pokemon-showdown/verifier.js

/**
 * Verifier process
 * Pokemon Showdown - http://pokemonshowdown.com/
 *
 * This is just an asynchronous implementation of a verifier for a
 * signed key, because Node.js's crypto functions are synchronous,
 * strangely, considering how everything else is asynchronous.
 *
 * I wrote this one day hoping it would help with performance, but
 * I don't think it had any noticeable effect.
 *
 * @license MIT license
 */

'use strict';

// Because I don't want two files, we're going to fork ourselves.

if (!process.send) {
	// This is the parent

	let guid = 1;
	let resolvers = Object.create(null);

	let child = exports.child = require('child_process').fork('verifier.js', {cwd: __dirname});

	exports.verify = function (data, signature) {
		return new Promise((resolve, reject) => {
			let localGuid = guid++;
			resolvers[localGuid] = resolve;
			child.send({data: data, sig: signature, guid: localGuid});
		});
	};

	child.on('message', response => {
		if (response.guid in resolvers) {
			resolvers[response.guid](response.success);
			delete resolvers[response.guid];
		}
	});
} else {
	// This is the child

	global.Config = require('./config/config.js');
	let crypto = require('crypto');

	let keyalgo = Config.loginserverkeyalgo;
	let pkey = Config.loginserverpublickey;

	process.on('message', message => {
		let verifier = crypto.createVerify(keyalgo);
		verifier.update(message.data);
		let success = false;
		try {
			success = verifier.verify(pkey, message.sig, 'hex');
		} catch (e) {}
		process.send({
			success: success,
			guid: message.guid,
		});
	});

	process.on('disconnect', () => {
		process.exit();
	});

	require('./repl.js').start('verifier', cmd => eval(cmd));
}