I can't receive QTcpServer Socket message on Android

Dewy · wrote on 9 Sept 2023, 15:38

Hello all,

NetworkManager.h

// networkmanager.h
#ifndef NETWORKMANAGER_H
#define NETWORKMANAGER_H

#include <QObject>
#include <QString>
#include <QNetworkInterface>
#include <QTcpServer>
#include <QTcpSocket>

#include "hdr/constants.h"

class NetworkManager : public QObject
{
    Q_OBJECT
    Q_PROPERTY(ConnectionStatus connectionStatus READ connectionStatus WRITE setConnectionStatus NOTIFY connectionStatusChanged)

public:
    explicit NetworkManager(QObject *parent = nullptr);

    QString getMacAddress();
    QTcpSocket* clientSocket;

    ConnectionStatus connectionStatus();

public slots:
    void setConnectionStatus(ConnectionStatus status);

private:
    QNetworkInterface findActiveNetworkInterface();
    QHostAddress m_address;
    int m_port;

    ConnectionStatus m_connectionStatus;

signals:
    void connectionStatusChanged();
};

#endif // NETWORKMANAGER_H

NetworkManager.cpp

#include "hdr/managers/networkmanager.h"

NetworkManager::NetworkManager(QObject *parent)
    : QObject(parent),
      m_address("192.168.1.153"),
      m_port(1453),
      m_connectionStatus(ConnectionStatus::Disconnected)
{
    clientSocket = new QTcpSocket(this);
    clientSocket->connectToHost(m_address,m_port);
}

QString NetworkManager::getMacAddress()
{
    QNetworkInterface activeInterface = findActiveNetworkInterface();
    if (!activeInterface.isValid()) {
        return QString();
    }

    QByteArray macBytes = activeInterface.hardwareAddress().toUtf8();
    QString macAddress = QString(macBytes.toHex(':')).toUpper(); // Convert QByteArray to formatted QString
    return macAddress;
}

ConnectionStatus NetworkManager::connectionStatus()
{
    return m_connectionStatus;
}

void NetworkManager::setConnectionStatus(ConnectionStatus status)
{
    if(m_connectionStatus == status)
        return;

    m_connectionStatus = status;

    emit connectionStatusChanged();
}

QNetworkInterface NetworkManager::findActiveNetworkInterface()
{
    QList<QNetworkInterface> interfaces = QNetworkInterface::allInterfaces();
    foreach (QNetworkInterface interface, interfaces) {
        if (!(interface.flags() & QNetworkInterface::IsLoopBack) &&
            (interface.flags() & QNetworkInterface::IsUp) &&
            (interface.flags() & QNetworkInterface::IsRunning)) {
            return interface;
        }
    }
    return QNetworkInterface(); // Invalid interface
}

ApplicationManager.cpp


void ApplicationManager::initObjects()
{
    nManager = new NetworkManager();
    if (nManager->clientSocket->waitForConnected()) {
        nManager->setConnectionStatus(ConnectionStatus::Connected);

        qDebug() << "Connection Successful.";

        QByteArray veri = "Hello Server!";
        nManager->clientSocket->write(veri);
        nManager->clientSocket->flush();
        nManager->clientSocket->waitForBytesWritten();

        connect(nManager->clientSocket, &QTcpSocket::readyRead, this, [=](){
            qDebug() <<"Data came!";
        });

//        connect(nManager->clientSocket, &QTcpSocket::readyRead, this, &ApplicationManager::readData);
//        connect(nManager->clientSocket, SIGNAL(readyRead()), this, SLOT(readData()));
    }
}

myserver.h

#ifndef MYSERVER_H
#define MYSERVER_H

#include <QObject>
#include <QTcpServer>
#include <QTcpSocket>
#include <QAbstractSocket>

#include "myclient.h"

class MyServer : public QTcpServer
{
    Q_OBJECT
public:
    explicit MyServer(QObject *parent = nullptr);
    void startServer();

public slots:
    void newCon();
    void readyRead();
    void sockDisc();

protected:
    QTcpSocket *socket;
//    void incomingConnection(int handle);
};

#endif // MYSERVER_H

myserver.cpp

#include "myserver.h"

MyServer::MyServer(QObject *parent) :
    QTcpServer(parent)
{
}

void MyServer::startServer()
{
    if (listen(QHostAddress::Any, 1453))
    {
        connect(this, &QTcpServer::newConnection, this, &MyServer::newCon);
        qDebug() << "started";
    }
    else
    {
        qDebug() << "not started";
    }
}

void MyServer::newCon()
{
    socket = nextPendingConnection();

    if(socket == nullptr)
    {
        qDebug() << "No new socket...";
        return;
    }
    connect(socket,&QTcpSocket::readyRead,this,&MyServer::readyRead);
    connect(socket,&QTcpSocket::disconnected, this,&MyServer::sockDisc);

    socket->write("You are connect");
    socket->flush();
    socket->waitForBytesWritten();
    qDebug()<<"Send client connect status - YES";
}

void MyServer::readyRead()
{
    qDebug() << socket->readAll();
}

void MyServer::sockDisc()
{
    qDebug()<<"Disconnect";
    socket->deleteLater();
}

Hello All,
I created an android application using Qt 5.15.2. The app connect to backend and the app can send message to server, but the application can't receive message correctly. I tested server application using nc and it works. also I tested the app on x86_64 and it worked too. But when I want to run it on Android, it doesn't work.

