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File Content: tokenbucket.php

<?php

namespace WordfenceLS;

class Model_TokenBucket {
	/* Constants to map from tokens per unit to tokens per second */
	const MICROSECOND =        0.000001;
	const MILLISECOND =        0.001;
	const SECOND      =        1;
	const MINUTE      =       60;
	const HOUR        =     3600;
	const DAY         =    86400;
	const WEEK        =   604800;
	const MONTH       =  2629743.83;
	const YEAR        = 31556926;
	
	const BACKING_REDIS = 'redis';
	const BACKING_WP_OPTIONS = 'wpoptions';
	
	private $_identifier;
	private $_bucketSize;
	private $_tokensPerSecond;
	
	private $_backing;
	private $_redis;
	
	/**
	 * Model_TokenBucket constructor.
	 *
	 * @param string $identifier The identifier for the bucket record in the database
	 * @param int $bucketSize The maximum capacity of the bucket.
	 * @param double $tokensPerSecond The number of tokens per second added to the bucket.
	 * @param string $backing The backing storage to use.
	 */
	public function __construct($identifier, $bucketSize, $tokensPerSecond, $backing = self::BACKING_WP_OPTIONS) {
		$this->_identifier = $identifier;
		$this->_bucketSize = $bucketSize;
		$this->_tokensPerSecond = $tokensPerSecond;
		$this->_backing = $backing;
		
		if ($backing == self::BACKING_REDIS) {
			$this->_redis = new \Redis();
			$this->_redis->pconnect('127.0.0.1');
		}
	}
	
	/**
	 * Attempts to acquire a lock for the bucket.
	 *
	 * @param int $timeout
	 * @return bool Whether or not the lock was acquired.
	 */
	private function _lock($timeout = 30) {
		if ($this->_backing == self::BACKING_WP_OPTIONS) {
			$start = microtime(true);
			while (!$this->_wp_options_create_lock($this->_identifier)) {
				if (microtime(true) - $start > $timeout) {
					return false;
				}
				usleep(5000); // 5 ms
			}
			return true;
		}
		else if ($this->_backing == self::BACKING_REDIS) {
			if ($this->_redis === false) {
				return false;
			}
			
			$start = microtime(true);
			while (!$this->_redis->setnx('lock:' . $this->_identifier, '1')) {
				if (microtime(true) - $start > $timeout) {
					return false;
				}
				usleep(5000); // 5 ms
			}
			$this->_redis->expire('lock:' . $this->_identifier, 30);
			return true;
		}
		return false;
	}
	
	private function _unlock() {
		if ($this->_backing == self::BACKING_WP_OPTIONS) {
			$this->_wp_options_release_lock($this->_identifier);
		}
		else if ($this->_backing == self::BACKING_REDIS) {
			if ($this->_redis === false) {
				return;
			}
			
			$this->_redis->del('lock:' . $this->_identifier);
		}
	}
	
	private function _wp_options_create_lock($name, $timeout = null) { //Our own version of WP_Upgrader::create_lock
		global $wpdb;
		
		if (!$timeout) {
			$timeout = 3600;
		}
		
		$lock_option = 'wfls_' . $name . '.lock';
		$lock_result = $wpdb->query($wpdb->prepare("INSERT IGNORE INTO `{$wpdb->options}` (`option_name`, `option_value`, `autoload`) VALUES (%s, %s, 'no')", $lock_option, time()));
		
		if (!$lock_result) {
			$lock_result = get_option($lock_option);
			if (!$lock_result) {
				return false;
			}
			
			if ($lock_result > (time() - $timeout)) {
				return false;
			}
			
			$this->_wp_options_release_lock($name);
			return $this->_wp_options_create_lock($name, $timeout);
		}
		
		return true;
	}
	
	private function _wp_options_release_lock($name) {
		return delete_option('wfls_' . $name . '.lock');
	}
	
	/**
	 * Atomically checks the available token count, creating the initial record if needed, and updates the available token count if the requested number of tokens is available.
	 *
	 * @param int $tokenCount
	 * @return bool Whether or not there were enough tokens to satisfy the request.
	 */
	public function consume($tokenCount = 1) {
		if (!$this->_lock()) { return false; }
		
		if ($this->_backing == self::BACKING_WP_OPTIONS) {
			$record = get_transient('wflsbucket:' . $this->_identifier);
		}
		else if ($this->_backing == self::BACKING_REDIS) {
			$record = $this->_redis->get('bucket:' . $this->_identifier);
		}
		else {
			$this->_unlock();
			return false;
		}
		
		if ($record === false) {
			if ($tokenCount > $this->_bucketSize) {
				$this->_unlock();
				return false;
			}
			
			$this->_bootstrap($this->_bucketSize - $tokenCount);
			$this->_unlock();
			return true;
		}
		
		$tokens = min($this->_secondsToTokens(microtime(true) - (float) $record), $this->_bucketSize);
		if ($tokenCount > $tokens) {
			$this->_unlock();
			return false;
		}
		
		if ($this->_backing == self::BACKING_WP_OPTIONS) {
			set_transient('wflsbucket:' . $this->_identifier, (string) (microtime(true) - $this->_tokensToSeconds($tokens - $tokenCount)), ceil($this->_tokensToSeconds($this->_bucketSize)));
		}
		else if ($this->_backing == self::BACKING_REDIS) {
			$this->_redis->set('bucket:' . $this->_identifier, (string) (microtime(true) - $this->_tokensToSeconds($tokens - $tokenCount)));
		}
		
		$this->_unlock();
		return true;
	}
	
	public function reset() {
		if (!$this->_lock()) { return false; }
		
		if ($this->_backing == self::BACKING_WP_OPTIONS) {
			delete_transient('wflsbucket:' . $this->_identifier);
		}
		else if ($this->_backing == self::BACKING_REDIS) {
			$this->_redis->del('bucket:' . $this->_identifier);
		}
		
		$this->_unlock();
	}
	
	/**
	 * Creates an initial record with the given number of tokens.
	 *
	 * @param int $initialTokens
	 */
	protected function _bootstrap($initialTokens) {
		$microtime = microtime(true) - $this->_tokensToSeconds($initialTokens);
		if ($this->_backing == self::BACKING_WP_OPTIONS) {
			set_transient('wflsbucket:' . $this->_identifier, (string) $microtime, ceil($this->_tokensToSeconds($this->_bucketSize)));
		}
		else if ($this->_backing == self::BACKING_REDIS) {
			$this->_redis->set('bucket:' . $this->_identifier, (string) $microtime);
		}
	}
	
	protected function _tokensToSeconds($tokens) {
		return $tokens / $this->_tokensPerSecond;
	}
	
	protected function _secondsToTokens($seconds) {
		return (int) $seconds * $this->_tokensPerSecond;
	}
}

Name	Size	Permission
crypto	---	0755
settings	---	0755
text	---	0755
view	---	0755
2fainitializationdata.php	1290 bytes	0644
asset.php	1929 bytes	0644
compat.php	248 bytes	0644
crypto.php	8305 bytes	0644
ip.php	5178 bytes	0644
notice.php	1124 bytes	0644
request.php	5893 bytes	0644
script.php	1277 bytes	0644
settings.php	643 bytes	0644
style.php	811 bytes	0644
tokenbucket.php	5966 bytes	0644
view.php	2245 bytes	0644