http_forward.js

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

const url         = require('url');
const http        = require('http');
const https       = require('https');
const querystring = require('querystring');
const public_url  = url.parse(require('../etc/config').public_url);

var global_forward_timeout;

exports.setTimeout = function(to) {
  if (typeof to !== 'number') throw 'setTimeout expects a numeric argument';
  global_forward_timeout = to;
};

exports.forward = function(dest, req, res, cb) {
  var _cb = cb;
  var requestTimeout;
  cb = function() {
    if (requestTimeout) clearTimeout(requestTimeout);
    if (_cb) _cb.apply(null, arguments);
  };

  function cleanupReq() {
    if (preq) {
      preq.removeAllListeners();
      preq.destroy();
      preq = undefined;
    }
  }

  var u = url.parse(dest.toString());

  var m = u.protocol === 'http:' ? http : https;

  var preq = m.request({
    host: u.hostname,
    port: u.port,
    path: u.path,
    method: req.method,
    agent: false
  }, function(pres) {

    res.statusCode = pres.statusCode;

    // forward necessary headers
    ['Content-Type', 'Content-Length', 'Set-Cookie', 'Vary', 'Cache-Control', 'ETag', 'X-Frame-Options', 'Location', 'Access-Control-Allow-Origin']
      .forEach(function (header) {
        if (pres.headers.hasOwnProperty(header.toLowerCase())) {
          res.setHeader(header, pres.headers[header.toLowerCase()]);
        }
      });

    pres.on('data', function (chunk) {
      res.write(chunk);
    }).on('end', function() {
      res.end();
      pres.removeAllListeners();
      pres.destroy();
      pres = undefined;
      cleanupReq();
      cb();
    });
  }).on('error', function(e) {
    cleanupReq();
    cb(e);
  });

  if (global_forward_timeout) {
    requestTimeout = setTimeout(function() { preq.destroy(); }, global_forward_timeout);
  }

  if (req.headers['content-type']) {
    preq.setHeader('Content-Type', req.headers['content-type']);
  }

  // forward cookies
  if (req.headers.cookie) {
    preq.setHeader('Cookie', req.headers.cookie);
  }

  // forward header
  if (req.headers['accept-language']) {
    preq.setHeader('Accept-Language', req.headers['accept-language']);
  }
  if (req.headers['if-none-match']) {
    preq.setHeader('If-None-Match', req.headers['if-none-match']);
  }
  if (req.headers['authorization']) {
    preq.setHeader('Authorization', req.headers['authorization']);
  }

  // Hawk checks a single host header when generating the MAC,
  // so ensure that the correct port is included when using ssl
  var host = req.headers.host;
  if (host.indexOf(':') < 0 && public_url.protocol === 'https:') host += ':443';

  preq.setHeader('X-Forwarded-Host', host);

  // if the body has already been parsed, we'll write it
  if (req.body) {
    var data;
    if (req.headers['content-type'].indexOf('application/json') === 0) data = JSON.stringify(req.body);
    else data = querystring.stringify(req.body);
    preq.setHeader('content-length', Buffer.byteLength(data));
    preq.write(data);
    preq.end();
  } else {
    req.on('data', function(chunk) { preq.write(chunk); })
      .on('end', function() { preq.end(); });
  }
  console.log('forwarding request: ' + req.url + ' -> ' + dest);
};