qnetworkinformation.cpp

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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
// #define DEBUG_LOADING
 
#include "qnetworkinformation.h"
#include <QtNetwork/private/qnetworkinformation_p.h>
#include <QtNetwork/qnetworkinformation.h>
 
#include <QtCore/private/qobject_p.h>
#include <QtCore/qcoreapplication.h>
#include <QtCore/qmutex.h>
#include <QtCore/qthread.h>
#include <QtCore/private/qfactoryloader_p.h>
 
#include <algorithm>
#include <memory>
#include <mutex>
 
QT_BEGIN_NAMESPACE
Q_DECLARE_LOGGING_CATEGORY(lcNetInfo)
Q_LOGGING_CATEGORY(lcNetInfo, "qt.network.info");
 
struct QNetworkInformationDeleter
{
    void operator()(QNetworkInformation *information) { delete information; }
};
 
Q_GLOBAL_STATIC_WITH_ARGS(QFactoryLoader, qniLoader,
                          (QNetworkInformationBackendFactory_iid,
                           QStringLiteral("/networkinformation")))
 
struct QStaticNetworkInformationDataHolder
{
    QMutex instanceMutex;
    std::unique_ptr<QNetworkInformation, QNetworkInformationDeleter> instanceHolder;
    QList<QNetworkInformationBackendFactory *> factories;
};
Q_GLOBAL_STATIC(QStaticNetworkInformationDataHolder, dataHolder);
 
static void networkInfoCleanup()
{
    if (!dataHolder.exists())
        return;
    QMutexLocker locker(&dataHolder->instanceMutex);
    QNetworkInformation *instance = dataHolder->instanceHolder.get();
    if (!instance)
        return;
 
    dataHolder->instanceHolder.reset();
}
 
using namespace Qt::Literals::StringLiterals;
 
class QNetworkInformationDummyBackend : public QNetworkInformationBackend {
    Q_OBJECT
public:
    QString name() const override { return u"dummy"_s; }
    QNetworkInformation::Features featuresSupported() const override
    {
        return {};
    }
};
 
class QNetworkInformationPrivate : public QObjectPrivate
{
    Q_DECLARE_PUBLIC(QNetworkInformation)
public:
    QNetworkInformationPrivate(QNetworkInformationBackend *backend) : backend(backend) {
        qAddPostRoutine(&networkInfoCleanup);
     }
 
    static QNetworkInformation *create(QNetworkInformation::Features features);
    static QNetworkInformation *create(QStringView name);
    static QNetworkInformation *createDummy();
    static QNetworkInformation *instance()
    {
        if (!dataHolder())
            return nullptr;
        QMutexLocker locker(&dataHolder->instanceMutex);
        return dataHolder->instanceHolder.get();
    }
    static QStringList backendNames();
    static void addToList(QNetworkInformationBackendFactory *factory);
    static void removeFromList(QNetworkInformationBackendFactory *factory);
 
private:
    static bool initializeList();
 
    std::unique_ptr<QNetworkInformationBackend> backend;
};
 
bool QNetworkInformationPrivate::initializeList()
{
    if (!qniLoader())
        return false;
    if (!dataHolder())
        return false;
    Q_CONSTINIT static QBasicMutex mutex;
    QMutexLocker initLocker(&mutex);
 
#if QT_CONFIG(library)
    qniLoader->update();
#endif
    // Instantiates the plugins (and registers the factories)
    int index = 0;
    while (qniLoader->instance(index))
        ++index;
    initLocker.unlock();
 
    // Now sort the list on number of features available (then name)
    const auto featuresNameOrder = [](QNetworkInformationBackendFactory *a,
                                      QNetworkInformationBackendFactory *b) {
        if (!a || !b)
            return a && !b;
        auto aFeaturesSupported = qPopulationCount(unsigned(a->featuresSupported()));
        auto bFeaturesSupported = qPopulationCount(unsigned(b->featuresSupported()));
        return aFeaturesSupported > bFeaturesSupported
                || (aFeaturesSupported == bFeaturesSupported
                    && a->name().compare(b->name(), Qt::CaseInsensitive) < 0);
    };
    QMutexLocker instanceLocker(&dataHolder->instanceMutex);
    std::sort(dataHolder->factories.begin(), dataHolder->factories.end(), featuresNameOrder);
 
    return !dataHolder->factories.isEmpty();
}
 
void QNetworkInformationPrivate::addToList(QNetworkInformationBackendFactory *factory)
{
    // @note: factory is in the base class ctor
    if (!dataHolder())
        return;
    QMutexLocker locker(&dataHolder->instanceMutex);
    dataHolder->factories.append(factory);
}
 
void QNetworkInformationPrivate::removeFromList(QNetworkInformationBackendFactory *factory)
{
    // @note: factory is in the base class dtor
    if (!dataHolder.exists())
        return;
    QMutexLocker locker(&dataHolder->instanceMutex);
    dataHolder->factories.removeAll(factory);
}
 
