peermanager.cpp Example File

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  #include <QtNetwork>

  #include "client.h"
  #include "connection.h"
  #include "peermanager.h"

  static const qint32 BroadcastInterval = 2000;
  static const unsigned broadcastPort = 45000;

  PeerManager::PeerManager(Client *client)
      : QObject(client)
  {
      this->client = client;

      QStringList envVariables;
      envVariables << "USERNAME.*" << "USER.*" << "USERDOMAIN.*"
                   << "HOSTNAME.*" << "DOMAINNAME.*";

      QStringList environment = QProcess::systemEnvironment();
      foreach (QString string, envVariables) {
          int index = environment.indexOf(QRegExp(string));
          if (index != -1) {
              QStringList stringList = environment.at(index).split('=');
              if (stringList.size() == 2) {
                  username = stringList.at(1).toUtf8();
                  break;
              }
          }
      }

      if (username.isEmpty())
          username = "unknown";

      updateAddresses();
      serverPort = 0;

      broadcastSocket.bind(QHostAddress::Any, broadcastPort, QUdpSocket::ShareAddress
                           | QUdpSocket::ReuseAddressHint);
      connect(&broadcastSocket, SIGNAL(readyRead()),
              this, SLOT(readBroadcastDatagram()));

      broadcastTimer.setInterval(BroadcastInterval);
      connect(&broadcastTimer, SIGNAL(timeout()),
              this, SLOT(sendBroadcastDatagram()));
  }

  void PeerManager::setServerPort(int port)
  {
      serverPort = port;
  }

  QByteArray PeerManager::userName() const
  {
      return username;
  }

  void PeerManager::startBroadcasting()
  {
      broadcastTimer.start();
  }

  bool PeerManager::isLocalHostAddress(const QHostAddress &address)
  {
      foreach (QHostAddress localAddress, ipAddresses) {
          if (address == localAddress)
              return true;
      }
      return false;
  }

  void PeerManager::sendBroadcastDatagram()
  {
      QByteArray datagram(username);
      datagram.append('@');
      datagram.append(QByteArray::number(serverPort));

      bool validBroadcastAddresses = true;
      foreach (QHostAddress address, broadcastAddresses) {
          if (broadcastSocket.writeDatagram(datagram, address,
                                            broadcastPort) == -1)
              validBroadcastAddresses = false;
      }

      if (!validBroadcastAddresses)
          updateAddresses();
  }

  void PeerManager::readBroadcastDatagram()
  {
      while (broadcastSocket.hasPendingDatagrams()) {
          QHostAddress senderIp;
          quint16 senderPort;
          QByteArray datagram;
          datagram.resize(broadcastSocket.pendingDatagramSize());
          if (broadcastSocket.readDatagram(datagram.data(), datagram.size(),
                                           &senderIp, &senderPort) == -1)
              continue;

          QList<QByteArray> list = datagram.split('@');
          if (list.size() != 2)
              continue;

          int senderServerPort = list.at(1).toInt();
          if (isLocalHostAddress(senderIp) && senderServerPort == serverPort)
              continue;

          if (!client->hasConnection(senderIp)) {
              Connection *connection = new Connection(this);
              emit newConnection(connection);
              connection->connectToHost(senderIp, senderServerPort);
          }
      }
  }

  void PeerManager::updateAddresses()
  {
      broadcastAddresses.clear();
      ipAddresses.clear();
      foreach (QNetworkInterface interface, QNetworkInterface::allInterfaces()) {
          foreach (QNetworkAddressEntry entry, interface.addressEntries()) {
              QHostAddress broadcastAddress = entry.broadcast();
              if (broadcastAddress != QHostAddress::Null && entry.ip() != QHostAddress::LocalHost) {
                  broadcastAddresses << broadcastAddress;
                  ipAddresses << entry.ip();
              }
          }
      }
  }