QTcpSocket why SocketTimeoutError is raised ?

CHPOG

Hi,

I have a simple class to connect to a sever using a QTcpSocket. I test this class with QUnit.
But when I want to check that my socket is correctly open by QVERIFY(socket->open() ==true) the test fails. I just call socket->open() with no QVERIFY and the I am able to read data from my socket. But a SocketTimeoutError is raised. I d'ont know why ? And what is the cause.
The error is raised when I'am doing this :

/**
 * @brief UniwheelConnection::isWaitingForCommand
 * @return true if sensor wait command
 */
bool UniwheelConnection::isWaitingForCommand() {
    QString fullData;
    int maxSize = 5000;
    //We wait end of data transmission but not too much if device is in start mode
    while(this->waitForReadyRead(1000) && fullData.size() < maxSize) {
        QByteArray data = readAll();
        skipHeader(&data);
        qDebug()<< "data added  " << data.toHex();
        QString dataAsString(data);
        qDebug()<< "data added in string  " << dataAsString;
        fullData.append(dataAsString);
    }
    qDebug()<< "isWaitingForCommand " << fullData;
    qDebug()<< "end ok " << fullData.endsWith(PROMPT_END);

    return fullData.endsWith(PROMPT_END) && this->atEnd();
}

Any idea why ?

JonB

@CHPOG

But when I want to check that my socket is correctly open by QVERIFY(socket->open() ==true) the test fails.

Do you intend QSocket::open() or QSocket::isOpen()?

SGaist

Hi,

Why are you using open ?
The connectToHost method is usually used to setup a connection or maybe bind depending on your use case.

CHPOG

sorry it lacks some informations.
My Tcpsocket is connectTohost by doing this in the constructor :

    m_socket->connectToHost(ipAddress,port);

And the function open call the open one of QIOdevice and return a boolean value that is set to true when signal connected is emitted.

bool WifiUniwheel::open() {
    qDebug() << m_socket->state();
    UniwheelConnection::open();
    qDebug() << m_socket->state();
    return this->m_isConnected;
}

May be I must not call open of super class. My aim is to have a parent class which could be instantiate as a TCPSocket or a RS232 connection. Like an interface in Java.

But by inspecting the result of my log I saw that the boolean value to know if this is open is set to true. The mystery is why this Socket error is raised ? Because I do a connectToHost and then an open ? I try this but the error raised again.

jsulm

@CHPOG If you want to check whether open or not call https://doc.qt.io/qt-5/qiodevice.html#isOpen not open()

JonB

@jsulm

@CHPOG If you want to check whether open or not call https://doc.qt.io/qt-5/qiodevice.html#isOpen not open()

Which is why I asked the OP that above, but he didn't respond....

jsulm

@JonB said in QTcpSocket why SocketTimeoutError is raised ?:

but he didn't respond....

This is often the case...

JonB

@jsulm
Sigh, yes :)
I'm wondering whether the OP's "timeout error" is because he's open()ing the same socket twice, and maybe that's what you get if you try to do that....

CHPOG

Thanks for your answer and sorry if I didn't directly try what you said @JonB .
So I try to remove all the call to open(). I call open() in my constructor of my Rs232 object and connectToHost in the object of my socket connection.
I had the same error raised.
But right to check that connection is open isOpen works fine.
But as I have this socketTimeoutError my tests fails.

jsulm

@CHPOG said in QTcpSocket why SocketTimeoutError is raised ?:

I call open() in my constructor of my Rs232 object and connectToHost in the object of my socket connection.

Why do you call open()? connectToHost() is enough.

CHPOG

@jsulm
Sorry if I am not really clear.
But I have two classes one for a RS232 which call open() in the constructor.
An other one for Socket which call connectToHost() in the constructor.
So for now I am not calling open() for Socket connection. I only use connectToHost().
And the SocketTimeouError is still raised.

jsulm

@CHPOG You wrote: "But when I want to check that my socket is correctly open by QVERIFY(socket->open() ==true) the test fails". So, you do call open() to check whether the socket is open? If so, then please change it to isOpen().

CHPOG

@jsulm Yes you're right I write this at the start of my post. But after I follow you advice and use conn->isOpen() instead. This does not solve my issue with SocketTimeoutError.

CHPOG

To be easier for everyone to understand I test with a main and get the same error.

#include <QCoreApplication>
#include <QTcpSocket>
#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QTcpSocket *socket = new QTcpSocket();
    socket->connectToHost("10.1.0.1",1470);
    socket->write("list\r");
    QString fullData;
    int maxSize = 5000;
    //We wait end of data transmission but not too much if device is in start mode
    while(socket->waitForReadyRead(1000) && fullData.size() < maxSize) {
        QByteArray data = socket->readAll();
        //Removing TCP header
        data.remove(0,32);
        //qDebug()<< "data added  " << data.toHex();
        QString dataAsString(data);
        //qDebug()<< "data added in string  " << dataAsString;
        fullData.append(dataAsString);
    }
    qDebug()<< "isWaitingForCommand " << fullData;
    qDebug()<< "ERROR = " << socket->errorString();
    socket->close();

    return a.exec();

}

I can do more simple. And I always do not understood why this error is raised.
Below this is the ouput :

isWaitingForCommand  "; value ; unity ; minimum value ; maximum value ; description\r\nsample_rate     ;      800 ;           Hz ;      200 ;     1100 ; FrÚquence d'Úchantillonnage de la centrale ADIS ; \r\nsensors         ;        7 ;              ;        1 ;        7 ; Capteurs actifs (BIT0=gyros BIT1=accÚlÚros BIT2=magnÚtos) ; \r\nsynchro         ;        0 ;              ;        0 ;        1 ; Active l'emission d'un 0x02 en dÚbut de trame ; \r\ncounter         ;        0 ;              ;        0 ;    compteur de trame avant les donnÚes capteurs ; \r\nbt_rate         ;   230400 ;              ;   115200 ;   230400 ; Baudrate pour la communication bluetooth ; \r\npassword        ;        0 ;              ;        0 ;   999999 ; Mot de passe pour accÞs aux paramÞtres systÞmes ; \r\nsensor$ "
ERROR =  "Network operation timed out"

J.Hilk

@CHPOG since you insist on using the synchronous api, you should at least use https://doc.qt.io/qt-5/qabstractsocket.html#waitForConnected

for the connection to the host to be established...

CHPOG

@J-Hilk I tried what you said. But the error is still raised. And the message "Connected!" is displayed.
The two lines of code are added just after the connectToHost.