[Bug 1849644] Re: QEMU VNC websocket proxy requires non-standard 'binary' subprotocol

[Christian Ehrhardt ]

I can confirm the test steps mentioned above. In an unchanged scenario a
formerly failing-to-connect case got working when replacing the qemu (on
Focal) in use with a patched one.

Adding an SRU Template for Focal to the bug description ...

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https://bugs.launchpad.net/bugs/1849644

Title:
  QEMU VNC websocket proxy requires non-standard 'binary' subprotocol

Status in QEMU:
  Fix Released
Status in qemu package in Ubuntu:
  Fix Released
Status in qemu source package in Focal:
  Confirmed

Bug description:
  When running a machine using "-vnc" and the "websocket" option QEMU
  seems to require the subprotocol called 'binary'. This subprotocol
  does not exist in the WebSocket specification. In fact it has never
  existed in the spec, in one of the very early drafts of WebSockets it
  was briefly mentioned but it never made it to a final version.

  When the WebSocket server requires a non-standard subprotocol any
  WebSocket client that works correctly won't be able to connect.

  One example of such a client is noVNC, it tells the server that it
  doesn't want to use any subprotocol. QEMU's WebSocket proxy doesn't
  let noVNC connect. If noVNC is modified to ask for 'binary' it will
  work, this is, however, incorrect behavior.

  Looking at the code in "io/channel-websock.c" it seems it's quite
  hard-coded to binary:

  Look at line 58 and 433 here:
  https://git.qemu.org/?p=qemu.git;a=blob;f=io/channel-websock.c

  This code has to be made more dynamic, and shouldn't require binary.

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