busybox/examples/var_service/dhcp_if/dhcp_handler

#!/bin/sh
# executed by udhcpc
# parameters: $1 and environment
#
# $1 is:
# deconfig: This argument is used when udhcpc starts, and
# when a leases is lost. The script should put the interface in an
# up, but deconfigured state, ie: ifconfig $interface 0.0.0.0.
#
# bound: This argument is used when udhcpc moves from an
# unbound, to a bound state. All of the paramaters are set in
# enviromental variables, The script should configure the interface,
# and set any other relavent parameters (default gateway, dns server,
# etc).
#
# renew: This argument is used when a DHCP lease is renewed. All of
# the paramaters are set in enviromental variables. This argument is
# used when the interface is already configured, so the IP address,
# will not change, however, the other DHCP paramaters, such as the
# default gateway, subnet mask, and dns server may change.
#
# nak: This argument is used with udhcpc receives a NAK message.
# The script with the deconfig argument will be called directly
# afterwards, so no changes to the network interface are neccessary.
# This hook is provided for purely informational purposes (the
# message option may contain a reason for the NAK).
#
# env shows something like:
# dhcptype=5
# serverid=172.16.42.102
# lease=97200
# interface=eth0
# ip=172.16.42.177
# subnet=255.255.255.0
# mask=24
# broadcast=172.16.22.255
# router=172.16.42.98
# dns=10.34.32.125 10.32.63.5 10.34.255.7 10.11.255.27
# domain=lab.example.com example.com
# ntpsrv=10.34.32.125 10.34.255.7

# TODO: put domain into /etc/resolv.conf (thru /var/service/fw)
# TODO: feed ntp IPs to /var/service/ntp

service=${PWD##*/}
file_ipconf="$service.ipconf"
file_ntpconf="$service.ntpconf"
dir_ipconf="/var/run/service/fw"
dir_ntpconf="/var/run/service/ntp"

exec >/dev/null
#exec >>"$0.out"  #debug
exec 2>&1

echo "`date`: Params: $*"

if test x"$1" != x"bound" && test x"$1" != x"renew" ; then
	# Reconfigure network with this interface disabled
	echo "Deconfiguring"
	rm "$service.out"
	rm "$file_ipconf"
	rm "$file_ntpconf"
	rm "$dir_ipconf/$file_ipconf"
	rm "$dir_ntpconf/$file_ntpconf"
	sv u /var/service/fw
	exit
fi

# Bound: we've got the lease
#env >"$service.out"  # debug

./convert2ipconf  "$file_ipconf"
# Reconfigure routing and firewall if needed
diff --brief "$file_ipconf" "$dir_ipconf/$file_ipconf" >/dev/null 2>&1
if test "$?" != "0"; then
	echo "Reconfiguring fw"
	mkdir -p "$dir_ipconf" 2>/dev/null
	cp "$file_ipconf" "$dir_ipconf/$file_ipconf"
	sv u /var/service/fw
fi

./convert2ntpconf "$file_ntpconf"
# Reconfigure ntp server addresses if needed
diff --brief "$file_ntpconf" "$dir_ntpconf/$file_ntpconf" >/dev/null 2>&1
if test "$?" != "0"; then
	echo "Reconfiguring ntp"
	mkdir -p "$dir_ntpconf" 2>/dev/null
	cp "$file_ntpconf" "$dir_ntpconf/$file_ntpconf"
	sv t /var/service/ntp
	sv u /var/service/ntp
fi