docs/server/proxy.js

/*
Based on code from: https://github.com/chimurai/http-proxy-middleware
Includes Fixes:
 - Fixed bug where domains with `-` would not work when rewriting cookie headers

The MIT License (MIT)

Copyright (c) 2015 Steven Chim

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.
*/

/* eslint-disable */

var os = require('os');
var http = require('http');
var https = require('https');
var owns = {}.hasOwnProperty;

module.exports = function proxyMiddleware(options) {
  //enable ability to quickly pass a url for shorthand setup
  if(typeof options === 'string'){
      options = require('url').parse(options);
  }

  var httpLib = options.protocol === 'https:' ? https : http;
  var request = httpLib.request;

  options = options || {};
  options.hostname = options.hostname;
  options.port = options.port;
  options.pathname = options.pathname || '/';

  return function (req, resp, next) {
    var url = req.url;
    // You can pass the route within the options, as well
    if (typeof options.route === 'string') {
      if (url === options.route) {
        url = '';
      } else if (url.slice(0, options.route.length) === options.route) {
        url = url.slice(options.route.length);
      } else {
        return next();
      }
    }

    //options for this request
    var opts = extend({}, options);
    if (url && url.charAt(0) === '?') { // prevent /api/resource/?offset=0
      if (options.pathname.length > 1 && options.pathname.charAt(options.pathname.length - 1) === '/') {
        opts.path = options.pathname.substring(0, options.pathname.length - 1) + url;
      } else {
        opts.path = options.pathname + url;
      }
    } else if (url) {
      opts.path = slashJoin(options.pathname, url);
    } else {
      opts.path = options.pathname;
    }
    opts.method = req.method;
    opts.headers = options.headers ? merge(req.headers, options.headers) : req.headers;

    applyViaHeader(req.headers, opts, opts.headers);

    if (!options.preserveHost) {
      // Forwarding the host breaks dotcloud
      delete opts.headers.host;
    }

    var myReq = request(opts, function (myRes) {
      var statusCode = myRes.statusCode
        , headers = myRes.headers
        , location = headers.location;
      // Fix the location
      if (((statusCode > 300 && statusCode < 304) || statusCode === 201) && location && location.indexOf(options.href) > -1) {
        // absoulte path
        headers.location = location.replace(options.href, slashJoin('/', slashJoin((options.route || ''), '')));
      }
      applyViaHeader(myRes.headers, opts, myRes.headers);
      rewriteCookieHosts(myRes.headers, opts, myRes.headers, req);
      resp.writeHead(myRes.statusCode, myRes.headers);
      myRes.on('error', function (err) {
        next(err);
      });
      myRes.pipe(resp);
    });
    myReq.on('error', function (err) {
      next(err);
    });
    if (!req.readable) {
      myReq.end();
    } else {
      req.pipe(myReq);
    }
  };
};

function applyViaHeader(existingHeaders, opts, applyTo) {
  if (!opts.via) return;

  var viaName = (true === opts.via) ?  os.hostname() : opts.via;
  var viaHeader = '1.1 ' + viaName;
  if(existingHeaders.via) {
    viaHeader = existingHeaders.via + ', ' + viaHeader;
  }

  applyTo.via = viaHeader;
}

function rewriteCookieHosts(existingHeaders, opts, applyTo, req) {
  if (!opts.cookieRewrite || !owns.call(existingHeaders, 'set-cookie')) {
    return;
  }

  var existingCookies = existingHeaders['set-cookie'],
      rewrittenCookies = [],
      rewriteHostname = (true === opts.cookieRewrite) ? os.hostname() : opts.cookieRewrite;

  if (!Array.isArray(existingCookies)) {
    existingCookies = [ existingCookies ];
  }

  for (var i = 0; i < existingCookies.length; i++) {

    // Fixed bug where domains with `-` would not work when rewriting cookie headers
    var rewrittenCookie = existingCookies[i].replace(/(Domain)=[a-z\.-_-]*?(;|$)/gi, '$1=' + rewriteHostname + '$2');

    if (!req.connection.encrypted) {
      rewrittenCookie = rewrittenCookie.replace(/;\s*?(Secure)/i, '');
    }
    rewrittenCookies.push(rewrittenCookie);
  }

  applyTo['set-cookie'] = rewrittenCookies;
}

function slashJoin(p1, p2) {
  var trailing_slash = false;

  if (p1.length && p1[p1.length - 1] === '/') { trailing_slash = true; }
  if (trailing_slash && p2.length && p2[0] === '/') {p2 = p2.substring(1); }

  return p1 + p2;
}

function extend(obj, src) {
  for (var key in src) if (owns.call(src, key)) obj[key] = src[key];
  return obj;
}

//merges data without changing state in either argument
function merge(src1, src2) {
    var merged = {};
    extend(merged, src1);
    extend(merged, src2);
    return merged;
}