qBittorrent/src/reverseresolution.h
Christophe Dumez 4ba5e43933 Improve peer host name resolution (closes #360)
- Take a QString in argument to avoid converting it twice. The caller already
  has the IP as a QString.
- Fix bug where hostnames coming from the cache would not the displayed.
- Fix bug where the resolved hostnames would not be displayed if the IP we know
  does not match the first one in the QHostInfo::addresses() list. It may come
  later in the list or may be formatted differently (possible with IPv6).
- Avoid requesting again host names for IPs that were already requested recently
  but whose resolution did not return a useful hostname.
2013-03-28 21:47:45 +02:00

105 lines
3.3 KiB
C++

/*
* Bittorrent Client using Qt4 and libtorrent.
* Copyright (C) 2006 Christophe Dumez
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* In addition, as a special exception, the copyright holders give permission to
* link this program with the OpenSSL project's "OpenSSL" library (or with
* modified versions of it that use the same license as the "OpenSSL" library),
* and distribute the linked executables. You must obey the GNU General Public
* License in all respects for all of the code used other than "OpenSSL". If you
* modify file(s), you may extend this exception to your version of the file(s),
* but you are not obligated to do so. If you do not wish to do so, delete this
* exception statement from your version.
*
* Contact : chris@qbittorrent.org
*/
#ifndef REVERSERESOLUTION_H
#define REVERSERESOLUTION_H
#include <QList>
#include <QCache>
#include <QDebug>
#include <QHostInfo>
#include "misc.h"
#include <boost/version.hpp>
#if BOOST_VERSION < 103500
#include <libtorrent/asio/ip/tcp.hpp>
#else
#include <boost/asio/ip/tcp.hpp>
#endif
const int CACHE_SIZE = 500;
class ReverseResolution: public QObject {
Q_OBJECT
Q_DISABLE_COPY(ReverseResolution)
public:
explicit ReverseResolution(QObject* parent): QObject(parent) {
m_cache.setMaxCost(CACHE_SIZE);
}
~ReverseResolution() {
qDebug("Deleting host name resolver...");
}
void resolve(const QString &ip) {
if (m_cache.contains(ip)) {
const QString& hostname = *m_cache.object(ip);
qDebug() << "Resolved host name using cache: " << ip << " -> " << hostname;
if (isUsefulHostName(hostname, ip))
emit ip_resolved(ip, hostname);
return;
}
// Actually resolve the ip
m_lookups.insert(QHostInfo::lookupHost(ip, this, SLOT(hostResolved(QHostInfo))), ip);
}
signals:
void ip_resolved(const QString &ip, const QString &hostname);
private slots:
void hostResolved(const QHostInfo& host) {
const QString& ip = m_lookups.take(host.lookupId());
Q_ASSERT(!ip.isNull());
if (host.error() != QHostInfo::NoError) {
qDebug() << "DNS Reverse resolution error: " << host.errorString();
return;
}
const QString& hostname = host.hostName();
qDebug() << Q_FUNC_INFO << ip << QString("->") << hostname;
m_cache.insert(ip, new QString(hostname));
if (isUsefulHostName(hostname, ip))
emit ip_resolved(ip, hostname);
}
private:
static inline bool isUsefulHostName(const QString& hostname, const QString& ip) {
return (!hostname.isEmpty() && hostname != ip);
}
QHash<int /* LookupID */, QString /* IP */> m_lookups;
QCache<QString /* IP */, QString /* HostName */> m_cache;
};
#endif // REVERSERESOLUTION_H