#!/bin/bash

# VPN Client app for YunoHost
# Copyright (C) 2015 Julien Vaubourg <julien@vaubourg.com>
# Contribute at https://github.com/labriqueinternet/vpnclient_ynh
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Functions
## State functions

has_nativeip6() {
  ip -6 route | grep -q default\ via
}

has_ip6delegatedprefix() {
  [ "${ynh_ip6_addr}" != none ]
}

has_hotspot_app() {
  [ -e /tmp/.ynh-hotspot-started ]
}

is_hotspot_knowme() {
  gotcha=0

  while [ "${gotcha}" -eq 0 ]; do
    value=$(yunohost app setting hotspot vpnclient)

    if [[ "${value}" =~ "An instance is already running" ]]; then
      sleep $(($((RANDOM%5)) + 1))
    else
      gotcha=1
    fi
  done

  [ "${value}" == yes ]
}

is_ip6addr_set() {
  ip address show dev tun0 2> /dev/null | grep -q "${ynh_ip6_addr}/128"
}

is_serverip6route_set() {
  server_ip6=${1}

  if [ -z "${server_ip6}" ]; then
    false
  else
    ip -6 route | grep -q "${server_ip6}/"
  fi
}

is_openvpn_running() {
  systemctl is-active openvpn@client.service &> /dev/null
}

is_running() {
  ((has_nativeip6 && is_serverip6route_set "${new_server_ip6}") || ! has_nativeip6)\
  && ((! has_hotspot_app && has_ip6delegatedprefix && is_ip6addr_set) || has_hotspot_app || ! has_ip6delegatedprefix)\
  && is_openvpn_running
}

## Setters

set_ip6addr() {
  ip address add "${ynh_ip6_addr}/128" dev tun0
}

set_serverip6route() {
  server_ip6=${1}
  ip6_gw=${2}
  wired_device=${3}

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

start_openvpn() {
  ip6_gw=${1}
  server_ip6=${2}

  if [ ! -z "${ip6_gw}" -a ! -z "${server_ip6}" ]; then
    proto=udp6
    [ "${ynh_server_proto}" == tcp ] && proto=tcp6-client
  else
    proto=udp
    [ "${ynh_server_proto}" == tcp ] && proto=tcp-client
  fi

  cp /etc/openvpn/client.conf{.tpl,}

  sed "s|<TPL:SERVER_NAME>|${ynh_server_name}|g" -i /etc/openvpn/client.conf
  sed "s|<TPL:SERVER_PORT>|${ynh_server_port}|g" -i /etc/openvpn/client.conf
  sed "s|<TPL:PROTO>|${proto}|g" -i /etc/openvpn/client.conf

  if [ -e /etc/openvpn/keys/user.key ]; then
    sed 's|^<TPL:CERT_COMMENT>||' -i /etc/openvpn/client.conf
  else
    sed 's|^<TPL:CERT_COMMENT>|;|' -i /etc/openvpn/client.conf
  fi

  if [[ "${proto}" =~ udp ]]; then
    sed 's|^<TPL:UDP_COMMENT>||' -i /etc/openvpn/client.conf
  else
    sed 's|^<TPL:UDP_COMMENT>|;|' -i /etc/openvpn/client.conf
  fi

  if [ -z "${ynh_login_user}" ]; then
    sed 's|^<TPL:LOGIN_COMMENT>|;|' -i /etc/openvpn/client.conf
  else
    sed 's|^<TPL:LOGIN_COMMENT>||' -i /etc/openvpn/client.conf
  fi

  systemctl start openvpn@client.service
}

## Unsetters

unset_ip6addr() {
  ip address delete "${ynh_ip6_addr}/128" dev tun0
}

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

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

stop_openvpn() {
  systemctl stop openvpn.service
}

## Tools

moulinette_get() {
  var=${1}
  gotcha=0

  while [ "${gotcha}" -eq 0 ]; do
    value=$(yunohost app setting vpnclient "${var}")

