getGAS_IPAddressList.php

<?php
/*
 * [CLI] Create IP address list of request source of Google Apps Script
 *
 * Copyright (C) 2018 M.Katsube
 * This software is released under the MIT License.
 * http://opensource.org/licenses/mit-license.php
 */


define('START_DOMAIN', '_cloud-netblocks.googleusercontent.com');

$hosts = getDomains(START_DOMAIN);
foreach($hosts as $host){
  echo implode("\n", getIP($host));
  echo "\n";
}

/**
 * Retrieve domain list of SPF records
 *
 * @param {string} $start
 */
function getDomains($start){
  $result = [];
  $buff   = getDNSRecord($start, DNS_TXT);
  foreach( explode(' ', $buff[0]['txt']) as $host ){
    if( preg_match('/^include:([0-9a-zA-Z\.\-_]{1,})$/', $host, $match) ){
      array_push($result, $match[1]);
    }
  }

  return($result);
}

/**
 * Create IP address list
 *
 * @param {string} $domain
 */
function getIP($domain){
  $result = [];
  $buff   = getDNSRecord($domain, DNS_TXT);
  foreach( explode(' ', $buff[0]['txt']) as $host ){
    if( preg_match('/^ip4:([0-9\.\/]{1,})$/', $host, $match) ){
      array_push($result, $match[1]);
    }
  }

  return($result);
}


/**
 * Get DNS record
 *
 * @param {string}  $domain
 * @param {integer} $option  DNS_A, DNS_CNAME, DNS_HINFO, DNS_CAA, DNS_MX, DNS_NS, DNS_PTR, DNS_SOA, DNS_TXT, DNS_AAAA, DNS_SRV, DNS_NAPTR, DNS_A6, DNS_ALL DNS_ANY
 */
function getDNSRecord($domain, $option){
  $buff = dns_get_record($domain, $option);
  if( $buff === false || count($buff) === 0 ){
    echo "[ERROR] Can not GET DNS Record: $domain\n";
    exit;
  }
  return($buff);
}