Add announce_port support

The `announce_port` setting permits to overwrite the port passed along to trackers as the `&port=` parameter. If left as the default, the listening port is used. This setting is only meant for very special cases where a seed's listening port differs from the effectively exposed port (e.g., through external NAT-PMP). See https://github.com/arvidn/libtorrent/pull/7771 for an example use-case.

This PR adds the relevant setting alongside the existing `announce_ip` setting.

PR #21692.

src/gui/advancedsettings.cpp

@@ -163,6 +163,7 @@ namespace
         ANNOUNCE_ALL_TRACKERS,
         ANNOUNCE_ALL_TIERS,
         ANNOUNCE_IP,
+        ANNOUNCE_PORT,
         MAX_CONCURRENT_HTTP_ANNOUNCES,
         STOP_TRACKER_TIMEOUT,
         PEER_TURNOVER,
@@ -309,6 +310,8 @@ void AdvancedSettings::saveAdvancedSettings() const
     // Construct a QHostAddress to filter malformed strings
     const QHostAddress addr(m_lineEditAnnounceIP.text().trimmed());
     session->setAnnounceIP(addr.toString());
+    // Announce Port
+    session->setAnnouncePort(m_spinBoxAnnouncePort.value());
     // Max concurrent HTTP announces
     session->setMaxConcurrentHTTPAnnounces(m_spinBoxMaxConcurrentHTTPAnnounces.value());
     // Stop tracker timeout
@@ -801,6 +804,13 @@ void AdvancedSettings::loadAdvancedSettings()
     addRow(ANNOUNCE_IP, (tr("IP address reported to trackers (requires restart)")
         + u' ' + makeLink(u"https://www.libtorrent.org/reference-Settings.html#announce_ip", u"(?)"))
         , &m_lineEditAnnounceIP);
+    // Announce port
+    m_spinBoxAnnouncePort.setMinimum(0);
+    m_spinBoxAnnouncePort.setMaximum(65535);
+    m_spinBoxAnnouncePort.setValue(session->announcePort());
+    addRow(ANNOUNCE_PORT, (tr("Port reported to trackers (requires restart) [0: listening port]")
+        + u' ' + makeLink(u"https://www.libtorrent.org/reference-Settings.html#announce_port", u"(?)"))
+        , &m_spinBoxAnnouncePort);
     // Max concurrent HTTP announces
     m_spinBoxMaxConcurrentHTTPAnnounces.setMaximum(std::numeric_limits<int>::max());
     m_spinBoxMaxConcurrentHTTPAnnounces.setValue(session->maxConcurrentHTTPAnnounces());

src/gui/advancedsettings.h

@@ -73,7 +73,7 @@ private:
              m_spinBoxOutgoingPortsMin, m_spinBoxOutgoingPortsMax, m_spinBoxUPnPLeaseDuration, m_spinBoxPeerToS,
              m_spinBoxListRefresh, m_spinBoxTrackerPort, m_spinBoxSendBufferWatermark, m_spinBoxSendBufferLowWatermark,
              m_spinBoxSendBufferWatermarkFactor, m_spinBoxConnectionSpeed, m_spinBoxSocketSendBufferSize, m_spinBoxSocketReceiveBufferSize, m_spinBoxSocketBacklogSize,
-             m_spinBoxMaxConcurrentHTTPAnnounces, m_spinBoxStopTrackerTimeout, m_spinBoxSessionShutdownTimeout,
+             m_spinBoxAnnouncePort, m_spinBoxMaxConcurrentHTTPAnnounces, m_spinBoxStopTrackerTimeout, m_spinBoxSessionShutdownTimeout,
              m_spinBoxSavePathHistoryLength, m_spinBoxPeerTurnover, m_spinBoxPeerTurnoverCutoff, m_spinBoxPeerTurnoverInterval, m_spinBoxRequestQueueSize;
     QCheckBox m_checkBoxOsCache, m_checkBoxRecheckCompleted, m_checkBoxResolveCountries, m_checkBoxResolveHosts,
               m_checkBoxProgramNotifications, m_checkBoxTorrentAddedNotifications, m_checkBoxReannounceWhenAddressChanged, m_checkBoxTrackerFavicon, m_checkBoxTrackerStatus,