#!/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/>.

###################################################################################
# Logging helpers                                                                 #
###################################################################################

LOGFILE="/var/log/ynh-vpnclient.log"
touch $LOGFILE
chown root:root $LOFILE
chmod 600 $LOGFILE

function success()
{
  echo "[ OK ] $1" | tee -a $LOGFILE
}

function info()
{
  echo "[INFO] $1" | tee -a $LOGFILE
}

function warn()
{
  echo "[WARN] $1" | tee -a $LOGFILE >&2
}

function error()
{
  echo "[FAIL] $1" | tee -a $LOGFILE >&2
}

function critical()
{
  echo "[CRIT] $1" | tee -a $LOGFILE >&2
  exit 1
}

###################################################################################
# IPv6 and route config stuff                                                     #
###################################################################################

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

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

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

set_ip6addr() {
  info "Adding IPv6 from VPN configuration"
  ip address add "${ynh_ip6_addr}/128" dev tun0
}

unset_ip6addr() {
  info "Removing IPv6 from VPN configuration"
  ip address delete "${ynh_ip6_addr}/128" dev tun0
}

#
# Server IPv6 route
#

is_serverip6route_set() {
  server_ip6=${1}

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

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

  info "Adding IPv6 server route"
  ip route add "${server_ip6}/128" via "${ip6_gw}" dev "${wired_device}"
}


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

  info "Removing IPv6 server route"
  ip route delete "${server_ip6}/128" via "${ip6_gw}" dev "${wired_device}"
}


###################################################################################
# Hotspot app                                                                     #
###################################################################################

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

is_hotspot_knowme() {
  hotspot_vpnclient=$(ynh_setting_get hotspot vpnclient)

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

###################################################################################
# DNS rules                                                                       #
###################################################################################

is_dns_set() {
  # FIXME : having the ynh_dns0 in the resolv.dnsmasq.conf is not necessarily good enough
  # We want it to be the only one (with ynh_dns1) but nowadays for example ARN's resolver is
  # in the default list from yunohost...
  [ -e /etc/dhcp/dhclient-exit-hooks.d/ynh-vpnclient ]\
  && ( grep -q ${ynh_dns0} /etc/resolv.conf || grep -q ${ynh_dns0} /etc/resolv.dnsmasq.conf )
}

set_dns() {
  info "Enforcing custom DNS resolvers from vpnclient"

  resolvconf=/etc/resolv.conf
  [ -e /etc/resolv.dnsmasq.conf ] && resolvconf=/etc/resolv.dnsmasq.conf

  cp -fa "${resolvconf}" "${resolvconf}.ynh"

  cat << EOF > /etc/dhcp/dhclient-exit-hooks.d/ynh-vpnclient
echo nameserver ${ynh_dns0} > ${resolvconf}
echo nameserver ${ynh_dns1} >> ${resolvconf}
EOF

  bash /etc/dhcp/dhclient-exit-hooks.d/ynh-vpnclient
}

unset_dns() {
  resolvconf=/etc/resolv.conf
  [ -e /etc/resolv.dnsmasq.conf ] && resolvconf=/etc/resolv.dnsmasq.conf

  info "Removing custom DNS resolvers from vpnclient"
  rm -f /etc/dhcp/dhclient-exit-hooks.d/ynh-vpnclient
  mv "${resolvconf}.ynh" "${resolvconf}"

  # FIXME : this situation happened to a user ...
  # We could try to force regen the dns conf 
  # (though for now it's tightly coupled to dnsmasq)
  grep -q "^nameserver" "${resolvconf}" || error "${resolvconf} does not have any nameserver line !?"
}

###################################################################################
# Firewall rules management                                                       #
###################################################################################

is_firewall_set() {
  wired_device=${1}

  ip6tables -w -nvL OUTPUT | grep vpnclient_out | grep -q "${wired_device}"\
  && iptables -w -nvL OUTPUT | grep vpnclient_out | grep -q "${wired_device}"
}

set_firewall() {
  info "Adding vpnclient custom rules to the firewall"

  wired_device=${1}

  cp /etc/yunohost/hooks.d/{90-vpnclient.tpl,post_iptable_rules/90-vpnclient}

  sed "s|<TPL:SERVER_NAME>|${ynh_server_name}|g" -i /etc/yunohost/hooks.d/post_iptable_rules/90-vpnclient
  sed "s|<TPL:SERVER_PORT>|${ynh_server_port}|g" -i /etc/yunohost/hooks.d/post_iptable_rules/90-vpnclient
  sed "s|<TPL:PROTO>|${ynh_server_proto}|g" -i /etc/yunohost/hooks.d/post_iptable_rules/90-vpnclient
  sed "s|<TPL:WIRED_DEVICE>|${wired_device}|g" -i /etc/yunohost/hooks.d/post_iptable_rules/90-vpnclient
  sed "s|<TPL:DNS0>|${ynh_dns0}|g" -i /etc/yunohost/hooks.d/post_iptable_rules/90-vpnclient
  sed "s|<TPL:DNS1>|${ynh_dns1}|g" -i /etc/yunohost/hooks.d/post_iptable_rules/90-vpnclient

