WebAPI: Resolve peer host names

WebAPI_Changelog.md

@@ -1,5 +1,9 @@
 # WebAPI Changelog
 
+## 2.15.1
+* [#23708](https://github.com/qbittorrent/qBittorrent/pull/23708)
+  * `sync/torrentPeers` endpoint now includes peer `host_name` when peer host name resolution is enabled
+
 ## 2.14.1
 * [#23212](https://github.com/qbittorrent/qBittorrent/pull/23212)
   * Add `app/rotateAPIKey` endpoint for generating, and rotating, the WebAPI API key

src/webui/CMakeLists.txt

@@ -16,6 +16,7 @@ add_library(qbt_webui STATIC
     api/transfercontroller.h
     api/serialize/serialize_torrent.h
     clientdatastorage.h
+    peerhostnameresolver.h
     webapplication.h
     webui.h
 
@@ -34,6 +35,7 @@ add_library(qbt_webui STATIC
     api/transfercontroller.cpp
     api/serialize/serialize_torrent.cpp
     clientdatastorage.cpp
+    peerhostnameresolver.cpp
     webapplication.cpp
     webui.cpp
 )

src/webui/api/appcontroller.cpp

@@ -398,6 +398,8 @@ void AppController::preferencesAction()
     data[u"app_instance_name"_s] = app()->instanceName();
     // Refresh interval
     data[u"refresh_interval"_s] = session->refreshInterval();
+    // Resolve peer host names
+    data[u"resolve_peer_host_names"_s] = pref->resolvePeerHostNames();
     // Resolve peer countries
     data[u"resolve_peer_countries"_s] = pref->resolvePeerCountries();
     // Reannounce to all trackers when ip/port changed
@@ -1029,6 +1031,9 @@ void AppController::setPreferencesAction()
     // Refresh interval
     if (hasKey(u"refresh_interval"_s))
         session->setRefreshInterval(it.value().toInt());
+    // Resolve peer host names
+    if (hasKey(u"resolve_peer_host_names"_s))
+        pref->resolvePeerHostNames(it.value().toBool());
     // Resolve peer countries
     if (hasKey(u"resolve_peer_countries"_s))
         pref->resolvePeerCountries(it.value().toBool());

src/webui/api/synccontroller.cpp

@@ -49,6 +49,7 @@
 #include "base/utils/string.h"
 #include "apierror.h"
 #include "serialize/serialize_torrent.h"
+#include "webui/peerhostnameresolver.h"
 
 namespace
 {
@@ -70,6 +71,7 @@ namespace
     const QString KEY_PEER_FILES = u"files"_s;
     const QString KEY_PEER_FLAGS = u"flags"_s;
     const QString KEY_PEER_FLAGS_DESCRIPTION = u"flags_desc"_s;
+    const QString KEY_PEER_HOST_NAME = u"host_name"_s;
     const QString KEY_PEER_IP = u"ip"_s;
     const QString KEY_PEER_I2P_DEST = u"i2p_dest"_s;
     const QString KEY_PEER_PORT = u"port"_s;
@@ -441,8 +443,9 @@ namespace
     }
 }
 
-SyncController::SyncController(IApplication *app, QObject *parent)
+SyncController::SyncController(PeerHostNameResolver *peerHostNameResolver, IApplication *app, QObject *parent)
     : APIController(app, parent)
+    , m_peerHostNameResolver {peerHostNameResolver}
 {
 }
 
@@ -839,7 +842,9 @@ void SyncController::torrentPeersAction()
 
     const QList<BitTorrent::PeerInfo> peersList = torrent->fetchPeerInfo().takeResult();
 
-    bool resolvePeerCountries = Preferences::instance()->resolvePeerCountries();
+    const auto *pref = Preferences::instance();
+    const bool resolvePeerHostNames = pref->resolvePeerHostNames();
+    const bool resolvePeerCountries = pref->resolvePeerCountries();
 
     data[KEY_SYNC_TORRENT_PEERS_SHOW_FLAGS] = resolvePeerCountries;
 
@@ -873,6 +878,9 @@ void SyncController::torrentPeersAction()
             peer.insert(KEY_PEER_FILES, filesForPiece.join(u'\n'));
         }
 
+        if (resolvePeerHostNames && !useI2PSocket)
+            peer[KEY_PEER_HOST_NAME] = m_peerHostNameResolver->lookupHostName(pi.address().ip);
+
         if (resolvePeerCountries && !useI2PSocket)
         {
             peer[KEY_PEER_COUNTRY_CODE] = pi.country().toLower();

src/webui/api/synccontroller.h

@@ -35,6 +35,8 @@
 #include "base/tag.h"
 #include "apicontroller.h"
 
