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# trackerclient.cpp Example File

network/torrent/trackerclient.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2015 The Qt Company Ltd.
     ** Contact: http://www.qt.io/licensing/
     **
     ** This file is part of the examples of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:BSD$
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     ** modification, are permitted provided that the following conditions are
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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 = qvariant_cast<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);
         }
     }