Socket error 9

fouffa89

My problem was with udp sockets , I have two machines connected with a cable , the problem is that I always got this error 9 from the socket and I can't understand why?.

this my sender :
@
#include <QtWidgets>
#include <QtNetwork>

#include "sender.h"

Sender::Sender(QWidget *parent)
: QWidget(parent)
{
statusLabel = new QLabel(tr("Ready to send datagrams on port 45454"));
statusLabel->setWordWrap(true);

startButton = new QPushButton(tr("&Start"));
quitButton = new QPushButton(tr("&Quit"));

buttonBox = new QDialogButtonBox;
buttonBox->addButton(startButton, QDialogButtonBox::ActionRole);
buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);

adress=QHostAddress("192.168.20.230");
//udpSocket->connectToHost(adress,88);
timer = new QTimer(this);

//! [0]
udpSocket = new QUdpSocket(this);
//! [0]
messageNo = 1;

connect(startButton, SIGNAL(clicked()), this, SLOT(startBroadcasting()));
connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
connect(timer, SIGNAL(timeout()), this, SLOT(broadcastDatagram()));

QVBoxLayout *mainLayout = new QVBoxLayout;
mainLayout->addWidget(statusLabel);
mainLayout->addWidget(buttonBox);
setLayout(mainLayout);

setWindowTitle(tr("Broadcast Sender"));

}

void Sender::startBroadcasting()
{
startButton->setEnabled(false);
timer->start(3000);
}

void Sender::broadcastDatagram()
{

//! [1]
QByteArray datagram = "RB00010040A94C";
statusLabel->setText(tr("Now sending datagram: \"%1\" Numero: %2").arg(datagram.data()).arg(messageNo));


if(udpSocket->writeDatagram(datagram.data(), datagram.size(),adress,88)==-1)
{
    statusLabel->setText("can't send to server");
}

//! [1]
++messageNo;
}

@
and my receiver:
@
#include <QtWidgets>
#include <QtNetwork>
#include <QMessageBox>
#include "receiver.h"

Receiver::Receiver(QWidget *parent)
: QWidget(parent)
{
statusLabel = new QLabel(tr("Listening for messages"));
statusLabel->setWordWrap(true);

quitButton = new QPushButton(tr("&Quit"));

//! [0]
udpSocket = new QUdpSocket(this);
connect(udpSocket,SIGNAL(error(QAbstractSocket::SocketError)),this,SLOT(ShowError(QAbstractSocket::SocketError)));
connect(udpSocket,SIGNAL(hostFound()),SLOT(ShowHostFound()));
connect(udpSocket,SIGNAL(stateChanged(QAbstractSocket::SocketState)),SLOT(showState(QAbstractSocket::SocketState)));
//adresse et port

QHostAddress adress=QHostAddress("192.168.20.230");
if (!udpSocket->bind(adress,88))
  {
  statusLabel->setText("Impossible de créer le socket en écoute");
  }

//! [0]

//! [1]udpS
connect(udpSocket, SIGNAL(readyRead()),
this, SLOT(processPendingDatagrams()),Qt::DirectConnection);
//! [1]
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(" Receiver"));

}

void Receiver::processPendingDatagrams()
{
//! [2]

while (udpSocket->hasPendingDatagrams()) {
    QByteArray datagram;
    datagram.resize(udpSocket->pendingDatagramSize());

    udpSocket->readDatagram(datagram.data(), datagram.size(),&senderAddress,&senderPort);
    statusLabel->setText(tr("Received datagram: \"%1\" from: \"%2\"")
                         .arg(datagram.data()).arg(senderAddress.toString()));
}
//! [2]

}

void Receiver::ShowError(QAbstractSocket::SocketError erreur)
{
QMessageBox::critical(this, tr("Socket Error"), tr(QString::number(erreur).toStdString().c_str()));
}

void Receiver::ShowHostFound()
{
statusLabel->setText("host found !");

}

void Receiver::showState(QAbstractSocket::SocketState state)
{
statusLabel->setText("Socket State"+QString::number(state));

}

@

I guess that it's a problems with firewall or something like that because bind is never accepted ,but I'm not sure .

ChrisW67

Which end reports the error? At what point?

Here are some random thoughts:

Your sender never calls bind() before you try to writeDatagram().
Ports less than 1024 are often restricted to privileged processes.

fouffa89

I call the receiver first :
@
Receiver receiver;
receiver.show();
Sender sender;
sender.show();
@
and bind is called in receiver and not in the sender.
I modify the port number to 8888 and still not working.