amazon-cognito-identity-js/src/utils/getRandomValues.native.js

Amazon Cognito Identity Provider JavaScript SDK

import base64Decode from 'fast-base64-decode';
import getRandomBase64 from './getRandomBase64';

class TypeMismatchError extends Error {}
class QuotaExceededError extends Error {}

let warned = false;
function insecureRandomValues(array) {
	if (!warned) {
		console.warn(
			'Using an insecure random number generator, this should only happen when running in a debugger without support for crypto.getRandomValues'
		);
		warned = true;
	}

	for (let i = 0, r; i < array.length; i++) {
		if ((i & 0x03) === 0) r = Math.random() * 0x100000000;
		array[i] = (r >>> ((i & 0x03) << 3)) & 0xff;
	}

	return array;
}

/**
 * @param {Int8Array|Uint8Array|Int16Array|Uint16Array|Int32Array|Uint32Array|Uint8ClampedArray} array
 */
export default function getRandomValues(array) {
	if (
		!(
			array instanceof Int8Array ||
			array instanceof Uint8Array ||
			array instanceof Int16Array ||
			array instanceof Uint16Array ||
			array instanceof Int32Array ||
			array instanceof Uint32Array ||
			array instanceof Uint8ClampedArray
		)
	) {
		throw new TypeMismatchError('Expected an integer array');
	}

	if (array.byteLength > 65536) {
		throw new QuotaExceededError('Can only request a maximum of 65536 bytes');
	}

	// Calling getRandomBase64 in debug mode leads to the error
	// "Calling synchronous methods on native modules is not supported in Chrome".
	// So in that specific case we fall back to just using Math.random.
	if (__DEV__) {
		if (typeof global.nativeCallSyncHook === 'undefined') {
			return insecureRandomValues(array);
		}
	}

	base64Decode(
		getRandomBase64(array.byteLength),
		new Uint8Array(array.buffer, array.byteOffset, array.byteLength)
	);

	return array;
}