[Android] MAC address not available in system info

[joseluismarti]

Description

Android's new security restriction no longer allow to access MAC address on apps targeting Android 11 and higher.

NetworkInterface.getHardwareAddress() returns null for every interface. This method only returns the address when called by system apps.

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• Student submission (PR was done for educational purposes and will be treated as such)
• None of the above (please explain below)

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed

[joseluismarti]

Better option is to show ‘Not available’ when the returned address is empty.

[fuzzard]

I like this better.

[garbear]

Same