#!/bin/bash

is_serverip6route_set() {
  local server_ip6=${1}

  if [[ -z "${server_ip6}" ]]; then
    return 0
  fi

  if ! ip -6 route | grep -q "^${server_ip6}"; then
    return 1
  fi
}

unset_serverip6route() {
  local server_ip6=${1}
  local ip6_gw=${2}
  local wired_device=${3}

  ip route delete "${server_ip6}/128" via "${ip6_gw}" dev "${wired_device}"
}

wired_device=$(ip route | awk '/default via/ { print $5; }')

# See https://openvpn.net/community-resources/reference-manual-for-openvpn-2-4/#environmental-variables
# to have a list of variables provided by OpenVPN, i.e:
# - ifconfig_ipv6_remote
# - net_gateway_ipv6

# Check old state of the server ipv6 route
if [[ -n "${ifconfig_ipv6_remote}" && -n "${net_gateway_ipv6}" && -n "${wired_device}" ]]; then
  if is_serverip6route_set "${ifconfig_ipv6_remote}"; then
    unset_serverip6route "${ifconfig_ipv6_remote}" "${net_gateway_ipv6}" "${wired_device}"
  fi
fi