#!/bin/bash
# I, Ian Kelling, follow the GNU license recommendations at
# https://www.gnu.org/licenses/license-recommendations.en.html. They
# recommend that small programs, < 300 lines, be licensed under the
# Apache License 2.0. This file contains or is part of one or more small
# programs. If a small program grows beyond 300 lines, I plan to change
# to a recommended GPL license.

# Copyright 2024 Ian Kelling

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


# usage: wrt-reip PATTERN
# Removes pattern from dnsmasq leases file and restart dnsmasq.
# PATTERN should generally be an ip or a mac.

pattern=$1

exit_code=0

m() {
    printf "%s\n" "$*";
    "$@"
}

m /etc/init.d/dnsmasq stop

tmp=/tmp/dhcp.leases.iank
sed "/$pattern/d" /tmp/dhcp.leases >$tmp

if (( $(wc -l /tmp/dhcp.leases | awk '{print $1}') - 1 == $(wc -l $tmp | awk '{print $1}') )); then
  echo "info: found one less line after removing $pattern. installing new leases file"
  cp /tmp/dhcp.leases /tmp/dhcp.leases.iank-backup
  cat $tmp >/tmp/dhcp.leases
  m rm -f $tmp
else
  exit_code=1
  cat <<EOF
error: unexpected line count in /tmp/dhcp.leases.iank"
try diffing /tmp/dhcp.leases{,.iank}
EOF
fi

m /etc/init.d/dnsmasq start

m exit $exit_code