polling-jsonp.js
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/**
* Module dependencies.
*/
var Polling = require('./polling');
var qs = require('querystring');
var rDoubleSlashes = /\\\\n/g;
var rSlashes = /(\\)?\\n/g;
var util = require('util');
/**
* Module exports.
*/
module.exports = JSONP;
/**
* JSON-P polling transport.
*
* @api public
*/
function JSONP (req) {
Polling.call(this, req);
this.head = '___eio[' + (req._query.j || '').replace(/[^0-9]/g, '') + '](';
this.foot = ');';
}
/**
* Inherits from Polling.
*/
util.inherits(JSONP, Polling);
/**
* Handles incoming data.
* Due to a bug in \n handling by browsers, we expect a escaped string.
*
* @api private
*/
JSONP.prototype.onData = function (data) {
// we leverage the qs module so that we get built-in DoS protection
// and the fast alternative to decodeURIComponent
data = qs.parse(data).d;
if ('string' === typeof data) {
// client will send already escaped newlines as \\\\n and newlines as \\n
// \\n must be replaced with \n and \\\\n with \\n
data = data.replace(rSlashes, function (match, slashes) {
return slashes ? match : '\n';
});
Polling.prototype.onData.call(this, data.replace(rDoubleSlashes, '\\n'));
}
};
/**
* Performs the write.
*
* @api private
*/
JSONP.prototype.doWrite = function (data, options, callback) {
// we must output valid javascript, not valid json
// see: http://timelessrepo.com/json-isnt-a-javascript-subset
var js = JSON.stringify(data)
.replace(/\u2028/g, '\\u2028')
.replace(/\u2029/g, '\\u2029');
// prepare response
data = this.head + js + this.foot;
Polling.prototype.doWrite.call(this, data, options, callback);
};