v4.2.3

• network layer:
  • ensure the http headers cache is never modified unintentionally
  • invalid packet encoder names should not cause fatal errors
  • preserve audio packets chunking (avoids an HTML5 client bug)
  • prefer https links
  • prefer sha256 to sha1 for file transfer checksums
  • mmap setup error handling
  • sndbuf_bytes value was incorrect (currently unused)
  • socket timeout too long - broke VNC connections
  • AES DoS with unreasonably large number of password stretching iterations
  • tone down http content security policy for the HTML5 client
  • parsing of remote ssh command output
  • reply with a 404 if we have no http data to send
  • stricter validation of challenge digest attribute
  • stricter validation of packet indexes
  • specifying invalid compressors should not be fatal
  • handle more VNC clients correctly
  • server errors when VNC clients are connected
  • proxy sessions not found due to socket-dirs
  • mmap group lookup
• encodings:
  • don't enable video encoders not present in 'encodings' option
  • ffmpeg H264 errors with unreleased version
  • ffmpeg codecs silencing too many warnings
  • vpx encoder lossless mode detection
  • potential race conditions in the proxy server's encoder loop
  • visual corruption with scaled jpeg updates
  • incorrect error messages with the jpeg YUV decoder
  • error in 'void' paint events (currently unused)
  • CUDA 11.4 and Ampere cards
  • RPM build errors when CUDA is disabled
  • restrict the number of NVENC errors tagged as transient
  • more robust OpenGL picture decoding sanity checks
• packaging and platforms:
  • find the fakeXinerama library more reliably on all platforms
  • platform detection for CentOS / RedHat
  • missing default configuration files on MS Windows
  • missing webp with latest Pillow builds on MacOS
  • build fix for non-amd64 Debian (missing nvfbc)
• clipboard selections getting stuck with MS Windows and MacOS clients
• clipboard errors with some packet encoders sending strings
• authentication modules not honouring socket-dirs option
• make it easier to dismiss the splash screen
• ssh password and key dialogs timing out without being shown
• menu loading race condition causing empty start menu
• window size hints may not have been honoured (rare case)
• honour the force-replace-wm flag when upgrading
• correctly handle command timeouts when probing servers
• test scripts and command line tools fixups: unit tests, U2F tool, audio test, etc
• system tray save-to-file debugging failures
• minor cosmetic fixes to logging messages, unreachable code, icon loading errors
• make it easier to run in a prefixed installation