#!/bin/sh

function saveFile {

	file=$1
	save=$1.save
	dhcp=$1.dhcp

	test -f $dhcp || return 0
	test -f $save || cp $file $save
	mv $dhcp $file
	return 0
}

function restoreFile {

	file=$1
	save=$1.save

	test -f $save && mv $save $file
	return 0
}

interface=$1
HostFile="/etc/hosts" 
DHCPHostFile="${HostFile}.dhcp" 
MYCURRENTHOSTNAME=$(/bin/hostname)
MYCURRENTDOMAIN=$(/bin/dnsdomainname)

case $0 in
*ifup*)
	echo "Trying to obtain network configuration via DHCP."

	/sbin/dhcpcd -HD $interface >/dev/null || {
		echo "No response from DHCP server" >&2
		exit 1
	}

	if test -f /var/run/dhcpcd-$interface.info; then
		. /var/run/dhcpcd-$interface.info
		if test -n "$NISDOMAIN"; then
			cat >/etc/nis.conf.dhcp <<-EOF
			#
			# Generated by DHCP boot script
			#
			EOF
			if test -n "$NISSERVER"; then
				echo "domainname $NISDOMAIN server $NISSERVER"
			else
				echo "domainname $NISDOMAIN broadcast"
			fi >> /etc/nis.conf.dhcp
		fi

################################################################################  
# 
# Update /etc/hosts file with Hostname, DomainName, and IPAddress from DHCP 
# 
# Assumes that hosts file is in the format : 
# 
# <<<<IP-Address Fully-Qualified-Hostname Short-Hostname>>>> 
# 
# And that IPADDR, HOSTNAME and DOMAIN are configure by DHCP.
#
# NOTES:  
#           1.  The Update Logic will handle the situation where the
#               DHCP Server returns a Fully Qualified Domain Name
#               for the HOSTNAME.  From the FQDN, the logic generates
#               a Short HOSTNAME that is compatible with the 
#               /etc/hosts notation.
#           2.  The Update Logic will not modify the /etc/hosts file
#               if a duplicate entry exists.
#           3.  The Update Logic will use the current HOSTNAME if the
#               DHCP Server does not provide a HOSTNAME Setting.
#           4.  The Update Logic will use the current DNS DOMAIN Name
#               if the DHCP Server does not provide DOMAIN NAME
#               Setting.
#
#           *** WARNING **** With respect to Items 3 and 4, this logic 
#           may be a problem on Multi-Homed Systems (i.e. Multiple NICs 
#           with multiple Subnet Connections).  To disable this logic, 
#           modify the below "INHIBITDEFAULTS" variable to "TRUE", 
#           otherwise, set to "FALSE".
#
# 
################################################################################ 

		INHIBITDEFAULTS="FALSE"
 
		if [ -z "${HOSTNAME}" ] && [ -n "${MYCURRENTHOSTNAME}" ] && [ ${INHIBITDEFAULTS} = "FALSE" ]
     		then
			HOSTNAME=${MYCURRENTHOSTNAME}
  		fi

		if [ -z "${DOMAIN}" ] && [ -n "${MYCURRENTDOMAIN}" ] && [ ${INHIBITDEFAULTS} = "FALSE" ]
   		then
 			DOMAIN=${MYCURRENTDOMAIN}
 		fi

		if [ -n "${IPADDR}" ] && [ -n "${HOSTNAME}" ] && [ -n "${DOMAIN}" ]
 		then
			/usr/bin/awk -v a="${IPADDR}" -v b="${HOSTNAME}" -v c="${DOMAIN}" '
			BEGIN	{
				IPADDR		= a
                                HOSTIDX         = match(b,/[[:punct:]]/)
  				if (HOSTIDX == 0)
				{
 					HOSTNAME = b
				}
				else
				{
					HOSTNAME = substr(b,1,HOSTIDX-1)
  				}
				DOMAIN		= c
 				FQDN		= sprintf("%s.%s", HOSTNAME, DOMAIN)
				MATCHENTRY	= 0
  				}
			{
			if((substr($0,1, 1) == "#") || (($1 != IPADDR) && ($2 != FQDN) && ($3 !=HOSTNAME)))
				{
 				print $0
				}
			else
				{
				if (($1 == IPADDR) && ($2 == FQDN) && ($3 == HOSTNAME))
 					{ 			
					MATCHENTRY=1
 					print $0
					}
				else
					{
					printf ("# Commented by DHCPCD configscripts: %s\n", $0)
 					}
				}
			} 
			END	{
			if (MATCHENTRY == 0)
				{
				print "#The following entry added by DHCPCD configuration scripts"
				printf("%s\t%s\t%s\n",IPADDR,FQDN,HOSTNAME)
				}
 			}' ${HostFile} > ${DHCPHostFile}

			saveFile ${HostFile} 
		fi 

	fi

	saveFile /etc/nis.conf
	saveFile /etc/resolv.conf
	: ;;
*ifdown*)
	echo "Shutting down DHCP daemon."
	/sbin/dhcpcd -k $interface

	restoreFile /etc/nis.conf
	restoreFile /etc/resolv.conf
	restoreFile ${HOSTFILE}
	: ;;
*)
	echo "$0: unknown mode of operation for DHCP script" >&2
	exit 1;;
esac

exit 0