rules.pl: Add tiny ipset_restore function.

This helper function is used to load a previously exported list of
networks for a given country code into the ipset module, so it can be
used for any kind of firewall rules.

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>
Reviewed-by: Peter Müller <peter.mueller@ipfire.org>
Reviewed-by: Michael Tremer <michael.tremer@ipfire.org>

config/firewall/rules.pl

@@ -888,3 +888,10 @@ sub firewall_is_in_subnet {
 
 	return 0;
 }
+
+sub ipset_restore ($) {
+	my ($ccode) = @_;
+
+	# Run ipset and restore the list of the given country code.
+	run("$IPSET restore < $Location::Functions::ipset_db_directory/$ccode.ipset4");
+}