#!/bin/bash

# usage: I run this script on a timer to correct the dns on wrt for
# clients where dns is updated dynamically by openvpn, in the case that
# openvpn crashes or the computer running openvpn crashes.

set -eE -o pipefail
trap 'echo "$0:$LINENO:error: \"$BASH_COMMAND\" returned $?" >&2' ERR

x="$(readlink -f "$BASH_SOURCE")"; cd ${x%/*} # directory of this file

while read -r ip host; do
    found=false
    is_connected="grep -q "^CLIENT_LIST,$host," /run/openvpn-server/status-server.log"
    if $is_connected; then continue; fi
    if ! grep -q "^CLIENT_LIST,$host," /run/openvpn-server/status-server.log; then
        cd $(mktemp -d); dir=$PWD
        ssh wrt tar -C /etc -c hosts | tar -x
        if grep -qFx "$ip $host" hosts; then continue; fi
        # openvpn udpates its status file every 60 seconds by default
        if (( $(stat -c%Y hosts) > $(( $(date +%s) + 60 )) )); then
            sleep 60
            if $is_connected; then continue; fi
        fi
        ssh root@wrt.b8.nz cedit ovpn-$host <<<"$ip $host" || [[ $? == 1 ]]
    fi
done <lan-dns