[mer][qtnetwork] Create new QNetworkSession from the new online QNetw…

…orkConfiguration. Fixes JB#34613

When network configuration configuration changes, use the QNetworkConfiguration
argument within the slot as the QNetworkConfigurationManager::defaultConfiguration()
points to the previous default configuration. Default configration
in turn is wrong e.g. when turning WLAN on so that cellular is
already enabled. This happens because the Qt Connman Bearer plugin finds
the cellular AP from the access point list.

Further, do not close QNetworkSession when changing from WLAN to cellular
as the network session created for WLAN should be kept alive.

src/network/access/qnetworkaccessmanager.cpp

@@ -61,6 +61,7 @@
 #include "qnetworkreplyfileimpl_p.h"
 
 #include "QtCore/qbuffer.h"
+#include "QtCore/qloggingcategory.h"
 #include "QtCore/qurl.h"
 #include "QtCore/qvector.h"
 #include "QtNetwork/private/qauthenticator_p.h"
@@ -85,6 +86,8 @@
 
 QT_BEGIN_NAMESPACE
 
+Q_LOGGING_CATEGORY(lcNetworkAccess, "qt.network.access", QtWarningMsg)
+
 Q_GLOBAL_STATIC(QNetworkAccessFileBackendFactory, fileBackend)
 #if QT_CONFIG(ftp)
 Q_GLOBAL_STATIC(QNetworkAccessFtpBackendFactory, ftpBackend)
@@ -1098,6 +1101,37 @@ QSharedPointer<QNetworkSession> QNetworkAccessManagerPrivate::getNetworkSession(
     return networkSessionWeakRef.toStrongRef();
 }
 
+bool QNetworkAccessManagerPrivate::networkSessionCreationAllowed(const QNetworkConfiguration &configuration) const
+{
+    // Do not allow network session creation if changing to non Wlan when Wlan already active.
+    // cellular to WLAN        -> ok
+    // cellular to cellular    -> ok
+    // WLAN to cellular        -> not ok
+    // WLAN to WLAN            -> ok
+
+    bool wlanActive = false;
+    const auto activeConfigurations = networkConfigurationManager.allConfigurations(QNetworkConfiguration::Active);
+    if (configuration.bearerTypeFamily() != QNetworkConfiguration::BearerWLAN) {
+        for (const QNetworkConfiguration &config : activeConfigurations) {
+            if (config.bearerType() == QNetworkConfiguration::BearerWLAN) {
+                wlanActive = true;
+                break;
+            }
+        }
+    }
+
+    QSharedPointer<QNetworkSession> session(getNetworkSession());
+    if (session) {
+        // Prevent moving from WLAN to mobile data.
+        return !((session->configuration().bearerTypeFamily() == QNetworkConfiguration::BearerWLAN && wlanActive) &&
+                 (configuration.bearerTypeFamily() == QNetworkConfiguration::Bearer2G ||
+                  configuration.bearerTypeFamily() == QNetworkConfiguration::Bearer3G ||
+                  configuration.bearerTypeFamily() == QNetworkConfiguration::Bearer4G));
+    }
+
+    return false;
+}
+
 #endif // QT_NO_BEARERMANAGEMENT
 
 
@@ -1773,8 +1807,10 @@ void QNetworkAccessManagerPrivate::createSession(const QNetworkConfiguration &co
     networkSessionStrongRef = networkSessionWeakRef.toStrongRef();
 
     QSharedPointer<QNetworkSession> newSession;
-    if (config.isValid())
+    if (config.isValid()) {
         newSession = QSharedNetworkSessionManager::getSession(config);
+        qCDebug(lcNetworkAccess) << "QNAM: get network session from network configuration.";
+    }
 
     if (networkSessionStrongRef) {
         //do nothing if new and old session are the same
@@ -1807,11 +1843,16 @@ void QNetworkAccessManagerPrivate::createSession(const QNetworkConfiguration &co
     QObject::connect(networkSessionStrongRef.data(), SIGNAL(opened()), q, SIGNAL(networkSessionConnected()), Qt::QueuedConnection);
     //QueuedConnection is used to avoid deleting the networkSession inside its closed signal
     QObject::connect(networkSessionStrongRef.data(), SIGNAL(closed()), q, SLOT(_q_networkSessionClosed()), Qt::QueuedConnection);
-    QObject::connect(networkSessionStrongRef.data(), SIGNAL(stateChanged(QNetworkSession::State)),
-                     q, SLOT(_q_networkSessionStateChanged(QNetworkSession::State)), Qt::QueuedConnection);
+    QObject::connect(networkSessionStrongRef.data(), &QNetworkSession::stateChanged,
+                     q, [this](QNetworkSession::State s) {
+        qCDebug(lcNetworkAccess) << "QNAM: network session state changed:" << s;
+        _q_networkSessionStateChanged(s);
+    }, Qt::QueuedConnection);
     QObject::connect(networkSessionStrongRef.data(), SIGNAL(error(QNetworkSession::SessionError)),
                         q, SLOT(_q_networkSessionFailed(QNetworkSession::SessionError)));
 
+
+    qCDebug(lcNetworkAccess) << "QNAM: initial network session" << networkSessionStrongRef->configuration().name() << "state:" << networkSessionStrongRef->state();
     _q_networkSessionStateChanged(networkSessionStrongRef->state());
 }
 
@@ -1914,15 +1955,19 @@ void QNetworkAccessManagerPrivate::_q_configurationChanged(const QNetworkConfigu
         if (!onlineConfigurations.contains(id)) {
             QSharedPointer<QNetworkSession> session(getNetworkSession());
             if (session) {
-                if (online && session->configuration().identifier()
-                        != networkConfigurationManager.defaultConfiguration().identifier()) {
-
+                bool canCreateNetworkSession = networkSessionCreationAllowed(configuration);
+                // Use the id of the configuration over here as the networkConfigurationManager.defaultConfiguration()
+                // points to previous default configuration i.e. not yet changed.
+                if (canCreateNetworkSession && online && session->configuration().identifier() != id) {
+                    qCDebug(lcNetworkAccess) << "QNAM: network session changing from" << session->configuration().name() << "to" << configuration.name();
                     onlineConfigurations.insert(id);
                     // CHECK: If it's having Active flag - why would it be disconnected ???
                     //this one disconnected but another one is online,
                     // close and create new session
                     _q_networkSessionClosed();
-                    createSession(networkConfigurationManager.defaultConfiguration());
+                    createSession(configuration);
+                } else if (!canCreateNetworkSession) {
+                    qCDebug(lcNetworkAccess) << "QNAM: network session changed prevented from" << session->configuration().name() << "to" << configuration.name() << "as WLAN access point already online.";
                 }
             }
         }

src/network/access/qnetworkaccessmanager_p.h

@@ -150,6 +150,8 @@ class QNetworkAccessManagerPrivate: public QObjectPrivate
     void createSession(const QNetworkConfiguration &config);
     QSharedPointer<QNetworkSession> getNetworkSession() const;
 
+    bool networkSessionCreationAllowed(const QNetworkConfiguration &configuration) const;
+
     void _q_networkSessionClosed();
     void _q_networkSessionNewConfigurationActivated();
     void _q_networkSessionPreferredConfigurationChanged(const QNetworkConfiguration &config,