bufferutil/fallback.js

/*!
 * bufferutil: WebSocket buffer utils
 * Copyright(c) 2015 Einar Otto Stangvik <[email protected]>
 * MIT Licensed
 */

'use strict';

/**
 * Merges an array of buffers into a target buffer.
 *
 * @param {Buffer} target The target buffer
 * @param {Buffer[]} buffers The array of buffers to merge
 * @public
 */
const merge = (target, buffers) => {
  var offset = 0;
  for (var i = 0; i < buffers.length; i++) {
    const buf = buffers[i];
    buf.copy(target, offset);
    offset += buf.length;
  }
};

/**
 * Masks a buffer using the given mask.
 *
 * @param {Buffer} source The buffer to mask
 * @param {Buffer} mask The mask to use
 * @param {Buffer} output The buffer where to store the result
 * @param {Number} offset The offset at which to start writing
 * @param {Number} length The number of bytes to mask.
 * @public
 */
const mask = (source, mask, output, offset, length) => {
  for (var i = 0; i < length; i++) {
    output[offset + i] = source[i] ^ mask[i & 3];
  }
};

/**
 * Unmasks a buffer using the given mask.
 *
 * @param {Buffer} buffer The buffer to unmask
 * @param {Buffer} mask The mask to use
 * @public
 */
const unmask = (buffer, mask) => {
  // Required until https://github.com/nodejs/node/issues/9006 is resolved.
  const length = buffer.length;
  for (var i = 0; i < length; i++) {
    buffer[i] ^= mask[i & 3];
  }
};

module.exports = { merge, mask, unmask };