index.js

const util = require('util');
const dns = require('dns');
const ipaddr = require('ipaddr.js');
const fetch = require('cross-fetch');

const CIDRS_URL =
  'https://raw.githubusercontent.com/mongodb-js/mongodb-cloud-info/main/cidrs.json';

const dnsLookup = util.promisify(dns.lookup.bind(dns));

let unparsedCIDRsPromise;

function rangesContainsIP(ipRanges, ip) {
  if (ip.kind() === 'ipv4') {
    return !!ipRanges.v4.find((cidr) => ip.match(cidr));
  }

  return !!ipRanges.v6.find((cidr) => ip.match(cidr));
}

async function getCloudInfo(host) {
  if (!host) {
    return {
      isAws: false,
      isGcp: false,
      isAzure: false
    };
  }

  const address = await dnsLookup(host);
  const ip = ipaddr.parse(address);

  if (!unparsedCIDRsPromise) {
    unparsedCIDRsPromise = fetch(CIDRS_URL, { timeout: 5000 }).then((res) => {
      return res.json();
    });
  }
  let unparsedCIDRs;
  try {
    unparsedCIDRs = await unparsedCIDRsPromise;
  } catch (err) {
    // If we failed to fetch, clean up the cached promise so that the next call
    // can try again
    unparsedCIDRsPromise = undefined;
    throw err;
  }
  const cidrs = {};
  for (const [name, { v4, v6 }] of Object.entries(unparsedCIDRs)) {
    cidrs[name] = {
      v4: v4.map((cidr) => [new ipaddr.IPv4(cidr[0]), cidr[1]]),
      v6: v6.map((cidr) => [new ipaddr.IPv6(cidr[0]), cidr[1]])
    };
  }

  return {
    isAws: rangesContainsIP(cidrs.aws, ip),
    isGcp: rangesContainsIP(cidrs.gcp, ip),
    isAzure: rangesContainsIP(cidrs.azure, ip)
  };
}

module.exports = { getCloudInfo };