1/*!
  2 * ws: a node.js websocket client
  3 * Copyright(c) 2011 Einar Otto Stangvik <einaros@gmail.com>
  4 * MIT Licensed
  5 */
  6
  7/**
  8 * Returns a Buffer from a "ff 00 ff"-type hex string.
  9 */
 10
 11getBufferFromHexString = function(byteStr) {
 12  var bytes = byteStr.split(' ');
 13  var buf = new Buffer(bytes.length);
 14  for (var i = 0; i < bytes.length; ++i) {
 15    buf[i] = parseInt(bytes[i], 16);
 16  }
 17  return buf;
 18}
 19
 20/**
 21 * Returns a hex string from a Buffer.
 22 */
 23
 24getHexStringFromBuffer = function(data) {
 25  var s = '';
 26  for (var i = 0; i < data.length; ++i) {
 27    s += padl(data[i].toString(16), 2, '0') + ' ';
 28  }
 29  return s.trim();
 30}
 31
 32/**
 33 * Splits a buffer in two parts.
 34 */
 35
 36splitBuffer = function(buffer) {
 37  var b1 = new Buffer(Math.ceil(buffer.length / 2));
 38  buffer.copy(b1, 0, 0, b1.length);
 39  var b2 = new Buffer(Math.floor(buffer.length / 2));
 40  buffer.copy(b2, 0, b1.length, b1.length + b2.length);
 41  return [b1, b2];
 42}
 43
 44/**
 45 * Performs hybi07+ type masking on a hex string or buffer.
 46 */
 47
 48mask = function(buf, maskString) {
 49  if (typeof buf == 'string') buf = new Buffer(buf);
 50  var mask = getBufferFromHexString(maskString || '34 83 a8 68');
 51  for (var i = 0; i < buf.length; ++i) {
 52    buf[i] ^= mask[i % 4];    
 53  }
 54  return buf;
 55}
 56
 57/**
 58 * Returns a hex string representing the length of a message
 59 */
 60 
 61getHybiLengthAsHexString = function(len, masked) {  
 62  if (len < 126) {
 63    var buf = new Buffer(1);
 64    buf[0] = (masked ? 0x80 : 0) | len;
 65  }
 66  else if (len < 65536) {
 67    var buf = new Buffer(3);
 68    buf[0] = (masked ? 0x80 : 0) | 126;
 69    getBufferFromHexString(pack(4, len)).copy(buf, 1);
 70  }
 71  else {
 72    var buf = new Buffer(9);
 73    buf[0] = (masked ? 0x80 : 0) | 127;
 74    getBufferFromHexString(pack(16, len)).copy(buf, 1);
 75  }
 76  return getHexStringFromBuffer(buf);
 77}
 78
 79/**
 80 * Unpacks a Buffer into a number.
 81 */
 82
 83unpack = function(buffer) {
 84  var n = 0;
 85  for (var i = 0; i < buffer.length; ++i) {
 86    n = (i == 0) ? buffer[i] : (n * 256) + buffer[i];
 87  }
 88  return n;
 89}
 90
 91/**
 92 * Returns a hex string, representing a specific byte count 'length', from a number.
 93 */
 94
 95pack = function(length, number) {
 96  return padl(number.toString(16), length, '0').replace(/([0-9a-f][0-9a-f])/gi, '$1 ').trim();
 97}
 98
 99/**
100 * Left pads the string 's' to a total length of 'n' with char 'c'.
101 */
102
103padl = function(s, n, c) { 
104  return new Array(1 + n - s.length).join(c) + s;
105}