    if [[ "${value}" =~ "An instance is already running" ]]; then
      sleep $(($((RANDOM%5)) + 1))
    else
      gotcha=1
    fi
  done

  echo "${value}"
}

moulinette_set() {
  var=${1}
  value=${2}

  msg=$(yunohost app setting vpnclient "${var}" -v "${value}")

  if [ ! $? -eq 0 ]; then
    echo "${msg}" >&2
    exit 1
  fi
}

if [ "$1" != restart ]; then

  # Restart php5-fpm at the first start (it needs to be restarted after the slapd start)
  if [ ! -e /tmp/.ynh-vpnclient-boot ]; then
    touch /tmp/.ynh-vpnclient-boot
    systemctl restart php5-fpm
  fi

  # Check configuration consistency

  if [[ ! "${1}" =~ stop ]]; then
    exitcode=0

    if [ ! -e /etc/openvpn/keys/ca-server.crt ]; then
      echo "[WARN] You need a CA server (you can add it through the web admin)"
      exitcode=1
    fi

    empty=$(find /etc/openvpn/keys/ -empty -name credentials &> /dev/null | wc -l)
    if [ "${empty}" -gt 0 -a ! -e /etc/openvpn/keys/user.key ]; then
      echo "[WARN] You need either a client certificate, either a username, or both (you can add one through the web admin)"
      exitcode=1
    fi

    [ "${exitcode}" -ne 0 ] && exit ${exitcode}
  fi

  # Variables

  echo -n "Retrieving Yunohost settings... "

  ynh_service_enabled=$(moulinette_get service_enabled)
  ynh_server_name=$(moulinette_get server_name)
  ynh_server_port=$(moulinette_get server_port)
  ynh_server_proto=$(moulinette_get server_proto)
  ynh_ip6_addr=$(moulinette_get ip6_addr)
  ynh_login_user=$(moulinette_get login_user)

  old_ip6_gw=$(moulinette_get ip6_gw)
  old_wired_device=$(moulinette_get wired_device)
  old_server_ip6=$(moulinette_get server_ip6)

  new_ip6_gw=$(ip -6 route | grep default\ via | awk '{ print $3 }')
  new_wired_device=$(ip route | awk '/default via/ { print $NF; }')
  new_server_ip6=$(host "${ynh_server_name}" | awk '/IPv6/ { print $NF; }')

  if [ -z "${new_server_ip6}" ]; then
    new_server_ip6=$(host "${ynh_server_name}" 80.67.188.188 | awk '/IPv6/ { print $NF; }')
  fi

  echo "OK"

fi

# Script

case "${1}" in
  start)
    if is_running; then
      echo "Already started"
    elif [ "${ynh_service_enabled}" -eq 0 ]; then
      echo "Disabled service"
    else
      echo "[vpnclient] Starting..."
      touch /tmp/.ynh-vpnclient-started

      # Run openvpn
      if ! is_openvpn_running; then
        echo "Run openvpn"

        start_openvpn "${new_ip6_gw}" "${new_server_ip6}"

        if [ ! $? -eq 0 ]; then
          exit 1
        fi

        i=0; false || while [ $? -ne 0 ]; do
          sleep 1 && (( i++ ))
          [ ${i} -gt 20 ] && stop_openvpn
          [ ${i} -gt 20 ] && exit 1
          ip link show dev tun0 &> /dev/null
        done
      fi

      # Check old state of the server ipv6 route
      if [ ! -z "${old_server_ip6}" -a ! -z "${old_ip6_gw}" -a ! -z "${old_wired_device}"\
           -a \( "${new_server_ip6}" != "${old_server_ip6}" -o "${new_ip6_gw}" != "${old_ip6_gw}"\
           -o "${new_wired_device}" != "${old_wired_device}" \) ]\
         && is_serverip6route_set "${old_server_ip6}"; then

        unset_serverip6route "${old_server_ip6}" "${old_ip6_gw}" "${old_wired_device}"
      fi

