#!/bin/sh
# -*- mode: shell-script; coding: utf-8 -*-
#
# hostlocal
#
# Script to test whether given host is on the local network.
#
# Copyright (C) 2021 Elmar Hoffmann
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#

set -e

if [ $# -ne 1 ]; then
    echo "Usage: $(basename -- "$0") HOSTNAME"
    exit 2
fi

host="${1}"

ip="$(getent ahostsv4 "${host}" | sed --quiet --expression='s/^\([[:xdigit:]:.]\+\)[[:space:]]\+STREAM[[:space:]]\+.*$/\1/p' | head --lines=1)"

if [ -z "${ip}" ]
then
    exit 1
fi

gateway="$(ip route get "${ip}" | sed --quiet --expression='s/^[[:xdigit:]:.]\+[[:space:]]\+via[[:space:]]\+\([[:xdigit:]:.]\+\)[[:space:]]\+dev[[:space:]]\+[[:alnum:]]\+[[:space:]]\+.*$/\1/p')"

test -z "${gateway}"
