SearchQueries.php: add

inc/Data/SearchQueries.php

@@ -0,0 +1,98 @@
+<?php
+namespace Vichan\Data;
+
+
+/**
+ * Implements flood control for search queries.
+ */
+class SearchQueries {
+	private \PDO $pdo;
+	private int $queries_for_single;
+	private int $range_for_single;
+	private int $queries_for_all;
+	private int $range_for_all;
+	private bool $auto_gc;
+
+
+	private function checkFloodImpl(string $ip, string $phrase): bool {
+		$now = \time();
+
+		$query = $this->pdo->prepare("SELECT COUNT(2) FROM `search_queries` WHERE `ip` = :ip AND `time` > :time");
+		$query->bindValue(':ip', $ip);
+		$query->bindValue(':time', $now - $this->range_for_single, \PDO::PARAM_INT);
+		$query->execute();
+		if ($query->fetchColumn() > $this->queries_for_single) {
+			return true;
+		}
+
+		$query = $this->pdo->prepare("SELECT COUNT(2) FROM `search_queries` WHERE `time` > :time");
+		$query->bindValue(':time', $now - $this->range_for_all, \PDO::PARAM_INT);
+		$query->execute();
+		if ($query->fetchColumn() > $this->queries_for_all) {
+			return true;
+		}
+
+		$query = $this->pdo->prepare("INSERT INTO `search_queries` VALUES (:ip, :time, :query)");
+		$query->bindValue(':ip', $ip);
+		$query->bindValue(':time', $now, \PDO::PARAM_INT);
+		$query->bindValue(':query', $phrase);
+		$query->execute();
+
+		if ($this->auto_gc) {
+			$this->purgeExpired();
+		}
+
+		return false;
+	}
+
+	/**
+	 * @param \PDO $pdo PDO to access the DB.
+	 * @param int $queries_for_single Maximum number of queries for a single IP, in seconds.
+	 * @param int $range_for_single Maximum age of the oldest query to consider from a single IP.
+	 * @param int $queries_for_all Maximum number of queries for all IPs.
+	 * @param int $range_for_all Maximum age of the oldest query to consider from all IPs, in seconds.
+	 * @param bool $auto_gc If to run the cleanup at every check. Must be invoked from the outside otherwise.
+	 */
+	public function __construct(
+		\PDO $pdo,
+		int $queries_for_single,
+		int $range_for_single,
+		int $queries_for_all,
+		int $range_for_all,
+		bool $auto_gc
+	) {
+		$this->pdo = $pdo;
+		$this->queries_for_single = $queries_for_single;
+		$this->range_for_single = $range_for_single;
+		$this->queries_for_all = $queries_for_all;
+		$this->range_for_all = $range_for_all;
+		$this->auto_gc = $auto_gc;
+	}
+
+	/**
+	 * Check if the IP-query pair overflows the limit.
+	 *
+	 * @param string $ip Source IP.
+	 * @param string $phrase The search query.
+	 * @return bool True if the request goes over the limit.
+	 */
+	public function checkFlood(string $ip, string $phrase): bool {
+		$this->pdo->beginTransaction();
+		try {
+			$ret = $this->checkFloodImpl($ip, $phrase);
+			$this->pdo->commit();
+			return $ret;
+		} catch (\Exception $e) {
+			$this->pdo->rollBack();
+			throw $e;
+		}
+	}
+
+	public function purgeExpired(): int {
+		// Cleanup search queries table.
+		$query = $this->pdo->prepare("DELETE FROM `search_queries` WHERE `time` <= :expiry_limit");
+		$query->bindValue(':expiry_limit', \time() - $this->range_for_all, \PDO::PARAM_INT);
+		$query->execute();
+		return $query->rowCount();
+	}
+}