/
random.js
327 lines (277 loc) Β· 8.89 KB
/
random.js
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'use strict';
const {
MathMin,
NumberIsNaN,
NumberIsSafeInteger
} = primordials;
const { AsyncWrap, Providers } = internalBinding('async_wrap');
const {
Buffer,
kMaxLength,
} = require('buffer');
const {
randomBytes: _randomBytes,
secureBuffer,
} = internalBinding('crypto');
const {
codes: {
ERR_INVALID_ARG_TYPE,
ERR_INVALID_CALLBACK,
ERR_OUT_OF_RANGE,
ERR_OPERATION_FAILED,
}
} = require('internal/errors');
const {
validateBoolean,
validateNumber,
validateObject,
} = require('internal/validators');
const { isArrayBufferView } = require('internal/util/types');
const { FastBuffer } = require('internal/buffer');
const kMaxInt32 = 2 ** 31 - 1;
const kMaxPossibleLength = MathMin(kMaxLength, kMaxInt32);
function assertOffset(offset, elementSize, length) {
validateNumber(offset, 'offset');
offset *= elementSize;
const maxLength = MathMin(length, kMaxPossibleLength);
if (NumberIsNaN(offset) || offset > maxLength || offset < 0) {
throw new ERR_OUT_OF_RANGE('offset', `>= 0 && <= ${maxLength}`, offset);
}
return offset >>> 0; // Convert to uint32.
}
function assertSize(size, elementSize, offset, length) {
validateNumber(size, 'size');
size *= elementSize;
if (NumberIsNaN(size) || size > kMaxPossibleLength || size < 0) {
throw new ERR_OUT_OF_RANGE('size',
`>= 0 && <= ${kMaxPossibleLength}`, size);
}
if (size + offset > length) {
throw new ERR_OUT_OF_RANGE('size + offset', `<= ${length}`, size + offset);
}
return size >>> 0; // Convert to uint32.
}
function randomBytes(size, callback) {
size = assertSize(size, 1, 0, Infinity);
if (callback !== undefined && typeof callback !== 'function')
throw new ERR_INVALID_CALLBACK(callback);
const buf = new FastBuffer(size);
if (!callback) return handleError(_randomBytes(buf, 0, size), buf);
const wrap = new AsyncWrap(Providers.RANDOMBYTESREQUEST);
wrap.ondone = (ex) => { // Retains buf while request is in flight.
if (ex) return callback.call(wrap, ex);
callback.call(wrap, null, buf);
};
_randomBytes(buf, 0, size, wrap);
}
function randomFillSync(buf, offset = 0, size) {
if (!isArrayBufferView(buf)) {
throw new ERR_INVALID_ARG_TYPE('buf', 'ArrayBufferView', buf);
}
const elementSize = buf.BYTES_PER_ELEMENT || 1;
offset = assertOffset(offset, elementSize, buf.byteLength);
if (size === undefined) {
size = buf.byteLength - offset;
} else {
size = assertSize(size, elementSize, offset, buf.byteLength);
}
return handleError(_randomBytes(buf, offset, size), buf);
}
function randomFill(buf, offset, size, callback) {
if (!isArrayBufferView(buf)) {
throw new ERR_INVALID_ARG_TYPE('buf', 'ArrayBufferView', buf);
}
const elementSize = buf.BYTES_PER_ELEMENT || 1;
if (typeof offset === 'function') {
callback = offset;
offset = 0;
size = buf.bytesLength;
} else if (typeof size === 'function') {
callback = size;
size = buf.byteLength - offset;
} else if (typeof callback !== 'function') {
throw new ERR_INVALID_CALLBACK(callback);
}
offset = assertOffset(offset, elementSize, buf.byteLength);
if (size === undefined) {
size = buf.byteLength - offset;
} else {
size = assertSize(size, elementSize, offset, buf.byteLength);
}
const wrap = new AsyncWrap(Providers.RANDOMBYTESREQUEST);
wrap.ondone = (ex) => { // Retains buf while request is in flight.
if (ex) return callback.call(wrap, ex);
callback.call(wrap, null, buf);
};
_randomBytes(buf, offset, size, wrap);
}
// Largest integer we can read from a buffer.
// e.g.: Buffer.from("ff".repeat(6), "hex").readUIntBE(0, 6);
const RAND_MAX = 0xFFFF_FFFF_FFFF;
// Generates an integer in [min, max) range where min is inclusive and max is
// exclusive.
function randomInt(min, max, callback) {
// Detect optional min syntax
// randomInt(max)
// randomInt(max, callback)
const minNotSpecified = typeof max === 'undefined' ||
typeof max === 'function';
if (minNotSpecified) {
callback = max;
max = min;
min = 0;
}
const isSync = typeof callback === 'undefined';
if (!isSync && typeof callback !== 'function') {
throw new ERR_INVALID_CALLBACK(callback);
}
if (!NumberIsSafeInteger(min)) {
throw new ERR_INVALID_ARG_TYPE('min', 'a safe integer', min);
}
if (!NumberIsSafeInteger(max)) {
throw new ERR_INVALID_ARG_TYPE('max', 'a safe integer', max);
}
if (max <= min) {
throw new ERR_OUT_OF_RANGE(
'max', `greater than the value of "min" (${min})`, max
);
}
// First we generate a random int between [0..range)
const range = max - min;
if (!(range <= RAND_MAX)) {
throw new ERR_OUT_OF_RANGE(`max${minNotSpecified ? '' : ' - min'}`,
`<= ${RAND_MAX}`, range);
}
// For (x % range) to produce an unbiased value greater than or equal to 0 and
// less than range, x must be drawn randomly from the set of integers greater
// than or equal to 0 and less than randLimit.
