add list of domains serving advertising

Add a script to download a list of domains which serves ads.
This list can be used to block these servers in the DNS server.

utils/banhosts/files/updatebanhost

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+file=/tmp/banhost
+
+gethosts() {
+	logger -t "banhost[$$]" "Update $file"
+	wget -qO- http://winhelp2002.mvps.org/hosts.txt |awk 'BEGIN{printf "0.0.0.0"}/^0\.0\.0\.0/{printf " "$2}END{exit(!FNR)}' >$file || exit 1
+	echo -n $time >$file.time
+	exec killall -HUP dnsmasq
+}
+
+if [ "$ACTION" = ifup -a "$INTERFACE" = wan ]; then
+	read time </proc/uptime
+	time=${time%%.*}
+
+	[ -f $file -a -f $file.time ] || gethosts
+	read oldtime <$file.time
+	[ $((time - oldtime)) -lt 604800 ] || gethosts
+fi