  yunohost firewall reload
}

unset_firewall() {
  info "Cleaning vpnclient custom rules from the firewall"
  rm -f /etc/yunohost/hooks.d/post_iptable_rules/90-vpnclient
  yunohost firewall reload
}

###################################################################################
# Time sync                                                                       #
###################################################################################

sync_time() {
  info "Now synchronizing time using ntp..."
  systemctl stop ntp
  timeout 20 ntpd -qg &> /dev/null
  
  # Some networks drop ntp port (udp 123). 
  # Try to get the date with an http request on the internetcube web site
  if [ $? -ne 0 ]; then
    info "ntp synchronization failed, falling back to curl method"
    http_date=`curl -sD - labriqueinter.net | grep '^Date:' | cut -d' ' -f3-6`
    http_date_seconds=`date -d "${http_date}" +%s`
    curr_date_seconds=`date +%s`

    # Set the new date if it's greater than the current date
    # So it does if 1970 year or if old fake-hwclock date is used
    if [ $http_date_seconds -ge $curr_date_seconds ]; then
      date -s "${http_date}"
    fi
  fi 
  systemctl start ntp
}

###################################################################################
# OpenVPN client start/stop procedures                                            #
###################################################################################

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

start_openvpn() {
  info "Preparing openvpn configuration..."

  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

  # Unset firewall to let DNS and NTP resolution works
  # Firewall is reset after vpn is mounted (more details on #1016)
  unset_firewall

  sync_time

  info "Preparing openvpn configuration..."
  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 [ -e /etc/openvpn/keys/user_ta.key ]; then
    sed 's|^<TPL:TA_COMMENT>||' -i /etc/openvpn/client.conf
  else
    sed 's|^<TPL:TA_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

  info "Now actually starting OpenVPN client..."
  systemctl start openvpn@client.service

  if [ ! $? -eq 0 ]
  then
    tail -n 20 /var/log/openvpn-client.log
	critical "Failed to start OpenVPN :/"
  else
    info "OpenVPN client started ... waiting for tun0 interface to show up"
  fi

  for attempt in $(seq 0 20)
  do
    sleep 1
    if ip link show dev tun0 &> /dev/null
    then
       success "tun0 interface is up!"
       return 0
    fi
  done
  
  tail -n 20 /var/log/openvpn-client.log
  error "Tun0 interface did not show up ... possibly an issue with OpenVPN client"
  stop_openvpn && exit 1
}

stop_openvpn() {
  # FIXME : isn't openvpn@client ? (idk)
  info "Stopping OpenVPN service"
  systemctl stop openvpn.service

  info "(Waiting for tun0 to disappear if it was up)"
  for attempt in $(seq 0 20)
  do
    if ip link show dev tun0 &> /dev/null
    then
       sleep 1
    fi
  done
}

###################################################################################
# Yunohost settings interface                                                     #
###################################################################################

ynh_setting_get() {
  app=${1}
  setting=${2}

  grep "^${setting}:" "/etc/yunohost/apps/${app}/settings.yml" | sed s/^[^:]\\+:\\s*[\"\']\\?// | sed s/\\s*[\"\']\$//
}

ynh_setting_set() {
  app=${1}
  setting=${2}
  value=${3}

  yunohost app setting "${app}" "${setting}" -v "${value}"
}

###################################################################################
# The actual ynh vpnclient management thing                                       #
###################################################################################

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_dns_set && is_firewall_set && is_openvpn_running
}


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

  # Restart php-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 php7.0-fpm
  fi

  # Check configuration consistency

  if [[ ! "${1}" =~ stop ]]; then
    if [ ! -e /etc/openvpn/keys/ca-server.crt ]; then
      critical "You need a CA server (you can add it through the web admin)"
    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
      critical "You need either a client certificate, either a username, or both (you can add one through the web admin)"
    fi
  fi

