seria/public/announce.php

<?php
require_once __DIR__ . '/../seria.php';

function announce_fail(string $reason): never {
    die(bencode(['failure reason' => $reason]));
}

if(empty($_GET))
    die('There is nothing here.');

header('Content-Type: text/plain; charset=us-ascii');
header('X-Tracker-Version: Seria/' . SERIA_VERSION);

if(!$sIsIPv4)
    announce_fail('Tracker is only supported over IPv4, please reset your DNS cache.');

//file_put_contents(SERIA_ERRORS, $_SERVER['REQUEST_URI'] . PHP_EOL, FILE_APPEND);

$urlParts = explode('/', trim($_SERVER['PATH_INFO'], '/'));

$cInfoHash = (string)filter_input(INPUT_GET, 'info_hash');
if(strlen($cInfoHash) !== 20)
    announce_fail('Invalid info hash.');

$cPeerId = (string)filter_input(INPUT_GET, 'peer_id');
if(strlen($cPeerId) !== 20)
    announce_fail('Invalid peer id format.');

$cPeerAddress = $_SERVER['REMOTE_ADDR'];

$cPeerPort = (int)filter_input(INPUT_GET, 'port', FILTER_SANITIZE_NUMBER_INT);
if($cPeerPort < 1 || $cPeerPort > 0xFFFF)
    announce_fail('Invalid port number.');

$cPeerKey = (string)filter_input(INPUT_GET, 'key');
if(strlen($cPeerKey) > 128)
    announce_fail('Key is ridiculous.');

$cPeerEvent = (string)filter_input(INPUT_GET, 'event');
if(strlen($cPeerEvent) > 128)
    announce_fail('Event is fucked up.');

$cPeerAgent = (string)filter_input(INPUT_SERVER, 'HTTP_USER_AGENT');
if(strlen($cPeerAgent) > 255)
    announce_fail('Agent is stupid.');

$cCompactPeers = !empty($_GET['compact']);
$cNoPeerId = !empty($_GET['no_peer_id']);
$cShortAnnounce = !empty($_GET['short']);

$cBytesUploaded = (int)filter_input(INPUT_GET, 'uploaded', FILTER_SANITIZE_NUMBER_INT);
$cBytesDownloaded = (int)filter_input(INPUT_GET, 'downloaded', FILTER_SANITIZE_NUMBER_INT);
$cBytesRemaining = (int)filter_input(INPUT_GET, 'left', FILTER_SANITIZE_NUMBER_INT);
$cPeerWant = (int)filter_input(INPUT_GET, 'numwant', FILTER_SANITIZE_NUMBER_INT);

$cPassKey = $urlParts[0] ?? '';
if(!empty($cPassKey)) {
    try {
        $cUserInfo = SeriaUser::byPassKey($pdo, $cPassKey);
    } catch(SeriaUserNotFoundException $ex) {
        sleep(3);
        announce_fail('Authentication failed.');
    }
} else $cUserInfo = SeriaUser::anonymous();

$interval = SERIA_ANNOUNCE_INTERVAL;
$minInterval = SERIA_ANNOUNCE_INTERVAL_MIN;

if($cShortAnnounce && SERIA_ANNOUNCE_SHORT) {
    $interval = SERIA_ANNOUNCE_SHORT_INTERVAL;
    $minInterval = SERIA_ANNOUNCE_SHORT_INTERVAL_MIN;
}

try {
    $cTorrentInfo = SeriaTorrent::byHash($pdo, $cInfoHash);
} catch(SeriaTorrentNotFoundException $ex) {
    announce_fail('Info hash not found.');
}

$cCanDownload = $cTorrentInfo->canDownload($cUserInfo);
if($cCanDownload !== '')
    switch($cCanDownload) {
        case 'inactive':
            announce_fail('This download is inactive.');
        case 'private':
            announce_fail('You must be logged in for this download.');
        case 'pending':
            announce_fail('This download is pending approval.');
        default:
            announce_fail($cCanDownload);
    }

$cPeerInfo = SeriaTorrentPeer::byPeerId($pdo, $cTorrentInfo, $cPeerId);

if(empty($cPeerInfo)) {
    // could probably skip this is the event is 'stopped'
    $cPeerInfo = SeriaTorrentPeer::create(
        $pdo, $cTorrentInfo, $cUserInfo, $cPeerId, $cPeerAddress, $cPeerPort, $interval,
        $cPeerAgent, $cPeerKey, $cBytesUploaded, $cBytesDownloaded, $cBytesRemaining
    );
} else {
    if(!$cPeerInfo->verifyKey($cPeerKey)) {
        sleep(3);
        announce_fail('Peer verification failed.');
    }

    if(!$cPeerInfo->verifyUser($cUserInfo)) {
        sleep(3);
        announce_fail('User verification failed.');
    }

    $cUserInfo->incrementTransferCounts(
        $cBytesDownloaded - $cPeerInfo->getBytesDownloaded(),
        $cBytesUploaded - $cPeerInfo->getBytesUploaded()
    );

    $cPeerInfo->update(
        $cUserInfo, $cPeerAddress, $cPeerPort, $interval, $cPeerAgent,
        $cBytesUploaded, $cBytesDownloaded, $cBytesRemaining
    );
}

if($cPeerEvent === 'stopped') {
    $cPeerInfo->delete();
    die(bencode(new SeriaAnnounceResponse));
}

SeriaTorrentPeer::deleteExpired($pdo);

$response = new SeriaAnnounceResponse(
    $interval + mt_rand(0, 10),
    $minInterval,
    $cTorrentInfo,
    $cNoPeerId && SERIA_ANNOUNCE_NO_PEER_ID,
    $cCompactPeers
);

if(!$cPeerInfo->isSeed() || !SERIA_ANNOUNCE_NO_SEED_P2P) {
    $peers = $cTorrentInfo->getSeeds($cPeerInfo);
    foreach($peers as $peer)
        $response->addPeer($peer);
}

echo bencode($response);