+class PeerHostNameResolver;
+
 namespace BitTorrent
 {
     class Torrent;
@@ -47,9 +49,7 @@ class SyncController : public APIController
     Q_DISABLE_COPY_MOVE(SyncController)
 
 public:
-    using APIController::APIController;
-
-    explicit SyncController(IApplication *app, QObject *parent = nullptr);
+    explicit SyncController(PeerHostNameResolver *peerHostNameResolver, IApplication *app, QObject *parent = nullptr);
 
 public slots:
     void updateFreeDiskSpace(qint64 freeDiskSpace);
@@ -83,6 +83,7 @@ private slots:
     void onTorrentTrackerEntryStatusesUpdated(const BitTorrent::Torrent *torrent
             , const QHash<QString, BitTorrent::TrackerEntryStatus> &updatedTrackers);
 
+    PeerHostNameResolver *m_peerHostNameResolver = nullptr;
     qint64 m_freeDiskSpace = 0;
 
     QVariantMap m_lastPeersResponse;

src/webui/peerhostnameresolver.cpp

@@ -0,0 +1,71 @@
+/*
+ * Bittorrent Client using Qt and libtorrent.
+ * Copyright (C) 2026  Thomas Piccirello <[email protected]>
+ *
+ * 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.
+ */
+
+#include "peerhostnameresolver.h"
+
+#include "base/net/reverseresolution.h"
+#include "base/preferences.h"
+
+PeerHostNameResolver::PeerHostNameResolver(QObject *parent)
+    : QObject(parent)
+{
+    connect(Preferences::instance(), &Preferences::changed, this, &PeerHostNameResolver::updateState);
+    updateState();
+}
+
+QString PeerHostNameResolver::lookupHostName(const QHostAddress &ip)
+{
+    const QString hostName = m_resolvedHosts.value(ip);
+    if (m_resolver && hostName.isEmpty())
+        m_resolver->resolve(ip);
+
+    return hostName;
+}
+
+void PeerHostNameResolver::onHostNameResolved(const QHostAddress &ip, const QString &hostname)
+{
+    m_resolvedHosts.insert(ip, hostname);
+}
+
+void PeerHostNameResolver::updateState()
+{
+    if (Preferences::instance()->resolvePeerHostNames())
+    {
+        if (!m_resolver)
+        {
+            m_resolver = new Net::ReverseResolution(this);
+            connect(m_resolver, &Net::ReverseResolution::ipResolved
+                    , this, &PeerHostNameResolver::onHostNameResolved);
+        }
+    }
+    else
+    {
+        delete m_resolver;
+        m_resolver = nullptr;
+    }
+}

src/webui/peerhostnameresolver.h

@@ -0,0 +1,57 @@
+/*
+ * Bittorrent Client using Qt and libtorrent.
+ * Copyright (C) 2026  Thomas Piccirello <[email protected]>
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <QHash>
+#include <QHostAddress>
+#include <QObject>
+
+namespace Net
+{
+    class ReverseResolution;
+}
+
+class PeerHostNameResolver final : public QObject
+{
+    Q_OBJECT
+    Q_DISABLE_COPY_MOVE(PeerHostNameResolver)
+
+public:
+    explicit PeerHostNameResolver(QObject *parent = nullptr);
+
+    QString lookupHostName(const QHostAddress &ip);
+
+private slots:
+    void onHostNameResolved(const QHostAddress &ip, const QString &hostname);
+    void updateState();
+
+private:
+    Net::ReverseResolution *m_resolver = nullptr;
+    QHash<QHostAddress, QString> m_resolvedHosts;
+};

src/webui/webapplication.cpp

@@ -70,6 +70,7 @@
 #include "api/torrentscontroller.h"
 #include "api/transfercontroller.h"
 #include "clientdatastorage.h"
+#include "peerhostnameresolver.h"
 
 const int MAX_ALLOWED_FILESIZE = 10 * 1024 * 1024;
 const QString SESSION_COOKIE_NAME_PREFIX = u"QBT_SID_"_s;
@@ -161,6 +162,7 @@ WebApplication::WebApplication(IApplication *app, QObject *parent)
     , m_authController {new AuthController(this, app, this)}
     , m_torrentCreationManager {new BitTorrent::TorrentCreationManager(app, this)}
     , m_clientDataStorage {new ClientDataStorage(this)}
+    , m_peerHostNameResolver {new PeerHostNameResolver(this)}
 {
     declarePublicAPI(u"auth/login"_s);
 
