netcfg/dhclient-script

#!/bin/sh

set -e

# reduced dhclient-script for the Debian installer

# dhclient-script for Linux. Dan Halbert, March, 1997.
# Updated for Linux 2.[12] by Brian J. Murrell, January 1999.
# Modified for Debian.  Matt Zimmerman and Eloy Paris, December 2003

# The alias handling in here probably still sucks. -mdz

make_resolv_conf() {
    if [ -n "$new_domain_name" -a -n "$new_domain_name_servers" ]; then
        local new_resolv_conf=/etc/resolv.conf.dhclient-new
        rm -f $new_resolv_conf
        if [ -n "$new_domain_name" ]; then
            echo search $new_domain_name >>$new_resolv_conf
        fi
        for nameserver in $new_domain_name_servers; do
            echo nameserver $nameserver >>$new_resolv_conf
        done
        mv $new_resolv_conf /etc/resolv.conf
    fi
}

set_hostname() {
    local current_hostname=$(cat /proc/sys/kernel/hostname)
    if [ -z "$current_hostname" -o "$current_hostname" = "(none)" ]; then
        echo "$new_host_name" > /proc/sys/kernel/hostname
    fi
}

release=$(uname -r)
relminor=$(expr $release : '[0-9]*\.[0-9]*\.\([0-9]*\).*')
relmajor=$(expr $release : '[0-9]*\.\([0-9]*\)\..*')
release=$(expr $release : '\([0-9]*\)\..*')

if [ -n "$new_broadcast_address" ]; then
    new_broadcast_arg="broadcast $new_broadcast_address"
fi
if [ -n "$old_broadcast_address" ]; then
    old_broadcast_arg="broadcast $old_broadcast_address"
fi
if [ -n "$new_subnet_mask" ]; then
    new_subnet_arg="netmask $new_subnet_mask"
fi
if [ -n "$old_subnet_mask" ]; then
    old_subnet_arg="netmask $old_subnet_mask"
fi
if [ -n "$alias_subnet_mask" ]; then
    alias_subnet_arg="netmask $alias_subnet_mask"
fi
if [ -n "$new_interface_mtu" ]; then
    mtu_arg="mtu $new_interface_mtu"
fi


# Execute the operation
case "$reason" in
    MEDIUM|ARPCHECK|ARPSEND)
        # Do nothing
        ;;
    PREINIT)
        # The DHCP client is requesting that an interface be
        # configured as required in order to send packets prior to
        # receiving an actual address. - dhclient-script(8)

        if [ -n "$alias_ip_address" ]; then
            # Bring down alias interface. Its routes will disappear too.
            ifconfig $interface:0- inet 0
        fi
        if [ $relmajor -lt 2 ] || ( [ $relmajor -eq 2 ] && [ $relminor -eq 0 ] ); then
            # Older Linux needs this hackery
            ifconfig $interface inet 0.0.0.0 netmask 0.0.0.0 \
		broadcast 255.255.255.255 up
            route add default dev $interface netmask 0.0.0.0
        else
            # Newer Linux doesn't
            ifconfig $interface 0 up
        fi

        # We need to give the kernel some time to get the interface up.
        sleep 1
        ;;
    BOUND|RENEW|REBIND|REBOOT)

        set_hostname
        
        if [ -n "$old_ip_address" -a -n "$alias_ip_address" -a \
             "$alias_ip_address" != "$old_ip_address" ]; then
            # Possible new alias. Remove old alias.
            ifconfig $interface:0- inet 0
        fi

        if [ -n "$old_ip_address" -a \
             "$old_ip_address" != "$new_ip_address" ]; then
            # IP address changed. Bringing down the interface will delete all routes,
            # and clear the ARP cache.
            ifconfig $interface inet 0 down

        fi

        if [ -z "$old_ip_address" -o "$old_ip_address" != "$new_ip_address" -o \
            "$reason" = "BOUND" -o "$reason" = "REBOOT" ]; then

            ifconfig $interface $new_ip_address $new_subnet_arg \
                $new_broadcast_arg $mtu_arg

            if [ $relmajor -lt 2 ] || \
		( [ $relmajor -eq 2 ] && [ $relminor -eq 0 ] ); then
                # Ancient kernel: add a network route to the computed network address.
                route add -net $new_network_number $new_subnet_arg dev $interface
            fi

            for router in $new_routers; do
                route add default gw $router
            done
        fi

        if [ "$new_ip_address" != "$alias_ip_address" -a -n "$alias_ip_address" ];
            then
            ifconfig $interface:0- inet 0
            ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
            route add -host $alias_ip_address $interface:0
        fi

        make_resolv_conf

        ;;

    EXPIRE|FAIL|RELEASE|STOP)
        if [ -n "$alias_ip_address" ]; then
            # Turn off alias interface.
            ifconfig $interface:0- inet 0
        fi

        if [ -n "$old_ip_address" ]; then
            # Shut down interface, which will delete routes and clear arp cache.
            ifconfig $interface inet 0 down
        fi

        if [ -n "$alias_ip_address" ]; then
            ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
            route add -host $alias_ip_address $interface:0
        fi

        ;;

    TIMEOUT)
        if [ -n "$alias_ip_address" ]; then
            ifconfig $interface:0- inet 0
        fi

        ifconfig $interface inet $new_ip_address $new_subnet_arg \
            $new_broadcast_arg $mtu_arg

        set -- $new_routers
        first_router="$1"

        if ping -q -c 1 $first_router; then
            if [ "$new_ip_address" != "$alias_ip_address" -a \
                -n "$alias_ip_address" ]; then
                ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
                route add -host $alias_ip_address dev $interface:0
            fi

            if [ $relmajor -lt 2 ] || \
		( [ $relmajor -eq 2 ] && [ $relminor -eq 0 ] ); then
                route add -net $new_network_number
            fi

            for router in $new_routers; do
                route add default gw $router
            done

            make_resolv_conf
        else
            # Changed from 'ifconfig $interface inet 0 down' - see Debian bug #144666
            ifconfig $interface inet 0
            exit 2
        fi

        ;;
esac

exit 0