#!/bin/sh -
#
#	@(#)rblookup            e07@nikhef.nl (Eric Wassenaar) 990127
#
# Author:	E.Wassenaar, Nikhef-H
# Version:	11-NOV-1997
# Revision:	02-NOV-1998, Select MAPS (default) or alternatively ORBS
# Revision:	07-NOV-1998, Anticipate hosts with multiple addresses
# Revision:	27-JAN-1999, ORBS has moved to a new site
#
# Lookup a dotted quad IP address in the Realtime Blackhole List
# of the Mail Abuse Prevention System. See: http://maps.vix.com/rbl
#
#	Syntax:
#		rblookup hostname
#		rblookup -i dottedquad
#
#	Returns:
#		zero if the given host was found on the blacklist.
#		nonzero if not, or if undetermined.
#
# The RBL is an on-line, dynamically updated database of spam hosts,
# maintained via the DNS. The search key is the reversed dotted quad
# IP address of the given host, within the zone "rbl.maps.vix.com".
# A query should be done for an A resource record. If it exists, the
# given host is blacklisted as a notorious spam host. The value of the
# retrieved A record is irrelevant and can be ignored. Additional info
# may be found via an extra query for a TXT resource record.
#
# The RBL data in the DNS is replicated by several nameservers, using
# a refresh time of 10 minutes. The TTL for local caching is 5 minutes.
# The RBL nameservers do not allow zone transfers from arbitrary hosts,
# thereby preventing the setup of a stealth server, unless you sign a
# non-proliferation agreement (and you are running BIND version 8).
#
# This script is just an example of a quick and dirty wrapper for the
# ``host'' utility. The technique can relatively easy be integrated 
# into MTA programs like sendmail.

exec=echo
exec=

# ----------------------------------------------------------------------
# Setup environment.
# ----------------------------------------------------------------------

# This is where the ``host'' executable lives.
BINDIR=/usr/local/bin

PATH=${BINDIR}:/bin:/usr/bin:/usr/ucb ; export PATH

cmd=`basename $0`

options="[-maps] [-orbs] [-i] [-v]"
usage="Usage: $cmd $options hostname"

# ----------------------------------------------------------------------
# Configuration.
# ----------------------------------------------------------------------

MAPSROOT="rbl.maps.vix.com"
ORBSROOT="relays.orbs.org"

# ----------------------------------------------------------------------
# Exit codes from <sysexits.h>
# ----------------------------------------------------------------------

EX_OK=0
EX_USAGE=64
EX_UNAVAILABLE=69

# ----------------------------------------------------------------------
# Auxiliary routines.
# ----------------------------------------------------------------------

fatal ()
{
	message="$*"
	echo "$message" 1>&2
	exit $EX_USAGE
}

# ----------------------------------------------------------------------
# Process options.
# ----------------------------------------------------------------------

verbose=
reverse=
orbs=

skip=
for i
do
	[ $skip ] && skip= && continue

	case "$i" in
	-orbs)	orbs=true ;;
	-maps)	orbs= ;;
	-i)	reverse=true ;;
	-v)	verbose="-v" ;;
	-d)	exec=echo ;;
	-*)	fatal "$cmd: Unknown option $i" ;;
	*)	break ;;
	esac
	shift
done

# ----------------------------------------------------------------------
# Process arguments.
# ----------------------------------------------------------------------

name="$1"

[ "X$name" = "X" ] && fatal "$usage"

# Remove trailing dots.
name=`echo $name | sed 's/\.*$//'`

if [ $reverse ]
then
	# Assume this is already a dotted quad.
	addresslist="$name"
else
	# Try to resolve domain name into dotted quad.
	addresslist=`host "$name" | awk '$2 == "A" {print $3}'`
fi

# ----------------------------------------------------------------------
# Auxiliary routines.
# ----------------------------------------------------------------------

invalid ()
{
	fatal "Invalid dotted quad $address"
}

numeric ()
{
	[ "X$1" = "X" ] && invalid

	# Must be numeric.
	value=`expr $1 + 0` ; [ "X$value" = "X" ] && invalid

	# Must be in range.
	[ "$value" -lt 0 -o "$value" -gt 255 ] && invalid

	return $EX_OK
}

invert ()
{
	labels=`echo "$address" | sed -e 's/\./ /g'`
	set - $labels
	case "$#" in
	1)
		numeric $1
		reversed="0.0.0.$1"
		;;
	2)
		numeric $1 && numeric $2
		reversed="0.0.$2.$1"
		;;
	3)
		numeric $1 && numeric $2 && numeric $3
		reversed="0.$3.$2.$1"
		;;
	4)
		numeric $1 && numeric $2 && numeric $3 && numeric $4
		reversed="$4.$3.$2.$1"
		;;
	*)
		invalid
		;;
	esac
}

# ----------------------------------------------------------------------
# Main procedure.
# ----------------------------------------------------------------------

exitstat=$EX_UNAVAILABLE

for address in $addresslist
do
	# Swap dotted quad labels.
	invert

	# Construct proper name in map.
	[ $orbs ] && map="$ORBSROOT" || map="$MAPSROOT"
	name="$reversed.$map"

	echo "--- $name ---"
	$exec host $verbose -t A $name
	found=$?
	[ $found -eq $EX_OK ] && exitstat=$EX_OK
	[ $found -eq $EX_OK ] && $exec host $verbose -t TXT $name
done

exit $exitstat