ca-apm-probe/lib/utils/guidgenerator.js

CA APM Node.js Agent monitors real-time health and performance of Node.js applications

 
/**
 * Copyright (c) 2015 CA. All rights reserved.
 *
 * This software and all information contained therein is confidential and proprietary and
 * shall not be duplicated, used, disclosed or disseminated in any way except as authorized
 * by the applicable license agreement, without the express written permission of CA. All
 * authorized reproductions must be marked with this language.
 *
 * EXCEPT AS SET FORTH IN THE APPLICABLE LICENSE AGREEMENT, TO THE EXTENT
 * PERMITTED BY APPLICABLE LAW, CA PROVIDES THIS SOFTWARE WITHOUT WARRANTY
 * OF ANY KIND, INCLUDING WITHOUT LIMITATION, ANY IMPLIED WARRANTIES OF
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT WILL CA BE
 * LIABLE TO THE END USER OR ANY THIRD PARTY FOR ANY LOSS OR DAMAGE, DIRECT OR
 * INDIRECT, FROM THE USE OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, LOST
 * PROFITS, BUSINESS INTERRUPTION, GOODWILL, OR LOST DATA, EVEN IF CA IS
 * EXPRESSLY ADVISED OF SUCH LOSS OR DAMAGE.
 */

// module for generating guid
// algorithm used over here is almost similar to the one used in core Java Agent to generate guid

'use strict';
var os = require('os');
var dns = require('dns');
var logger = require("../logger.js");

var CHARS_HEX_DIGITS = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'];
var DEFAULT_IP = '127.0.0.1';
var defaultSeeder = new SimpleRandomSeeder(0, 99999);

// random number generator
function SimpleRandomSeeder(low, high) {
  this.low = low;
  this.high = high;

  this.nextInt = function() {
    return Math.floor(Math.random() * (high - low) + low);
  }
};

// utility functions
var toHex = function(value, length) {
  var buffer = '';
  var shift = (length - 1) << 2;
  var i = -1;

  while (++i < length) {
    buffer = buffer.concat(CHARS_HEX_DIGITS[(value >> shift) & 0x0000000F]);
    value <<= 4;
  }
  return buffer;
}

var convertIpToBytes = function(ipAddress) {
  var arr = ipAddress.split('.');
  var bytes = [];
  var i = -1;

  while (++i < arr.length) {
    bytes[i] = parseInt(arr[i]);
  }
  return bytes;
};

var toInt = function(bytes) {
  var value = 0;
  var b = 0;
  var i = -1;

  while (++i < bytes.length) {
    value <<= 8;
    b = bytes[i] & 0xff;
    value |= b;
  }
  return value;
};

var makeGuidGenerator = function() {
  var hostAndSystemId;
  var findHostAndSystemId = function() {
    var processId = toHex(process.pid, 8);
    var host = os.hostname();
    hostAndSystemId = toHex(toInt(convertIpToBytes(DEFAULT_IP)), 8).concat(processId);

    dns.lookup(host, function onLookup(err, address, family) {

      if(err) {
        logger.debug('Error while looking up ipaddress for host: ' + host); 
        return;
      }
      hostAndSystemId = toHex(toInt(convertIpToBytes(address)), 8).concat(processId);
    });
  };

  //invoke function to find host and system id
  findHostAndSystemId();

  // generates guid key
  return function() {
    var guid = toHex((Date.now() & 0xFFFFFFFF), 8);
    guid = guid.concat(hostAndSystemId).concat(toHex(defaultSeeder.nextInt(), 8));
    return guid;
  };
};

function GuidGenerator() {
  this.generateGuid = makeGuidGenerator();
}

module.exports = new GuidGenerator();