qt 如何创建tcp隧道

Qt提供了QTcpServer和QTcpSocket类来创建TCP隧道。以下是一个简单的例子：

1. 创建QTcpServer对象并监听一个端口。

QTcpServer server;
if(!server.listen(QHostAddress::Any, 1234)) {
    qDebug() << "Server could not start";
    return -1;
}

2. 在新连接到来时，创建QTcpSocket对象并连接到目标地址和端口。

void MyServer::incomingConnection(qintptr socketDescriptor) {
    QTcpSocket *client = new QTcpSocket(this);
    if(client->setSocketDescriptor(socketDescriptor)) {
        // Connect to destination address and port
        client->connectToHost("destination.address", 5678);
    }
}

3. 在QTcpSocket的connected()信号中，将客户端发送的数据转发到目标地址和端口。

void MyServer::onConnected() {
    QTcpSocket *client = qobject_cast<QTcpSocket*>(sender());
    if(client) {
        connect(client, &QTcpSocket::readyRead, this, &MyServer::onReadyRead);
        connect(client, &QTcpSocket::disconnected, this, &MyServer::onDisconnected);

        // Forward client data to destination
        connect(client, &QTcpSocket::readyRead, [=]() {
            QByteArray data = client->readAll();
            destination->write(data);
        });
    }
}

4. 在QTcpSocket的disconnected()信号中，关闭连接。

void MyServer::onDisconnected() {
    QTcpSocket *client = qobject_cast<QTcpSocket*>(sender());
    if(client) {
        client->deleteLater();
    }
}

完整的示例代码如下：

#include <QtCore>
#include <QtNetwork>

class MyServer : public QTcpServer {
    Q_OBJECT
public:
    MyServer(QObject *parent = nullptr) : QTcpServer(parent) {}

protected:
    void incomingConnection(qintptr socketDescriptor) override {
        QTcpSocket *client = new QTcpSocket(this);
        if(client->setSocketDescriptor(socketDescriptor)) {
            connect(client, &QTcpSocket::connected, this, &MyServer::onConnected);
        } else {
            client->deleteLater();
        }
    }

private slots:
    void onConnected() {
        QTcpSocket *client = qobject_cast<QTcpSocket*>(sender());
        if(client) {
            connect(client, &QTcpSocket::readyRead, this, &MyServer::onReadyRead);
            connect(client, &QTcpSocket::disconnected, this, &MyServer::onDisconnected);

            destination = new QTcpSocket(this);
            connect(destination, &QTcpSocket::connected, [=]() {
                // Forward destination data to client
                connect(destination, &QTcpSocket::readyRead, [=]() {
                    QByteArray data = destination->readAll();
                    client->write(data);
                });

                // Forward client data to destination
                connect(client, &QTcpSocket::readyRead, [=]() {
                    QByteArray data = client->readAll();
                    destination->write(data);
                });
            });
            destination->connectToHost("destination.address", 5678);
        }
    }

    void onReadyRead() {
        QTcpSocket *client = qobject_cast<QTcpSocket*>(sender());
        if(client) {
            QByteArray data = client->readAll();
            qDebug() << "Received data from client:" << data;
        }
    }

    void onDisconnected() {
        QTcpSocket *client = qobject_cast<QTcpSocket*>(sender());
        if(client) {
            client->deleteLater();
        }
        if(destination) {
            destination->deleteLater();
        }
    }

private:
    QTcpSocket *destination = nullptr;
};

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

    MyServer server;
    if(!server.listen(QHostAddress::Any, 1234)) {
        qDebug() << "Server could not start";
        return -1;
    }
    qDebug() << "Server started on port 1234";

    return a.exec();
}

#include "main.moc"