socket->connectToHost doesn't work in Qt 5.8

MChe

Hello!

Pro-file:

QT       += core gui network
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = QTCP
TEMPLATE = app
DEFINES += QT_DEPRECATED_WARNINGS
SOURCES += main.cpp\
        widget.cpp
HEADERS  += widget.h
FORMS    += widget.ui

I have simple code:

#include "widget.h"
#include <QApplication>

#include <QtNetwork/QTcpSocket>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QTcpSocket *socket = new QTcpSocket();
    socket->connectToHost("mymail.local", 25);

    if (socket->waitForConnected(5000)) {
        qDebug() << "Connected";
    } else {
        qDebug() << "Not connected";
    }

    return a.exec();
}

Run project in Qt 5.7 — it's work (Connected).

Run project in Qt 5.8 — it's doesn't work (Not connected).

OS Windows 7.

How can I fix it?

mrjj

@MChe

Hi
This is the same pc ?
Where you have both 5.7 and 5.8 installed ?

MChe

@mrjj Yes, it's same PC.

Use MinGW.

mrjj

@MChe

Well it could be a bug in 5.8 (regression)
I would go look in
https://bugreports.qt.io/secure/Dashboard.jspa

Make sure its not something simple. Like you allowed the 5.7 exe but forgot the 5.8 one etc.

J.Hilk

what does

SocketError return, whenn the connection failed?

Hopefully not -1/UnknownSocketError :)

MChe

@J.Hilk

socket->errorString() returns 'Proxy denied connection' in Qt 5.8.

#include "widget.h"
#include <QApplication>

#include <QtNetwork/QTcpSocket>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QTcpSocket *socket = new QTcpSocket();
    socket->connectToHost("mymail.local", 25);

    if (socket->waitForConnected(5000)) {
        qDebug() << "Connected";
    } else {
        qDebug() << "Not connected";
        qDebug() << socket->errorString();
    }

    return a.exec();
}

jsulm

@MChe Try

socket->setProxy(QNetworkProxy::NoProxy);

See http://doc.qt.io/qt-5/qabstractsocket.html#setProxy

MChe

@jsulm said in socket->connectToHost doesn't work in Qt 5.8:

socket->setProxy(QNetworkProxy::NoProxy);

It's returns same result.

#include "widget.h"
#include <QApplication>

#include <QtNetwork/QTcpSocket>
#include <QtNetwork/QNetworkProxy>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QTcpSocket *socket = new QTcpSocket();
    socket->connectToHost("mymail.local", 25);
    socket->setProxy(QNetworkProxy::NoProxy);

    if (socket->waitForConnected(5000)) {
        qDebug() << "Connected";
    } else {
        qDebug() << "Not connected";
        qDebug() << socket->errorString();
    }

    return a.exec();
}

jsulm

@MChe You should put socket->setProxy(QNetworkProxy::NoProxy); before socket->connectToHost("mymail.local", 25);

MChe

@jsulm

It's work, super! Thx :)

yundorri

@jsulm
Very Thanks!!!
Without setProxy(), the connectToHost() and write() seemed ok with no errorString(), but could not Tx and Rx.
You gave me the lights. :-)