MAC address of UDP packet's sender

[mastupristi]

Hi,

I have to write a program to "discover" (retrieving IP and MAC address) some network device. To this end I send difined UDP datagram to broadcast on a certain port. All device present on network will replies.
I have the following class:

#include <QDialog>
#include <QUdpSocket>
 
namespace Ui {
    class Discovery;
}
 
class Discovery : public QDialog
{
    Q_OBJECT
 
public:
    explicit Discovery(QWidget *parent = 0);
    ~Discovery();
 
private:
    Ui::Discovery *ui;
 
    QUdpSocket sock;
 
public slots:
    void processPendingDatagrams(void);
};

#include <QDialog>
#include <QUdpSocket>

namespace Ui {
    class Discovery;
}

class Discovery : public QDialog
{
    Q_OBJECT

public:
    explicit Discovery(QWidget *parent = 0);
    ~Discovery();

private:
    Ui::Discovery *ui;

    QUdpSocket sock;

public slots:
    void processPendingDatagrams(void);
};

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#include "discovery.h"
#include "ui_discovery.h"
 
#include <QUdpSocket>
 
Discovery::Discovery(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Discovery),
    sock(this)
{
    ui->setupUi(this);
 
    connect(&sock, SIGNAL(readyRead ()), this, SLOT (processPendingDatagrams ()));
 
    QByteArray dg;
    static const char datagramma[] = {00, 01, 00, 0xF6 };
    dg.append(datagramma, sizeof(datagramma));
    sock.bind();
    sock.writeDatagram(dg,QHostAddress("255.255.255.255"), 0x77FE);
}
 
Discovery::~Discovery()
{
    delete ui;
}
 
void Discovery::processPendingDatagrams(void)
{
    char data[64];
    QHostAddress host;
    quint16 port;
 
    sock.readDatagram(data, sizeof(data), &host, &port);
    qDebug("read from %s", host.toString().toAscii().constData());
}

#include "discovery.h"
#include "ui_discovery.h"

#include <QUdpSocket>

Discovery::Discovery(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Discovery),
    sock(this)
{
    ui->setupUi(this);

    connect(&sock, SIGNAL(readyRead ()), this, SLOT (processPendingDatagrams ()));

    QByteArray dg;
    static const char datagramma[] = {00, 01, 00, 0xF6 };
    dg.append(datagramma, sizeof(datagramma));
    sock.bind();
    sock.writeDatagram(dg,QHostAddress("255.255.255.255"), 0x77FE);
}

Discovery::~Discovery()
{
    delete ui;
}

void Discovery::processPendingDatagrams(void)
{
    char data[64];
    QHostAddress host;
    quint16 port;

    sock.readDatagram(data, sizeof(data), &host, &port);
    qDebug("read from %s", host.toString().toAscii().constData());
}

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Doing this I can recover IP address
Now I must recover the MAC address.

How can I retrieve MAC address from packet received?

thanks