AuthKeyProvider.php

<?php
 
/*
 *
 *  ____            _        _   __  __ _                  __  __ ____
 * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
 * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
 * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
 * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * @author PocketMine Team
 * @link http://www.pocketmine.net/
 *
 *
 */
 
declare(strict_types=1);
 
namespace pocketmine\network\mcpe\auth;
 
use pocketmine\network\mcpe\JwtException;
use pocketmine\network\mcpe\JwtUtils;
use pocketmine\network\mcpe\protocol\types\login\openid\api\AuthServiceKey;
use pocketmine\promise\Promise;
use pocketmine\promise\PromiseResolver;
use pocketmine\scheduler\AsyncPool;
use pocketmine\utils\AssumptionFailedError;
use function array_keys;
use function count;
use function implode;
use function time;
 
class AuthKeyProvider{
    private const ALLOWED_REFRESH_INTERVAL = 30 * 60; // 30 minutes
 
    private ?AuthKeyring $keyring = null;
 
    private ?PromiseResolver $resolver = null;
 
    private int $lastFetch = 0;
 
    public function __construct(
        private readonly \Logger $logger,
        private readonly AsyncPool $asyncPool,
        private readonly int $keyRefreshIntervalSeconds = self::ALLOWED_REFRESH_INTERVAL
    ){}
 
    public function getKey(string $keyId) : Promise{
        $resolver = new PromiseResolver();
 
        if(
            $this->keyring === null || //we haven't fetched keys yet
            ($this->keyring->getKey($keyId) === null && $this->lastFetch < time() - $this->keyRefreshIntervalSeconds) //we don't recognise this one & keys might be outdated
        ){
            //only refresh keys when we see one we don't recognise
            $this->fetchKeys()->onCompletion(
                onSuccess: fn(AuthKeyring $newKeyring) => $this->resolveKey($resolver, $newKeyring, $keyId),
                onFailure: $resolver->reject(...)
            );
        }else{
            $this->resolveKey($resolver, $this->keyring, $keyId);
        }
 
        return $resolver->getPromise();
    }
 
    private function resolveKey(PromiseResolver $resolver, AuthKeyring $keyring, string $keyId) : void{
        $key = $keyring->getKey($keyId);
        if($key === null){
            $this->logger->debug("Key $keyId not recognised!");
            $resolver->reject();
            return;
        }
 
        $this->logger->debug("Key $keyId found in keychain");
        $resolver->resolve([$keyring->getIssuer(), $key]);
    }
 
    private function onKeysFetched(?array $keys, string $issuer, ?array $errors) : void{
        $resolver = $this->resolver;
        if($resolver === null){
            throw new AssumptionFailedError("Not expecting this to be called without a resolver present");
        }
        if($errors !== null){
            $this->logger->error("The following errors occurred while fetching new keys:\n\t- " . implode("\n\t-", $errors));
            //we might've still succeeded in fetching keys even if there were errors, so don't return
        }
 
        if($keys === null){
            $this->logger->critical("Failed to fetch authentication keys from Mojang's API. Xbox players may not be able to authenticate!");
            $resolver->reject();
        }else{
            $pemKeys = [];
            foreach($keys as $keyModel){
                if($keyModel->use !== "sig" || $keyModel->kty !== "RSA"){
                    $this->logger->error("Key ID $keyModel->kid doesn't have the expected properties: expected use=sig, kty=RSA, got use=$keyModel->use, kty=$keyModel->kty");
                    continue;
                }
                $derKey = JwtUtils::rsaPublicKeyModExpToDer($keyModel->n, $keyModel->e);
 
                //make sure the key is valid
                try{
                    JwtUtils::parseDerPublicKey($derKey);
                }catch(JwtException $e){
                    $this->logger->error("Failed to parse RSA public key for key ID $keyModel->kid: " . $e->getMessage());
                    $this->logger->logException($e);
                    continue;
                }
 
                //retain PEM keys instead of OpenSSLAsymmetricKey since these are easier and cheaper to copy between threads
                $pemKeys[$keyModel->kid] = $derKey;
            }
 
            if(count($keys) === 0){
                $this->logger->critical("No valid authentication keys returned by Mojang's API. Xbox players may not be able to authenticate!");
                $resolver->reject();
            }else{
                $this->logger->info("Successfully fetched " . count($keys) . " new authentication keys from issuer $issuer, key IDs: " . implode(", ", array_keys($pemKeys)));
                $this->keyring = new AuthKeyring($issuer, $pemKeys);
                $this->lastFetch = time();
                $resolver->resolve($this->keyring);
            }
        }
    }
 
    private function fetchKeys() : Promise{
        if($this->resolver !== null){
            $this->logger->debug("Key refresh was requested, but it's already in progress");
            return $this->resolver->getPromise();
        }
 
        $this->logger->notice("Fetching new authentication keys");
 
        $resolver = new PromiseResolver();
        $this->resolver = $resolver;
        //TODO: extract this so it can be polyfilled for unit testing
        $this->asyncPool->submitTask(new FetchAuthKeysTask($this->onKeysFetched(...)));
        return $this->resolver->getPromise();
    }
}