buffer-util.js (1899B)
1 'use strict'; 2 3 /** 4 * Merges an array of buffers into a new buffer. 5 * 6 * @param {Buffer[]} list The array of buffers to concat 7 * @param {Number} totalLength The total length of buffers in the list 8 * @return {Buffer} The resulting buffer 9 * @public 10 */ 11 function concat(list, totalLength) { 12 const target = Buffer.allocUnsafe(totalLength); 13 var offset = 0; 14 15 for (var i = 0; i < list.length; i++) { 16 const buf = list[i]; 17 buf.copy(target, offset); 18 offset += buf.length; 19 } 20 21 return target; 22 } 23 24 /** 25 * Masks a buffer using the given mask. 26 * 27 * @param {Buffer} source The buffer to mask 28 * @param {Buffer} mask The mask to use 29 * @param {Buffer} output The buffer where to store the result 30 * @param {Number} offset The offset at which to start writing 31 * @param {Number} length The number of bytes to mask. 32 * @public 33 */ 34 function _mask(source, mask, output, offset, length) { 35 for (var i = 0; i < length; i++) { 36 output[offset + i] = source[i] ^ mask[i & 3]; 37 } 38 } 39 40 /** 41 * Unmasks a buffer using the given mask. 42 * 43 * @param {Buffer} buffer The buffer to unmask 44 * @param {Buffer} mask The mask to use 45 * @public 46 */ 47 function _unmask(buffer, mask) { 48 // Required until https://github.com/nodejs/node/issues/9006 is resolved. 49 const length = buffer.length; 50 for (var i = 0; i < length; i++) { 51 buffer[i] ^= mask[i & 3]; 52 } 53 } 54 55 try { 56 const bufferUtil = require('bufferutil'); 57 const bu = bufferUtil.BufferUtil || bufferUtil; 58 59 module.exports = { 60 mask(source, mask, output, offset, length) { 61 if (length < 48) _mask(source, mask, output, offset, length); 62 else bu.mask(source, mask, output, offset, length); 63 }, 64 unmask(buffer, mask) { 65 if (buffer.length < 32) _unmask(buffer, mask); 66 else bu.unmask(buffer, mask); 67 }, 68 concat 69 }; 70 } catch (e) /* istanbul ignore next */ { 71 module.exports = { concat, mask: _mask, unmask: _unmask }; 72 }