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#include "qtlsbackend_p.h"
#include "qsslsocket_p.h"
#include "qssl_p.h"

#include <QtCore/private/qfactoryloader_p.h>

#include <QtCore/qmutex.h>

#include <algorithm>
#include <vector>

QT_BEGIN_NAMESPACE

Q_GLOBAL_STATIC_WITH_ARGS(QFactoryLoader, loader,
                          (QTlsBackendFactory_iid, QStringLiteral("/tlsbackends")))

const QString QTlsBackendFactory::builtinBackendNames[] = {
    QStringLiteral("schannel"),
    QStringLiteral("securetransport"),
    QStringLiteral("openssl")
};


QTlsBackend::QTlsBackend() = default;
QTlsBackend::~QTlsBackend() = default;

const QString dummyName = QStringLiteral("dummyTLS");

QString QTlsBackend::backendName() const
{
    return dummyName;
}

QSsl::TlsKey *QTlsBackend::createKey() const
{
    qCWarning(lcSsl, "Dummy TLS backend, cannot generate a key");
    return nullptr;
}

QSsl::X509Certificate *QTlsBackend::createCertificate() const
{
    qCWarning(lcSsl, "Dummy TLS backend, cannot create a certificate");
    return nullptr;
}

QSsl::TlsCryptograph *QTlsBackend::createTlsCryptograph() const
{
    qCWarning(lcSsl, "Dummy TLS backend, cannot create TLS session");
    return nullptr;
}

QSsl::DtlsCryptograph *QTlsBackend::createDtlsCryptograph() const
{
    qCWarning(lcSsl, "Dummy TLS backend, cannot create DTLS session");
    return nullptr;
}

QSsl::DtlsCookieVerifier *QTlsBackend::createDtlsCookieVerifier() const
{
    qCWarning(lcSsl, "Dummy TLS backend, cannot create DTLS cookie generator/verifier");
    return nullptr;
}

QSsl::X509ChainVerifyPtr QTlsBackend::X509Verifier() const
{
    qCWarning(lcSsl, "Dummy TLS backend, cannot verify X509 chain");
    return nullptr;
}

QSsl::X509PemReaderPtr QTlsBackend::X509PemReader() const
{
    qCWarning(lcSsl, "Dummy TLS backend, cannot read PEM format");
    return nullptr;
}

QSsl::X509DerReaderPtr QTlsBackend::X509DerReader() const
{
    qCWarning(lcSsl, "Dummy TLS backend, don't know how to read DER");
    return nullptr;
}

QSsl::X509Pkcs12ReaderPtr QTlsBackend::X509Pkcs12Reader() const
{
    qCWarning(lcSsl, "Dummy TLS backend, cannot read PKCS12");
    return nullptr;
}

namespace {

class BackEndFactoryCollection
{
public:
    void addFactory(QTlsBackendFactory *newFactory)
    {
        Q_ASSERT(newFactory);
        Q_ASSERT(std::find(backendFactories.begin(), backendFactories.end(), newFactory) == backendFactories.end());
        const QMutexLocker locker(&collectionMutex);
        backendFactories.push_back(newFactory);
    }

    void removeFactory(QTlsBackendFactory *factory)
    {
        Q_ASSERT(factory);
        const QMutexLocker locker(&collectionMutex);
        const auto it = std::find(backendFactories.begin(), backendFactories.end(), factory);
        Q_ASSERT(it != backendFactories.end());
        backendFactories.erase(it);
    }

    bool tryPopulateCollection()
    {
        if (!loader())
            return false;

        static QBasicMutex mutex;
        const QMutexLocker locker(&mutex);
        if (loaded)
            return true;

#if QT_CONFIG(library)
        loader->update();
#endif
        int index = 0;
        while (loader->instance(index))
            ++index;

        // TLSTODO: obviously, this one should go away:
        QSslSocketPrivate::registerAdHocFactory();

        return loaded = true;
    }

    QList<QString> backendNames()
    {
        QList<QString> names;
        if (!tryPopulateCollection())
            return names;

        const QMutexLocker locker(&collectionMutex);
        if (!backendFactories.size())
            return names;

        names.reserve(backendFactories.size());
        for (const auto *factory : backendFactories)
            names.append(factory->backendName());

        return names;
    }

    QTlsBackendFactory *factory(const QString &name)
    {
        if (!tryPopulateCollection())
            return nullptr;

        const QMutexLocker locker(&collectionMutex);
        const auto it = std::find_if(backendFactories.begin(), backendFactories.end(),
                                     [&name](const auto *fct) {return fct->backendName() == name;});

        return it == backendFactories.end()  ? nullptr : *it;
    }

private:
    std::vector<QTlsBackendFactory *> backendFactories;
    QMutex collectionMutex;
    bool loaded = false;
};

Q_GLOBAL_STATIC(BackEndFactoryCollection, factories);

} // unnamed namespace

QTlsBackendFactory::QTlsBackendFactory()
{
    if (factories())
        factories->addFactory(this);
}

QTlsBackendFactory::~QTlsBackendFactory()
{
    if (factories())
        factories->removeFactory(this);
}

QString QTlsBackendFactory::backendName() const
{
    return dummyName;
}

QList<QString> QTlsBackendFactory::availableBackendNames()
{
    if (!factories())
        return {};

    return factories->backendNames();
}

QString QTlsBackendFactory::defaultBackendName()
{
    // We prefer native as default:
    const auto names = availableBackendNames();
    auto name = builtinBackendNames[nameIndexSchannel];
    if (names.contains(name))
        return name;
    name = builtinBackendNames[nameIndexSecureTransport];
    if (names.contains(name))
        return name;
    name = builtinBackendNames[nameIndexOpenSSL];
    if (names.contains(name))
        return name;

    return {};
}

QTlsBackend *QTlsBackendFactory::create(const QString &backendName)
{
    if (!factories())
        return {};

    if (const auto *fct = factories->factory(backendName))
        return fct->create();

    qCWarning(lcSsl) << "Cannot create unknown backend named" << backendName;
    return nullptr;
}

QList<QSsl::SslProtocol> QTlsBackendFactory::supportedProtocols(const QString &backendName)
{
    if (!factories())
        return {};

    if (const auto *fct = factories->factory(backendName))
        return fct->supportedProtocols();

    return {};
}

QList<QSsl::SupportedFeature> QTlsBackendFactory::supportedFeatures(const QString &backendName)
{
    if (!factories())
        return {};

    if (const auto *fct = factories->factory(backendName))
        return fct->supportedFeatures();

    return {};
}

QList<QSsl::ImplementedClass> QTlsBackendFactory::implementedClasses(const QString &backendName)
{
    if (!factories())
        return {};

    if (const auto *fct = factories->factory(backendName))
        return fct->implementedClasses();

    return {};

}

QT_END_NAMESPACE