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.