-host-internal-name:23", which would be decoded to set up an SSH tunnel through gateway.example.com as user "user" using SSH port 22, forwarding to vnc-host-internal-name port 5923. This isn't very user-friendy, though. An alternative would be to construct a bogus server name in this format for use in the icon box and on start up.

SSH authentication issues can be handled by the GNOME keyring, ssh-askpass, or ssh-add. Unfortunately at the moment the application pauses while waiting for the SSH connection to start; a non-modal setup allowing the user to abort would be friendlier.

In any case, this patch allows me to actually use gtkvncviewer where I couldn't before.