102 lines
1.9 KiB
JavaScript
102 lines
1.9 KiB
JavaScript
/*!
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* random-bytes
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* Copyright(c) 2016 Douglas Christopher Wilson
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* MIT Licensed
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*/
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'use strict'
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/**
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* Module dependencies.
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* @private
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*/
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var crypto = require('crypto')
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/**
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* Module variables.
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* @private
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*/
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var generateAttempts = crypto.randomBytes === crypto.pseudoRandomBytes ? 1 : 3
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/**
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* Module exports.
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* @public
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*/
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module.exports = randomBytes
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module.exports.sync = randomBytesSync
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/**
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* Generates strong pseudo-random bytes.
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*
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* @param {number} size
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* @param {function} [callback]
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* @return {Promise}
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* @public
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*/
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function randomBytes(size, callback) {
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// validate callback is a function, if provided
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if (callback !== undefined && typeof callback !== 'function') {
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throw new TypeError('argument callback must be a function')
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}
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// require the callback without promises
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if (!callback && !global.Promise) {
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throw new TypeError('argument callback is required')
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}
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if (callback) {
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// classic callback style
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return generateRandomBytes(size, generateAttempts, callback)
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}
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return new Promise(function executor(resolve, reject) {
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generateRandomBytes(size, generateAttempts, function onRandomBytes(err, str) {
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if (err) return reject(err)
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resolve(str)
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})
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})
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}
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/**
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* Generates strong pseudo-random bytes sync.
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*
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* @param {number} size
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* @return {Buffer}
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* @public
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*/
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function randomBytesSync(size) {
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var err = null
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for (var i = 0; i < generateAttempts; i++) {
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try {
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return crypto.randomBytes(size)
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} catch (e) {
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err = e
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}
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}
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throw err
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}
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/**
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* Generates strong pseudo-random bytes.
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*
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* @param {number} size
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* @param {number} attempts
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* @param {function} callback
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* @private
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*/
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function generateRandomBytes(size, attempts, callback) {
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crypto.randomBytes(size, function onRandomBytes(err, buf) {
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if (!err) return callback(null, buf)
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if (!--attempts) return callback(err)
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setTimeout(generateRandomBytes.bind(null, size, attempts, callback), 10)
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})
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}
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