Poor man's adblock using hosts file

adblock.sh

#!/bin/sh
# Most of the code below has been adapted from several different scripts
mkdir -p /tmp/adblock &> /dev/null
temphosts1=`mktemp`
temphosts2=`mktemp`
# I prefer to separate adblock entries from my vanilla hosts file.
# I also use dnsmasq, which allows me to chain-load an additional
# hosts file, which is what i have done here.
target_file=/etc/hosts.dnsmasq

#function arguments -> filename to compare against current time
function compareDate() {
	if [ ! -f $1 ]; then
		#echo "$1 does not exist."
  		echo 1
  		return
	fi
	MAXAGE=$(bc <<< '12*60*60') # seconds in 12 hours
	# file age in seconds = current_time - file_modification_time.
	FILEAGE=$(($(date +%s) - $(stat -c '%Y' "$1")))
	test $FILEAGE -lt $MAXAGE && {
	    #echo "$1 is less than 12 hours old."
	    echo 0
	    return
	}
	#echo "$1 is older than 12 hours seconds."
	echo 1
}


getHash() {
	/bin/echo "$1" | /usr/bin/md5sum | /bin/cut -f1 -d " "
}

downloadIfOlder() {
	url="$1"
	fileName="$2"
	download=$(compareDate "$fileName")
	if [ $download -ne 0 ]; then
		#echo "Downloading $url"
		curl -sS "$url" > "$fileName"
	#else
		#echo "Not Downloading $url"
	fi
}
cd /tmp
# set sources
servers=(
"http://adaway.org/hosts.txt"
"http://hosts-file.net/ad_servers.txt"
"http://hostsfile.mine.nu/hosts0"
"http://mirror2.malwaredomains.com/files/BOOT"
"http://pgl.yoyo.org/adservers/serverlist.php?hostformat=hosts&showintro=0&mimetype=plaintext"
"http://someonewhocares.org/hosts/hosts"
"http://hosts-file.net/download/HOSTS-Optimized.txt"
"http://winhelp2002.mvps.org/hosts.txt"
"http://www.malwaredomainlist.com/hostslist/hosts.txt"
"https://jansal.googlecode.com/svn/trunk/adblock/hosts"
"https://raw.githubusercontent.com/StevenBlack/hosts/master/data/StevenBlack/hosts"
)
for i in "${servers[@]}"
do
	hash=$(getHash "$i")
	fileName="/tmp/adblock/$hash"
	echo "Trying $i to $fileName"
	$(downloadIfOlder "$i" "$fileName")
	cat "$fileName" >> $temphosts1
	#rm "$fileName" 2> /dev/null
done
# Do some work on the file:
# 1. Remove MS-DOS carriage returns
# 2. Delete any lines containing the word localhost because we'll obtain that from the original hosts file
# 3. Replace 127.0.0.1 with 0.0.0.0 because then we don't have to wait for the resolver to fail
# 4. Scrunch extraneous spaces separating address from name into a single tab
# 5. Delete any comments on lines
# 6. Clean up leftover trailing blanks
# Pass all this through sort with the unique flag to remove duplicates and save the result
echo "Patching up hosts file"
# /etc/hosts.block is a custom file that contains hosts I am not comfortable with
cat /etc/hosts.block >> $temphosts1
# Excluding google, kat*, godaddy and few other sites
sed -e 's/\r//' -e 's/127.0.0.1/0.0.0.0/' -e 's/0.0.0.0 0.0.0.0/0.0.0.0 /' -e 's/PRIMARY/0.0.0.0/' -e '/localhost/d' -e 's/ \+/\t/' -e 's/#.*$//' -e 's/[ \t]*$//' < $temphosts1 | egrep -v ">|<" | grep -v 'gstatic' | grep -v "//" | grep -v "xn-----6kcvb6bctkco1byg.xn--p1ai" | grep -v 'kickass\.' | grep -v "kat\." | grep -v "google" | grep -v "d-h\.st" | grep -v "secureserver.net"  | sort -u > $temphosts2

# Combine system's vhosts file with adblock's
echo "Merging hosts file"
echo -e "\n# Ad blocking hosts generated "`date` | cat /etc/hosts.vhosts - $temphosts2  > /tmp/adblock/hosts

echo "Copy /tmp/hosts as $target_file"
sudo cp /tmp/adblock/hosts $target_file
echo "Cleaning up temp files"
rm $temphosts1 $temphosts2 2> /dev/null
echo "Restarting dnsmasq"
sudo systemctl restart dnsmasq
cd - &>> /dev/null
exit 0

shoaibi-dnsmasq.conf

# /etc/dnsmasq.d/shoaibi.conf
port=53
filterwin2k
strict-order
no-resolv
no-poll
# server=192.168.20.1
# server=192.168.5.1
server=208.67.220.222
server=8.8.8.8
server=8.8.4.4
server=141.1.27.249
server=216.146.36.36
server=194.6.240.1
server=212.94.32.32
server=156.154.71.1
server=208.67.220.220
server=208.67.222.222
no-dhcp-interface=lo
addn-hosts=/etc/hosts.dnsmasq