      # Set the new server ipv6 route
      if has_nativeip6 && ! is_serverip6route_set "${new_server_ip6}"; then
        echo "Set IPv6 server route"
        set_serverip6route "${new_server_ip6}" "${new_ip6_gw}" "${new_wired_device}"
      fi

      # Set the ipv6 address
      if ! has_hotspot_app && has_ip6delegatedprefix && ! is_ip6addr_set; then
        echo "Set IPv6 address"
        set_ip6addr
      fi

      # Update dynamic settings
      moulinette_set server_ip6 "${new_server_ip6}"
      moulinette_set ip6_gw "${new_ip6_gw}"
      moulinette_set wired_device "${new_wired_device}"

      # Fix configuration
      if has_hotspot_app && ! is_hotspot_knowme; then
        ynh-hotspot start
      fi
    fi
  ;;
  stop)
    echo "[vpnclient] Stopping..."
    rm -f /tmp/.ynh-vpnclient-started

    if ! has_hotspot_app && has_ip6delegatedprefix && is_ip6addr_set; then
      echo "Unset IPv6 address"
      unset_ip6addr
    fi

    if is_serverip6route_set "${old_server_ip6}"; then
      echo "Unset IPv6 server route"
      unset_serverip6route "${old_server_ip6}" "${old_ip6_gw}" "${old_wired_device}"
    fi

    if is_openvpn_running; then
      echo "Stop openvpn"
      stop_openvpn

      i=0; true && while [ $? -eq 0 ]; do
        sleep 1 && (( i++ ))
        [ ${i} -gt 20 ] && exit 1
        ip link show dev tun0 &> /dev/null
      done
    fi

    # Fix configuration
    if has_hotspot_app && is_hotspot_knowme; then
      ynh-hotspot start
    fi
  ;;
  restart)
    $0 stop
    $0 start
  ;;
  status)
    exitcode=0

    if [ "${ynh_service_enabled}" -eq 0 ]; then
      echo "[ERR] VPN Client Service disabled"
      exitcode=1
    fi

    echo "[INFO] Autodetected internet interface: ${new_wired_device} (last start: ${old_wired_device})"
    echo "[INFO] Autodetected IPv6 address for the VPN server: ${new_server_ip6} (last start: ${old_server_ip6})"

    if has_ip6delegatedprefix; then
      echo "[INFO] IPv6 delegated prefix found"
      echo "[INFO] IPv6 address computed from the delegated prefix: ${ynh_ip6_addr}"

      if ! has_hotspot_app; then
        echo "[INFO] No Hotspot app detected"

        if is_ip6addr_set; then
          echo "[OK] IPv6 address correctly set"
        else
          echo "[ERR] No IPv6 address set"
          exitcode=1
        fi
      else
        echo "[INFO] Hotspot app detected"
        echo "[INFO] No IPv6 address to set"
      fi
    else
      echo "[INFO] No IPv6 delegated prefix found"
    fi

    if has_nativeip6; then
      echo "[INFO] Native IPv6 detected"
      echo "[INFO] Autodetected native IPv6 gateway: ${new_ip6_gw} (last start: ${old_ip6_gw})"

      if is_serverip6route_set "${new_server_ip6}"; then
        echo "[OK] IPv6 server route correctly set"
      else
        echo "[ERR] No IPv6 server route set"
        exitcode=1
      fi
    else
      echo "[INFO] No native IPv6 detected"
      echo "[INFO] No IPv6 server route to set"
    fi

    if is_openvpn_running; then
      echo "[OK] Openvpn is running"
    else
      echo "[ERR] Openvpn is not running"
      exitcode=1
    fi

    exit ${exitcode}
  ;;
  *)
    echo "Usage: $0 {start|stop|litestop|restart|status}"
    exit 1
  ;;
esac

exit 0