c++ - 如何使用 QtMqtt 和 SSL 执行安全的 MQTT？

Question

我正在尝试使用 QtMQtt 示例项目 simpleclient。但我想执行安全的 MQTT。我该如何处理？

我已阅读此博客 ( https://www.qt.io/blog/2017/08/14/introducing-qtmqtt-protocol )。但这对我帮助不大。

我必须使用 QsslSocket 的 connectToHostEncrypted() 还是应该使用 QTMQTT 客户端的 connectToHostEncrypted()

如果我使用 QTMQTT 客户端的 connectToHostEncrypted()。它只允许我设置 sslpeername。它不允许我设置证书或私钥

或者如果我使用QSSLSOCKECT 的 connectToHostEncrypted()。如何通知我的 MQTT 客户端已建立连接。我现在应该可以发布和订阅了

现在我正在做这样的事情:

connect(this->(QSslSockets's Object),SIGNAL(encrypted),this, SLOT(foo()))
void foo()
{
QTMQTTClient's object->connectToHostEncrypted("Hostname")
}

这不允许我发布或订阅。 如果有人能指出我正确的方向。一些对我有很大帮助的文档或示例

Answer 1

QMqttClient如果您的 Qt 支持 SSL，将用作 QSslSocket 的传输设备，以验证它是否支持 SSL QSslSocket::supportsSsl()函数必须返回真。如果它不支持它，那么您必须按照指南启用它:Enabling and Disabling SSL Support .

---

考虑到上面的工作，那么你可以全局设置证书，以便所有 QSslSocket 默认使用它:

QSslCertificate cert = QSslCertificate(...);
QSslSocket::addDefaultCaCertificate(cert);

QMqttClient client;
client.setHostname(...);
client.setPort(...);
// ...
client.connectToHostEncrypted();

例如使用 http://test.mosquitto.org/ :

#include <QtMqtt>

const QByteArray pem = R"(-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
)";

int main(int argc, char *argv[]) {
    QCoreApplication a(argc, argv);

    const QString hostname{"test.mosquitto.org"};
    const quint16 port = 8883;
    const QMqttTopicName topic{"qtmqtt/ssl_test"};
    const QMqttTopicFilter filter{"qtmqtt/#"};

    QSslCertificate cert = QSslCertificate(pem, QSsl::Pem);
    QSslSocket::addDefaultCaCertificate(cert);

    QMqttClient client;
    client.setHostname(hostname);
    client.setPort(port);

    QObject::connect(&client, &QMqttClient::stateChanged, [](QMqttClient::ClientState state){
        if(state == QMqttClient::Disconnected)
            qDebug() << " State: Disconnected";
        else if(state == QMqttClient::Connecting)
            qDebug() << " State: Connecting";
        else if(state == QMqttClient::Connected)
            qDebug() << " State: Connected";
    });

    QObject::connect(&client, &QMqttClient::errorChanged, [](QMqttClient::ClientError error){
        qDebug() << error;

    });

    QObject::connect(&client, &QMqttClient::messageReceived, [](const QByteArray &message, const QMqttTopicName &topic){
        qDebug() << " Received Topic:" << topic.name() << " Message: " << message;
    });

    QTimer timer;
    QObject::connect(&timer, &QTimer::timeout, [&client, &topic](){
        if(client.publish(topic,  QDateTime::currentDateTime().toString().toUtf8()) == -1)
            qDebug() << "Error: Could not publish message";
    });

    QObject::connect(&client, &QMqttClient::connected, [&client, &timer, &filter](){
        QMqttSubscription *subscription = client.subscribe(filter);
        if(!subscription)
            qDebug() << "Could not subscribe";
        timer.start(1000);
    });

    client.connectToHostEncrypted();

    return a.exec();
}

输出:

 State: Connecting
 State: Connected
 Received Topic: "qtmqtt/ssl_test"  Message:  "Sat Sep 7 00:58:08 2019"
 Received Topic: "qtmqtt/ssl_test"  Message:  "Sat Sep 7 00:58:09 2019"
 Received Topic: "qtmqtt/ssl_test"  Message:  "Sat Sep 7 00:58:10 2019"
 Received Topic: "qtmqtt/ssl_test"  Message:  "Sat Sep 7 00:58:11 2019"
 Received Topic: "qtmqtt/ssl_test"  Message:  "Sat Sep 7 00:58:12 2019"
 ...

---

您还可以使用 QSslConfiguration 来设置证书和/或私钥:

QSslCertificate cert = QSslCertificate(...);
QSslConfiguration conf;
conf.setCaCertificates({cert});
// conf.setPrivateKey();
QSslConfiguration::setDefaultConfiguration(conf);

QMqttClient client;
client.setHostname(...);
client.setPort(...);
// ...
client.connectToHostEncrypted();

---

也可以直接将QSslSocket设置为传输设备来传递:

QSslCertificate cert = QSslCertificate(...);
QSslSocket socket;
socket.addCaCertificate(cert);
// conf.setPrivateKey();

QMqttClient client;
client.setHostname(...);
client.setPort(...);
client.setTransport(&socket, QMqttClient::SecureSocket);
// ...
client.connectToHostEncrypted();