#!/bin/sh

# Add an initial /var/lib/dhcp/dhclient.leases to make
# sure the IP which dhclient try to renew is the same
# with the IP which kernel got from dhcp server during
# boot
update_dhclient_leases()
{
    local addr=$1
    local interface=$2
    echo "lease {" >> /var/lib/dhcp/dhclient.leases
    echo "  interface \"${addr}\";" >> /var/lib/dhcp/dhclient.leases
    echo "  fixed-address ${interface:0:-3};" >> /var/lib/dhcp/dhclient.leases
    echo "}" >> /var/lib/dhcp/dhclient.leases
}

# In case the interface is used for nfs, skip it.
nfsroot=0
interfaces=""
exec 9<&0 < /proc/mounts
while read dev mtpt fstype rest; do
    if test $mtpt = "/" ; then
        case $fstype in
            nfs | nfs4)
                nfsroot=1
                nfs_addr=`echo $rest | sed -e 's/^.*addr=\([0-9.]*\).*$/\1/'`
                break
                ;;
            *)
                ;;
        esac
    fi
done
exec 0<&9 9<&-


if [ $nfsroot -eq 0 ]; then
    interfaces="$INTERFACES"
else
    if [ -x /bin/ip -o -x /sbin/ip ] ; then
	nfs_iface=`ip route get $nfs_addr | grep dev | sed -e 's/^.*dev \([-a-z0-9.]*\).*$/\1/'`
    fi
    for i in $INTERFACES; do
	if test "x$i" = "x$nfs_iface"; then
            interface_addr=`ip -4 address show $nfs_iface | grep 'inet '|sed 's/.*inet \(\S\+\).*/\1/'`
            if [ "x$interface_addr" != "x" ] && cat /proc/cmdline | grep "ip=dhcp" > /dev/null ; then
                # use to renew lease if needed
                interfaces="$interfaces $i"
                # use to update /var/lib/dhcp/dhclient.leases if needed
                # when the ip got by kernel, we need use dhclient to renew the ip
                update_dhclient_leases $nfs_iface $interface_addr
            else
                echo "dhclient skipping nfsroot interface $i"
            fi
	else
	    interfaces="$interfaces $i"
	fi
    done
fi

if test "x$interfaces" != "x"; then
    /sbin/dhclient -d -cf /etc/dhcp/dhclient.conf -q -lf /var/lib/dhcp/dhclient.leases $interfaces
fi