#!/bin/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.
function 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 wg-quick, curl and jq.
check_tool curl
check_tool jq

# Check if the mandatory environment variables are set.
if [[ ! $PF_GATEWAY || ! $PIA_TOKEN || ! $PF_HOSTNAME ]]; then
  echo This script requires 3 env vars:
  echo PF_GATEWAY  - the IP of your gateway
  echo PF_HOSTNAME - name of the host used for SSL/TLS certificate verification
  echo PIA_TOKEN   - the token you use to connect to the vpn services
  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 https://github.com/pia-foss/manual-connections
exit 1
fi

# Check if terminal allows output, if yes, define colors for output
if test -t 1; then
  ncolors=$(tput colors)
  if test -n "$ncolors" && test $ncolors -ge 8; then
    GREEN='\033[0;32m'
    RED='\033[0;31m'
    NC='\033[0m' # No Color
  else
    GREEN=''
    RED=''
    NC='' # No Color
  fi
fi

# The port forwarding system has required two variables:
# PAYLOAD: contains the token, the port and the expiration date
# SIGNATURE: certifies the payload originates from the PIA network.

# Basically PAYLOAD+SIGNATURE=PORT. You can use the same PORT on all servers.
# The system has been designed to be completely decentralized, so that your
# privacy is protected even if you want to host services on your systems.

# You can get your PAYLOAD+SIGNATURE with a simple curl request to any VPN
# gateway, no matter what protocol you are using. Considering WireGuard has
# already been automated in this repo, here is a command to help you get
# your gateway if you have an active OpenVPN connection:
# $ ip route | head -1 | grep tun | awk '{ print $3 }'
# This section will get updated as soon as we created the OpenVPN script.

# Get the payload and the signature from the PF API. This will grant you
# access to a random port, which you can activate on any server you connect to.
# If you already have a signature, and you would like to re-use that port,
# save the payload_and_signature received from your previous request
# in the env var PAYLOAD_AND_SIGNATURE, and that will be used instead.
if [[ ! $PAYLOAD_AND_SIGNATURE ]]; then
  echo
  echo -n "Getting new signature... "
  payload_and_signature="$(curl -s -m 5 \
    --connect-to "$PF_HOSTNAME::$PF_GATEWAY:" \
    --cacert "ca.rsa.4096.crt" \
    -G --data-urlencode "token=${PIA_TOKEN}" \
    "https://${PF_HOSTNAME}:19999/getSignature")"
else
  payload_and_signature="$PAYLOAD_AND_SIGNATURE"
  echo -n "Checking the payload_and_signature from the env var... "
fi
export payload_and_signature

# Check if the payload and the signature are OK.
# If they are not OK, just stop the script.
if [ "$(echo "$payload_and_signature" | jq -r '.status')" != "OK" ]; then
  echo -e "${RED}The payload_and_signature variable does not contain an OK status.${NC}"
  exit 1
fi
echo -e "${GREEN}OK!${NC}"

# We need to get the signature out of the previous response.
# The signature will allow the us to bind the port on the server.
signature="$(echo "$payload_and_signature" | jq -r '.signature')"

# The payload has a base64 format. We need to extract it from the
# previous response and also get the following information out:
# - port: This is the port you got access to
# - expires_at: this is the date+time when the port expires
payload="$(echo "$payload_and_signature" | jq -r '.payload')"
port="$(echo "$payload" | base64 -d | jq -r '.port')"

# The port normally expires after 2 months. If you consider
# 2 months is not enough for your setup, please open a ticket.
expires_at="$(echo "$payload" | base64 -d | jq -r '.expires_at')"

echo -ne "
Signature ${GREEN}$signature${NC}
Payload   ${GREEN}$payload${NC}

--> The port is ${GREEN}$port${NC} and it will expire on ${RED}$expires_at${NC}. <--

Trying to bind the port... "

# Now we have all required data to create a request to bind the port.
# We will repeat this request every 15 minutes, in order to keep the port
# alive. The servers have no mechanism to track your activity, so they
# will just delete the port forwarding if you don't send keepalives.
while true; do
  bind_port_response="$(curl -Gs -m 5 \
    --connect-to "$PF_HOSTNAME::$PF_GATEWAY:" \
    --cacert "ca.rsa.4096.crt" \
    --data-urlencode "payload=${payload}" \
    --data-urlencode "signature=${signature}" \
    "https://${PF_HOSTNAME}:19999/bindPort")"
    echo -e "${GREEN}OK!${NC}"

    # If port did not bind, just exit the script.
    # This script will exit in 2 months, since the port will expire.
    export bind_port_response
    if [ "$(echo "$bind_port_response" | jq -r '.status')" != "OK" ]; then
      echo -e "${RED}The API did not return OK when trying to bind port... Exiting."
      exit 1
    fi
    echo -e Forwarded port'\t'${GREEN}$port${NC}
    echo -e Refreshed on'\t'${GREEN}$(date)${NC}
    echo -e Expires on'\t'${RED}$(date --date="$expires_at")${NC}

    # sleep 15 minutes
    sleep 900
done