proxy-util.js

const parseUrl = require('url').parse;
const { isEmpty } = require('lodash');
const { HttpsProxyAgent } = require('https-proxy-agent');

const DEFAULT_PORTS = {
  ftp: 21,
  gopher: 70,
  http: 80,
  https: 443,
  ws: 80,
  wss: 443
};
/**
 * check for proxy bypass, copied form 'proxy-from-env'
 */
const shouldUseProxy = (url, proxyBypass) => {
  if (proxyBypass === '*') {
    return false; // Never proxy if wildcard is set.
  }

  // use proxy if no proxyBypass is set
  if (!proxyBypass || typeof proxyBypass !== 'string' || isEmpty(proxyBypass.trim())) {
    return true;
  }

  const parsedUrl = typeof url === 'string' ? parseUrl(url) : url || {};
  let proto = parsedUrl.protocol;
  let hostname = parsedUrl.host;
  let port = parsedUrl.port;
  if (typeof hostname !== 'string' || !hostname || typeof proto !== 'string') {
    return false; // Don't proxy URLs without a valid scheme or host.
  }

  proto = proto.split(':', 1)[0];
  // Stripping ports in this way instead of using parsedUrl.hostname to make
  // sure that the brackets around IPv6 addresses are kept.
  hostname = hostname.replace(/:\d*$/, '');
  port = parseInt(port) || DEFAULT_PORTS[proto] || 0;

  return proxyBypass.split(/[,;\s]/).every(function (dontProxyFor) {
    if (!dontProxyFor) {
      return true; // Skip zero-length hosts.
    }
    const parsedProxy = dontProxyFor.match(/^(.+):(\d+)$/);
    let parsedProxyHostname = parsedProxy ? parsedProxy[1] : dontProxyFor;
    const parsedProxyPort = parsedProxy ? parseInt(parsedProxy[2]) : 0;
    if (parsedProxyPort && parsedProxyPort !== port) {
      return true; // Skip if ports don't match.
    }

    if (!/^[.*]/.test(parsedProxyHostname)) {
      // No wildcards, so stop proxying if there is an exact match.
      return hostname !== parsedProxyHostname;
    }

    if (parsedProxyHostname.charAt(0) === '*') {
      // Remove leading wildcard.
      parsedProxyHostname = parsedProxyHostname.slice(1);
    }
    // Stop proxying if the hostname ends with the no_proxy host.
    return !hostname.endsWith(parsedProxyHostname);
  });
};

/**
 * Patched version of HttpsProxyAgent to get around a bug that ignores
 * options like ca and rejectUnauthorized when upgrading the socket to TLS:
 * https://github.com/TooTallNate/proxy-agents/issues/194
 */
class PatchedHttpsProxyAgent extends HttpsProxyAgent {
  constructor(proxy, opts) {
    super(proxy, opts);
    this.constructorOpts = opts;
  }

  async connect(req, opts) {
    const url = parseUrl(req.path);
    url.port = Number(url.port) || (url.protocol.includes('https') ? 443 : 80);
    const combinedOpts = { ...this.constructorOpts, ...opts, ...url };
    return super.connect(req, combinedOpts);
  }
}

module.exports = {
  shouldUseProxy,
  PatchedHttpsProxyAgent
};