Correctly detect AutoConfigURL on managed Windows systems

[pbourguignon-enertrag]

On Windows systems managed by an MDM (e.g. InTune), the value of AutoConfigURL might be found under a different key in the registry, namely HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings. This changeset ensures that the URL is found successfully in such situations.

[carsonyl]

Thanks for the PR. While looking into this, I found https://learn.microsoft.com/en-us/windows-hardware/customize/desktop/unattend/microsoft-windows-ie-clientnetworkprotocolimplementation-hklmproxyenable, which suggests the selection of HKCU/HKLM depends on ProxySettingsPerUser. Is that true in your situation?

[pbourguignon-enertrag]

You're very welcome!

Indeed, under the path Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\CurrentVersion\Internet Settings, I do have the key ProxySettingsPerUser with a value of 0.

Then, under Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings, I actually have ProxyEnable set to 0 alongside AutoConfigURL set to the URL of the PAC file. It looks like ProxyEnable is set to 1 when a fixed proxy server is defined via (HKCU|HKLM)ProxyServer and ``(HKCU|HKLM)ProxyPort`, but not when a PAC file is in use. That's at least what Copilot claims, but I haven't found a clear statement in the Microsoft docs that clarifies that point.

Anyway, the PR could rely on a lookup of ProxySettingsPerUser rather than catching the exception. Before I proceed, could you confirm that this key also exists on non-managed Windows systems?

[carsonyl]

On my own PC, HKLM\SOFTWARE\Policies\Microsoft\Windows\CurrentVersion\Internet Settings doesn't have ProxySettingsPerUser at all.