Add support for CIDR in "$network"

[DandelionSprout]

I received a good tip on Slack that propellerads primarily rotate their domains within the CIDR range 139.45.192.0/18, as seen with https://securitytrails.com/list/ip/139.45.192.0%2f18. So I initially opened up my AdGuard for Windows installation and tried to enter 139.45.192.0/18$network into the "User Filters"... and saw that AdGuard refused that entry, claiming it was incorrectly formatted.

Thus I propose adding CIDR support in $network blocking rules.

The alternative would be for AdGuard Base to add entries against all 16,384 individual IP addresses, which I assume would be very impractical.

Steps to reproduce

1. Go to Settings → Adblocker → User filter
2. Try to add 139.45.192.0/18$network as a new entry.
3. See that the textbox receives red error edges and that AdGuard refuses to save the entry.

Expected behavior

CIDR can be used in $network entries.

Actual behavior

CIDR cannot be used in $network entries.

Screenshot:

Customer ID

Can't find within the AdGuard program.

Your environment

• Environment name and version: AdGuard for Windows 7.4.2
• Operating system and version: Windows 10 May 2020 Update, build 19041.388

[Alex-302]

But too much useful sites will be blocked. Of the first look - ati.su(477-513)

[DandelionSprout]

Okay, that is admittedly a fair point.