WebUI: Preserve the network interfaces when down

PR #19286.

src/webui/api/appcontroller.cpp

@@ -320,8 +320,10 @@ void AppController::preferencesAction()
     data[u"memory_working_set_limit"_s] = app()->memoryWorkingSetLimit();
     // Current network interface
     data[u"current_network_interface"_s] = session->networkInterface();
+    // Current network interface name
+    data[u"current_interface_name"_s] = session->networkInterfaceName();
     // Current network interface address
-    data[u"current_interface_address"_s] = BitTorrent::Session::instance()->networkInterfaceAddress();
+    data[u"current_interface_address"_s] = session->networkInterfaceAddress();
     // Save resume data interval
     data[u"save_resume_data_interval"_s] = session->saveResumeDataInterval();
     // Recheck completed torrents
@@ -845,6 +847,7 @@ void AppController::setPreferencesAction()
         const QString ifaceName = (ifacesIter != ifaces.cend()) ? ifacesIter->humanReadableName() : QString {};
 
         session->setNetworkInterface(ifaceValue);
+        if (!ifaceName.isEmpty() || ifaceValue.isEmpty())
             session->setNetworkInterfaceName(ifaceName);
     }
     // Current network interface address

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

@@ -1749,7 +1749,7 @@ Use ';' to split multiple entries. Can use wildcard '*'.)QBT_TR[CONTEXT=OptionsD
         };
 
         // Advanced Tab
-        const updateNetworkInterfaces = function(default_iface) {
+        const updateNetworkInterfaces = function(default_iface, default_iface_name) {
             const url = 'api/v2/app/networkInterfaceList';
             $('networkInterface').empty();
             new Request.JSON({
@@ -1760,9 +1760,13 @@ Use ';' to split multiple entries. Can use wildcard '*'.)QBT_TR[CONTEXT=OptionsD
                     alert("Could not contact qBittorrent");
                 },
                 onSuccess: function(ifaces) {
-                    if (!ifaces)
+                    if (!Array.isArray(ifaces))
                         return;
 
+                    // add the current network interface to the options if needed
+                    if (default_iface && !ifaces.some((item) => item.value === default_iface))
+                        ifaces.push({ name: default_iface_name || default_iface, value: default_iface });
+
                     $('networkInterface').options.add(new Option('QBT_TR(Any interface)QBT_TR[CONTEXT=OptionsDialog]', ''));
                     ifaces.forEach(function(item, index) {
                         $('networkInterface').options.add(new Option(item.name, item.value));
@@ -2144,7 +2148,7 @@ Use ';' to split multiple entries. Can use wildcard '*'.)QBT_TR[CONTEXT=OptionsD
                         // qBittorrent section
                         $('resumeDataStorageType').setProperty('value', pref.resume_data_storage_type);
                         $('memoryWorkingSetLimit').setProperty('value', pref.memory_working_set_limit);
-                        updateNetworkInterfaces(pref.current_network_interface);
+                        updateNetworkInterfaces(pref.current_network_interface, pref.current_interface_name);
                         updateInterfaceAddresses(pref.current_network_interface, pref.current_interface_address);
                         $('saveResumeDataInterval').setProperty('value', pref.save_resume_data_interval);
                         $('recheckTorrentsOnCompletion').setProperty('checked', pref.recheck_completed_torrents);