buffer-util.js - buddy - node MVC discord bot

buffer-util.js (3044B)
      1 'use strict';
      2 
      3 const { EMPTY_BUFFER } = require('./constants');
      4 
      5 /**
      6  * Merges an array of buffers into a new buffer.
      7  *
      8  * @param {Buffer[]} list The array of buffers to concat
      9  * @param {Number} totalLength The total length of buffers in the list
     10  * @return {Buffer} The resulting buffer
     11  * @public
     12  */
     13 function concat(list, totalLength) {
     14   if (list.length === 0) return EMPTY_BUFFER;
     15   if (list.length === 1) return list[0];
     16 
     17   const target = Buffer.allocUnsafe(totalLength);
     18   let offset = 0;
     19 
     20   for (let i = 0; i < list.length; i++) {
     21     const buf = list[i];
     22     target.set(buf, offset);
     23     offset += buf.length;
     24   }
     25 
     26   if (offset < totalLength) return target.slice(0, offset);
     27 
     28   return target;
     29 }
     30 
     31 /**
     32  * Masks a buffer using the given mask.
     33  *
     34  * @param {Buffer} source The buffer to mask
     35  * @param {Buffer} mask The mask to use
     36  * @param {Buffer} output The buffer where to store the result
     37  * @param {Number} offset The offset at which to start writing
     38  * @param {Number} length The number of bytes to mask.
     39  * @public
     40  */
     41 function _mask(source, mask, output, offset, length) {
     42   for (let i = 0; i < length; i++) {
     43     output[offset + i] = source[i] ^ mask[i & 3];
     44   }
     45 }
     46 
     47 /**
     48  * Unmasks a buffer using the given mask.
     49  *
     50  * @param {Buffer} buffer The buffer to unmask
     51  * @param {Buffer} mask The mask to use
     52  * @public
     53  */
     54 function _unmask(buffer, mask) {
     55   // Required until https://github.com/nodejs/node/issues/9006 is resolved.
     56   const length = buffer.length;
     57   for (let i = 0; i < length; i++) {
     58     buffer[i] ^= mask[i & 3];
     59   }
     60 }
     61 
     62 /**
     63  * Converts a buffer to an `ArrayBuffer`.
     64  *
     65  * @param {Buffer} buf The buffer to convert
     66  * @return {ArrayBuffer} Converted buffer
     67  * @public
     68  */
     69 function toArrayBuffer(buf) {
     70   if (buf.byteLength === buf.buffer.byteLength) {
     71     return buf.buffer;
     72   }
     73 
     74   return buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength);
     75 }
     76 
     77 /**
     78  * Converts `data` to a `Buffer`.
     79  *
     80  * @param {*} data The data to convert
     81  * @return {Buffer} The buffer
     82  * @throws {TypeError}
     83  * @public
     84  */
     85 function toBuffer(data) {
     86   toBuffer.readOnly = true;
     87 
     88   if (Buffer.isBuffer(data)) return data;
     89 
     90   let buf;
     91 
     92   if (data instanceof ArrayBuffer) {
     93     buf = Buffer.from(data);
     94   } else if (ArrayBuffer.isView(data)) {
     95     buf = Buffer.from(data.buffer, data.byteOffset, data.byteLength);
     96   } else {
     97     buf = Buffer.from(data);
     98     toBuffer.readOnly = false;
     99   }
    100 
    101   return buf;
    102 }
    103 
    104 try {
    105   const bufferUtil = require('bufferutil');
    106   const bu = bufferUtil.BufferUtil || bufferUtil;
    107 
    108   module.exports = {
    109     concat,
    110     mask(source, mask, output, offset, length) {
    111       if (length < 48) _mask(source, mask, output, offset, length);
    112       else bu.mask(source, mask, output, offset, length);
    113     },
    114     toArrayBuffer,
    115     toBuffer,
    116     unmask(buffer, mask) {
    117       if (buffer.length < 32) _unmask(buffer, mask);
    118       else bu.unmask(buffer, mask);
    119     }
    120   };
    121 } catch (e) /* istanbul ignore next */ {
    122   module.exports = {
    123     concat,
    124     mask: _mask,
    125     toArrayBuffer,
    126     toBuffer,
    127     unmask: _unmask
    128   };
    129 }