[Android] Add an explicit "Block connections without VPN" setting to VPN (VPN kill switch)

[bsclifton]

Description

When users purchase and use VPN on Android, a new connection will be created by the OS for the VPN (w/ hostname/user/pass)

When visiting in settings, you can enable Always on functionality which should force a reconnection if service is lost. We could offer a new setting (screenshot below has for reference) where we can block any outbound traffic on the device when the VPN is not used. Here's an example from Express VPN:

This is useful so that DNS or other info isn't leaked if the VPN connection is unintentionally dropped

cc: @mattmcalister

[mattmcalister]

is this is a device-wide setting?

[bsclifton]

@mattmcalister yes it is

Looks like our VPN is already showing this unfortunately (and it doesn't work). See https://twitter.com/Maxdani99970966/status/1622043555362398209 for the report

[deeppandya]

@bsclifton @mattmcalister i checked with latest release. if you have Block connections without VPN selected and turn off the vpn connection, it stops the connections from all other apps except Brave as tunnel is created with the Brave app.

[igornazarov1991]

@deeppandya , is "kill switch" available on iOS platform as well?

[deeppandya]

@deeppandya , is "kill switch" available on iOS platform as well?

@igornazarov1991 it's not available on IOS AFAIK

[timchilds]

Figma: https://www.figma.com/file/J4LKBMftiWhqromRWfUQLG/VPN-design?type=design&node-id=113%3A12449&mode=design&t=97wqlOD5r8wAFWgb-1

[timchilds]

This will be done alongside adding option to Always on VPN in settings #37013

[GeetaSarvadnya]

Verification PASSED on Vivo X70 Pro version 12 running Bravemonoarm64.apk_1.67.113

• Verified as part of [Android] Remove kill switch option for VPN #38853 - verification notes are linked in [Android] Remove kill switch option for VPN #38853 (comment)