Anybody can help me please?

The main problem is that, android application cannot receive QTcpSocket message.

Thanks!

SGaist · 9 Sept 2023, 20:10

Hi,

First thing: you should do all your connections prior to starting to use your objects.

There's also nothing related to error management. You should add that as well.

Dewy · 9 Sept 2023, 20:11

@SGaist Hello,
But main thing is that the project works on x86_64. But it doesn't work on Android. I added these permissions to AndroidManifest.xml file;

<uses-permission android:name="android.permission.READ_CONTACTS"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

I updated my classes and i moved all things to NetworkManager class like that;

Android NetworkManager.h

// networkmanager.h
#ifndef NETWORKMANAGER_H
#define NETWORKMANAGER_H

#include <QObject>
#include <QString>
#include <QNetworkInterface>
#include <QTcpServer>
#include <QTcpSocket>

#include "hdr/constants.h"

class NetworkManager : public QObject
{
    Q_OBJECT
    Q_PROPERTY(ConnectionStatus connectionStatus READ connectionStatus WRITE setConnectionStatus NOTIFY connectionStatusChanged)

public:
    explicit NetworkManager(QObject *parent = nullptr);

    QString getMacAddress();
    QTcpSocket* clientSocket;

    ConnectionStatus connectionStatus();

    QHostAddress address();
    int port();

public slots:
    void setConnectionStatus(ConnectionStatus status);

    void readyRead();


private:
    QNetworkInterface findActiveNetworkInterface();
    QHostAddress m_address;
    int m_port;

    ConnectionStatus m_connectionStatus;

signals:
    void connectionStatusChanged();
};

#endif // NETWORKMANAGER_H

Android NetworkManager.cpp

#include "hdr/managers/networkmanager.h"

NetworkManager::NetworkManager(QObject *parent)
    : QObject(parent),
      m_address("192.168.1.107"),
      m_port(1453),
      m_connectionStatus(ConnectionStatus::Disconnected)
{
    clientSocket = new QTcpSocket(this);



    clientSocket->connectToHost(address(),port());


    if (clientSocket->waitForConnected()) {

        connect(clientSocket, &QTcpSocket::connected, this, [=](){
            qDebug() << "[.] connected";
        });
        connect(clientSocket, &QTcpSocket::disconnected, this, [=](){
            qDebug() << "[.] disconnected";
        });
        connect(clientSocket, &QTcpSocket::readyRead,this, &NetworkManager::readyRead);
        connect(clientSocket, &QTcpSocket::errorOccurred, this, [=](QAbstractSocket::SocketError socketError) {
            if (socketError == QAbstractSocket::RemoteHostClosedError) {
                qDebug() << "Sunucu bağlantısı kapattı.";
            } else if (socketError == QAbstractSocket::HostNotFoundError) {
                qDebug() << "Sunucu bulunamadı.";
            } else if (socketError == QAbstractSocket::ConnectionRefusedError) {
                qDebug() << "Bağlantı reddedildi.";
            } else {
                qDebug() << "Bilinmeyen bir hata oluştu: " << clientSocket->errorString();
            }
        });

        connect(clientSocket, &QTcpSocket::stateChanged, this, [=](QAbstractSocket::SocketState socketState) {
            if (socketState == QAbstractSocket::ConnectedState) {
                qDebug() << "Bağlantı başarılı.";
            } else if (socketState == QAbstractSocket::UnconnectedState) {
                qDebug() << "Bağlantı kesildi.";
            }
        });

        setConnectionStatus(ConnectionStatus::Connected);

        qDebug() << "Connection Successful.";

        QByteArray veri = "Hello Server!";
        clientSocket->write(veri);
        clientSocket->flush();
        clientSocket->waitForBytesWritten();
    }
}

QString NetworkManager::getMacAddress()
{
    QNetworkInterface activeInterface = findActiveNetworkInterface();
    if (!activeInterface.isValid()) {
        return QString();
    }

    QByteArray macBytes = activeInterface.hardwareAddress().toUtf8();
    QString macAddress = QString(macBytes.toHex(':')).toUpper(); // Convert QByteArray to formatted QString
    return macAddress;
}

ConnectionStatus NetworkManager::connectionStatus()
{
    return m_connectionStatus;
}

