1
  2/**
  3 * Module dependencies.
  4 */
  5
  6var Polling = require('./polling');
  7var Transport = require('../transport');
  8var debug = require('debug')('engine:polling-xhr');
  9
 10/**
 11 * Module exports.
 12 */
 13
 14module.exports = XHR;
 15
 16/**
 17 * Ajax polling transport.
 18 *
 19 * @api public
 20 */
 21
 22function XHR(req){
 23  Polling.call(this, req);
 24}
 25
 26/**
 27 * Inherits from Polling.
 28 */
 29
 30XHR.prototype.__proto__ = Polling.prototype;
 31
 32/**
 33 * Overrides `onRequest` to handle `OPTIONS`..
 34 *
 35 * @param {http.ServerRequest}
 36 * @api private
 37 */
 38
 39XHR.prototype.onRequest = function (req) {
 40  if ('OPTIONS' == req.method) {
 41    var res = req.res;
 42    var headers = this.headers(req);
 43    headers['Access-Control-Allow-Headers'] = 'Content-Type';
 44    res.writeHead(200, headers);
 45    res.end();
 46  } else {
 47    Polling.prototype.onRequest.call(this, req);
 48  }
 49};
 50
 51/**
 52 * Frames data prior to write.
 53 *
 54 * @api private
 55 */
 56
 57XHR.prototype.doWrite = function(data){
 58  // explicit UTF-8 is required for pages not served under utf
 59  var isString = typeof data == 'string';
 60  var contentType = isString
 61    ? 'text/plain; charset=UTF-8'
 62    : 'application/octet-stream';
 63  var contentLength = '' + (isString ? Buffer.byteLength(data) : data.length);
 64
 65  var headers = {
 66    'Content-Type': contentType,
 67    'Content-Length': contentLength
 68  };
 69
 70  // prevent XSS warnings on IE
 71  // https://github.com/LearnBoost/socket.io/pull/1333
 72  var ua = this.req.headers['user-agent'];
 73  if (ua && (~ua.indexOf(';MSIE') || ~ua.indexOf('Trident/'))) {
 74    headers['X-XSS-Protection'] = '0';
 75  }
 76
 77  this.res.writeHead(200, this.headers(this.req, headers));
 78  this.res.end(data);
 79};
 80
 81/**
 82 * Returns headers for a response.
 83 *
 84 * @param {http.ServerRequest} request
 85 * @param {Object} extra headers
 86 * @api private
 87 */
 88
 89XHR.prototype.headers = function(req, headers){
 90  headers = headers || {};
 91
 92  if (req.headers.origin) {
 93    headers['Access-Control-Allow-Credentials'] = 'true';
 94    headers['Access-Control-Allow-Origin'] = req.headers.origin;
 95  } else {
 96    headers['Access-Control-Allow-Origin'] = '*';
 97  }
 98
 99  this.emit('headers', headers);
100  return headers;
101};