enable dhcp and add helper script for lease setup

config/busybox.config

@@ -1,7 +1,7 @@
 #
 # Automatically generated make config: don't edit
 # Busybox version: 1.25.0
-# Mon Mar 27 14:20:49 2017
+# Mon Mar 27 14:21:05 2017
 #
 CONFIG_HAVE_DOT_CONFIG=y
 
@@ -909,7 +909,7 @@ CONFIG_FEATURE_UDHCPC_SANITIZEOPT=y
 CONFIG_UDHCP_DEBUG=9
 CONFIG_FEATURE_UDHCP_RFC3397=y
 CONFIG_FEATURE_UDHCP_8021Q=y
-CONFIG_UDHCPC_DEFAULT_SCRIPT="/usr/share/udhcpc/default.script"
+CONFIG_UDHCPC_DEFAULT_SCRIPT="/sbin/config-dhcp.sh"
 CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS=80
 CONFIG_IFUPDOWN_UDHCPC_CMD_OPTIONS=""
 # CONFIG_UDPSVD is not set

initrd/init

@@ -1,6 +1,6 @@
 #!/bin/ash
 # First thing it is vital to mount the /dev and other system directories
-mkdir /proc /sys /dev /tmp /boot 2>&- 1>&-
+mkdir /proc /sys /dev /tmp /etc /boot 2>&- 1>&-
 mount -t devtmpfs none /dev
 mount -t proc none /proc
 mount -t sysfs none /sys

initrd/sbin/config-dhcp.sh

@@ -0,0 +1,46 @@
+#!/bin/sh
+
+# udhcpc script
+
+[ -z "$1" ] && echo "Error: should be called from udhcpc" && exit 1
+
+RESOLV_CONF="/etc/resolv.conf"
+[ -n "$broadcast" ] && BROADCAST="broadcast $broadcast"
+[ -n "$subnet" ] && NETMASK="netmask $subnet"
+
+case "$1" in
+	deconfig)
+		grep -q -v ip= /proc/cmdline
+		if [ $? -eq 0 ]; then
+			/sbin/ifconfig $interface up
+		fi
+		grep -q -v nfsroot= /proc/cmdline
+		if [ $? -eq 0 ]; then
+			/sbin/ifconfig $interface 0.0.0.0
+		fi
+		;;
+
+	renew|bound)
+		/sbin/ifconfig $interface $ip $BROADCAST $NETMASK
+
+		if [ -n "$router" ] ; then
+			echo "deleting routers"
+			while route del default gw 0.0.0.0 dev $interface ; do
+				:
+			done
+
+			for i in $router ; do
+				route add default gw $i dev $interface
+			done
+		fi
+
+		echo -n > $RESOLV_CONF
+		[ -n "$domain" ] && echo search $domain >> $RESOLV_CONF
+		for i in $dns ; do
+			echo adding dns $i
+			echo nameserver $i >> $RESOLV_CONF
+		done
+		;;
+esac
+
+exit 0