setting `$ICAInstDir/timezone` to `UTC` causes wrong timezone on Windows remote (VDA & RDP)

[GsakuL]

Describe the bug

When connecting with my personal machine (NixOS) the timezone on my work PC (Windows) is wrong. My TZ is Europe/Berlin ("standard", with auto DST). Due to recent Group Policy additions by my company, I cannot re-configure the Windows machine myself - the timezone dropdown is "greyed out" (see below). However the Policy is correctly set to our local TZ/standards (again Europe/Berlin) from what I'm told, as it also works on-site (Windows Thin Clients) and for coworkers that use Citrix from their personal Windows machines.

Steps To Reproduce

Steps to reproduce the behavior:

1. install citric_workspace
2. connect through browser (?) (because #319360 )
3. connect to to remote Windows machine (VDA or RDP) that is not set to UTC
   • not sure if Windows would retain manual TZ settings, I cannot test this anymore
   • I also don't know what Policies/Registry Entries affect these settings, neither do I know their values

Expected behavior

Citrix forwarding the correct TZ info

Screenshots

(I'm tracking this issue over multiple weeks now, so current date/time in screenshots is not relevant, but "generally correct", issue is with TZ only) Time sync server is company internal.

default Citrix install: with my overlay, now correct (only seen Working via VDA, RDP still wrong [not sure why though]):

Additional context

• what if found: https://github.com/NixOS/nixpkgs/blob/560737213b77b03824594fa4cc73c6f3fbcdd16e/pkgs/applications/networking/remote/citrix-workspace/generic.nix#L208-L209
• workaround-overlay: https://github.com/GsakuL/mynix/blob/477a7329440ba50242f8c794c5f8c4dd511172fa/overlays/citrix-fixes.nix
  • this only fixes VDA from what it seems, RDP is still wrong (or I have to reboot, because Citrix keeps thing in background running?)
  • however, I mainly use VDA anyways, so "works for me", but maybe not others that depend on RDP
• (obviously if something like that would be implemented in the package, i'd be totally okay with it being opt-in/override only, because of breaking changes for others)
• can't remember how Windows was behaving before the new Policy.
• don't know why the "Set time zone automatically" switch is off in Windows/GP.
• only noticed this, because websites and Electron Apps (ie MS Teams) where showing wrong time infos (mainly -1h from current local summer time; ie UTC+1 instead of UTC+2 which is currently in effect due to DST)
• my local machine has the "normal" NixOS TZ set: https://github.com/GsakuL/mynix/blob/3e90f526793c677314c733787bb6e2688ab53368/modules/system/locale.nix#L5
• i have no idea why the TZ is "so wrong" under windows. I would expect it to be either UTC, given the package or Berlin given system settings

Notify maintainers

@michaeladler

Metadata

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
 - system: `"x86_64-linux"`
 - host os: `Linux 6.6.32, NixOS, 24.11 (Vicuña), 24.11.20240607.051f920`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.18.2`
 - nixpkgs: `/nix/store/3dr5pyja36lvvrszhzffww1jwyrx6i09-source`

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[GsakuL]

I just took a look at https://wiki.archlinux.org/title/citrix where at 5. Troubleshooting, the last bullet point is

If your timezone inside the VDI is reset to UTC when starting session from Firefox, you might need to go to about:config and set privacy.resistFingerprinting=false. This feature spoofs the browser's timezone to UTC which is then redirected to the Citrix session.

I do in fact use Firefox but checking, my work profile (which only ever opens the work store addresss) about:config reveals my privacy.resistFingerprinting is still/already false. And JavaScript seems to get valid time zone infos too: So I would not suspect Firefox in this case