QStringList QNetworkInformationPrivate::backendNames()
{
    if (!dataHolder())
        return {};
    if (!initializeList())
        return {};
 
    QMutexLocker locker(&dataHolder->instanceMutex);
    const QList copy = dataHolder->factories;
    locker.unlock();
 
    QStringList result;
    result.reserve(copy.size());
    for (const auto *factory : copy)
        result << factory->name();
    return result;
}
 
QNetworkInformation *QNetworkInformationPrivate::create(QStringView name)
{
    if (name.isEmpty())
        return nullptr;
    if (!dataHolder())
        return nullptr;
#ifdef DEBUG_LOADING
    qDebug().nospace() << "create() called with name=\"" << name
                       << "\". instanceHolder initialized? " << !!dataHolder->instanceHolder;
#endif
    if (!initializeList()) {
#ifdef DEBUG_LOADING
        qDebug("Failed to initialize list, returning.");
#endif
        return nullptr;
    }
 
    QMutexLocker locker(&dataHolder->instanceMutex);
    if (dataHolder->instanceHolder)
        return dataHolder->instanceHolder.get();
 
 
    const auto nameMatches = [name](QNetworkInformationBackendFactory *factory) {
        return factory->name().compare(name, Qt::CaseInsensitive) == 0;
    };
    auto it = std::find_if(dataHolder->factories.cbegin(), dataHolder->factories.cend(),
                            nameMatches);
    if (it == dataHolder->factories.cend()) {
#ifdef DEBUG_LOADING
        if (dataHolder->factories.isEmpty()) {
            qDebug("No plugins available");
        } else {
            QString listNames;
            listNames.reserve(8 * dataHolder->factories.count());
            for (const auto *factory : std::as_const(dataHolder->factories))
                listNames += factory->name() + ", "_L1;
            listNames.chop(2);
            qDebug().nospace() << "Couldn't find " << name << " in list with names: { "
                                << listNames << " }";
        }
#endif
        return nullptr;
    }
#ifdef DEBUG_LOADING
    qDebug() << "Creating instance using loader named " << (*it)->name();
#endif
    QNetworkInformationBackend *backend = (*it)->create((*it)->featuresSupported());
    if (!backend)
        return nullptr;
    dataHolder->instanceHolder.reset(new QNetworkInformation(backend));
    Q_ASSERT(name.isEmpty()
             || dataHolder->instanceHolder->backendName().compare(name, Qt::CaseInsensitive) == 0);
    return dataHolder->instanceHolder.get();
}
 
QNetworkInformation *QNetworkInformationPrivate::create(QNetworkInformation::Features features)
{
    if (!dataHolder())
        return nullptr;
#ifdef DEBUG_LOADING
    qDebug().nospace() << "create() called with features=\"" << features
                       << "\". instanceHolder initialized? " << !!dataHolder->instanceHolder;
#endif
    if (features == 0)
        return nullptr;
 
    if (!initializeList()) {
#ifdef DEBUG_LOADING
        qDebug("Failed to initialize list, returning.");
#endif
        return nullptr;
    }
    QMutexLocker locker(&dataHolder->instanceMutex);
    if (dataHolder->instanceHolder)
        return dataHolder->instanceHolder.get();
 
    const auto supportsRequestedFeatures = [features](QNetworkInformationBackendFactory *factory) {
        return factory && factory->featuresSupported().testFlags(features);
    };
 
    for (auto it = dataHolder->factories.cbegin(), end = dataHolder->factories.cend(); it != end;
         ++it) {
        it = std::find_if(it, end, supportsRequestedFeatures);
        if (it == end) {
#ifdef DEBUG_LOADING
            if (dataHolder->factories.isEmpty()) {
                qDebug("No plugins available");
            } else {
                QStringList names;
                names.reserve(dataHolder->factories.count());
                for (const auto *factory : std::as_const(dataHolder->factories))
                    names += factory->name();
                qDebug() << "None of the following backends has all the requested features:"
                         << names << features;
            }
#endif
            break;
        }
#ifdef DEBUG_LOADING
        qDebug() << "Creating instance using loader named" << (*it)->name();
#endif
        if (QNetworkInformationBackend *backend = (*it)->create(features)) {
            dataHolder->instanceHolder.reset(new QNetworkInformation(backend));
            Q_ASSERT(dataHolder->instanceHolder->supports(features));
            return dataHolder->instanceHolder.get();
        }
#ifdef DEBUG_LOADING
        else {
            qDebug() << "The factory returned a nullptr";
        }
#endif
    }
#ifdef DEBUG_LOADING
    qDebug() << "Couldn't find/create an appropriate backend.";
#endif
    return nullptr;
}
 
QNetworkInformation *QNetworkInformationPrivate::createDummy()
{
    if (!dataHolder())
        return nullptr;
 
