Authorisation asked for local network on iOS 14 on cellular network

[ben-j69]

Hello,

if the lib is inclued in an app running on iOS 14 an authorisation is asked at launch in a system popup :

"NAME_OF_YOUR_APP" would like to find and connect to devices on your local network.
This app will be able to discover and connect to devices on the networks you use.
Don't allow - OK

This does not appear on Wi-Fi, it is displayed only if the phone is on cellular network like 4G.

This is triggered by Clock.sync()

Why Kronos wants to use local network ? How to avoid this popup in any case ?

Thanks

[buranmert]

i can reproduce the issue only with local NTP pools, such as 127.0.0.1 or 127.255.255.255:

Clock.sync(from: "127.0.0.1", ...) { ... }

otherwise i can't reproduce the issue and Kronos source code doesn't seem to try to access local network by itself.

can you please make sure that your NTP pool isn't in your local network by any chance?

[leearmstrong]

Interestingly I have been setting up test environments to try and get this to trigger and failed. Until today.

On a cellular connection with a VPN active I got the prompt!

[ncreated]

👋 As a follow up from corresponding issue in Datadog iOS SDK, we managed to collect Kronos telemetry which shows an evidence of resolving NTP pool to a private / local IP in some (unknown) circumstances. As a fix, we're going to apply private IP filtering in DataDog/dd-sdk-ios#830 on our side. We believe this could be a desired change to Kronos lib as well.

[jeannustre]

Thanks @ncreated !

I have opened PR #100 which includes DataDog's changes. Let me know if there are any issue with it.