qtbase/examples/network/secureudpclient/association.cpp

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#include "association.h"

QT_BEGIN_NAMESPACE

DtlsAssociation::DtlsAssociation(const QHostAddress &address, quint16 port,
                                 const QString &connectionName)
    : name(connectionName),
      crypto(QSslSocket::SslClientMode)
{
    auto configuration = QSslConfiguration::defaultDtlsConfiguration();
    configuration.setPeerVerifyMode(QSslSocket::VerifyNone);
    crypto.setRemote(address, port);
    crypto.setDtlsConfiguration(configuration);

    connect(&crypto, &QDtls::handshakeTimeout, this, &DtlsAssociation::handshakeTimeout);
    connect(&crypto, &QDtls::pskRequired, this, &DtlsAssociation::pskRequired);

    connect(&socket, &QUdpSocket::readyRead, this, &DtlsAssociation::readyRead);

    pingTimer.setInterval(5000);
    connect(&pingTimer, &QTimer::timeout, this, &DtlsAssociation::pingTimeout);
}

DtlsAssociation::~DtlsAssociation()
{
    if (crypto.connectionEncrypted())
        crypto.sendShutdownAlert(&socket);
}

void DtlsAssociation::startHandshake()
{
    if (!crypto.doHandshake(&socket, {}))
        emit errorMessage(name + tr(": failed to start a handshake - ") + crypto.dtlsErrorString());
    else
        emit infoMessage(name + tr(": starting a handshake"));
}

void DtlsAssociation::readyRead()
{
    QByteArray dgram(socket.pendingDatagramSize(), '\0');
    const qint64 bytesRead = socket.readDatagram(dgram.data(), dgram.size());
    if (bytesRead <= 0) {
        emit warningMessage(name + tr(": spurious read notification?"));
        return;
    }

    dgram.resize(bytesRead);
    if (crypto.connectionEncrypted()) {
        const QByteArray plainText = crypto.decryptDatagram(&socket, dgram);
        if (plainText.size()) {
            emit serverResponse(name, dgram, plainText);
            pingTimer.start();
            return;
        }

        if (crypto.dtlsError() == QDtlsError::RemoteClosedConnectionError) {
            emit errorMessage(name + tr(": shutdown alert received"));
            socket.close();
            pingTimer.stop();
            return;
        }

        emit warningMessage(name + tr(": zero-length datagram received?"));
    } else {
        if (!crypto.doHandshake(&socket, dgram)) {
            emit errorMessage(name + tr(": handshake error - ") + crypto.dtlsErrorString());
            return;
        }
        if (crypto.connectionEncrypted()) {
            emit infoMessage(name + tr(": encrypted connection established!"));
            pingTimer.start();
            pingTimeout();
        } else {
            emit infoMessage(name + tr(": continuing with handshake ..."));
        }
    }
}

void DtlsAssociation::handshakeTimeout()
{
    emit warningMessage(name + tr(": handshake timeout, trying to re-transmit"));
    if (!crypto.handleTimeout(&socket))
        emit errorMessage(name + tr(": failed to re-transmit - ") + crypto.dtlsErrorString());
}

void DtlsAssociation::pskRequired(QSslPreSharedKeyAuthenticator *auth)
{
    Q_ASSERT(auth);

    emit infoMessage(name + tr(": providing pre-shared key ..."));
    auth->setIdentity(name.toLatin1());
    auth->setPreSharedKey(QByteArrayLiteral("\x1a\x2b\x3c\x4d\x5e\x6f"));
}

void DtlsAssociation::pingTimeout()
{
    static const QString message = QStringLiteral("I am %1, please, accept our ping %2");
    const qint64 written = crypto.writeDatagramEncrypted(&socket, message.arg(name).arg(ping).toLatin1());
    if (written <= 0) {
        emit errorMessage(name + tr(": failed to send a ping - ") + crypto.dtlsErrorString());
        pingTimer.stop();
        return;
    }

    ++ping;
}

QT_END_NAMESPACE