trackerclient.cpp Example File
network/torrent/trackerclient.cpp

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 #include "bencodeparser.h"
 #include "connectionmanager.h"
 #include "torrentclient.h"
 #include "torrentserver.h"
 #include "trackerclient.h"

 #include <QtCore>

 TrackerClient::TrackerClient(TorrentClient *downloader, QObject *parent)
     : QObject(parent), torrentDownloader(downloader)
 {
     length = 0;
     requestInterval = 5 * 60;
     requestIntervalTimer = -1;
     firstTrackerRequest = true;
     lastTrackerRequest = false;
     firstSeeding = true;

     connect(&http, SIGNAL(done(bool)), this, SLOT(httpRequestDone(bool)));
 }

 void TrackerClient::start(const MetaInfo &info)
 {
     metaInfo = info;
     QTimer::singleShot(0, this, SLOT(fetchPeerList()));

     if (metaInfo.fileForm() == MetaInfo::SingleFileForm) {
         length = metaInfo.singleFile().length;
     } else {
         QList<MetaInfoMultiFile> files = metaInfo.multiFiles();
         for (int i = 0; i < files.size(); ++i)
             length += files.at(i).length;
     }
 }

 void TrackerClient::startSeeding()
 {
     firstSeeding = true;
     fetchPeerList();
 }

 void TrackerClient::stop()
 {
     lastTrackerRequest = true;
     http.abort();
     fetchPeerList();
 }

 void TrackerClient::timerEvent(QTimerEvent *event)
 {
     if (event->timerId() == requestIntervalTimer) {
         if (http.state() == QHttp::Unconnected)
             fetchPeerList();
     } else {
         QObject::timerEvent(event);
     }
 }

 void TrackerClient::fetchPeerList()
 {
     // Prepare connection details
     QString fullUrl = metaInfo.announceUrl();
     QUrl url(fullUrl);
     QString passkey = "?";
     if (fullUrl.contains("?passkey")) {
         passkey = metaInfo.announceUrl().mid(fullUrl.indexOf("?passkey"), -1);
         passkey += "&";
     }

     // Percent encode the hash
     QByteArray infoHash = torrentDownloader->infoHash();
     QString encodedSum;
     for (int i = 0; i < infoHash.size(); ++i) {
         encodedSum += '%';
         encodedSum += QString::number(infoHash[i], 16).right(2).rightJustified(2, '0');
     }

     bool seeding = (torrentDownloader->state() == TorrentClient::Seeding);
     QByteArray query;
     query += url.path().toLatin1();
     query += passkey;
     query += "info_hash=" + encodedSum;
     query += "&peer_id=" + ConnectionManager::instance()->clientId();
     query += "&port=" + QByteArray::number(TorrentServer::instance()->serverPort());
     query += "&compact=1";
     query += "&uploaded=" + QByteArray::number(torrentDownloader->uploadedBytes());

     if (!firstSeeding) {
         query += "&downloaded=0";
         query += "&left=0";
     } else {
         query += "&downloaded=" + QByteArray::number(
             torrentDownloader->downloadedBytes());
         int left = qMax<int>(0, metaInfo.totalSize() - torrentDownloader->downloadedBytes());
         query += "&left=" + QByteArray::number(seeding ? 0 : left);
     }

     if (seeding && firstSeeding) {
         query += "&event=completed";
         firstSeeding = false;
     } else if (firstTrackerRequest) {
         firstTrackerRequest = false;
         query += "&event=started";
     } else if(lastTrackerRequest) {
         query += "&event=stopped";
     }

     if (!trackerId.isEmpty())
         query += "&trackerid=" + trackerId;

     http.setHost(url.host(), url.port() == -1 ? 80 : url.port());
     if (!url.userName().isEmpty())
         http.setUser(url.userName(), url.password());
     http.get(query);
 }

 void TrackerClient::httpRequestDone(bool error)
 {
     if (lastTrackerRequest) {
         emit stopped();
         return;
     }

     if (error) {
         emit connectionError(http.error());
         return;
     }

     QByteArray response = http.readAll();
     http.abort();

     BencodeParser parser;
     if (!parser.parse(response)) {
         qWarning("Error parsing bencode response from tracker: %s",
                  qPrintable(parser.errorString()));
         http.abort();
         return;
     }

     QMap<QByteArray, QVariant> dict = parser.dictionary();

     if (dict.contains("failure reason")) {
         // no other items are present
         emit failure(QString::fromUtf8(dict.value("failure reason").toByteArray()));
         return;
     }

     if (dict.contains("warning message")) {
         // continue processing
         emit warning(QString::fromUtf8(dict.value("warning message").toByteArray()));
     }

     if (dict.contains("tracker id")) {
         // store it
         trackerId = dict.value("tracker id").toByteArray();
     }

     if (dict.contains("interval")) {
         // Mandatory item
         if (requestIntervalTimer != -1)
             killTimer(requestIntervalTimer);
         requestIntervalTimer = startTimer(dict.value("interval").toInt() * 1000);
     }

     if (dict.contains("peers")) {
         // store it
         peers.clear();
         QVariant peerEntry = dict.value("peers");
         if (peerEntry.type() == QVariant::List) {
             QList<QVariant> peerTmp = peerEntry.toList();
             for (int i = 0; i < peerTmp.size(); ++i) {
                 TorrentPeer tmp;
                 QMap<QByteArray, QVariant> peer = qVariantValue<QMap<QByteArray, QVariant> >(peerTmp.at(i));
                 tmp.id = QString::fromUtf8(peer.value("peer id").toByteArray());
                 tmp.address.setAddress(QString::fromUtf8(peer.value("ip").toByteArray()));
                 tmp.port = peer.value("port").toInt();
                 peers << tmp;
             }
         } else {
             QByteArray peerTmp = peerEntry.toByteArray();
             for (int i = 0; i < peerTmp.size(); i += 6) {
                 TorrentPeer tmp;
                 uchar *data = (uchar *)peerTmp.constData() + i;
                 tmp.port = (int(data[4]) << 8) + data[5];
                 uint ipAddress = 0;
                 ipAddress += uint(data[0]) << 24;
                 ipAddress += uint(data[1]) << 16;
                 ipAddress += uint(data[2]) << 8;
                 ipAddress += uint(data[3]);
                 tmp.address.setAddress(ipAddress);
                 peers << tmp;
             }
         }
         emit peerListUpdated(peers);
     }
 }