udhcpc config script

gistfile1.sh

#!/bin/sh

# udhcpc config script

# $interface is the name of the device udhcpc is using
# $router is the (space_separated) list of gateways
# $broadcast is the broadcast address
# $ip is the ip address that we get from the dhcp server
# $dns is the list of dns servers we get from the dhcp server
# $domain is the domain of the network

# constants for the resolv.conf and backup files
resolv_conf="/etc/resolv.conf"
resolv_bak="/etc/resolv.backup_dhcp"


case $1 in
    deconfig)
        # deconfig - put the interface up but deconfigured
        # called when udhcpc is started or a lease is lost

        # replace resolv.conf with the backup, if the backup exists:
        if [ -f "$resolv_bak" ]; then
            mv "$resolv_bak" "$resolv_conf"
        fi
        
        # set the interface's address to 0.0.0.0 for now
        ifconfig $interface 0.0.0.0;;

    renew|bound)
        # renew - lease is renewed
        # bound - move from unbound to bound state
        
        # configure the interface with the given ip, broadcast address, and netmask
        ifconfig $interface $ip ${broadcast:+broadcast $broadcast} ${subnet:+netmask $subnet}

        # for each given gateway, overwrite the defaults??? hell if I know.
        for i in $router; do
            route add default gw $i dev $interface
        done
        
        #
        if [ ! -f "$resolv_bak" ] && [ -f "$resolv_conf" ]; then
            mv "$resolv_conf" "$resolv_bak"
        fi

        # clear `resolv.conf`
        echo -n "" > "$resolv_conf"
        
        # if there's a domain given, add it to `resolv.conf`.
        if [ -n "$domain" ]; then
            echo "search $domain" >> "$resolv_conf"
        fi
    
        # for each given dns server, add it to `resolv.conf`.
        for i in $dns; do
            echo "nameserver $i" >> "$resolv_conf"
        done;;
esac

exit 0

# adapted from http://lists.debian.org/debian-boot/2002/11/msg00500.html