GUI RPC drops keystroke flags such as `repeat`

[iacore]

How to file a helpful issue

Qubes OS release

r4.1

Brief summary

Key repeat is usable in dom0, but the Qubes gui protocol gui-common doesn't include flags for keys.

This makes games extremely confused, because they can't differentiate between "pressing a key repeatedly" and "holding down a key".

Steps to reproduce

Run xinput test-xi2 in dom0. Hold any key. You will see something like this in stdout:

EVENT type 2 (KeyPress)
    device: 3 (3)
    detail: 113
    flags: repeat

Run xinput test-xi2 in a VM other than dom0. Hold any key. The flags are empty.

EVENT type 2 (KeyPress)
    device: 3 (3)
    detail: 113
    flags:

Expected behavior

X input events should include flags like repeat too.

[iacore]

In qubes-gui-protocol.h, seems like there is no flags here. I could really use some comments here.

struct msg_keypress {
    uint32_t type;
    uint32_t x;
    uint32_t y;
    uint32_t state;
    uint32_t keycode;
};

[DemiMarie]

Ouch. Thanks for reporting this.

@marmarek is this something that can be fixed in an R4.1 update? On the one hand it does require a protocol change, but on the other hand it seems to be causing actual problems for at least one user.

[iacore]

Maybe...

• create a new event KEYPRESS2
• make gui rpc server emit both KEYPRESS and KEYPRESS2
• make new rpc client only handle KEYPRESS2

[iacore]

Mouse scroll wheel event also has flags. Has not met problem with this so far.

EVENT type 4 (ButtonPress)
    device: 25 (25)
    detail: 5
    flags: emulated

[iacore]

There are too many RawKeyPress events, one for each repeated key event. There should only be one when the key is initially pressed.

[iacore]

Is there a plan to use TLV encoding for qubes events? That way, we can extend existing events with new fields in the future by simply adding new fields.

[DemiMarie]

@locriacyber Not that I am aware of. The encoding is deliberately kept as simple as possible to minimize attack surface. The protocol does support version negotiation, though, and the agent ignores events it is not aware of.