receiver.cpp Example File

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 #include <QtWidgets>
 #include <QtNetwork>

 #include "receiver.h"

 Receiver::Receiver(QWidget *parent)
     : QDialog(parent),
       groupAddress4(QStringLiteral("239.255.43.21")),
       groupAddress6(QStringLiteral("ff12::2115"))
 {
     statusLabel = new QLabel(tr("Listening for multicast messages on both IPv4 and IPv6"));
     auto quitButton = new QPushButton(tr("&Quit"));

     auto buttonLayout = new QHBoxLayout;
     buttonLayout->addStretch(1);
     buttonLayout->addWidget(quitButton);
     buttonLayout->addStretch(1);

     auto mainLayout = new QVBoxLayout;
     mainLayout->addWidget(statusLabel);
     mainLayout->addLayout(buttonLayout);
     setLayout(mainLayout);

     setWindowTitle(tr("Multicast Receiver"));

     udpSocket4.bind(QHostAddress::AnyIPv4, 45454, QUdpSocket::ShareAddress);
     udpSocket4.joinMulticastGroup(groupAddress4);

     if (!udpSocket6.bind(QHostAddress::AnyIPv6, 45454, QUdpSocket::ShareAddress) ||
             !udpSocket6.joinMulticastGroup(groupAddress6))
         statusLabel->setText(tr("Listening for multicast messages on IPv4 only"));

     connect(&udpSocket4, SIGNAL(readyRead()),
             this, SLOT(processPendingDatagrams()));
     connect(&udpSocket6, &QUdpSocket::readyRead, this, &Receiver::processPendingDatagrams);
     connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
 }

 void Receiver::processPendingDatagrams()
 {
     QByteArray datagram;

     // using QUdpSocket::readDatagram (API since Qt 4)
     while (udpSocket4.hasPendingDatagrams()) {
         datagram.resize(int(udpSocket4.pendingDatagramSize()));
         udpSocket4.readDatagram(datagram.data(), datagram.size());
         statusLabel->setText(tr("Received IPv4 datagram: \"%1\"")
                              .arg(datagram.constData()));
     }

     // using QUdpSocket::receiveDatagram (API since Qt 5.8)
     while (udpSocket6.hasPendingDatagrams()) {
         QNetworkDatagram dgram = udpSocket6.receiveDatagram();
         statusLabel->setText(statusLabel->text() +
                              tr("\nReceived IPv6 datagram from [%2]:%3: \"%1\"")
                              .arg(dgram.data().constData(), dgram.senderAddress().toString())
                              .arg(dgram.senderPort()));
     }
 }