@@ -838,7 +840,7 @@ void WebApplication::sessionStartImpl(const QString &sessionId, const bool useCo
     m_currentSession->registerAPIController(u"transfer"_s, new TransferController(app(), m_currentSession));
 
     const auto *btSession = BitTorrent::Session::instance();
-    auto *syncController = new SyncController(app(), m_currentSession);
+    auto *syncController = new SyncController(m_peerHostNameResolver, app(), m_currentSession);
     syncController->updateFreeDiskSpace(btSession->freeDiskSpace());
     connect(btSession, &BitTorrent::Session::freeDiskSpaceChecked, syncController, &SyncController::updateFreeDiskSpace);
     m_currentSession->registerAPIController(u"sync"_s, syncController);

src/webui/webapplication.h

@@ -57,7 +57,7 @@
 
 using namespace std::chrono_literals;
 
-inline const Utils::Version<3, 2> API_VERSION {2, 15, 0};
+inline const Utils::Version<3, 2> API_VERSION {2, 15, 1};
 
 class APIController;
 class AuthController;
@@ -69,6 +69,8 @@ namespace BitTorrent
     class TorrentCreationManager;
 }
 
+class PeerHostNameResolver;
+
 class WebSession final : public ApplicationComponent<QObject>, public ISession
 {
 public:
@@ -283,6 +285,7 @@ class WebApplication final : public ApplicationComponent<QObject>
 
     BitTorrent::TorrentCreationManager *m_torrentCreationManager = nullptr;
     ClientDataStorage *m_clientDataStorage = nullptr;
+    PeerHostNameResolver *m_peerHostNameResolver = nullptr;
 
     struct FailedLogin
     {

src/webui/www/private/scripts/dynamicTable.js

@@ -1835,6 +1835,7 @@ window.qBittorrent.DynamicTable ??= (() => {
             this.newColumn("files", "", "QBT_TR(Files)QBT_TR[CONTEXT=PeerListWidget]", 100, true);
 
             this.columns["country"].dataProperties.push("country_code");
+            this.columns["ip"].dataProperties.push("host_name");
             this.columns["flags"].dataProperties.push("flags_desc");
             this.initColumnsFunctions();
         }
@@ -1858,6 +1859,14 @@ window.qBittorrent.DynamicTable ??= (() => {
             };
 
             // ip
+            this.columns["ip"].updateTd = function(td, row) {
+                const ip = this.getRowValue(row, 0);
+                const hostname = this.getRowValue(row, 1);
+                // Display hostname if resolved, otherwise display IP
+                const displayValue = hostname || ip;
+                td.textContent = displayValue;
+                td.title = displayValue;
+            };
             this.columns["ip"].compareRows = function(row1, row2) {
                 const ip1 = this.getRowValue(row1);
                 const ip2 = this.getRowValue(row2);

src/webui/www/private/views/preferences.html

@@ -1276,6 +1276,14 @@
                         <input type="text" id="refreshInterval" style="width: 15em;" title="QBT_TR(It controls the internal state update interval which in turn will affect UI updates)QBT_TR[CONTEXT=OptionsDialog]">&nbsp;&nbsp;QBT_TR(ms)QBT_TR[CONTEXT=OptionsDialog]
                     </td>
                 </tr>
+                <tr>
+                    <td>
+                        <label for="resolvePeerHostNames">QBT_TR(Resolve peer host names:)QBT_TR[CONTEXT=OptionsDialog]</label>
+                    </td>
+                    <td>
+                        <input type="checkbox" id="resolvePeerHostNames">
+                    </td>
+                </tr>
                 <tr>
                     <td>
                         <label for="resolvePeerCountries">QBT_TR(Resolve peer countries:)QBT_TR[CONTEXT=OptionsDialog]</label>
@@ -2641,6 +2649,7 @@
                     document.getElementById("recheckTorrentsOnCompletion").checked = pref.recheck_completed_torrents;
                     document.getElementById("appInstanceName").value = pref.app_instance_name;
                     document.getElementById("refreshInterval").value = pref.refresh_interval;
+                    document.getElementById("resolvePeerHostNames").checked = pref.resolve_peer_host_names;
                     document.getElementById("resolvePeerCountries").checked = pref.resolve_peer_countries;
                     document.getElementById("reannounceWhenAddressChanged").checked = pref.reannounce_when_address_changed;
                     document.getElementById("enableEmbeddedTracker").checked = pref.enable_embedded_tracker;
@@ -3125,6 +3134,7 @@
             settings["recheck_completed_torrents"] = document.getElementById("recheckTorrentsOnCompletion").checked;
             settings["app_instance_name"] = document.getElementById("appInstanceName").value;
             settings["refresh_interval"] = Number(document.getElementById("refreshInterval").value);
+            settings["resolve_peer_host_names"] = document.getElementById("resolvePeerHostNames").checked;
             settings["resolve_peer_countries"] = document.getElementById("resolvePeerCountries").checked;
             settings["reannounce_when_address_changed"] = document.getElementById("reannounceWhenAddressChanged").checked;
             settings["enable_embedded_tracker"] = document.getElementById("enableEmbeddedTracker").checked;