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  1. 27th May 2011, 15:37 #1
    valdemar593 Guest

    Default QTcpSocket connection problem

    Hello everyone. I'm trying to write a chat using QTcpSocket and QTcpServer, but strange things are happening. In the first example QTcpServer emits newConnection(), but QTcpSocket remains in connecting state without emiting error(...). In the second example I receive SIGSEGV when trying connectToHost() . What is more, FortuneClient/Server (single threaded) example runs just fine. In both examples network sessiong is not required. Being discouraged I examined the Fortune code and discovored that it is just the same concerning establishing connection. Here are both examples.

    FIRST

    Qt Code: 
    1. //CLIENT
    2. ChatClient::ChatClient(QObject *parent)
    3.     : QObject(parent) {
    4.     tcpSocket = new QTcpSocket(this);
    5.     QNetworkConfigurationManager manager;
    6.     if (QNetworkConfigurationManager::NetworkSessionRequired
    7.         & manager.capabilities()) {
    8.         qDebug() << "Network session required";
    9.     }
    10.     connect(tcpSocket, SIGNAL(error(QAbstractSocket::SocketError)),
    11.             this, SLOT(error(QAbstractSocket::SocketError)));
    12.     connect(tcpSocket, SIGNAL(connected()),
    13.             this, SLOT(requestForID()));
    14.     connect(tcpSocket, SIGNAL(readyRead()),
    15.             this, SLOT(receiveMessage()));
    16.     tcpSocket->connectToHost("192.168.0.100", PORT);
    17. }
    18. ...
    19. void ChatClient::error(QAbstractSocket::SocketError error) {
    20.     qDebug() << "Socket error" << error;
    21. }
    22.  
    23. void ChatClient::requestForID() {
    24.     qDebug() << "Connected, requesting for ID";
    25.     QByteArray segment;
    26.     QDataStream out(&segment, QIODevice::WriteOnly);
    27.     out.setVersion(QDataStream::Qt_4_7);
    28.     out << (quint16)0 << ID;
    29.     out.device()->seek(0);
    30.     out << (quint16)(segment.size() - sizeof(quint16));
    31.     tcpSocket->write(segment);
    32. }
    33.  
    34. //SERVER
    35. ChatServer::ChatServer(QObject *parent)
    36.     : QObject(parent) {
    37.     tcpServer = new QTcpServer(this);
    38.     if (!tcpServer->listen(/*QHostAddress::Any, PORT*/)) {
    39.         qDebug() << "Unable to start the server"
    40.                  << tcpServer->errorString();
    41.     }
    42.     qDebug() << "Server port" << tcpServer->serverPort();
    43.     connect(tcpServer, SIGNAL(newConnection()),
    44.             this, SLOT(processConnection()));
    45. }
    46.  
    47. void ChatServer::processConnection() {
    48.     qDebug() << "Incoming connection";
    49.     QTcpSocket *clientSocket = tcpServer->nextPendingConnection();
    50.     /*connect(clientSocket, SIGNAL(readyRead()),
    51.             this, SLOT(readData()));
    52.     readData(clientSocket);
    53.     connect(clientSocket, SIGNAL(disconnected()),
    54.             clientSocket, SLOT(deleteLater()));*/
    55.     QByteArray segment;
    56.     QDataStream out(&segment, QIODevice::WriteOnly);
    57.     out.setVersion(QDataStream::Qt_4_7);
    58.     out << (quint16)0 << (quint16)Message
    59.         << "Successfully connected";
    60.     out.device()->seek(0);
    61.     out << (quint16)(segment.size() - sizeof(quint16));
    62.     clientSocket->write(segment);
    63.     clientSocket->disconnectFromHost();
    64. }
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    SECOND

    Qt Code: 
    1. //CLIENT
    2. Client::Client() {
    3.     QTcpSocket *clientSocket = new QTcpSocket(this);
    4.     connect(clientSocket, SIGNAL(connected()),
    5.             this, SLOT(connectionEstablished()));
    6.     connect(clientSocket, SIGNAL(error(QAbstractSocket::SocketError)),
    7.             this, SLOT(error()));
    8. }
    9.  
    10. void Client::establishConnection() {
    11. // throws SIGSEGV
    12.     clientSocket->connectToHost(QHostAddress("192.168.0.100"), 6178);
    13. }
    14.  
    15. void Client::connectionEstablished() {
    16.     qDebug() << "Connection established";
    17. }
    18.  
    19. void Client::error() {
    20.     qDebug() << clientSocket->errorString();
    21. }
    22.  
    23. //SERVER
    24. Server::Server() {
    25.     QNetworkConfigurationManager manager;
    26.     if (manager.capabilities() &
    27.         QNetworkConfigurationManager::NetworkSessionRequired) {
    28.         qDebug() << "Network session required";
    29.     } else {
    30.         sessionOpened();
    31.     }
    32.     connect(server, SIGNAL(newConnection()),
    33.             this, SLOT(processConnection()));
    34. }
    35.  
    36. void Server::processConnection() {
    37.     qDebug() << "Incoming connection";
    38. }
    39.  
    40. void Server::sessionOpened() {
    41.     server = new QTcpServer(this);
    42.     if (!server->listen(QHostAddress::Any, 6178)) {
    43.         qDebug() << QString("Unable to start the server: %1")
    44.                 .arg(server->errorString());
    45.         return;
    46.     }
    47.     qDebug() << "The server is running...";
    48. }
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    Any ideas?
    Last edited by valdemar593; 27th May 2011 at 15:51.
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