#!/bin/sh
# code found and bit modified
# http://forum.xda-developers.com/showthread.php?t=2127850
# two options rndis,adb or mtp,adb

prevconfig=$(getprop sys.usb.config)


#if [ "${prevconfig}" != "${prevconfig#rndis}" ] ; then
if [ "${prevconfig}" == "rndis,adb" ] ; then

	echo 'Is tethering already active?' >&2
	exit 1
fi

default_interface=$(ip route | head -n 1 | grep rmnet_usb0)
if [ -z  "$default_interface" ] ; then

	echo 'Please turn off your Wi-Fi first.' >&2
	exit 1
fi



#creates dev usb0
android-gadget-service enable rndis
sleep 6

echo "${prevconfig}" > /cache/usb_tether_prevconfig
setprop sys.usb.config 'rndis,adb'
until [ "$(getprop sys.usb.state)" = 'rndis,adb' ] ; do sleep 1 ; done

#change from ipv6 to ipv4
#ip rule add from all lookup main
ip addr flush dev usb0
ip addr add 192.168.22.1/255.255.255.0 dev usb0
ip link set usb0 up


#enable forwarding

echo 1 > /proc/sys/net/ipv4/ip_forward
#syscrl net.ipv4.ip_forward=1
#echo 1 > /proc/sys/net/ipv6/conf/forwarding
#echo 1 > /proc/sys/net/ipv6/conf/forwarding

#set iptables
#ip6
#ip6tables -t nat -I POSTROUTING 1 -o rmnet_usb0 -j MASQUERADE
#ip6tables -A FORWARD -i usb0 -j ACCEPT

#ip4
#this works but slow
iptables -t nat -I POSTROUTING 1 -o rmnet_usb0 -j MASQUERADE
iptables -A FORWARD -i usb0 -j ACCEPT

#iptables -t nat -I POSTROUTING 1 -o rmnet_usb0 -j MASQUERADE
#iptables -I FORWARD 1 --in-interface usb0 -j ACCEPT
#iptables -I INPUT 1 --in-interface usb0 -j ACCEPT
#iptables -A FORWARD -i rmnet_usb0 -j ACCEPT
#iptables -A FORWARD -i rmnet_usb0 -o usb0 -j ACCEPT
#iptables -A FORWARD -i usb0 -o rmnet_usb0 -j ACCEPT

#get usb0 ipv6
USB0_IP=$(ip addr show wlan0 | grep inet6)

dnsmasq --pid-file=/cache/usb_tether_dnsmasq.pid --interface=usb0 --bind-interfaces --bogus-priv --filterwin2k --no-resolv --domain-needed --server=8.8.8.8 --server=8.8.4.4 --cache-size=1000 --dhcp-range=192.168.22.2,192.168.22.3,255.255.255.0,192.168.22.255 --dhcp-lease-max=1 --dhcp-authoritative --dhcp-leasefile=/cache/usb_tether_dnsmasq.leases < /dev/null
#dnsmasq --pid-file=/cache/usb_tether_dnsmasq.pid --interface=usb0 --bind-interfaces --bogus-priv --filterwin2k --no-resolv --domain-needed --server=2001:4860:4860::8888 --server=2001:4860:4860::8844 --cache-size=1000 --dhcp-range=::1,::200,constuctor:usb0 --dhcp-lease-max=1 --dhcp-authoritative --dhcp-leasefile=/cache/usb_tether_dnsmasq.leases < /dev/null