#!/usr/bin/env bash
# Copyright (C) 2020 Private Internet Access, Inc.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# This function allows you to check if the required tools have been installed.
check_tool() {
  cmd=$1
  if ! command -v "$cmd" >/dev/null; then
    echo "$cmd could not be found"
    echo "Please install $cmd"
    exit 1
  fi
}

# Now we call the function to make sure we can use openvpn, curl and jq.
check_tool openvpn
check_tool curl
check_tool jq

# Check if terminal allows output, if yes, define colors for output
if [[ -t 1 ]]; then
  ncolors=$(tput colors)
  if [[ -n $ncolors && $ncolors -ge 8 ]]; then
    red=$(tput setaf 1) # ANSI red
    green=$(tput setaf 2) # ANSI green
    nc=$(tput sgr0) # No Color
  else
    red=''
    green=''
    nc='' # No Color
  fi
fi

# Check if manual PIA OpenVPN connection is already initialized.
# Multi-hop is out of the scope of this repo, but you should be able to
# get multi-hop running with both OpenVPN and WireGuard.
adapter_check=$( ip a s tun06 2>&1 )
should_read="Device \"tun06\" does not exist"
pid_filepath="/opt/piavpn-manual/pia_pid"
if [[ $adapter_check != *"$should_read"* ]]; then
  echo -e "${red}The tun06 adapter already exists, that interface is required"
  echo -e "for this configuration.${nc}"
  if [[ -f $pid_filepath ]]; then
    old_pid=$( cat "$pid_filepath" )
    old_pid_name=$( ps -p "$old_pid" -o comm= )
    if [[ $old_pid_name == "openvpn" ]]; then
      echo
      echo -e "It seems likely that process ${red}$old_pid${nc} is an OpenVPN connection"
      echo "that was established by using this script. Unless it is closed"
      echo "you would not be able to get a new connection."
      echo -ne "Do you want to run ${red}$ kill $old_pid${nc} (Y/n): "
      read -r close_connection
    fi
    if echo "${close_connection:0:1}" | grep -iq n; then
      echo -e "${red}Closing script. Resolve tun06 adapter conflict and run the script again."
      exit 1
    fi
    echo
    echo -e "${green}Killing the existing OpenVPN process and waiting 5 seconds...${nc}"
    kill "$old_pid"
    echo
    for i in {5..1}; do
      echo -n "$i..."
      sleep 1
      done
    echo
    echo
  fi
fi

# PIA currently does not support IPv6. In order to be sure your VPN
# connection does not leak, it is best to disabled IPv6 altogether.
# IPv6 can also be disabled via kernel commandline param, so we must
# first check if this is the case.
if [[ -f /proc/net/if_inet6 ]] &&
  [[ $(sysctl -n net.ipv6.conf.all.disable_ipv6) -ne 1 ||
     $(sysctl -n net.ipv6.conf.default.disable_ipv6) -ne 1 ]]
then
  echo -e "${red}You should consider disabling IPv6 by running:"
  echo "sysctl -w net.ipv6.conf.all.disable_ipv6=1"
  echo -e "sysctl -w net.ipv6.conf.default.disable_ipv6=1${nc}"
fi

# Check if the mandatory environment variables are set.
if [[ -z $OVPN_SERVER_IP ||
      -z $OVPN_HOSTNAME ||
      -z $PIA_TOKEN ||
      -z $CONNECTION_SETTINGS ]]; then
  echo -e "${red}This script requires 4 env vars:"
  echo "PIA_TOKEN           - the token used for authentication"
  echo "OVPN_SERVER_IP      - IP that you want to connect to"
  echo "OVPN_HOSTNAME       - name of the server, required for ssl"
  echo "CONNECTION_SETTINGS - the protocol and encryption specification"
  echo "                    - available options for CONNECTION_SETTINGS are:"
  echo "                        * openvpn_udp_standard"
  echo "                        * openvpn_udp_strong"
  echo "                        * openvpn_tcp_standard"
  echo "                        * openvpn_tcp_strong"
  echo
  echo "You can also specify optional env vars:"
  echo "PIA_PF                - enable port forwarding"
  echo "PAYLOAD_AND_SIGNATURE - In case you already have a port."
  echo
  echo "An easy solution is to just run get_region_and_token.sh"
  echo "as it will guide you through getting the best server and"
  echo "also a token. Detailed information can be found here:"
  echo -e "https://github.com/pia-foss/manual-connections${nc}"
  exit 1
fi

splitToken="dedicated_ip_$DIP_TOKEN"

# Create a credentials file with the login token
echo -n "Trying to write /opt/piavpn-manual/pia.ovpn..."
mkdir -p /opt/piavpn-manual
rm -f /opt/piavpn-manual/credentials /opt/piavpn-manual/route_info

if [[ -z $DIP_TOKEN ]]; then
  echo "${PIA_TOKEN:0:62}
${PIA_TOKEN:62}" > /opt/piavpn-manual/credentials || exit 1
  chmod 600 /opt/piavpn-manual/credentials
else
  echo "${splitToken:0:62}
${splitToken:62}" > /opt/piavpn-manual/credentials || exit 1
  chmod 600 /opt/piavpn-manual/credentials
fi
echo -e "${green}OK!${nc}"