QHostAddress NetworkManager::address()
{
    return m_address;
}

int NetworkManager::port()
{
    return m_port;
}

void NetworkManager::readyRead()
{
    qDebug()<<"data received!";
//    while (clientSocket->bytesAvailable() > 0) {
//        QByteArray data = clientSocket->readAll();
//        qDebug() << "Received data:" << data;
//    }
}

void NetworkManager::setConnectionStatus(ConnectionStatus status)
{
    if(m_connectionStatus == status)
        return;

    m_connectionStatus = status;

    emit connectionStatusChanged();
}

QNetworkInterface NetworkManager::findActiveNetworkInterface()
{
    QList<QNetworkInterface> interfaces = QNetworkInterface::allInterfaces();
    foreach (QNetworkInterface interface, interfaces) {
        if (!(interface.flags() & QNetworkInterface::IsLoopBack) &&
            (interface.flags() & QNetworkInterface::IsUp) &&
            (interface.flags() & QNetworkInterface::IsRunning)) {
            return interface;
        }
    }
    return QNetworkInterface(); // Invalid interface
}

x86_64 NetworkManager.h

// networkmanager.h
#ifndef NETWORKMANAGER_H
#define NETWORKMANAGER_H

#include <QObject>
#include <QString>
#include <QNetworkInterface>
#include <QTcpServer>
#include <QTcpSocket>

class NetworkManager : public QObject
{
    Q_OBJECT

public:
    explicit NetworkManager(QObject *parent = nullptr);

    QString getMacAddress();
    QTcpSocket* clientSocket;

    QHostAddress address();
    int port();


public slots:
    void readyRead();

private:
    QNetworkInterface findActiveNetworkInterface();
    QHostAddress m_address;
    int m_port;

signals:
    void connectionStatusChanged();
};

#endif // NETWORKMANAGER_H

x86_64 NetworkManager.cpp

#include "networkmanager.h"

NetworkManager::NetworkManager(QObject *parent)
    : QObject(parent),
      m_address("192.168.1.107"),
      m_port(1453)
{
    clientSocket = new QTcpSocket(this);
    clientSocket->connectToHost(address(),port());


    if (clientSocket->waitForConnected()) {

        connect(clientSocket, &QTcpSocket::connected, this, [=](){
            qDebug() << "[.] connected";
        });
        connect(clientSocket, &QTcpSocket::disconnected, this, [=](){
            qDebug() << "[.] disconnected";
        });
        connect(clientSocket, &QTcpSocket::readyRead,this, &NetworkManager::readyRead);
        connect(clientSocket, &QTcpSocket::errorOccurred, this, [=](QAbstractSocket::SocketError socketError) {
            if (socketError == QAbstractSocket::RemoteHostClosedError) {
                qDebug() << "Sunucu bağlantısı kapattı.";
            } else if (socketError == QAbstractSocket::HostNotFoundError) {
                qDebug() << "Sunucu bulunamadı.";
            } else if (socketError == QAbstractSocket::ConnectionRefusedError) {
                qDebug() << "Bağlantı reddedildi.";
            } else {
                qDebug() << "Bilinmeyen bir hata oluştu: " << clientSocket->errorString();
            }
        });

        connect(clientSocket, &QTcpSocket::stateChanged, this, [=](QAbstractSocket::SocketState socketState) {
            if (socketState == QAbstractSocket::ConnectedState) {
                qDebug() << "Bağlantı başarılı.";
            } else if (socketState == QAbstractSocket::UnconnectedState) {
                qDebug() << "Bağlantı kesildi.";
            }
        });


        qDebug() << "Connection Successful.";

        QByteArray veri = "Hello Server!";
        clientSocket->write(veri);
        clientSocket->flush();
        clientSocket->waitForBytesWritten();
    }
}

QString NetworkManager::getMacAddress()
{
    QNetworkInterface activeInterface = findActiveNetworkInterface();
    if (!activeInterface.isValid()) {
        return QString();
    }

    QByteArray macBytes = activeInterface.hardwareAddress().toUtf8();
    QString macAddress = QString(macBytes.toHex(':')).toUpper(); // Convert QByteArray to formatted QString
    return macAddress;
}

QHostAddress NetworkManager::address()
{
    return m_address;
}

int NetworkManager::port()
{
    return m_port;
}

void NetworkManager::readyRead()
{
    qDebug()<<"data received!";
//    while (clientSocket->bytesAvailable() > 0) {
//        QByteArray data = clientSocket->readAll();
//        qDebug() << "Received data:" << data;
//    }
}

QNetworkInterface NetworkManager::findActiveNetworkInterface()
{
    QList<QNetworkInterface> interfaces = QNetworkInterface::allInterfaces();
    foreach (QNetworkInterface interface, interfaces) {
        if (!(interface.flags() & QNetworkInterface::IsLoopBack) &&
            (interface.flags() & QNetworkInterface::IsUp) &&
            (interface.flags() & QNetworkInterface::IsRunning)) {
            return interface;
        }
    }
    return QNetworkInterface(); // Invalid interface
}

as I said - x86_64 class works but Android class doesn't work. I guess this is android issue but i couldn't solve yet. last 1 week I focused this and i couldn't do anything. project is waiting this issue and we want to use Qt for Android. if we can't solve we will change qt to another frameworks. I really need help about this issue.

Thanks for all helps!