QTcpServer listen QHostAddress::Any network operation timed out

[mikelij]

Using Desktop QT 5.9.1 Mingw 32bit, QTcpServer listen on QHostAddress::Any, sometimes it works, sometimes it reports "network operation timed out".
The OS is windows 10

Edit:
There was an error message in the Application out window:
QSocks5SocketEnginePrivate::_q_controlSocketReadNotification: Unexpectedly received data while in state=10 and mode=2

This seems to be a bug of QTcpServer.

[Taz742]

@mikelij
We need a little more knowledge.
Can you share full code?
https://forum.qt.io/topic/54727/solved-network-problems-qtcpsocket-qtcpserver/5

[VRonin]

Does upgrading to Qt 5.9.2 solve the problem?

[mikelij]

@Taz742 said in QTcpServer listen QHostAddress::Any network operation timed out:

@mikelij
We need a little more knowledge.
Can you share full code?
https://forum.qt.io/topic/54727/solved-network-problems-qtcpsocket-qtcpserver/5

This is my code.

void ServerSocket::startListening()
{
    while (!tcpServer.isListening() && !tcpServer.listen(QHostAddress::Any, this->serverPort)) {
        QMessageBox::StandardButton ret = QMessageBox::critical(NULL,
                                        tr("Loopback"),
                                        tr("Unable to start the test: %1.")
                                        .arg(tcpServer.errorString()),
                                        QMessageBox::Retry
                                        | QMessageBox::Cancel);
        if (ret == QMessageBox::Cancel)
            return;
    }
    connect(&tcpServer, SIGNAL(newConnection()),this, SLOT(acceptConnection()));
}

[mikelij]

@VRonin
Tried 5.9.2. It did not work. Still got the "network operation timed out" error.

[VRonin]

Ok, let's try not to stop the event loop:

void ServerSocket::startListening()
{
    while (!tcpServer.listen(QHostAddress::Any, this->serverPort)) {
        QMessageBox::StandardButton ret = QMessageBox::critical(NULL,
                                        tr("Loopback"),
                                        tr("Unable to start the test: %1.")
                                        .arg(tcpServer.errorString()),
                                        QMessageBox::Retry
                                        | QMessageBox::Cancel);
        if (ret == QMessageBox::Cancel)
            return;
    }
    connect(&tcpServer, SIGNAL(newConnection()),this, SLOT(acceptConnection()));
}

[mikelij]

@VRonin
Did not work. Still the same error.

[mikelij]

@Taz742
My code is copied from the official loopback example.
//dialog.h
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of The Qt Company Ltd nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <QTcpServer>
#include <QTcpSocket>

QT_BEGIN_NAMESPACE
class QDialogButtonBox;
class QLabel;
class QProgressBar;
class QPushButton;
class QTcpServer;
class QTcpSocket;
class QAction;
QT_END_NAMESPACE

class Dialog : public QDialog
{
Q_OBJECT

public:
Dialog(QWidget *parent = 0);

public slots:
void start();
void acceptConnection();
void startTransfer();
void updateServerProgress();
void updateClientProgress(qint64 numBytes);
void displayError(QAbstractSocket::SocketError socketError);

private:
QProgressBar *clientProgressBar;
QProgressBar *serverProgressBar;
QLabel *clientStatusLabel;
QLabel *serverStatusLabel;

QPushButton *startButton;
QPushButton *quitButton;
QDialogButtonBox *buttonBox;

QTcpServer tcpServer;
QTcpSocket tcpClient;
QTcpSocket *tcpServerConnection;
int bytesToWrite;
int bytesWritten;
int bytesReceived;

};

#endif

//dialog.cpp

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of The Qt Company Ltd nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include <QtWidgets>
#include <QtNetwork>

#include "dialog.h"

static const int TotalBytes = 50 * 1024 * 1024;
static const int PayloadSize = 64 * 1024; // 64 KB

Dialog::Dialog(QWidget *parent)
: QDialog(parent)
{
clientProgressBar = new QProgressBar;
clientStatusLabel = new QLabel(tr("Client ready"));
serverProgressBar = new QProgressBar;
serverStatusLabel = new QLabel(tr("Server ready"));

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

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

connect(startButton, SIGNAL(clicked()), this, SLOT(start()));
connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
connect(&tcpServer, SIGNAL(newConnection()),
        this, SLOT(acceptConnection()));
connect(&tcpClient, SIGNAL(connected()), this, SLOT(startTransfer()));
connect(&tcpClient, SIGNAL(bytesWritten(qint64)),
        this, SLOT(updateClientProgress(qint64)));
connect(&tcpClient, SIGNAL(error(QAbstractSocket::SocketError)),
        this, SLOT(displayError(QAbstractSocket::SocketError)));