const randLimit = RAND_MAX - (RAND_MAX % range);
if (isSync) {
// Sync API
while (true) {
const x = randomBytes(6).readUIntBE(0, 6);
if (x >= randLimit) {
// Try again.
continue;
}
return (x % range) + min;
}
} else {
// Async API
const pickAttempt = () => {
randomBytes(6, (err, bytes) => {
if (err) return callback(err);
const x = bytes.readUIntBE(0, 6);
if (x >= randLimit) {
// Try again.
return pickAttempt();
}
const n = (x % range) + min;
callback(null, n);
});
};
pickAttempt();
}
}
function handleError(ex, buf) {
if (ex) throw ex;
return buf;
}
// Implements an RFC 4122 version 4 random UUID.
// To improve performance, random data is generated in batches
// large enough to cover kBatchSize UUID's at a time. The uuidData
// and uuid buffers are reused. Each call to randomUUID() consumes
// 16 bytes from the buffer.
const kHexDigits = [
48, 49, 50, 51, 52, 53, 54, 55,
56, 57, 97, 98, 99, 100, 101, 102
];
const kBatchSize = 128;
let uuidData;
let uuidNotBuffered;
let uuid;
let uuidBatch = 0;
function getBufferedUUID() {
if (uuidData === undefined) {
uuidData = secureBuffer(16 * kBatchSize);
if (uuidData === undefined)
throw new ERR_OPERATION_FAILED('Out of memory');
}
if (uuidBatch === 0) randomFillSync(uuidData);
uuidBatch = (uuidBatch + 1) % kBatchSize;
return uuidData.slice(uuidBatch * 16, (uuidBatch * 16) + 16);
}
function randomUUID(options) {
if (options !== undefined)
validateObject(options, 'options');
const {
disableEntropyCache = false,
} = { ...options };
validateBoolean(disableEntropyCache, 'options.disableEntropyCache');
if (uuid === undefined) {
uuid = Buffer.alloc(36, '-');
uuid[14] = 52; // '4', identifies the UUID version
}
let uuidBuf;
if (!disableEntropyCache) {
uuidBuf = getBufferedUUID();
} else {
uuidBuf = uuidNotBuffered;
if (uuidBuf === undefined)
uuidBuf = uuidNotBuffered = secureBuffer(16);
if (uuidBuf === undefined)
throw new ERR_OPERATION_FAILED('Out of memory');
randomFillSync(uuidBuf);
}
// Variant byte: 10xxxxxx (variant 1)
uuidBuf[8] = (uuidBuf[8] & 0x3f) | 0x80;
// This function is structured the way it is for performance.
// The uuid buffer stores the serialization of the random
// bytes from uuidData.
// xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
let n = 0;
uuid[0] = kHexDigits[uuidBuf[n] >> 4];
uuid[1] = kHexDigits[uuidBuf[n++] & 0xf];
uuid[2] = kHexDigits[uuidBuf[n] >> 4];
uuid[3] = kHexDigits[uuidBuf[n++] & 0xf];
uuid[4] = kHexDigits[uuidBuf[n] >> 4];
uuid[5] = kHexDigits[uuidBuf[n++] & 0xf];
uuid[6] = kHexDigits[uuidBuf[n] >> 4];
uuid[7] = kHexDigits[uuidBuf[n++] & 0xf];
// -
uuid[9] = kHexDigits[uuidBuf[n] >> 4];
uuid[10] = kHexDigits[uuidBuf[n++] & 0xf];
uuid[11] = kHexDigits[uuidBuf[n] >> 4];
uuid[12] = kHexDigits[uuidBuf[n++] & 0xf];
// -
// 4, uuid[14] is set already...
uuid[15] = kHexDigits[uuidBuf[n++] & 0xf];
uuid[16] = kHexDigits[uuidBuf[n] >> 4];
uuid[17] = kHexDigits[uuidBuf[n++] & 0xf];
// -
uuid[19] = kHexDigits[uuidBuf[n] >> 4];
uuid[20] = kHexDigits[uuidBuf[n++] & 0xf];
uuid[21] = kHexDigits[uuidBuf[n] >> 4];
uuid[22] = kHexDigits[uuidBuf[n++] & 0xf];
// -
uuid[24] = kHexDigits[uuidBuf[n] >> 4];
uuid[25] = kHexDigits[uuidBuf[n++] & 0xf];
uuid[26] = kHexDigits[uuidBuf[n] >> 4];
uuid[27] = kHexDigits[uuidBuf[n++] & 0xf];
uuid[28] = kHexDigits[uuidBuf[n] >> 4];
uuid[29] = kHexDigits[uuidBuf[n++] & 0xf];
uuid[30] = kHexDigits[uuidBuf[n] >> 4];
uuid[31] = kHexDigits[uuidBuf[n++] & 0xf];
uuid[32] = kHexDigits[uuidBuf[n] >> 4];
uuid[33] = kHexDigits[uuidBuf[n++] & 0xf];
uuid[34] = kHexDigits[uuidBuf[n] >> 4];
uuid[35] = kHexDigits[uuidBuf[n] & 0xf];
return uuid.latin1Slice(0, 36);
}
module.exports = {
randomBytes,
randomFill,
randomFillSync,
randomInt,
randomUUID,
};