Pacp - Send Data

neda

Hi,
I use "pcap".
I wanna send and receive data.
But I have an error while sending the packet and "pcap_sendpacket" function return "-1".

myproject.pro

INCLUDEPATH += D:/WpdPack/Include
LIBS += -L"D:/WpdPack/Lib" -lwpcap -lPacket
code_text

main.cpp

QThread thread;
    thread.setObjectName("PCAPNetworkThread");
    mySerialPort.moveToThread(&thread);
    QObject::connect(&thread, SIGNAL(started()), &pcapNetwork, SLOT(openLanPort()));
    thread.start();

PCAPNetwork.cs

void PCAPNetwork::openLanPort()
{
    pcap_if_t *alldevs;
    pcap_if_t *d;
    int inum;
    int i=0;    
    char errbuf[PCAP_ERRBUF_SIZE];
    if (pcap_findalldevs( &alldevs, errbuf) == -1)
    {
        //Error in pcap_findalldevs
        return;
    }

    /* Print the list */
    for(d=alldevs; d; d=d->next)
    {
//print name and description        
    }

    if(i==0)
    {
        //No interfaces found! Make sure WinPcap is installed
        return;
    }

    //Enter the interface number
    inum=1;//I do not know how can I select adapter with mac address

    if(inum < 1 || inum > i)
    {
        //Interface number out of range
        /* Free the device list */
        pcap_freealldevs(alldevs);
        return;
    }

    /* Jump to the selected adapter */
    for(d=alldevs, i=0; i< inum-1 ;d=d->next, i++);

    /* Open the device */
    if ( (adhandle= pcap_open_live(d->name,     
                                   65536, 
                                   1,              
                                   1000,  
                                   NULL  
                                   ) ) == NULL)
    {
        //Unable to open the adapter.
        /* Free the device list */
        pcap_freealldevs(alldevs);
        return;
    }
    //listening
    pcap_freealldevs(alldevs);
     
    commandData();

    pcap_loop(adhandle, 0, packet_handler, NULL);
}
void PCAPNetwork::commandData(){   
    QByteArray data;
    data[0]=commands->COMMANDS_DATA;
    sendData(data);
}
void PCAPNetwork::sendData(const QByteArray &data)
{
const u_char* p;
std::memcpy(&p,data.constData(),data.size());
if(pcap_sendpacket(adhandle, 
                       p, 
                       sizeof(p)
                       ) != 0 )
    {
        //Error sending the packet
qDebug()<<"Error: "<<pcap_geterr( adhandle );
        return;
    }

}

jsulm

@neda said in Pacp - Send Data:

fprintf( stderr,"\nError sending the packet: \n", pcap_geterr( adhandle ));

What does this line print out?
And I'm not sure what this has to do with Qt.

neda

@jsulm said in Pacp - Send Data:

What does this line print out?

PacketSendPacket failed

And I'm not sure what this has to do with Qt.

I did not find a document or a good sample to use "pcap" in Qt.

mrjj

@neda
Hi
And you did install winpcap/Win10Pcap so the driver is running?
Also, you are using visual studio compiler ?
Im not sure it works with mingw.

neda

@mrjj said in Pacp - Send Data:

Also, you are using visual studio compiler ?

Qt 5.12.5 MSVC2017 32bit

And you did install winpcap/Win10Pcap so the driver is running?

I installed "http://www.win10pcap.org/download/Win10Pcap-v10.2-5002.msi".

Now "pcap_sendpacket" return 0, It's OK.
But I do not have a correct answer from the device.

I have a "QByteArray" Data for send such as:

"\x02\xFF\xFF\xFF\xFF\xFF\xFF\xFF"

I don't know this code is true or not.

void PCAPNetwork::sendData(const QByteArray &data)
{
const u_char* p= reinterpret_cast<const uchar *>(data.constData());
//std::memcpy(&p,data.constData(),data.size());
pcap_sendpacket(adhandle, 
                                        p, 
                                        sizeof(p)
                                        );

mrjj

@neda
Hi
from a quick glance - it looks ok.
Should not truncate values.

neda

I think I was wrong in reading data.
The device sends a lot of data in real-time.
I read them by this code.

void PCAPNetwork::packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data)
{

How can I convert "pkt_data" to decimal?

mrjj

@neda said in Pacp - Send Data:

u_char

But is this not a byte already ?

If you place cursor on u_char and press F2, what is it then defined as?

neda

@mrjj

u_char = unsigned char

qDebug()<<"data: "<<pkt_data;

output:

data:  0x46c16bc

I don't know how can I convert it to decimal.

mrjj

@neda
Is it zero terminated ?

That is the address it writes out. Not the actual data i think.

You can convert it to bytearray
QByteArray databuf = QByteArray(reinterpret_cast<char*>(pkt_data), header->len);
(i think but not 100% sure header->len is data len. check docs)

neda

@mrjj said in Pacp - Send Data:

Not the actual data i think.

You right.
The device sends a lot of data in real-time.
How can I read the actual data?

mrjj

@neda
The data is in pkt_data as far as i can see from docs
so try
QByteArray databuf = QByteArray(reinterpret_cast<char*>(pkt_data), header->len);
qDebug()<<"data: "<<databuf ;