QVBoxLayout *mainLayout = new QVBoxLayout;
mainLayout->addWidget(clientProgressBar);
mainLayout->addWidget(clientStatusLabel);
mainLayout->addWidget(serverProgressBar);
mainLayout->addWidget(serverStatusLabel);
mainLayout->addStretch(1);
mainLayout->addSpacing(10);
mainLayout->addWidget(buttonBox);
setLayout(mainLayout);

setWindowTitle(tr("Loopback"));

}

void Dialog::start()
{
startButton->setEnabled(false);

#ifndef QT_NO_CURSOR
QApplication::setOverrideCursor(Qt::WaitCursor);
#endif

bytesWritten = 0;
bytesReceived = 0;

while (!tcpServer.isListening() && !tcpServer.listen()) {
    QMessageBox::StandardButton ret = QMessageBox::critical(this,
                                    tr("Loopback"),
                                    tr("Unable to start the test: %1.")
                                    .arg(tcpServer.errorString()),
                                    QMessageBox::Retry
                                    | QMessageBox::Cancel);
    if (ret == QMessageBox::Cancel)
        return;
}

serverStatusLabel->setText(tr("Listening"));
clientStatusLabel->setText(tr("Connecting"));
tcpClient.connectToHost(QHostAddress::LocalHost, tcpServer.serverPort());

}

void Dialog::acceptConnection()
{
tcpServerConnection = tcpServer.nextPendingConnection();
connect(tcpServerConnection, SIGNAL(readyRead()),
this, SLOT(updateServerProgress()));
connect(tcpServerConnection, SIGNAL(error(QAbstractSocket::SocketError)),
this, SLOT(displayError(QAbstractSocket::SocketError)));

serverStatusLabel->setText(tr("Accepted connection"));
tcpServer.close();

}

void Dialog::startTransfer()
{
// called when the TCP client connected to the loopback server
bytesToWrite = TotalBytes - (int)tcpClient.write(QByteArray(PayloadSize, '@'));
clientStatusLabel->setText(tr("Connected"));
}

void Dialog::updateServerProgress()
{
bytesReceived += (int)tcpServerConnection->bytesAvailable();
tcpServerConnection->readAll();

serverProgressBar->setMaximum(TotalBytes);
serverProgressBar->setValue(bytesReceived);
serverStatusLabel->setText(tr("Received %1MB")
                           .arg(bytesReceived / (1024 * 1024)));

if (bytesReceived == TotalBytes) {
    tcpServerConnection->close();
    startButton->setEnabled(true);

#ifndef QT_NO_CURSOR
QApplication::restoreOverrideCursor();
#endif
}
}

void Dialog::updateClientProgress(qint64 numBytes)
{
// callen when the TCP client has written some bytes
bytesWritten += (int)numBytes;

// only write more if not finished and when the Qt write buffer is below a certain size.
if (bytesToWrite > 0 && tcpClient.bytesToWrite() <= 4*PayloadSize)
    bytesToWrite -= (int)tcpClient.write(QByteArray(qMin(bytesToWrite, PayloadSize), '@'));

clientProgressBar->setMaximum(TotalBytes);
clientProgressBar->setValue(bytesWritten);
clientStatusLabel->setText(tr("Sent %1MB")
                           .arg(bytesWritten / (1024 * 1024)));

}

void Dialog::displayError(QAbstractSocket::SocketError socketError)
{
if (socketError == QTcpSocket::RemoteHostClosedError)
return;

QMessageBox::information(this, tr("Network error"),
                         tr("The following error occurred: %1.")
                         .arg(tcpClient.errorString()));

tcpClient.close();
tcpServer.close();
clientProgressBar->reset();
serverProgressBar->reset();
clientStatusLabel->setText(tr("Client ready"));
serverStatusLabel->setText(tr("Server ready"));
startButton->setEnabled(true);

#ifndef QT_NO_CURSOR
QApplication::restoreOverrideCursor();
#endif
}

My code is a little different from the example. My code listens on QHostAddress::Any, and a port number. The loopback example, use listern(), without any parameter. The default value of address is QHostAddress::Any, the default port is 0.

Tried the loopback example again. It failed also.

[Sunfluxgames]

Your firewall or Router is blocking your listen function. Nothing wrong with your code as it works on my machine windows 10 x64.

[mikelij]

@Sunfluxgames
No idea now. My Windows 10 firewall is turned off. Regarding Router, no idea about how to do that.

[mikelij]

@Global-Moderators @Sunfluxgames @Taz742 @VRonin
Finally I found the root cause! I set the global proxy settings in internet options. Go to IE, Tools->Internet options->Connections tab->Lan Settings->Check "use a proxy server for your LAN(These settings will not apply to dial up or VPN connections). And set the proxy server ip address/port for protocols, this settings has impact to the QT server listen functionality, causing the "network operation timed out" error. After I turned off the proxy settings in internet options. the QT server listen functionality worked properly.