include/chrome-app/tcp-client.js: import upstream.

Import upstream code from Chrome extension telnet demo:
https://raw.github.com/GoogleChrome/chrome-app-samples/0ce28768087863c08aa04a2b9b27bd50796a77ec/telnet/tcp-client.js

include/chrome-app/tcp-client.js

+/*
+Copyright 2012 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+Author: Boris Smus (smus@chromium.org)
+*/
+
+(function(exports) {
+
+  // Define some local variables here.
+  var socket = chrome.socket || chrome.experimental.socket;
+  var dns = chrome.experimental.dns;
+
+  /**
+   * Creates an instance of the client
+   *
+   * @param {String} host The remote host to connect to
+   * @param {Number} port The port to connect to at the remote host
+   */
+  function TcpClient(host, port) {
+    this.host = host;
+    this.port = port;
+
+    // Callback functions.
+    this.callbacks = {
+      connect: null,    // Called when socket is connected.
+      disconnect: null, // Called when socket is disconnected.
+      recv: null,       // Called when client receives data from server.
+      sent: null        // Called when client sends data to server.
+    };
+
+    // Socket.
+    this.socketId = null;
+    this.isConnected = false;
+
+    log('initialized tcp client');
+  }
+
+  /**
+   * Connects to the TCP socket, and creates an open socket.
+   *
+   * @see http://developer.chrome.com/trunk/apps/socket.html#method-create
+   * @param {Function} callback The function to call on connection
+   */
+  TcpClient.prototype.connect = function(callback) {
+    // First resolve the hostname to an IP.
+    dns.resolve(this.host, function(result) {
+      this.addr = result.address;
+      socket.create('tcp', {}, this._onCreate.bind(this));
+
+      // Register connect callback.
+      this.callbacks.connect = callback;
+    }.bind(this));
+  };
+
+  /**
+   * Sends a message down the wire to the remote side
+   *
+   * @see http://developer.chrome.com/trunk/apps/socket.html#method-write
+   * @param {String} msg The message to send
+   * @param {Function} callback The function to call when the message has sent
+   */
+  TcpClient.prototype.sendMessage = function(msg, callback) {
+    this._stringToArrayBuffer(msg + '\n', function(arrayBuffer) {
+      socket.write(this.socketId, arrayBuffer, this._onWriteComplete.bind(this));
+    }.bind(this));
+
+    // Register sent callback.
+    this.callbacks.sent = callback;
+  };
+
+  /**
+   * Sets the callback for when a message is received
+   *
+   * @param {Function} callback The function to call when a message has arrived
+   */
+  TcpClient.prototype.addResponseListener = function(callback) {
+    // Register received callback.
+    this.callbacks.recv = callback;
+  };
+
+  /**
+   * Disconnects from the remote side
+   *
+   * @see http://developer.chrome.com/trunk/apps/socket.html#method-disconnect
+   */
+  TcpClient.prototype.disconnect = function() {
+    socket.disconnect(this.socketId);
+    this.isConnected = false;
+  };
+
+  /**
+   * The callback function used for when we attempt to have Chrome
+   * create a socket. If the socket is successfully created
+   * we go ahead and connect to the remote side.
+   *
+   * @private
+   * @see http://developer.chrome.com/trunk/apps/socket.html#method-connect
+   * @param {Object} createInfo The socket details
+   */
+  TcpClient.prototype._onCreate = function(createInfo) {
+    this.socketId = createInfo.socketId;
+    if (this.socketId > 0) {
+      socket.connect(this.socketId, this.addr, this.port, this._onConnectComplete.bind(this));
+      this.isConnected = true;
+    } else {
+      error('Unable to create socket');
+    }
+  };
+
+  /**
+   * The callback function used for when we attempt to have Chrome
+   * connect to the remote side. If a successful connection is
+   * made then polling starts to check for data to read
+   *
+   * @private
+   * @param {Number} resultCode Indicates whether the connection was successful
+   */
+  TcpClient.prototype._onConnectComplete = function(resultCode) {
+    // Start polling for reads.
+    setInterval(this._periodicallyRead.bind(this), 500);
+
+    if (this.callbacks.connect) {
+      console.log('connect complete');
+      this.callbacks.connect();
+    }
+    log('onConnectComplete');
+  };
+
+  /**
+   * Checks for new data to read from the socket
+   *
+   * @see http://developer.chrome.com/trunk/apps/socket.html#method-read
+   */
+  TcpClient.prototype._periodicallyRead = function() {
+    socket.read(this.socketId, null, this._onDataRead.bind(this));
+  };
+
+  /**
+   * Callback function for when data has been read from the socket.
+   * Converts the array buffer that is read in to a string
+   * and sends it on for further processing by passing it to
+   * the previously assigned callback function.
+   *
+   * @private
+   * @see TcpClient.prototype.addResponseListener
+   * @param {Object} readInfo The incoming message
+   */
+  TcpClient.prototype._onDataRead = function(readInfo) {
+    // Call received callback if there's data in the response.
+    if (readInfo.resultCode > 0 && this.callbacks.recv) {
+      log('onDataRead');
+      // Convert ArrayBuffer to string.
+      this._arrayBufferToString(readInfo.data, function(str) {
+        this.callbacks.recv(str);
+      }.bind(this));
+    }
+  };
+
+  /**
+   * Callback for when data has been successfully
+   * written to the socket.
+   *
+   * @private
+   * @param {Object} writeInfo The outgoing message
+   */
+  TcpClient.prototype._onWriteComplete = function(writeInfo) {
+    log('onWriteComplete');
+    // Call sent callback.
+    if (this.callbacks.sent) {
+      this.callbacks.sent(writeInfo);
+    }
+  };
+
+  /**
+   * Converts an array buffer to a string
+   *
+   * @private
+   * @param {ArrayBuffer} buf The buffer to convert
+   * @param {Function} callback The function to call when conversion is complete
+   */
+  TcpClient.prototype._arrayBufferToString = function(buf, callback) {
+    var bb = new Blob([new Uint8Array(buf)]);
+    var f = new FileReader();
+    f.onload = function(e) {
+      callback(e.target.result);
+    };
+    f.readAsText(bb);
+  };
+
+  /**
+   * Converts a string to an array buffer
+   *
+   * @private
+   * @param {String} str The string to convert
+   * @param {Function} callback The function to call when conversion is complete
+   */
+  TcpClient.prototype._stringToArrayBuffer = function(str, callback) {
+    var bb = new Blob([str]);
+    var f = new FileReader();
+    f.onload = function(e) {
+        callback(e.target.result);
+    };
+    f.readAsArrayBuffer(bb);
+  };
+
+  /**
+   * Wrapper function for logging
+   */
+  function log(msg) {
+    console.log(msg);
+  }
+
+  /**
+   * Wrapper function for error logging
+   */
+  function error(msg) {
+    console.error(msg);
+  }
+
+  exports.TcpClient = TcpClient;
+
+})(window);