#!/bin/sh

color_default=$(tput setaf 7);
color_config=$(tput setaf 3);
color_error=$(tput setaf 1);
color_log=$(tput setaf 8);
echo "${color_log}"
echo '  ___ _      _ _____ '
echo ' / __| |    /_\_   _|'
echo '| (__| |__ / _ \| |  '
echo ' \___|____/_/ \_\_|  '

####
# FETCH ENVIRONMENT
#
# nat64_prefix:
# 	- fetch by dns AAAA-entry ipv4only.arpa
# nat64_subnet:
# 	- /96
# ifname_ex:
# 	- get by route to "nat64_prefix"
# v4_address:
# 	- your ipv4 address
# v4_gw:
# 	- ipv4 address on gateway where routed
# v4_subnet:
#       - /30
# 	- subnet size of clat ipv4 address
# v4_status_ping:
# 	- 8.8.8.8
# v6_address_clat (not configable):
# 	- generated by internal link local and routed src
# v6_subnet_clat (should not configured):
# 	- /64
#
if [ -r /etc/clatd.env ]; then
	source /etc/clatd.env;
fi

#
# TODO:
# - skip if ipv4 default route exists
# - improve $v6_address_clat generation for ipv6 address in namespace

nat64_prefix=${nat64_prefix:-"$(dig +short ipv4only.arpa AAAA | sed 's/c000:a[ab]//' | head -1)"}
if [ $? -ne 0 ]; then
	echo "${color_error}dns failed: no request to ipv4only.arpa possible${color_log}"
	exit 1
fi
if [ "$nat64_prefix" == "" ]; then
	echo "${color_error}nat64 prefix/subnet unkown${color_log}"
	exit 1
fi
nat64_subnet=${nat64_subnet:-96}
echo "${color_default}nat64 prefix/subnet: ${color_config}$nat64_prefix${color_default}/${color_config}$nat64_subnet${color_log}"

ifname_ex="$(ip r g ${nat64_prefix}0 | grep -Po 'dev \K[0-9a-z]+')"
echo "${color_default}over interface: ${color_config}$ifname_ex${color_log}"

# ipv4
v4_address=${v4_address:-"192.0.0.2"}
v4_gw=${v4_gw:-"192.0.0.1"}
v4_subnet=${v4_subnet:-30}
echo "${color_default}ipv4: ${color_config}$v4_address${color_default}/${color_config}$v4_subnet${color_default} gw: ${color_config}$v4_gw${color_log}"
v4_status_ping=${v4_status_ping:-"8.8.8.8"}

# ipv6 subnet - should not be changed
v6_subnet_clat=${v6_subnet_clat:-64}

#
# END
####

namespace_setup() {
	echo "${color_default}> namespace setup${color_log}"
	ip netns add jool
	ip link add name clat type veth peer name to_world
	ip link set up dev clat
	ip link set up dev to_world netns jool
}

namespace_network() {
	echo "${color_default}> namespace network${color_log}"

	clat_ll=$(ip -6 address show scope link dev clat | grep -Po 'inet6 \K[0-9a-f:]+')
	internal_ll=$(ip netns exec jool ip -6 address show scope link dev to_world | grep -Po 'inet6 \K[0-9a-f:]+')

	v6_address_clat="$(ip r g ${nat64_prefix}0  | grep -Po 'src \K[0-9a-f]+:[0-9a-f]+:[0-9a-f]+:[0-9a-f]+:')$(echo $internal_ll | grep -Po 'fe80::\K[0-9a-f:]+')"

	echo "${color_default}ipv6 address clat: ${color_config}$v6_address_clat${color_default}/${color_config}$v6_subnet_clat${color_log}"
	ip netns exec jool ip -6 address add $v6_address_clat/$v6_subnet_clat dev to_world
	ip netns exec jool ip -6 route add default via $clat_ll dev to_world
	ip netns exec jool ip -4 address add $v4_gw/$v4_subnet dev to_world
}

jool_setup() {
	echo "${color_default}> setup jool in namespace${color_log}"
	if ! ip netns exec jool modprobe jool_siit; then
		echo "${color_error}module jool_siit not found${color_log}"
		ip netns del jool
		exit 1
	fi
	ip netns exec jool jool_siit instance add --netfilter --pool6 $nat64_prefix/$nat64_subnet
	ip netns exec jool jool_siit eamt add $v4_address $v6_address_clat
}

route_ipv6 () {
	echo "${color_default}> routing ipv6 to namespace${color_log}"
	echo 1 > /proc/sys/net/ipv6/conf/$ifname_ex/proxy_ndp
	echo 1 tee /proc/sys/net/ipv6/conf/*/forwarding
	ip -6 neigh add proxy $v6_address_clat dev $ifname_ex
	ip -6 route add $v6_address_clat/128 via $internal_ll dev clat
}

route_ipv4() {
	echo "${color_default}> routing ipv4 to namespace${color_log}"
	ip -4 address add $v4_address/$v4_subnet dev clat
	ip -4 route add default via $v4_gw dev clat
}

start() {
	echo "${color_default}clat start${color_log}"
	namespace_setup
	namespace_network
	jool_setup
	route_ipv6
	route_ipv4
}


stop() {
	echo "${color_default}clat stop${color_log}"
	ip netns del jool
}

status () {
	echo "${color_default}clat status${color_log}"
	if ip netns pids jool; then
		echo "${color_default}clat setup: ${color_config} yes"
		echo -n "${color_default}ipv6 address clat: ${color_config}"
		ip netns exec jool ip -6 a show to_world | grep -Po 'inet6 \K[0-9a-f:]+\/[0-9]+' | head -1
		ping -4 -I clat $v4_status_ping -c 1 1> /dev/null
		if [ $? -eq 0 ]; then
			echo "${color_default}clat ipv4 ping: ${color_config} yes${color_log}"
		else
			echo "${color_default}clat ipv4 ping: ${color_error} no${color_log}"
			exit 1
		fi
	else
		echo "${color_default}clat setup: ${color_error} no${color_log}"
		ping -4 $v4_status_ping -c 1 1> /dev/null
		if [ $? -eq 0 ]; then
			echo "${color_default}ipv4 ping: ${color_config} yes${color_log}"
		else
			echo "${color_default}ipv4 ping: ${color_error} no${color_log}"
			exit 2
		fi
		exit 1
	fi
}

reload() {
	if ip netns pids jool; then
		echo "${color_default}reload: clat found${color_log}"
		stop
		sleep 1
		echo "------------------------------"
	fi
	start
}

toggle() {
	if ip netns pids jool; then
		echo "${color_default}toggle: clat found${color_log}"
		stop
	else
		echo "${color_default}toggle: clat not found${color_log}"
		start
	fi

}


case "$1" in
	start)
		echo "------------------------------"
		start
		;;
	stop)
		echo "------------------------------"
		stop
		;;
	status)
		echo "------------------------------"
		status
		;;
	restart)
		echo "------------------------------"
		stop
		sleep 1
		echo "------------------------------"
		start
		;;
	reload)
		echo "------------------------------"
		reload
		;;
	help)
		echo "------------------------------"
		echo "${color_default}Usage:  {start|stop|status|reload|restart|toggle}${color_log}"
		exit 1
		;;
	"")
		echo "------------------------------"
		toggle
		;;
esac
exit $?