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validate_object.ts
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validate_object.ts
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/*
* Licensed to Elasticsearch B.V. under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch B.V. licenses this file to you under
* the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
interface StackItem {
value: any;
previousKey: string | null;
}
// we have to do Object.prototype.hasOwnProperty because when you create an object using
// Object.create(null), and I assume other methods, you get an object without a prototype,
// so you can't use current.hasOwnProperty
const hasOwnProperty = (obj: any, property: string) =>
Object.prototype.hasOwnProperty.call(obj, property);
const isObject = (obj: any) => typeof obj === 'object' && obj !== null;
// we're using a stack instead of recursion so we aren't limited by the call stack
export function validateObject(obj: any) {
if (!isObject(obj)) {
return;
}
const stack: StackItem[] = [
{
value: obj,
previousKey: null,
},
];
const seen = new WeakSet([obj]);
while (stack.length > 0) {
const { value, previousKey } = stack.pop()!;
if (!isObject(value)) {
continue;
}
if (hasOwnProperty(value, '__proto__')) {
throw new Error(`'__proto__' is an invalid key`);
}
if (hasOwnProperty(value, 'prototype') && previousKey === 'constructor') {
throw new Error(`'constructor.prototype' is an invalid key`);
}
// iterating backwards through an array is reportedly more performant
const entries = Object.entries(value);
for (let i = entries.length - 1; i >= 0; --i) {
const [key, childValue] = entries[i];
if (isObject(childValue)) {
if (seen.has(childValue)) {
throw new Error('circular reference detected');
}
seen.add(childValue);
}
stack.push({
value: childValue,
previousKey: key,
});
}
}
}