# Translate connection settings variable
IFS='_'
read -ra connection_settings <<< "$CONNECTION_SETTINGS"
IFS=' '
protocol=${connection_settings[1]}
encryption=${connection_settings[2]}

prefix_filepath="openvpn_config/standard.ovpn"
if [[ $encryption == "strong" ]]; then
  prefix_filepath="openvpn_config/strong.ovpn"
fi

if [[ $protocol == "udp" ]]; then
  if [[ $encryption == "standard" ]]; then
    port=1198
  else
    port=1197
  fi
else
  if [[ $encryption == "standard" ]]; then
    port=502
  else
    port=501
  fi
fi

# Create the OpenVPN config based on the settings specified
cat "$prefix_filepath" > /opt/piavpn-manual/pia.ovpn || exit 1
echo "remote $OVPN_SERVER_IP $port $protocol" >> /opt/piavpn-manual/pia.ovpn

# Copy the up/down scripts to /opt/piavpn-manual/
# based upon use of PIA DNS
if [[ $PIA_DNS != "true" ]]; then
  cp openvpn_config/openvpn_up.sh /opt/piavpn-manual/
  cp openvpn_config/openvpn_down.sh /opt/piavpn-manual/
  echo -e "${red}This configuration will not use PIA DNS.${nc}"
  echo "If you want to also enable PIA DNS, please start the script"
  echo "with the env var PIA_DNS=true. Example:"
  echo $ OVPN_SERVER_IP=\""$OVPN_SERVER_IP"\" OVPN_HOSTNAME=\""$OVPN_HOSTNAME"\" \
    PIA_TOKEN=\""$PIA_TOKEN"\" CONNECTION_SETTINGS=\""$CONNECTION_SETTINGS"\" \
    PIA_PF=true PIA_DNS=true ./connect_to_openvpn_with_token.sh
else
  cp openvpn_config/openvpn_up_dnsoverwrite.sh /opt/piavpn-manual/openvpn_up.sh
  cp openvpn_config/openvpn_down_dnsoverwrite.sh /opt/piavpn-manual/openvpn_down.sh
fi

# Start the OpenVPN interface.
# If something failed, stop this script.
# If you get DNS errors because you miss some packages,
# just hardcode /etc/resolv.conf to "nameserver 10.0.0.242".
#rm -f /opt/piavpn-manual/debug_info
echo "
Trying to start the OpenVPN connection..."
openvpn --daemon \
  --config "/opt/piavpn-manual/pia.ovpn" \
  --writepid "/opt/piavpn-manual/pia_pid" \
  --log "/opt/piavpn-manual/debug_info" || exit 1

echo -n "
The OpenVPN connect command was issued.

Confirming OpenVPN connection state..."

# Check if manual PIA OpenVPN connection is initialized.
# Manually adjust the connection_wait_time if needed
connection_wait_time=10
confirmation="Initialization Sequence Complete"
for (( timeout=0; timeout <= connection_wait_time; timeout++ )); do
  sleep 1
  if grep -q "$confirmation" /opt/piavpn-manual/debug_info; then
    connected=true
    break
  fi
done

ovpn_pid=$( cat /opt/piavpn-manual/pia_pid )
gateway_ip=$( cat /opt/piavpn-manual/route_info )

# Report and exit if connection was not initialized within 10 seconds.
if [[ $connected != "true" ]]; then
  echo -e "${red}The VPN connection was not established within 10 seconds.${nc}"
  kill "$ovpn_pid"
  exit 1
fi

echo -e "${green}Initialization Sequence Complete!${nc}

At this point, internet should work via VPN.
"

echo -e "OpenVPN Process ID: ${green}$ovpn_pid${nc}
VPN route IP: ${green}$gateway_ip${nc}

To disconnect the VPN, run:

--> ${green}sudo kill $ovpn_pid${nc} <--
"

# This section will stop the script if PIA_PF is not set to "true".
if [[ $PIA_PF != "true" ]]; then
  echo "If you want to also enable port forwarding, you can start the script:"
  echo -e "$ ${green}PIA_TOKEN=$PIA_TOKEN" \
    "PF_GATEWAY=$gateway_ip" \
    "PF_HOSTNAME=$OVPN_HOSTNAME" \
    "./port_forwarding.sh${nc}"
  echo
  echo "The location used must be port forwarding enabled, or this will fail."
  echo "Calling the ./get_region script with PIA_PF=true will provide a filtered list."
  exit 1
fi

echo -ne "This script got started with ${green}PIA_PF=true${nc}.

Starting port forwarding in "
for i in {5..1}; do
  echo -n "$i..."
  sleep 1
done
echo
echo

echo -e "Starting procedure to enable port forwarding by running the following command:
$ ${green}PIA_TOKEN=$PIA_TOKEN \\
  PF_GATEWAY=$gateway_ip \\
  PF_HOSTNAME=$OVPN_HOSTNAME \\
  ./port_forwarding.sh${nc}"

PIA_TOKEN=$PIA_TOKEN \
  PF_GATEWAY=$gateway_ip \
  PF_HOSTNAME=$OVPN_HOSTNAME \
  ./port_forwarding.sh