protocol.js

/*
 * MIT License
 *
 * Copyright (c) 2017 Wouter Klijn <contact@wuhkuh.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

'use strict'

const lib = require('./lib')                         // Library
const flattenSchema = lib.flattenSchema   // Flatten schema to linear form
const generate = lib.generate                   // Generate packets using schema
const parse = lib.parse                            // Parse packets using schema
const setup = lib.setup                            // Setup pre-assigned masks

/**
 * Create and read Buffers using a schema
 * @public
 */
class Protocol {
  constructor (schema) {
    const nodeMajorVersion = process.version.split('v')[1].split('.')[0]

    /*
     * Prevent usage on old node versions, due to the Buffer vulnerability
     * (node issue #4660).
     *
     * There will be no workaround for this vulnerability due to requiring API
     * changes. This might result in poor performance. In this application,
     * performance is critical.
     */

    if (nodeMajorVersion <= 4) {
      throw new Error('Protocol ERROR: This version of Node has a security ' +
      'problem with Buffers. Please update your installation. (issue #4660)')
    }

    this._schema = setup(flattenSchema(schema))
  }

  /**
   * Generate a Buffer from an Object according to the Protocol schema
   * @param {Object} input input
   * @returns {Buffer} output
   * @public
   */
  generate (input, callback) { return generate(input, this._schema, callback) }

  /**
   * Parse a Buffer, returning an Object according to the Protocol schema
   * @param {Buffer} input input
   * @returns {Object} output
   * @public
   */
  parse (input, callback) { return parse(input, this._schema, callback) }
}

module.exports = Protocol