iankelling.org Git - distro-setup/blob - disabled/home-vpn/lan-dyn-dns-update

   1 #!/bin/bash
   2 # I, Ian Kelling, follow the GNU license recommendations at
   3 # https://www.gnu.org/licenses/license-recommendations.en.html. They
   4 # recommend that small programs, < 300 lines, be licensed under the
   5 # Apache License 2.0. This file contains or is part of one or more small
   6 # programs. If a small program grows beyond 300 lines, I plan to switch
   7 # its license to GPL.
   8
   9 # Copyright 2024 Ian Kelling
  10
  11 # Licensed under the Apache License, Version 2.0 (the "License");
  12 # you may not use this file except in compliance with the License.
  13 # You may obtain a copy of the License at
  14
  15 #     http://www.apache.org/licenses/LICENSE-2.0
  16
  17 # Unless required by applicable law or agreed to in writing, software
  18 # distributed under the License is distributed on an "AS IS" BASIS,
  19 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  20 # See the License for the specific language governing permissions and
  21 # limitations under the License.
  22
  23
  24 # usage: I run this script on a timer to correct the dns on wrt for
  25 # clients where dns is updated dynamically by openvpn, in the case that
  26 # openvpn crashes or the computer running openvpn crashes.
  27
  28 set -eE -o pipefail
  29 trap 'echo "$0:$LINENO:error: \"$BASH_COMMAND\" returned $?" >&2' ERR
  30
  31 x="$(readlink -f "$BASH_SOURCE")"; cd ${x%/*} # directory of this file
  32
  33 while read -r ip host; do
  34     found=false
  35     is_connected="grep -q "^CLIENT_LIST,$host," /run/openvpn-server/status-server.log"
  36     if $is_connected; then continue; fi
  37     if ! grep -q "^CLIENT_LIST,$host," /run/openvpn-server/status-server.log; then
  38         cd $(mktemp -d); dir=$PWD
  39         ssh wrt tar -C /etc -c hosts | tar -x
  40         if grep -qFx "$ip $host" hosts; then continue; fi
  41         # openvpn udpates its status file every 60 seconds by default
  42         if (( $(stat -c%Y hosts) > EPOCHSECONDS + 60 )); then
  43             sleep 60
  44             if $is_connected; then continue; fi
  45         fi
  46         ssh root@wrt.b8.nz cedit ovpn-$host <<<"$ip $host" || [[ $? == 1 ]]
  47     fi
  48 done <lan-dns