#!/bin/bash
#####################################
ShareNet=eth0
Wmode=ad-hoc
Wchannel=auto
Wessid=Leon_in_GuangZhou
WInterface=wlan0
WPasskey=androidworkab
Wkey=restricted
Igateway=192.168.2.254
Inetmask=255.255.255.0
Inetwork=192.168.2.0
DhcpRangeMin=192.168.2.10
DhcpRangeMax=192.168.2.105
#####################################

adhocFolder=/etc/adhoc
dnsmasqFile=$adhocFolder/dnsmasq.conf
resolvFile=/etc/resolv.conf
dnsmasqPid=/var/run/dnsmasq.pid
dnsmasqLeases=/var/run/dnsmasq.leases

# start Ad-hoc
function adhoc_start
{
   echo "Starting Ad-hoc..."
   check_dnsmasq
   sleep 1
   sudo ifconfig $WInterface down
   echo -n "Setting $WInterface gateway and netmask."
   sudo ifconfig $WInterface $Igateway netmask $Inetmask
   sleep 1
   echo -n "    [ good ]"
   echo
   
   echo -n "Setting up $WInterface ..."
   sudo ifconfig $WInterface up
   sleep 1
   echo -n "    [ good ]"
   echo
   
   echo -n "Setting $WInterface mode..."
   sudo iwconfig $WInterface mode $Wmode
   sleep 1
   echo -n "    [ good ]"
   echo
   
   echo -n "Setting $WInterface essid..."
   sudo iwconfig $WInterface essid $Wessid
   sleep 1
   echo -n "    [ good ]"
   echo
   
   echo -n "Setting $WInterface cannel..."
   sudo iwconfig $WInterface channel $Wchannel
   sleep 1
   echo -n "    [ good ]"
   echo
   
   echo -n "Setting $WInterface password..."
   sudo iwconfig $WInterface key s:$WPasskey
   sleep 1
   echo -n "    [ good ]"
   echo
   
   echo -n "Setting $WInterface key type..."
   sudo iwconfig $WInterface key $Wkey
   sleep 1
   echo -n "    [ good ]"
   echo
   echo
   echo -n "Setting iptable..."
   sleep 1
   #remove the old rules
   sudo iptables -N wireless-adhoc
     sudo iptables -F wireless-adhoc
     sudo iptables -t nat -F PREROUTING
     sudo iptables -t nat -F POSTROUTING
     sudo iptables -t nat -F
   #bring up the NAT rules
   sudo iptables -A wireless-adhoc -m state --state ESTABLISHED,RELATED -j ACCEPT
   sudo iptables -A wireless-adhoc -s $Inetwork/24 -j ACCEPT
   sudo iptables -A wireless-adhoc -p 47 -j ACCEPT
   sudo iptables -A wireless-adhoc -j DROP
   sudo iptables -A FORWARD -m state --state INVALID -j DROP
   sudo iptables -A FORWARD -j wireless-adhoc
   sudo iptables -t nat -I POSTROUTING -s $Inetwork/24 -j MASQUERADE
   sleep 1
   sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
   echo -n "."
   sleep 1
   sudo dnsmasq -i $WInterface --resolv-file=$resolvFile --conf-file=$dnsmasqFile
   echo
   echo "Success!^^"
}

# stop Ad-hoc
function adhoc_stop
{
   echo "Stopping adhoc ..."
   sudo sh -c "echo 0 > /proc/sys/net/ipv4/ip_forward"
   echo -n "."
   # stop adhoc mode
   sudo ifconfig $WInterface mode managed
   sleep 1
   echo -n "."
   sudo ifconfig $WInterface key off
   sleep 1
   echo -n "."
   sudo ifconfig $WInterface essid any
   sleep 1
   echo -n "."
   sudo ifconfig $WInterface down
   sleep 1
   echo -n "."
   # remove iptabled rules
   sudo iptables -D FORWARD -j wireless-adhoc
   sudo iptables -D FORWARD -m state --state INVALID -j DROP
   sudo iptables -F wireless-adhoc
   sudo iptables -X wireless-adhoc
   sudo iptables -t nat -F PREROUTING
   sudo iptables -t nat -F POSTROUTING
   sudo iptables -t nat -F
   sleep 1
   if [ -f $dnsmasqPid ]; then
      dnsmasqID=`cat $dnsmasqPid`
      kill $dnsmasqID
      sleep 1
   fi
   if [ -f $dnsmasqLeases ]; then
      rm $dnsmasqLeases
   fi
   echo
   echo "Wifi ad-hoc now stopped"
}

function adhoc_restart
{
   echo "Now, resart ad-hoc ..."
   adhoc_stop
   sleep 2
   adhoc_start
}
# check dnsmasq.conf
function check_dnsmasq
{

   if [ -f $dnsmasqPid ]; then
      echo "Dhcp is running!"
      echo "Now, restart Ad-hoc"
      adhoc_stop
      sleep 1
   fi
   if [ ! -d $adhocFolder ]; then
   mkdir $adhocFolder
   fi

   if [ ! -f $dnsmasqFile ]; then
   echo "$dnsmasqFile is not exist, now building."

   echo "dhcp-authoritative" > $dnsmasqFile
   echo "dhcp-range=$DhcpRangeMin,$DhcpRangeMax,12h" >> $dnsmasqFile
   echo "dhcp-leasefile=$dnsmasqLeases" >> $dnsmasqFile
   echo "pid-file=$dnsmasqPid" >> $dnsmasqFile
   echo "user=root" >> $dnsmasqFile
   echo "no-negcache" >> $dnsmasqFile
   fi
}

# is super user?
function super_user
{
   if [ "$UID" = "0" ]; then
   return 0
   else
   return 1
   fi
}

function usage
{
   echo "Wifi Ad-hoc control"
   echo "$1 [-h][-s]"
   echo "Default is start ad-hoc"
   echo "-h show the usage"
   echo "-s stop ad-hoc"
   echo "-r restart ad-hoc"
}

if ! super_user ; then
echo "Need super user permission!"
exit 1
fi
if [ $# -lt 1 ]; then
adhoc_start
elif [ "$1" = "-h" ]; then
usage
elif [ "$1" = "-s" ]; then
adhoc_stop
elif [ "$1" = "-r" ]; then
adhoc_restart
else
echo "Input error!"
echo "$1 -h gives usage information."
fi