用qt写一段socket代理的代码实现两个上位机同时连接两个下位机，并通过上位机下发命令

好的，我可以为你提供一个基于Qt的socket代理代码，实现两个上位机同时连接两个下位机，并通过上位机下发命令的功能。代码如下：

#include <QtCore/QCoreApplication>
#include <QtCore/QDebug>
#include <QtCore/QCommandLineParser>
#include <QtNetwork/QTcpServer>
#include <QtNetwork/QTcpSocket>

class SocketProxy : public QObject
{
    Q_OBJECT
public:
    explicit SocketProxy(quint16 localPort, quint16 remotePort, QObject *parent = nullptr)
        : QObject(parent)
        , m_localPort(localPort)
        , m_remotePort(remotePort)
    {
        m_server = new QTcpServer(this);
        connect(m_server, &QTcpServer::newConnection, this, &SocketProxy::onNewConnection);
        if (!m_server->listen(QHostAddress::Any, m_localPort)) {
            qCritical() << "Failed to listen on port" << m_localPort;
            QCoreApplication::exit(1);
            return;
        }
        qDebug() << "Listening on port" << m_localPort << "forwarding to port" << m_remotePort;
    }
private slots:
    void onNewConnection()
    {
        QTcpSocket *clientSocket = m_server->nextPendingConnection();
        connect(clientSocket, &QTcpSocket::readyRead, this, &SocketProxy::onReadyRead);
        connect(clientSocket, &QTcpSocket::disconnected, clientSocket, &QTcpSocket::deleteLater);

        QTcpSocket *serverSocket = new QTcpSocket(this);
        connect(serverSocket, &QTcpSocket::connected, this, &SocketProxy::onConnected);
        connect(serverSocket, &QTcpSocket::readyRead, this, &SocketProxy::onReadyRead);
        connect(serverSocket, &QTcpSocket::disconnected, serverSocket, &QTcpSocket::deleteLater);
        serverSocket->connectToHost(QHostAddress::LocalHost, m_remotePort);

        m_clientToServer.insert(clientSocket, serverSocket);
        m_serverToClient.insert(serverSocket, clientSocket);
    }
    void onConnected()
    {
        QTcpSocket *serverSocket = qobject_cast<QTcpSocket *>(sender());
        QTcpSocket *clientSocket = m_serverToClient.value(serverSocket, nullptr);
        if (clientSocket) {
            qDebug() << "Connection established between" << clientSocket->peerAddress().toString() << ":" << clientSocket->peerPort() << "and localhost:" << m_remotePort;
        }
    }
    void onReadyRead()
    {
        QTcpSocket *socket = qobject_cast<QTcpSocket *>(sender());
        if (m_clientToServer.contains(socket)) {
            QTcpSocket *serverSocket = m_clientToServer[socket];
            serverSocket->write(socket->readAll());
        } else if (m_serverToClient.contains(socket)) {
            QTcpSocket *clientSocket = m_serverToClient[socket];
            clientSocket->write(socket->readAll());
        }
    }
private:
    quint16 m_localPort;
    quint16 m_remotePort;
    QTcpServer *m_server;
    QHash<QTcpSocket *, QTcpSocket *> m_clientToServer;
    QHash<QTcpSocket *, QTcpSocket *> m_serverToClient;
};

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);
    QCoreApplication::setApplicationName("SocketProxy");
    QCoreApplication::setApplicationVersion("1.0");

    QCommandLineParser parser;
    parser.setApplicationDescription("A simple socket proxy");
    parser.addHelpOption();
    parser.addVersionOption();
    parser.addOption({{"l", "local"}, "Local listening port", "port", "1234"});
    parser.addOption({{"r", "remote"}, "Remote target port", "port", "5678"});
    parser.process(app);

    quint16 localPort = parser.value("local").toUShort();
    quint16 remotePort = parser.value("remote").toUShort();

    SocketProxy proxy(localPort, remotePort);

    return app.exec();
}

#include "main.moc"

这个代码实例化了一个 SocketProxy 类，它监听本地的 localPort 端口，并将所有连接转发到远程的 remotePort 端口。然后，每当有新的连接时，它会在客户端和服务器之间建立两个QTcpSocket对象，并将其用于转发数据。