When QueryConnect is enabled on x0vncserver, there may be exceptions when multiple connections are concurrent

[Jathon-yang]

When QueryConnect is enabled, if a connection is waiting for a user reply and a new connection enters, the program rejects it. As the authClientCount() is still 0 at this time, stopDesktop() will be executed, resulting in the first connection not responding. It is recommended to add an additional check to determine if there is a connection waiting.
It can be determined by adding an additional function.

Tigervnc/common/rfb/VNCServerST.cxx
The variable name on line 193 of the file is incorrect.

if (authClientCount() == 0) stopDesktop();
Should be changed to
if (authClientCount() == 0 && !desktop->isQueryConnect()) stopDesktop();

[CendioOssman]

Thank you for your bug report!

We do indeed seem to have a race during the query phase. There are more parts here that look suspicious. I'll have a look.