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102 lines
1.9 KiB
JavaScript

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