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node_modules/websocket-extensions/lib/websocket_extensions.js

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