#!/bin/bash

#
# $Id: fixdns 21 2010-11-18 09:37:16Z deploy $
#
# Recursive/Caching Nameservers
#
# nsc-dl1 72.249.191.254 - Dallas, Standard Network
# nsc-dl2 206.123.113.254 - Dallas, Premium Network
# nsc-ny1 66.199.228.254 - New York
# nsc-ln1 92.48.122.126 - London 
# nsc-au1 122.100.15.254 - Australia

conf="/etc/resolv.conf"
bad_nameservers=(
206.123.64.245
206.123.69.4
72.29.96.250
207.210.212.202
72.249.0.34
206.123.69.254
66.199.228.130
206.123.113.132
207.99.0.41
207.99.0.42
207.99.0.1
207.99.0.2
66.199.235.50
72.9.108.146
210.56.80.56 
202.60.64.6 
203.25.185.119 
202.60.64.7
4.2.2.2
4.2.2.1
) 

au_nameservers="122.100.15.254 72.249.191.254"
ln_nameservers="92.48.122.126 72.249.191.254 66.199.228.254"
ny_nameservers="66.199.228.254 72.249.191.254 92.48.122.126"
dl_nameservers="72.249.191.254 206.123.113.254 66.199.228.254 92.48.122.126"

ny_ranges="63. 66.199. 72.9. 216."
ln_ranges="85. 94. 217. 92."
au_ranges="202. 122. 117."

eth0=$(/sbin/ifconfig eth0 | grep 'inet addr' | cut -f2 -d: | awk '{print $1}')

[ -e $conf ] || exit 1
old="/etc/$(basename $conf).rimu-$$"
cp $conf $old

for dc in ny ln au; do 
	eval ranges=\$\{${dc}_ranges\}
	for range in $ranges; do
		if [ $(echo $eth0 | grep -c ^$range) -gt 0 ]; then
			eval good_nameservers=\$\{${dc}_nameservers\}
			break
		fi
	done
	[ -n "$good_nameservers" ] && break
done

[ -z "$good_nameservers" ] && good_nameservers=$dl_nameservers

good_nameservers=($(echo "$good_nameservers"))

[ -e $conf ] || exit 1

count=0
for ((i=0;i<${#bad_nameservers[@]};i++)); do
	ns=${bad_nameservers[$i]}
	if [ $(grep -c "^nameserver $ns" $conf) -gt 0 ]; then
		sed s/"^nameserver $ns"/"#nameserver $ns"/g --in-place $conf
		if [ $? -ne 0 ]; then
			exit 1
		fi
		((count++))
	fi
done

# If there is less than 2 nameservers listed in resolv.conf, and we're going to add less than 2
if [ $(grep -c '^nameserver' $conf) -lt 2 -a ${count} -lt 2 ]; then
	count=2
fi

[ $count -eq 0 ] && exit 0

for ((i=0;i<$count;i++)); do
	for ((j=0;j<${#good_nameservers[@]};j++)); do
		ns=${good_nameservers[$j]}
		if [ $(grep -c "^nameserver $ns" $conf) -eq 0 ]; then
			echo "nameserver $ns" >> $conf
			break
		fi
	done
done

cat $conf
diff $old $conf
#rm -f $old
echo "Checking your current name servers:"
nameservers=$(cat /etc/resolv.conf | grep '^nameserver' | awk '{print $2}')
for i in $nameservers; do host google.com $i 2>&1 | grep -qai 'has address' || { echo "$i in /etc/resolv.conf is not working.  Remove it?"; continue; }; echo $i is working; done
exit 0