text: /****************************************************************************
  **
  ** Copyright (C) 2015 The Qt Company Ltd.
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  **
  ** This file is part of the examples of the Qt Toolkit.
  **
  ** $QT_BEGIN_LICENSE:BSD$
  ** You may use this file under the terms of the BSD license as follows:
  **
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  **     the documentation and/or other materials provided with the
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  ****************************************************************************/
  
  #include <QtWidgets>
  #include <QtNetwork>
  #include <sys/socket.h>
  
  #include "receiver.h"
  
  Receiver::Receiver(QWidget *parent)
      : QDialog(parent)
  {
      groupAddress = QHostAddress("239.255.43.21");
  
      statusLabel = new QLabel(tr("Listening for multicasted messages"));
      quitButton = new QPushButton(tr("&Quit"));
  
      udpSocket = new QUdpSocket(this);
      udpSocket->bind(QHostAddress::AnyIPv4, 45454, QUdpSocket::ShareAddress);
  #ifdef SO_REUSEPORT
      int v = 1;
      ::setsockopt(udpSocket->socketDescriptor(), SOL_SOCKET, SO_REUSEPORT, (char *) &v, sizeof(v));
  #endif
      udpSocket->joinMulticastGroup(groupAddress);
  
      connect(udpSocket, SIGNAL(readyRead()),
              this, SLOT(processPendingDatagrams()));
      connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
  
      QHBoxLayout *buttonLayout = new QHBoxLayout;
      buttonLayout->addStretch(1);
      buttonLayout->addWidget(quitButton);
      buttonLayout->addStretch(1);
  
      QVBoxLayout *mainLayout = new QVBoxLayout;
      mainLayout->addWidget(statusLabel);
      mainLayout->addLayout(buttonLayout);
      setLayout(mainLayout);
  
      setWindowTitle(tr("Multicast Receiver"));
  }
  
  void Receiver::processPendingDatagrams()
  {
      while (udpSocket->hasPendingDatagrams()) {
          QByteArray datagram;
          datagram.resize(udpSocket->pendingDatagramSize());
          udpSocket->readDatagram(datagram.data(), datagram.size());
          statusLabel->setText(tr("Received datagram: \"%1\"")
                               .arg(datagram.data()));
      }
  }
  