adblocker.sh for Tomato firmware

#!/bin/sh

# adblocker.sh - by Todd Stein ([email protected]), Saturday, October 25, 2014
# for use on routers running Tomato firmware

# Periodically download lists of known ad and malware servers, and prevents traffic from being sent to them.
# This is a complete rewrite of a script originally written by teffalump (https://gist.github.com/teffalump/7227752

HOST_LISTS="
       http://adaway.org/hosts.txt
       http://www.malwaredomainlist.com/hostslist/hosts.txt
       http://www.mvps.org/winhelp2002/hosts.txt
       http://pgl.yoyo.org/adservers/serverlist.php?hostformat=hosts&showintro=0&startdate%5Bday%5D=&startdate%5Bm
"

BLOCKLIST=/tmp/adblocker_hostlist
BLACKLIST=/etc/adblocker_blacklist
WHITELIST=/etc/adblocker_whitelist

# get script's absolute path and escape spaces
cd "${0%/*}"
SCRIPT_NAME="$PWD/${0##*/}"
SCRIPT_NAME="${SCRIPT_NAME// /' '}"
cd "$OLDPWD"

# await internet connectivity before proceeding
until ping -c1 -w3 google.com || ping -c1 -w3 yahoo.com; do
  sleep 5
done &>/dev/null

if [[ -f "$BLOCKLIST" ]]; then
  premd5=$(md5sum "$BLOCKLIST" | awk '{print $1}')
fi

# initialize block list
> "$BLOCKLIST"

# grab blacklisted domains if any have been specified
[ -s "$BLACKLIST" ] && awk '/^[^#]/ { print "0.0.0.0",$1 }' "$BLACKLIST" >> "$BLOCKLIST"

# grab host lists from the internet
wget -qO- $HOST_LISTS | sed -rn 's/^(127.0.0.1|0.0.0.0)/0.0.0.0/p' | awk '{ print $1,$2 }' | sort -uk2 >> "$BLOCKLIST"

# remove any whitelisted domains from the block list
if [ -s "$WHITELIST" ]; then
  # create a pipe-delimited list of all non-commented words in whitelist
  white_listed_regex=`echo \`grep -o '^[^#]\+' "$WHITELIST"\` | tr ' ' '|'`
  sed -ri "/$white_listed_regex/d" "$BLOCKLIST"
fi

# add IPv6 blocking
sed -ri 's/([^ ]+)$/\1\n::      \1/' "$BLOCKLIST"

# Add script to first empty custom scheduler if not already present
nvram show 2>/dev/null | grep sch | grep -Fq "$SCRIPT_NAME"
if [[ $? -ne "0" ]]; then
  # Find an empty scheduler, we have up to five
  for i in $(seq 1 5); do
    if [[ -z "$(nvram get sch_c$i\_cmd)" ]]; then
      tsch=$i
      break
    fi
  done
  if [[ -n "$tsch" ]]; then
    # Set target scheduler to run daily at 3 am.
    nvram set sch_c$tsch\_cmd="/bin/sh $SCRIPT_NAME"
    nvram set sch_c$tsch=1,180,127
    # Restart the scheduler
    service sched restart >/dev/null
  fi
fi

# Add block list to dnsmasq config if not already present
dnsmsq=$(nvram get dnsmasq_custom)
echo "$dnsmsq" | grep -Fq "$BLOCKLIST"
if [[ $? -ne "0" ]]; then
  # This can be a multi-line value, easier to dump it to a file and manipulate from there
  echo "$dnsmsq" > /tmp/$$.tmp
  echo "addn-hosts=$BLOCKLIST" >> /tmp/$$.tmp
  nvram set dnsmasq_custom="$(cat /tmp/$$.tmp)" && rm -f /tmp/$$.tmp
fi

# Restart dnsmasq if we need to
postmd5=$(md5sum "$BLOCKLIST" | awk '{print $1}')
if [[ "$premd5" != "$postmd5" ]]; then
  # Restart dnsmasq to pickup changes
  service dnsmasq restart >/dev/null
fi