dhcpd_to_unbound -- add dhcpd entries as local_data to unbound

dhcpd_to_unbound

#!/bin/sh

#
# Copyright (c) 2017, 2019 Aaron Poffenberger <akp@hypernote.com>
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#

#
# Add dhcpd(8) entries as local_data to unbound(8).
#
# v1.0.0
#
# Add host assignments from:
# /etc/dhcpd.conf
# /var/db/dhcpd.leases
#
# Clears existing entries for DOMAIN_NAME.
#
# Adds one entry per `host` declaration in `/etc/dhcpd.conf`
#
# Adds one unique entry per `hardware ethernet` (MAC address)
# in `/var/db/dhcpd.leases` (with hostname)
#
# Adds reverse lookup records.
#
# This script should be run regularly from cron(8). E.g.
# */3	*	*	*	*	dhcpd_to_unbound
# @reboot				dhcpd_to_unbound
#
# BUGS:
#	Probably doesn't work with IPv6.
#
#	Does not validate unbound(8) or dhcpd(8) are running.
#
#	Only works with the first `option domain-name` found
#	in /etc/dhcpd.conf, meaning it assumes all clients
#	found in `/var/db/dhcpd.leases` belong to first the
#	`option domain-name` found.


__progname="${0##*/}"

CONF='/etc/dhcpd.conf'
LEASES='/var/db/dhcpd.leases'
TMP_FILE='/tmp/dhcpd_to_unbound'
CUR_DATA='/tmp/dhcpd_to_unbound_cur_data'
UC_FLAGS='-q'


[ -f "$TMP_FILE" ] && exit


err() { log "$__progname: $*"; }
log() { printf "%s\\n" "$*" > /dev/stderr; }


[ ! -f "$CONF" ] && err "No $CONF file" && exit 1
[ ! -f "$LEASES" ] && err "No $LEASES file" && exit 1


cleanup() {
	trap "" EXIT
	rm -f "$TMP_FILE" "$CUR_DATA"
}
trap cleanup EXIT INT QUIT
touch "$TMP_FILE"


while getopts :c:hl:sv opt ; do
	case $opt in
		c)
			CONF="$OPTARG"
			;;
		h)
			CMD="usage"
			;;
		l)
			LEASES="$OPTARG"
			;;
		s)
			CMD=show
			;;
		v)
			unset UC_FLAGS
			;;
		:)
			echo "$__progname: option requires an argument" \
				"-- $OPTARG"
			CMD=abort
			;;
		\?)
			echo "$__progname: invalid option -- $OPTARG"
			CMD=abort
			;;
	esac
done
shift $(( OPTIND - 1 ))


DOMAIN_NAME=$(grep 'domain-name ' "$CONF" | \
	head -n1 | cut -d ' ' -f 3 | tr -d ';"')


case ${CMD:-run} in
	abort)
		exit;
		;;
	usage)
		log "usage: $__progname [-c file] [-h] [-l file] [-s] [-v]"
		log "  -c    path to conf to use instead of ${CONF}."
		log "  -h    this message."
		log "  -l    path to leases file to use instead of ${LEASES}."
		log "  -s    show unbound entries for the specified domain."
		log "  -v    verbose."
		exit
		;;
	show)
		unbound-control list_local_data | grep "$DOMAIN_NAME"
		exit
		;;
esac


# /etc/dhcpd.conf
grep -E 'host|fixed-address|{|}' "$CONF" \
	| grep -v subnet \
	| tr -d '\t' \
	| sed 's#host ##g' \
	| tr -d '\n' \
	| tr '{' ';' \
	| tr '}' '\n' \
	| tr -s ' ' \
	| tr -d '";' \
	| sort -k3 \
	| awk 'NF == 3 { print $3, $1 }' \
	> "$TMP_FILE"


# /var/db/dhcpd.leases
grep -E 'lease|starts|ends|hardware ethernet|abandoned|client-hostname|}' \
	"$LEASES" \
	| tr -d '\t' \
	| sed 's#starts [0-9]##g ; s#ends [0-9]##g ; s# UTC##g ; s#lease ##g ; s#{#;#g' \
	| tr -d '\n' \
	| tr '}' '\n' \
	| sed 's# *; *#;#g' \
	| awk -v cur_ts="$(date +%s)" '
	BEGIN { FS=";" }
	$0 !~ /abandon/ {
		end_ts = strptime($3)
		if ( length(end_ts) == 0 || cur_ts > end_ts ) { exit }

		split($4, hardwares, " ")
		mac = hardwares[3]
		if ( split($5, clients, " ") == 2) {
			hostname = clients[2]
			gsub("\"", "", hostname)
		} else {
			# use the MAC address as the hostname if none found
			hostname = mac
			gsub(":", "_", hostname)
		}

		print $1, hostname
	}


	# a static implementation .. only knows one format
	function strptime(str,		 elems, times, dt) {
		split(str, elems, " ")
		gsub("\/", "", elems[1])
		split(elems[2], times, ":")
		cmd = sprintf("date -uj \"+%s\" %s%s%s.%s\n",
			"%s", elems[1], times[1], times[2], times[3])
		cmd | getline dt
		return dt
	}

'	| sort -k5 -k4r \
	| uniq -f1 \
	>> "$TMP_FILE"


[ -z "$UC_FLAGS" ] && log "Add host entries for $DOMAIN_NAME to" \
	"unbound"


# remove all addresses for $DOMAIN_NAME
unbound-control $UC_FLAGS list_local_data | grep "$DOMAIN_NAME" \
	| cut -f 1 \
	| sed 's#.$##g' \
	> "$CUR_DATA"
unbound-control $UC_FLAGS local_datas_remove < "$CUR_DATA"


# load new data
awk -v domain_name="$DOMAIN_NAME" '
	{
		rev_ip = reverse_ip($1)
		printf("%s.%s IN A %s\n", $2, domain_name, $1)
		printf("%s.in-addr.arpa. IN PTR %s.%s\n",
			rev_ip, $2,domain_name)
	}

	function reverse_ip(ip,		 elems) {
		split(ip, elems, ".")
		rev_ip = sprintf("%s.%s.%s.%s",
			elems[4], elems[3], elems[2], elems[1])
		return rev_ip
	}
'	"$TMP_FILE" \
	| unbound-control $UC_FLAGS local_datas

Nice! Thanks for the comment.

…

--Aaron

On 2020-12-09 18:31 +0000, Michael Zhilin ***@***.***> wrote: Thank you for inspiration! https://github.com/mizhka/jdhcp2dns -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: https://gist.github.com/1c1b994a7b51dab34d1413ca7eab0628#gistcomment-3555961