Huong Nguyen
110 lines
3.7 KiB
PHP
110 lines
3.7 KiB
PHP
<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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namespace core_ai;
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use Psr\Clock\ClockInterface;
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/**
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* Rate limiting functionality that can be used by AI providers.
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*
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* @package core_ai
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* @copyright 2024 Matt Porritt <matt.porritt@moodle.com>
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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class rate_limiter {
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/** @var int TIME_WINDOW Time window in seconds (1 hour). */
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public const TIME_WINDOW = HOURSECS;
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/** @var null|rate_limiter Singleton instance of the rate limiter. */
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private static ?rate_limiter $instance = null;
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/** @var \cache_application Cache instance for rate limiter. */
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private \cache_application $cache;
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/**
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* Constructor.
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*
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* @param ClockInterface $clock Clock instance for time management.
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*/
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public function __construct(
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/** @var ClockInterface Clock instance for time management. */
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private ClockInterface $clock,
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) {
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$this->cache = \cache::make('core', 'ai_ratelimit');
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}
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/**
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* Check global rate limit for a component.
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*
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* @param string $component Name of the component.
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* @param int $ratelimit Number of requests per time window.
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* @return bool True if request is allowed, false otherwise.
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*/
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public function check_global_rate_limit(string $component, int $ratelimit): bool {
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$currenttime = $this->clock->now()->getTimestamp();
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return $this->check_limit("global_{$component}", $ratelimit, $currenttime);
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}
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/**
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* Check user rate limit for a component.
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*
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* @param string $component Name of the component.
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* @param int $ratelimit Number of requests per time window.
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* @param int $userid User ID for user-specific rate limit.
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* @return bool True if request is allowed, false otherwise.
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*/
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public function check_user_rate_limit(string $component, int $ratelimit, int $userid): bool {
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$currenttime = $this->clock->now()->getTimestamp();
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// Check and update user limit.
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return $this->check_limit("user_{$component}_{$userid}", $ratelimit, $currenttime);
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}
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/**
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* Helper function to check limit in cache.
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*
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* @param string $key Cache key.
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* @param int $ratelimit Number of requests per time window.
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* @param int $currenttime Current timestamp.
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* @return bool True if request is allowed, false otherwise.
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*/
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private function check_limit(string $key, int $ratelimit, int $currenttime): bool {
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$ratedata = $this->cache->get($key);
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if ($ratedata === false) {
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// No data found, initialize rate data.
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$ratedata = ['count' => 0, 'start_time' => $currenttime];
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}
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// Remove expired rate data.
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if ($currenttime - $ratedata['start_time'] > self::TIME_WINDOW) {
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$ratedata['count'] = 0;
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$ratedata['start_time'] = $currenttime;
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}
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// Check rate limit.
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if ($ratedata['count'] < $ratelimit) {
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$ratedata['count']++;
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$this->cache->set($key, $ratedata);
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return true;
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}
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// Rate limit exceeded.
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return false;
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}
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}
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