326 lines
8.8 KiB
JavaScript
326 lines
8.8 KiB
JavaScript
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var zlib = require('zlib');
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var AVAILABLE_WINDOW_BITS = [8, 9, 10, 11, 12, 13, 14, 15];
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var DEFAULT_WINDOW_BITS = 15;
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var DEFAULT_MEM_LEVEL = 8;
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PerMessageDeflate.extensionName = 'permessage-deflate';
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/**
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* Per-message Compression Extensions implementation
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*/
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function PerMessageDeflate(options, isServer) {
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if (this instanceof PerMessageDeflate === false) {
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throw new TypeError("Classes can't be function-called");
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}
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this._options = options || {};
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this._isServer = !!isServer;
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this._inflate = null;
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this._deflate = null;
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this.params = null;
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}
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/**
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* Create extension parameters offer
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*
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* @api public
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*/
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PerMessageDeflate.prototype.offer = function() {
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var params = {};
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if (this._options.serverNoContextTakeover) {
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params.server_no_context_takeover = true;
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}
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if (this._options.clientNoContextTakeover) {
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params.client_no_context_takeover = true;
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}
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if (this._options.serverMaxWindowBits) {
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params.server_max_window_bits = this._options.serverMaxWindowBits;
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}
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if (this._options.clientMaxWindowBits) {
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params.client_max_window_bits = this._options.clientMaxWindowBits;
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} else if (this._options.clientMaxWindowBits == null) {
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params.client_max_window_bits = true;
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}
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return params;
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};
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/**
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* Accept extension offer
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*
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* @api public
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*/
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PerMessageDeflate.prototype.accept = function(paramsList) {
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paramsList = this.normalizeParams(paramsList);
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var params;
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if (this._isServer) {
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params = this.acceptAsServer(paramsList);
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} else {
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params = this.acceptAsClient(paramsList);
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}
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this.params = params;
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return params;
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};
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/**
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* Releases all resources used by the extension
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*
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* @api public
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*/
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PerMessageDeflate.prototype.cleanup = function() {
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if (this._inflate) {
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if (this._inflate.writeInProgress) {
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this._inflate.pendingClose = true;
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} else {
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if (this._inflate.close) this._inflate.close();
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this._inflate = null;
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}
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}
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if (this._deflate) {
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if (this._deflate.writeInProgress) {
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this._deflate.pendingClose = true;
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} else {
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if (this._deflate.close) this._deflate.close();
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this._deflate = null;
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}
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}
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};
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/**
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* Accept extension offer from client
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*
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* @api private
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*/
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PerMessageDeflate.prototype.acceptAsServer = function(paramsList) {
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var accepted = {};
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var result = paramsList.some(function(params) {
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accepted = {};
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if (this._options.serverNoContextTakeover === false && params.server_no_context_takeover) {
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return;
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}
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if (this._options.serverMaxWindowBits === false && params.server_max_window_bits) {
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return;
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}
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if (typeof this._options.serverMaxWindowBits === 'number' &&
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typeof params.server_max_window_bits === 'number' &&
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this._options.serverMaxWindowBits > params.server_max_window_bits) {
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return;
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}
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if (typeof this._options.clientMaxWindowBits === 'number' && !params.client_max_window_bits) {
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return;
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}
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if (this._options.serverNoContextTakeover || params.server_no_context_takeover) {
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accepted.server_no_context_takeover = true;
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}
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if (this._options.clientNoContextTakeover) {
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accepted.client_no_context_takeover = true;
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}
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if (this._options.clientNoContextTakeover !== false && params.client_no_context_takeover) {
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accepted.client_no_context_takeover = true;
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}
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if (typeof this._options.serverMaxWindowBits === 'number') {
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accepted.server_max_window_bits = this._options.serverMaxWindowBits;
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} else if (typeof params.server_max_window_bits === 'number') {
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accepted.server_max_window_bits = params.server_max_window_bits;
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}
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if (typeof this._options.clientMaxWindowBits === 'number') {
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accepted.client_max_window_bits = this._options.clientMaxWindowBits;
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} else if (this._options.clientMaxWindowBits !== false && typeof params.client_max_window_bits === 'number') {
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accepted.client_max_window_bits = params.client_max_window_bits;
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}
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return true;
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}, this);
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if (!result) {
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throw new Error('Doesn\'t support the offered configuration');
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}
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return accepted;
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};
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/**
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* Accept extension response from server
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*
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* @api privaye
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*/
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PerMessageDeflate.prototype.acceptAsClient = function(paramsList) {
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var params = paramsList[0];
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if (this._options.clientNoContextTakeover != null) {
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if (this._options.clientNoContextTakeover === false && params.client_no_context_takeover) {
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throw new Error('Invalid value for "client_no_context_takeover"');
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}
