iopsys-feed/netmode/files/etc/hotplug.d/iface/70-shiftrange

#!/bin/sh
# this scripts shifts the lan network prefixes
# if a wan interface has the same network prefix.

# do not shift range if the feature is explicitly disabled
[ "$(uci -q get netmode.shiftrange.enabled)" == "0" ] && exit 0

. /lib/functions.sh
. /lib/functions/network.sh

LOCKFILE="/tmp/70-shiftrange.lock"
RESTRICTED_NETS=""
ALL_NETS=""

#####
##### initial functions
#####

initial_check()
{
	# run only on ifup
	[ "$ACTION" == "ifup" ] || exit 0

	# run only for uplink (not is_lan) interfaces
	local islan="$(uci -q get network.$INTERFACE.is_lan)"
	[ "$islan" != "1" ] || exit 0

	# run only if the uplink interface has a configured protocol
	local proto="$(uci -q get network.$INTERFACE.proto)"
	[ "$proto" != "none" ] || exit 0
}

finish()
{
    lock -u $LOCKFILE
    rm -f $LOCKFILE
}

# just one instance of this script at a time
just_one_instance()
{
	local counter=0
	local limit=10

	#wait for the lock to become free
	while [ -e $LOCKFILE ] ; do
		sleep 1
		counter=$((counter + 1))
		[ "$counter" -gt "$limit" ] && exit 1
	done

	lock $LOCKFILE
	trap finish EXIT INT TERM
}


#####
##### helper functions
#####

#given a an ip and a mask in the form of "192.168.1.1/24"
#return the network address like "192.168.1.0/24"
get_network_address()
{
	local ip="$1"
	[ -z "$ip" ] && return

	local prefix=${ip##*/}

	local ip1=${ip%%.*} ; ip=${ip#*.*}
	local ip2=${ip%%.*} ; ip=${ip#*.*}
	local ip3=${ip%%.*} ; ip=${ip#*.*}
	local ip4=${ip%%/*}

	local ip=$((($ip1 << 24) + ($ip2 << 16) + ($ip3 << 8) + $ip4))
	local mask=$((0xFFFFFFFF >> (32 - $prefix) << (32 - $prefix)))
	local network=$(($ip & $mask))

	local n1=$((($network & 0xFF000000) >> 24))
	local n2=$((($network & 0x00FF0000) >> 16))
	local n3=$((($network & 0x0000FF00) >> 8))
	local n4=$(( $network & 0x000000FF))

	echo "$n1.$n2.$n3.$n4/$prefix"
}

#given a network address (192.168.1.0/24)
#find the next network address (192.168.2.0/24)
next_network_address()
{
	local ip=$1
	local prefix=${ip##*/}

	local ip1=${ip%%.*} ; ip=${ip#*.*}
	local ip2=${ip%%.*} ; ip=${ip#*.*}
	local ip3=${ip%%.*} ; ip=${ip#*.*}
	local ip4=${ip%%/*}

	local ip=$((($ip1 << 24) + ($ip2 << 16) + ($ip3 << 8) + $ip4))
	local one="$((1 << (32-$prefix)))"
	local new=$(($ip + $one))

	local n1=$((($new & 0xFF000000) >> 24))
	local n2=$((($new & 0x00FF0000) >> 16))
	local n3=$((($new & 0x0000FF00) >> 8))
	local n4=$(( $new & 0x000000FF))

	echo "$n1.$n2.$n3.$n4/$prefix"
}

# given a network address and a prefix (192.168.2.0/24)
# return the first host ip available   (192.168.2.1)
first_host_in_network ()
{
	local ip=$1
	local prefix=${ip##*/}

	local ip1=${ip%%.*} ; ip=${ip#*.*}
	local ip2=${ip%%.*} ; ip=${ip#*.*}
	local ip3=${ip%%.*} ; ip=${ip#*.*}
	local ip4=${ip%%/*}

	local ip=$((($ip1 << 24) + ($ip2 << 16) + ($ip3 << 8) + $ip4))
	local new=$(($ip + 1))

	local n1=$((($new & 0xFF000000) >> 24))
	local n2=$((($new & 0x00FF0000) >> 16))
	local n3=$((($new & 0x0000FF00) >> 8))
	local n4=$(( $new & 0x000000FF))

	echo "$n1.$n2.$n3.$n4"
}

# given a network address,
# find the next available network address.
shift_range()
{
	local net="$1"
	while true ; do
		if [ "$RESTRICTED_NETS" == "${RESTRICTED_NETS//$net/}" ] && [ "$ALL_NETS" == "${ALL_NETS//$net/}" ]; then
			# found a net that is not in restricted nets nor in all nets
			break
		fi
		net=$(next_network_address $net)
	done

	echo "$net"
}


#####
##### parse all interfaces section
#####

# RESTRICTED_NETS = all the IPs on wan interfaces
# ALL_NETS = all the IPs on any interface
parse_interface()
{
	local interface=$1
	local nets=""		# "192.168.1.1/24"
	local networks=""	# "192.168.1.0/24"

	config_get is_lan $interface is_lan
	network_get_subnets nets $interface

	for n in $nets ; do
		networks="$networks $(get_network_address $n)"
	done

	[ "$is_lan" != "1" ] && RESTRICTED_NETS="$RESTRICTED_NETS $networks"
	ALL_NETS="$ALL_NETS $networks"
}

# parse all the interfaces
# get all the IPs on wan interfaces and store them in restrict_nets
# get all the IPs on all interfaces and store them in ALL_NETS
parse_interfaces()
{
	config_foreach parse_interface "interface"
}


#####
##### parse all lan interfaces section
#####

parse_lan()
{
	local interface=$1
	local nets=""
	local ips=""
	local newips=""
	local ips_changed=0

	[ "$interface" == "loopback" ] && return
	config_get is_lan $interface is_lan
	[ "$is_lan" == "1" ] || return

	network_get_subnets ips $interface

	for ip in $ips ; do
		net="$(get_network_address $ip)"

		if [ "$RESTRICTED_NETS" == "${RESTRICTED_NETS//$net/}" ] ; then
			# net is not in restricted nets
			# append ip to newips
			[ -z "$newips" ] && newips="${ip%/*}" ||  newips="$newips ${ip%/*}"
			continue
		fi

		#net is in RESTRICTED_NETS
		local newnet=$(shift_range $net)
		local newip="$(first_host_in_network $newnet)"
		# append newip to newips
		[ -z "$newips" ] && newips="$newip" ||  newips="$newips $newip"

		ips_changed=1
		logger "$0: Changing the ip on interface $interface from $ip to $newip/${newnet##*/}"
		echo "$0: Changing the ip on interface $interface from $ip to $newip/${newnet##*/}" >/dev/console
	done

	#assign the new ips
	if [ "$ips_changed" == "1" ] ; then
		uci -q set network.$interface.ipaddr="$newips"
	fi
}

# parse all the interface with is_lan=1
parse_lans()
{
	config_foreach parse_lan "interface"
}

#####
##### main
#####

main()
{
	initial_check
	just_one_instance

	config_load network
	parse_interfaces
	parse_lans

	if [ -n "$(uci changes network)" ] ; then
		ubus call uci commit '{"config":"network"}'
	fi
}

main $@