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					127 lines
				
				4.5 KiB
			| 
											3 years ago
										 | # secure-json-parse
 | ||
|  | 
 | ||
|  |  | ||
|  | [](https://www.npmjs.com/package/secure-json-parse) | ||
|  | [](https://standardjs.com/) | ||
|  | 
 | ||
|  | `JSON.parse()` drop-in replacement with prototype poisoning protection. | ||
|  | 
 | ||
|  | ## Introduction
 | ||
|  | 
 | ||
|  | Consider this: | ||
|  | 
 | ||
|  | ```js | ||
|  | > const a = '{"__proto__":{ "b":5}}';
 | ||
|  | '{"__proto__":{ "b":5}}' | ||
|  | 
 | ||
|  | > const b = JSON.parse(a);
 | ||
|  | { __proto__: { b: 5 } } | ||
|  | 
 | ||
|  | > b.b;
 | ||
|  | undefined | ||
|  | 
 | ||
|  | > const c = Object.assign({}, b);
 | ||
|  | {} | ||
|  | 
 | ||
|  | > c.b
 | ||
|  | 5 | ||
|  | ``` | ||
|  | 
 | ||
|  | The problem is that `JSON.parse()` retains the `__proto__` property as a plain object key. By | ||
|  | itself, this is not a security issue. However, as soon as that object is assigned to another or | ||
|  | iterated on and values copied, the `__proto__` property leaks and becomes the object's prototype. | ||
|  | 
 | ||
|  | ## Install
 | ||
|  | ``` | ||
|  | npm i secure-json-parse | ||
|  | ``` | ||
|  | 
 | ||
|  | ## Usage
 | ||
|  | 
 | ||
|  | Pass the option object as a second (or third) parameter for configuring the action to take in case of a bad JSON, if nothing is configured, the default is to throw a `SyntaxError`.<br/> | ||
|  | You can choose which action to perform in case `__proto__` is present, and in case `constructor.prototype` is present. | ||
|  | 
 | ||
|  | ```js | ||
|  | const sjson = require('secure-json-parse') | ||
|  | 
 | ||
|  | const goodJson = '{ "a": 5, "b": 6 }' | ||
|  | const badJson = '{ "a": 5, "b": 6, "__proto__": { "x": 7 }, "constructor": {"prototype": {"bar": "baz"} } }' | ||
|  | 
 | ||
|  | console.log(JSON.parse(goodJson), sjson.parse(goodJson, { protoAction: 'remove', constructorAction: 'remove' })) | ||
|  | console.log(JSON.parse(badJson), sjson.parse(badJson, { protoAction: 'remove', constructorAction: 'remove' })) | ||
|  | ``` | ||
|  | 
 | ||
|  | ## API
 | ||
|  | 
 | ||
|  | ### `sjson.parse(text, [reviver], [options])`
 | ||
|  | 
 | ||
|  | Parses a given JSON-formatted text into an object where: | ||
|  | - `text` - the JSON text string. | ||
|  | - `reviver` - the `JSON.parse()` optional `reviver` argument. | ||
|  | - `options` - optional configuration object where: | ||
|  |     - `protoAction` - optional string with one of: | ||
|  |         - `'error'` - throw a `SyntaxError` when a `__proto__` key is found. This is the default value. | ||
|  |         - `'remove'` - deletes any `__proto__` keys from the result object. | ||
|  |         - `'ignore'` - skips all validation (same as calling `JSON.parse()` directly). | ||
|  |     - `constructorAction` - optional string with one of: | ||
|  |         - `'error'` - throw a `SyntaxError` when a `constructor.prototype` key is found. This is the default value. | ||
|  |         - `'remove'` - deletes any `constructor` keys from the result object. | ||
|  |         - `'ignore'` - skips all validation (same as calling `JSON.parse()` directly). | ||
|  | 
 | ||
|  | ### `sjson.scan(obj, [options])`
 | ||
|  | 
 | ||
|  | Scans a given object for prototype properties where: | ||
|  | - `obj` - the object being scanned. | ||
|  | - `options` - optional configuration object where: | ||
|  |     - `protoAction` - optional string with one of: | ||
|  |         - `'error'` - throw a `SyntaxError` when a `__proto__` key is found. This is the default value. | ||
|  |         - `'remove'` - deletes any `__proto__` keys from the input `obj`. | ||
|  |     - `constructorAction` - optional string with one of: | ||
|  |         - `'error'` - throw a `SyntaxError` when a `constructor.prototype` key is found. This is the default value. | ||
|  |         - `'remove'` - deletes any `constructor` keys from the input `obj`. | ||
|  | 
 | ||
|  | ## Benchmarks
 | ||
|  | 
 | ||
|  | Machine: 2,7 GHz Quad-Core Intel Core i7 | ||
|  | 
 | ||
|  | ``` | ||
|  | v14.8.0 | ||
|  | 
 | ||
|  | > node ignore.js
 | ||
|  | 
 | ||
|  | JSON.parse x 679,376 ops/sec ±1.15% (84 runs sampled) | ||
|  | secure-json-parse x 649,605 ops/sec ±0.58% (87 runs sampled) | ||
|  | reviver x 244,414 ops/sec ±1.05% (88 runs sampled) | ||
|  | Fastest is JSON.parse | ||
|  | 
 | ||
|  | > node no__proto__.js
 | ||
|  | 
 | ||
|  | JSON.parse x 652,190 ops/sec ±0.67% (86 runs sampled) | ||
|  | secure-json-parse x 589,785 ops/sec ±1.01% (88 runs sampled) | ||
|  | reviver x 218,075 ops/sec ±1.58% (87 runs sampled) | ||
|  | Fastest is JSON.parse | ||
|  | 
 | ||
|  | > node remove.js
 | ||
|  | 
 | ||
|  | JSON.parse x 683,527 ops/sec ±0.62% (88 runs sampled) | ||
|  | secure-json-parse x 316,926 ops/sec ±0.63% (87 runs sampled) | ||
|  | reviver x 214,167 ops/sec ±0.63% (86 runs sampled) | ||
|  | Fastest is JSON.parse | ||
|  | 
 | ||
|  | > node throw.js
 | ||
|  | 
 | ||
|  | JSON.parse x 682,548 ops/sec ±0.60% (88 runs sampled) | ||
|  | JSON.parse error x 170,716 ops/sec ±0.93% (87 runs sampled) | ||
|  | secure-json-parse x 104,483 ops/sec ±0.62% (87 runs sampled) | ||
|  | reviver x 114,197 ops/sec ±0.63% (87 runs sampled) | ||
|  | Fastest is JSON.parse | ||
|  | ``` | ||
|  | 
 | ||
|  | # Acknowledgements
 | ||
|  | This project has been forked from [hapijs/bourne](https://github.com/hapijs/bourne). | ||
|  | All the credits before the commit [4690682](https://github.com/hapijs/bourne/commit/4690682c6cdaa06590da7b2485d5df91c09da889) goes to the hapijs/bourne project contributors. | ||
|  | After, the project will be maintained by the Fastify team. | ||
|  | 
 | ||
|  | # License
 | ||
|  | Licensed under BSD-3-Clause. |