QTcpSocket with static local port: extremely quick SocketTimeoutError

charango

Hi

I need to connect to some host several times, using the same local port. I use bind() to make static port for tcp socket.
First time it binds and connects to host successfully, but all subsequent connects finished with extremely quick (several ms) SocketTimeoutError, although I use waitForConnected() method.

What I'm doing wrong? Thanks in advance.

Test::Test(QObject *parent) : QObject(parent)
{
    QTcpSocket *sock = new QTcpSocket ();
    connect(sock, SIGNAL(stateChanged(QAbstractSocket::SocketState)), this, SLOT(stateChanged(QAbstractSocket::SocketState)));
    connect(sock, SIGNAL(error(QAbstractSocket::SocketError)), this, SLOT(error(QAbstractSocket::SocketError)));

    for (int i=0; i<3; i++)
    {
        qDebug() << "before abort" << sock->localPort();
        sock->abort();
        sock->close();
        qDebug() << "after abort" << sock->localPort();
        qDebug() << "bind 3310" << sock->bind(3310);

        qDebug() << i << QTime::currentTime().toString("HH:mm:ss:zzz") << "CONNECT TO HOST" << sock->localPort();
        sock->connectToHost(QString("192.168.1.6"), 90);

        if (sock->waitForConnected(10000))
            qDebug() << QTime::currentTime().toString("HH:mm:ss:zzz") << i << "CONNECTED" << sock->localPort();
        else
            qDebug() << QTime::currentTime().toString("HH:mm:ss:zzz") << i << "NOT connected";
    }

}


void Test::stateChanged(QAbstractSocket::SocketState state)
{
    QTcpSocket *socket = static_cast<QTcpSocket *>(sender());
    qDebug() << QTime::currentTime().toString("HH:mm:ss:zzz") << "stateChanged" << state << socket->localPort();
}


void Test::error(QAbstractSocket::SocketError error)
{
    QTcpSocket *socket = static_cast<QTcpSocket*>(sender());
    qDebug() << QTime::currentTime().toString("HH:mm:ss:zzz") << "error" << error << socket->localPort();
}

Application output:

before abort 0
after abort 0
"19:47:41:990" stateChanged QAbstractSocket::BoundState 3310
bind 3310 true
0 "19:47:41:997" CONNECT TO HOST 3310
"19:47:41:998" stateChanged QAbstractSocket::HostLookupState 3310
"19:47:42:001" stateChanged QAbstractSocket::ConnectingState 3310
"19:47:42:006" stateChanged QAbstractSocket::ConnectedState 3310
"19:47:42:006" 0 CONNECTED 3310
before abort 3310
"19:47:42:510" stateChanged QAbstractSocket::UnconnectedState 3310
after abort 0
"19:47:42:518" stateChanged QAbstractSocket::BoundState 3310
bind 3310 true
1 "19:47:42:523" CONNECT TO HOST 3310
"19:47:42:525" stateChanged QAbstractSocket::HostLookupState 3310
"19:47:42:529" stateChanged QAbstractSocket::ConnectingState 3310
"19:47:42:534" stateChanged QAbstractSocket::UnconnectedState 3310
"19:47:42:535" error QAbstractSocket::SocketTimeoutError 3310
"19:47:42:540" stateChanged QAbstractSocket::UnconnectedState 3310
"19:47:42:545" 1 NOT connected
before abort 3310
after abort 0
"19:47:43:051" stateChanged QAbstractSocket::BoundState 3310
bind 3310 true
2 "19:47:43:059" CONNECT TO HOST 3310
"19:47:43:065" stateChanged QAbstractSocket::HostLookupState 3310
"19:47:43:067" stateChanged QAbstractSocket::ConnectingState 3310
"19:47:43:072" stateChanged QAbstractSocket::UnconnectedState 3310
"19:47:43:073" error QAbstractSocket::SocketTimeoutError 3310
"19:47:43:080" stateChanged QAbstractSocket::UnconnectedState 3310
"19:47:43:082" 2 NOT connected