chrome/browser/resources/whispernet_proxy/js/wrapper.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 'use strict';
   6
   7 /**
   8  * Function to convert an array of bytes to a base64 string
   9  * TODO(rkc): Change this to use a Uint8array instead of a string.
  10  * @param {string} bytes String containing the bytes we want to convert.
  11  * @return {string} String containing the base64 representation.
  12  */
  13 function bytesToBase64(bytes) {
  14   var bstr = '';
  15   for (var i = 0; i < bytes.length; ++i)
  16     bstr += String.fromCharCode(bytes[i]);
  17   return btoa(bstr).replace(/=/g, '');
  18 }
  19
  20 /**
  21  * Function to convert a string to an array of bytes.
  22  * @param {string} str String to convert.
  23  * @return {Array} Array containing the string.
  24  */
  25 function stringToArray(str) {
  26   var buffer = [];
  27   for (var i = 0; i < str.length; ++i)
  28     buffer[i] = str.charCodeAt(i);
  29   return buffer;
  30 }
  31
  32 /**
  33  * Creates a whispernet encoder.
  34  * @constructor
  35  * @param {Object} params Audio parameters for the whispernet encoder.
  36  * @param {Object} whisperNacl The NaclBridge object, used to communicate with
  37  *     the whispernet wrapper.
  38  * @param {string} clientId A string identifying the requester.
  39  */
  40 function WhisperEncoder(params, whisperNacl, clientId) {
  41   this.whisperNacl_ = whisperNacl;
  42   this.whisperNacl_.addListener(this.onNaclMessage_.bind(this));
  43   this.clientId_ = clientId;
  44
  45   var msg = {
  46     type: 'initialize_encoder',
  47     client_id: clientId,
  48     params: params
  49   };
  50
  51   this.whisperNacl_.send(msg);
  52 }
  53
  54 /**
  55  * Method to encode a token.
  56  * @param {Object} params Encode token parameters object.
  57  */
  58 WhisperEncoder.prototype.encode = function(params) {
  59   // Pad the token before decoding it.
  60   var token = params.token.token;
  61   while (token.length % 4 > 0)
  62     token += '=';
  63
  64   var msg = {
  65     type: 'encode_token',
  66     client_id: this.clientId_,
  67     // Trying to send the token in binary form to Nacl doesn't work correctly.
  68     // We end up with the correct string + a bunch of extra characters. This is
  69     // true of returning a binary string too; hence we communicate back and
  70     // forth by converting the bytes into an array of integers.
  71     token: stringToArray(atob(token)),
  72     repetitions: params.repetitions,
  73     use_dtmf: params.token.audible,
  74     use_crc: params.tokenParams.crc,
  75     use_parity: params.tokenParams.parity
  76   };
  77
  78   this.whisperNacl_.send(msg);
  79 };
  80
  81 /**
  82  * Method to handle messages from the whispernet NaCl wrapper.
  83  * @param {Event} e Event from the whispernet wrapper.
  84  * @private
  85  */
  86 WhisperEncoder.prototype.onNaclMessage_ = function(e) {
  87   var msg = e.data;
  88   if (msg.type == 'encode_token_response' && msg.client_id == this.clientId_) {
  89     chrome.copresencePrivate.sendSamples(this.clientId_,
  90         { token: bytesToBase64(msg.token), audible: msg.audible }, msg.samples);
  91   }
  92 };
  93
  94 /**
  95  * Creates a whispernet decoder.
  96  * @constructor
  97  * @param {Object} params Audio parameters for the whispernet decoder.
  98  * @param {Object} whisperNacl The NaclBridge object, used to communicate with
  99  *     the whispernet wrapper.
 100  * @param {string} clientId A string identifying the requester.
 101  */
 102 function WhisperDecoder(params, whisperNacl, clientId) {
 103   this.whisperNacl_ = whisperNacl;
 104   this.whisperNacl_.addListener(this.onNaclMessage_.bind(this));
 105   this.clientId_ = clientId;
 106
 107   var msg = {
 108     type: 'initialize_decoder',
 109     client_id: clientId,
 110     params: params
 111   };
 112   this.whisperNacl_.send(msg);
 113 }
 114
 115 /**
 116  * Method to request the decoder to process samples.
 117  * @param {Object} params Process samples parameters object.
 118  */
 119 WhisperDecoder.prototype.processSamples = function(params) {
 120   var msg = {
 121     type: 'decode_tokens',
 122     client_id: this.clientId_,
 123     data: params.samples,
 124
 125     decode_audible: params.decodeAudible,
 126     token_length_dtmf: params.audibleTokenParams.length,
 127     crc_dtmf: params.audibleTokenParams.crc,
 128     parity_dtmf: params.audibleTokenParams.parity,
 129
 130     decode_inaudible: params.decodeInaudible,
 131     token_length_dsss: params.inaudibleTokenParams.length,
 132     crc_dsss: params.inaudibleTokenParams.crc,
 133     parity_dsss: params.inaudibleTokenParams.parity,
 134   };
 135
 136   this.whisperNacl_.send(msg);
 137 };
 138
 139 /**
 140  * Method to handle messages from the whispernet NaCl wrapper.
 141  * @param {Event} e Event from the whispernet wrapper.
 142  * @private
 143  */
 144 WhisperDecoder.prototype.onNaclMessage_ = function(e) {
 145   var msg = e.data;
 146   if (msg.type == 'decode_tokens_response' && msg.client_id == this.clientId_) {
 147     this.handleCandidates_(msg.tokens, msg.audible);
 148   }
 149 };
 150
 151 /**
 152  * Method to receive tokens from the decoder and process and forward them to the
 153  * token callback registered with us.
 154  * @param {!Array.string} candidates Array of token candidates.
 155  * @param {boolean} audible Whether the received candidates are from the audible
 156  *     decoder or not.
 157  * @private
 158  */
 159 WhisperDecoder.prototype.handleCandidates_ = function(candidates, audible) {
 160   if (!candidates || candidates.length == 0)
 161     return;
 162
 163   var returnCandidates = [];
 164   for (var i = 0; i < candidates.length; ++i) {
 165     returnCandidates[i] = { token: bytesToBase64(candidates[i]),
 166                             audible: audible };
 167   }
 168   chrome.copresencePrivate.sendFound(this.clientId_, returnCandidates);
 169 };