    QMutexLocker locker(&dataHolder->instanceMutex);
    if (dataHolder->instanceHolder)
        return dataHolder->instanceHolder.get();
 
    QNetworkInformationBackend *backend =  new QNetworkInformationDummyBackend;
    dataHolder->instanceHolder.reset(new QNetworkInformation(backend));
    return dataHolder->instanceHolder.get();
}
 
QNetworkInformationBackend::~QNetworkInformationBackend() = default;
 
QNetworkInformationBackendFactory::QNetworkInformationBackendFactory()
{
    QNetworkInformationPrivate::addToList(this);
}
 
QNetworkInformationBackendFactory::~QNetworkInformationBackendFactory()
{
    QNetworkInformationPrivate::removeFromList(this);
}
 
QNetworkInformation::QNetworkInformation(QNetworkInformationBackend *backend)
    : QObject(*(new QNetworkInformationPrivate(backend)))
{
    connect(backend, &QNetworkInformationBackend::reachabilityChanged, this,
            &QNetworkInformation::reachabilityChanged);
    connect(backend, &QNetworkInformationBackend::behindCaptivePortalChanged, this,
            &QNetworkInformation::isBehindCaptivePortalChanged);
    connect(backend, &QNetworkInformationBackend::transportMediumChanged, this,
            &QNetworkInformation::transportMediumChanged);
    connect(backend, &QNetworkInformationBackend::isMeteredChanged, this,
           &QNetworkInformation::isMeteredChanged);
 
    QThread *main = nullptr;
 
    if (QCoreApplication::instance())
        main = QCoreApplication::instance()->thread();
 
    if (main && thread() != main)
        moveToThread(main);
}
 
QNetworkInformation::~QNetworkInformation() = default;
 
QNetworkInformation::Reachability QNetworkInformation::reachability() const
{
    return d_func()->backend->reachability();
}
 
bool QNetworkInformation::isBehindCaptivePortal() const
{
    return d_func()->backend->behindCaptivePortal();
}
 
QNetworkInformation::TransportMedium QNetworkInformation::transportMedium() const
{
    return d_func()->backend->transportMedium();
}
 
bool QNetworkInformation::isMetered() const
{
    return d_func()->backend->isMetered();
}
 
QString QNetworkInformation::backendName() const
{
    return d_func()->backend->name();
}
 
bool QNetworkInformation::supports(Features features) const
{
    return (d_func()->backend->featuresSupported() & features) == features;
}
 
QNetworkInformation::Features QNetworkInformation::supportedFeatures() const
{
    return d_func()->backend->featuresSupported();
}
 
bool QNetworkInformation::loadDefaultBackend()
{
    int index = -1;
#ifdef Q_OS_WIN
    index = QNetworkInformationBackend::PluginNamesWindowsIndex;
#elif defined(Q_OS_DARWIN)
    index = QNetworkInformationBackend::PluginNamesAppleIndex;
#elif defined(Q_OS_ANDROID)
    index = QNetworkInformationBackend::PluginNamesAndroidIndex;
#elif defined(Q_OS_LINUX)
    index = QNetworkInformationBackend::PluginNamesLinuxIndex;
#endif
    if (index != -1 && loadBackendByName(QNetworkInformationBackend::PluginNames[index]))
        return true;
    // We assume reachability is the most commonly wanted feature, and try to
    // load the backend that advertises the most features including that:
    if (loadBackendByFeatures(Feature::Reachability))
        return true;
 
    // Fall back to the dummy backend
    return loadBackendByName(u"dummy");
}
 
bool QNetworkInformation::loadBackendByName(QStringView backend)
{
    if (backend == u"dummy")
        return QNetworkInformationPrivate::createDummy() != nullptr;
 
    auto loadedBackend = QNetworkInformationPrivate::create(backend);
    return loadedBackend && loadedBackend->backendName().compare(backend, Qt::CaseInsensitive) == 0;
}
 
#if QT_DEPRECATED_SINCE(6,4)
bool QNetworkInformation::load(QStringView backend)
{
    return loadBackendByName(backend);
}
#endif // QT_DEPRECATED_SINCE(6,4)
 
bool QNetworkInformation::loadBackendByFeatures(Features features)
{
    auto loadedBackend = QNetworkInformationPrivate::create(features);
    return loadedBackend && loadedBackend->supports(features);
}
 
#if QT_DEPRECATED_SINCE(6,4)
bool QNetworkInformation::load(Features features)
{
    return loadBackendByFeatures(features);
}
#endif // QT_DEPRECATED_SINCE(6,4)
 
QStringList QNetworkInformation::availableBackends()
{
    return QNetworkInformationPrivate::backendNames();
}
 
QNetworkInformation *QNetworkInformation::instance()
{
    return QNetworkInformationPrivate::instance();
}
 
QT_END_NAMESPACE
 
#include "moc_qnetworkinformation.cpp"
#include "moc_qnetworkinformation_p.cpp"
#include "qnetworkinformation.moc"