  # Variables

  info "Retrieving Yunohost settings... "

  ynh_service_enabled=$(ynh_setting_get vpnclient service_enabled)
  ynh_server_name=$(ynh_setting_get vpnclient server_name)
  ynh_server_port=$(ynh_setting_get vpnclient server_port)
  ynh_server_proto=$(ynh_setting_get vpnclient server_proto)
  ynh_ip6_addr=$(ynh_setting_get vpnclient ip6_addr)
  ynh_login_user=$(ynh_setting_get vpnclient login_user)
  ynh_dns0=$(ynh_setting_get vpnclient dns0)
  ynh_dns1=$(ynh_setting_get vpnclient dns1)

  old_ip6_gw=$(ynh_setting_get vpnclient ip6_gw)
  old_wired_device=$(ynh_setting_get vpnclient wired_device)
  old_server_ip6=$(ynh_setting_get vpnclient 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}" 2> /dev/null | awk '/IPv6/ { print $NF; }')

  if [ -z "${new_server_ip6}" ]; then
    # FIXME wtf is this hardcoded IP ...
    new_server_ip6=$(host "${ynh_server_name}" 80.67.188.188 2> /dev/null | awk '/IPv6/ { print $NF; }')
  fi

  success "Settings retrieved"

fi

###################################################################################
# Start / stop / restart / status handling                                        #
###################################################################################

case "${1}" in

  # ########## #
  #  Starting  #
  # ########## #

  start)

    if is_running; then
      info "Service is already running"
      exit 0
    elif [ "${ynh_service_enabled}" -eq 0 ]; then
      warn "Service is disabled, not starting it"
      exit 0
    fi

    info "[vpnclient] Starting..."
    touch /tmp/.ynh-vpnclient-started

    # Run openvpn
    if is_openvpn_running;
    then
      info "(openvpn is already running)"
    else
      start_openvpn "${new_ip6_gw}" "${new_server_ip6}"
    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 "${new_server_ip6}"
    then
      set_serverip6route "${new_server_ip6}" "${new_ip6_gw}" "${new_wired_device}"
    fi

    # Set the ipv6 address
    if ! has_hotspot_app && has_ip6delegatedprefix && ! is_ip6addr_set
    then
      set_ip6addr
    fi

    # Set host DNS resolvers
    if ! is_dns_set
    then
       set_dns
    fi

    # Set ipv6/ipv4 firewall
    if ! is_firewall_set "${new_wired_device}"
    then
      set_firewall "${new_wired_device}"
    fi

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

    # Fix configuration
    if has_hotspot_app && ! is_hotspot_knowme; then
      ynh-hotspot start
    fi
  ;;

  # ########## #
  #  Stopping  #
  # ########## #

  stop)
    info "[vpnclient] Stopping..."
    rm -f /tmp/.ynh-vpnclient-started

    if ! has_hotspot_app && has_ip6delegatedprefix && is_ip6addr_set; then
      unset_ip6addr
    fi

    if is_serverip6route_set "${old_server_ip6}"; then
      unset_serverip6route "${old_server_ip6}" "${old_ip6_gw}" "${old_wired_device}"
    fi

    is_firewall_set "${old_wired_device}" && unset_firewall

    is_dns_set && unset_dns

    is_openvpn_running && stop_openvpn

    # Fix configuration
    if has_hotspot_app && is_hotspot_knowme; then
      ynh-hotspot start
    fi
  ;;

  # ########## #
  #  Restart   #
  # ########## #

  restart)
    $0 stop
    $0 start
  ;;

  # ########## #
  #   Status   #
  # ########## #

  status)
    exitcode=0

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

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

    if has_ip6delegatedprefix; then
      info "IPv6 delegated prefix found"
      info "IPv6 address computed from the delegated prefix: ${ynh_ip6_addr}"

      if ! has_hotspot_app; then
        info "No Hotspot app detected"

        if is_ip6addr_set; then
          success "IPv6 address correctly set"
        else
          error "No IPv6 address set"
          exitcode=1
        fi
      else
        info "Hotspot app detected"
        info "No IPv6 address to set"
      fi
    else
      info "No IPv6 delegated prefix found"
    fi

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

      if is_serverip6route_set "${new_server_ip6}"; then
        success "IPv6 server route correctly set"
      else
        error "No IPv6 server route set"
        exitcode=1
      fi
    else
      info "No native IPv6 detected"
      info "No IPv6 server route to set"
    fi

    if is_firewall_set "${new_wired_device}"; then
      success "IPv6/IPv4 firewall set"
    else
      info "No IPv6/IPv4 firewall set"
      exitcode=1
    fi

    if is_dns_set; then
      success "Host DNS correctly set"
    else
      error "No host DNS set"
      exitcode=1
    fi

    if is_openvpn_running; then
      success "Openvpn is running"
    else
      error "Openvpn is not running"
      exitcode=1
    fi

    exit ${exitcode}
  ;;

  # ########## #
  #    Halp    #
  # ########## #

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

exit 0