Qt 5.11 | Qt Network | Multicast Receiver Example | receiver.cpp Example File

Qt 5.11.3 Reference Documentation

# receiver.cpp Example File

multicastreceiver/receiver.cpp

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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()));
          }
      }