'use strict';
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var Parser = require('./parser'),
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Pipeline = require('./pipeline');
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var Extensions = function() {
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this._rsv1 = this._rsv2 = this._rsv3 = null;
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this._byName = {};
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this._inOrder = [];
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this._sessions = [];
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this._index = {};
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};
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Extensions.MESSAGE_OPCODES = [1, 2];
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var instance = {
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add: function(ext) {
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if (typeof ext.name !== 'string') throw new TypeError('extension.name must be a string');
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if (ext.type !== 'permessage') throw new TypeError('extension.type must be "permessage"');
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if (typeof ext.rsv1 !== 'boolean') throw new TypeError('extension.rsv1 must be true or false');
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if (typeof ext.rsv2 !== 'boolean') throw new TypeError('extension.rsv2 must be true or false');
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if (typeof ext.rsv3 !== 'boolean') throw new TypeError('extension.rsv3 must be true or false');
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if (this._byName.hasOwnProperty(ext.name))
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throw new TypeError('An extension with name "' + ext.name + '" is already registered');
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this._byName[ext.name] = ext;
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this._inOrder.push(ext);
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},
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generateOffer: function() {
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var sessions = [],
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offer = [],
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index = {};
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this._inOrder.forEach(function(ext) {
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var session = ext.createClientSession();
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if (!session) return;
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var record = [ext, session];
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sessions.push(record);
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index[ext.name] = record;
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var offers = session.generateOffer();
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offers = offers ? [].concat(offers) : [];
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offers.forEach(function(off) {
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offer.push(Parser.serializeParams(ext.name, off));
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}, this);
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}, this);
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this._sessions = sessions;
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this._index = index;
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return offer.length > 0 ? offer.join(', ') : null;
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},
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activate: function(header) {
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var responses = Parser.parseHeader(header),
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sessions = [];
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responses.eachOffer(function(name, params) {
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var record = this._index[name];
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if (!record)
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throw new Error('Server sent an extension response for unknown extension "' + name + '"');
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var ext = record[0],
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session = record[1],
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reserved = this._reserved(ext);
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if (reserved)
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throw new Error('Server sent two extension responses that use the RSV' +
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reserved[0] + ' bit: "' +
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reserved[1] + '" and "' + ext.name + '"');
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if (session.activate(params) !== true)
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throw new Error('Server sent unacceptable extension parameters: ' +
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Parser.serializeParams(name, params));
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this._reserve(ext);
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sessions.push(record);
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}, this);
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this._sessions = sessions;
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this._pipeline = new Pipeline(sessions);
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},
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generateResponse: function(header) {
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var sessions = [],
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response = [],
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offers = Parser.parseHeader(header);
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this._inOrder.forEach(function(ext) {
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var offer = offers.byName(ext.name);
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if (offer.length === 0 || this._reserved(ext)) return;
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var session = ext.createServerSession(offer);
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if (!session) return;
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this._reserve(ext);
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sessions.push([ext, session]);
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response.push(Parser.serializeParams(ext.name, session.generateResponse()));
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}, this);
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this._sessions = sessions;
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this._pipeline = new Pipeline(sessions);
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return response.length > 0 ? response.join(', ') : null;
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},
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validFrameRsv: function(frame) {
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var allowed = { rsv1: false, rsv2: false, rsv3: false },
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ext;
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if (Extensions.MESSAGE_OPCODES.indexOf(frame.opcode) >= 0) {
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for (var i = 0, n = this._sessions.length; i < n; i++) {
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ext = this._sessions[i][0];
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allowed.rsv1 = allowed.rsv1 || ext.rsv1;
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allowed.rsv2 = allowed.rsv2 || ext.rsv2;
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allowed.rsv3 = allowed.rsv3 || ext.rsv3;
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}
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}
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return (allowed.rsv1 || !frame.rsv1) &&
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(allowed.rsv2 || !frame.rsv2) &&
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(allowed.rsv3 || !frame.rsv3);
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},
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processIncomingMessage: function(message, callback, context) {
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this._pipeline.processIncomingMessage(message, callback, context);
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},
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processOutgoingMessage: function(message, callback, context) {
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this._pipeline.processOutgoingMessage(message, callback, context);
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},
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close: function(callback, context) {
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if (!this._pipeline) return callback.call(context);
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this._pipeline.close(callback, context);
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},
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_reserve: function(ext) {
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this._rsv1 = this._rsv1 || (ext.rsv1 && ext.name);
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this._rsv2 = this._rsv2 || (ext.rsv2 && ext.name);
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this._rsv3 = this._rsv3 || (ext.rsv3 && ext.name);
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},
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_reserved: function(ext) {
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if (this._rsv1 && ext.rsv1) return [1, this._rsv1];
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if (this._rsv2 && ext.rsv2) return [2, this._rsv2];
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if (this._rsv3 && ext.rsv3) return [3, this._rsv3];
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return false;
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}
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};
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for (var key in instance)
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Extensions.prototype[key] = instance[key];
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module.exports = Extensions;
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