Mark WordPress comments from Tor exit nodes as spam

comment-tor-spam.php

<?php

/*
 * Plugin Name: Mark comments from Tor exit nodes as spam
 * Plugin URI: https://github.com/szepeviktor/wordpress-website-lifecycle
 */

/** @return string|null */
function getTorExitNodes()
{
    $listUrl = 'https://check.torproject.org/torbulkexitlist';
    $cacheFile = wp_upload_dir()['basedir'].'/tor-exit-nodes.txt';
    $cacheTime = HOUR_IN_SECONDS;

    if (file_exists($cacheFile) && (time() - filemtime($cacheFile) < $cacheTime)) {
        return file_get_contents($cacheFile);
    }

    $response = wp_remote_get($listUrl);
    if (is_wp_error($response)) {
        return null;
    }
    $list = wp_remote_retrieve_body($response);
    if ($list === '') {
        return null;
    }

    file_put_contents($cacheFile, $list);

    return $list;
}

function isTorExitNode($ipv4): bool
{
    $list = getTorExitNodes();
    if ($list === null) {
        return false;
    }

    $torExitNodes = explode("\n", trim($list));

    return in_array($ipv4, $torExitNodes);
}

add_action(
    'wp_insert_comment',
    static function ($id, $comment) {
        if (isTorExitNode($comment->comment_author_IP)) {
            wp_set_comment_status($id, 'spam');
        }
    },
    10,
    2
);