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}
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if (this._options.clientMaxWindowBits != null) {
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if (this._options.clientMaxWindowBits === false && params.client_max_window_bits) {
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throw new Error('Invalid value for "client_max_window_bits"');
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}
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if (typeof this._options.clientMaxWindowBits === 'number' &&
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(!params.client_max_window_bits || params.client_max_window_bits > this._options.clientMaxWindowBits)) {
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throw new Error('Invalid value for "client_max_window_bits"');
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}
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}
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return params;
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};
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/**
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* Normalize extensions parameters
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*
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* @api private
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*/
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PerMessageDeflate.prototype.normalizeParams = function(paramsList) {
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return paramsList.map(function(params) {
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Object.keys(params).forEach(function(key) {
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var value = params[key];
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if (value.length > 1) {
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throw new Error('Multiple extension parameters for ' + key);
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}
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value = value[0];
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switch (key) {
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case 'server_no_context_takeover':
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case 'client_no_context_takeover':
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if (value !== true) {
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throw new Error('invalid extension parameter value for ' + key + ' (' + value + ')');
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}
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params[key] = true;
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break;
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case 'server_max_window_bits':
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case 'client_max_window_bits':
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if (typeof value === 'string') {
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value = parseInt(value, 10);
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if (!~AVAILABLE_WINDOW_BITS.indexOf(value)) {
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throw new Error('invalid extension parameter value for ' + key + ' (' + value + ')');
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}
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}
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if (!this._isServer && value === true) {
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throw new Error('Missing extension parameter value for ' + key);
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}
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params[key] = value;
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break;
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default:
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throw new Error('Not defined extension parameter (' + key + ')');
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}
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}, this);
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return params;
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}, this);
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};
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/**
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* Decompress message
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*
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* @api public
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*/
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PerMessageDeflate.prototype.decompress = function (data, fin, callback) {
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var endpoint = this._isServer ? 'client' : 'server';
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if (!this._inflate) {
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var maxWindowBits = this.params[endpoint + '_max_window_bits'];
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this._inflate = zlib.createInflateRaw({
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windowBits: 'number' === typeof maxWindowBits ? maxWindowBits : DEFAULT_WINDOW_BITS
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});
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}
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this._inflate.writeInProgress = true;
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var self = this;
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var buffers = [];
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this._inflate.on('error', onError).on('data', onData);
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this._inflate.write(data);
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if (fin) {
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this._inflate.write(new Buffer([0x00, 0x00, 0xff, 0xff]));
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}
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this._inflate.flush(function() {
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cleanup();
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callback(null, Buffer.concat(buffers));
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});
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function onError(err) {
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cleanup();
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callback(err);
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}
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function onData(data) {
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buffers.push(data);
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}
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function cleanup() {
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if (!self._inflate) return;
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self._inflate.removeListener('error', onError);
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self._inflate.removeListener('data', onData);
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self._inflate.writeInProgress = false;
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if ((fin && self.params[endpoint + '_no_context_takeover']) || self._inflate.pendingClose) {
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if (self._inflate.close) self._inflate.close();
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self._inflate = null;
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}
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}
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};
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/**
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* Compress message
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*
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* @api public
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*/
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PerMessageDeflate.prototype.compress = function (data, fin, callback) {
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var endpoint = this._isServer ? 'server' : 'client';
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if (!this._deflate) {
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var maxWindowBits = this.params[endpoint + '_max_window_bits'];
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this._deflate = zlib.createDeflateRaw({
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flush: zlib.Z_SYNC_FLUSH,
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windowBits: 'number' === typeof maxWindowBits ? maxWindowBits : DEFAULT_WINDOW_BITS,
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memLevel: this._options.memLevel || DEFAULT_MEM_LEVEL
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});
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}
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this._deflate.writeInProgress = true;
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var self = this;
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var buffers = [];
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this._deflate.on('error', onError).on('data', onData);
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this._deflate.write(data);
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this._deflate.flush(function() {
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cleanup();
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var data = Buffer.concat(buffers);
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if (fin) {
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data = data.slice(0, data.length - 4);
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}
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callback(null, data);
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});
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function onError(err) {
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cleanup();
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callback(err);
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}
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function onData(data) {
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buffers.push(data);
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}
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function cleanup() {
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if (!self._deflate) return;
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self._deflate.removeListener('error', onError);
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self._deflate.removeListener('data', onData);
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self._deflate.writeInProgress = false;
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if ((fin && self.params[endpoint + '_no_context_takeover']) || self._deflate.pendingClose) {
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if (self._deflate.close) self._deflate.close();
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self._deflate = null;
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}
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}
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};
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module.exports = PerMessageDeflate;
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