Listens incoming DNS A queries. If query is for one of the domains in the whitelist, an allow/pass firewall rule is added with the source and destination IP as the source of the DNS query and the returned A record respectively. The firewall rule lives for a certain period and automatically removed after reaching the time limit. In a way, traffic between the source IP and the domain is allowed to pass through the router/device.
If this project helped you in any way, you can buy me a bottle of beer or a shot of whiskey :)