Greetings,

First, great site... very helpful. Second, I'm a QT newbie but have been programming for 25 years.

I'm having some difficulty getting a simple QTcpServer & QTcpSocket working. It's just a console app that acts as either a server or a client. It's base on the Fortune demo, without the GUI code. I've ran the fortune demo on the same PC where I'm writing the app and it works just fine so I know the problem is related to something I've done incorrectly.

I've already searched this forum for answers but I haven't found anything that seems to apply to this problem. So any help is appreciated! Thanks in advance!

Here's all of the code (main.cpp, ipcomm.h, ipcomm.cpp - built w/ MSVS 2005) -

main.cpp:
Qt Code: 
  1. #include <QtCore/QCoreApplication>
  2. #include "IPComm.h"
  3.  
  4. int main(int argc, char *argv[])
  5. {
  6.     QCoreApplication a(argc, argv);
  7.  
  8.     // select "server" or "client"
  9.     if(argc > 1)
  10.     {
  11.         printf("instan ipcomm\n");
  12.         IPComm  ipcomm;
  13.         ipcomm.init();
  14.  
  15.         if(strcmp((const char *)argv[1], "s") == 0)
  16.         {
  17.             // server
  18.             printf("starting server\n");
  19.             ipcomm.server();
  20.         }
  21.         else
  22.         {
  23.             if(strcmp((const char *)argv[1], "c") == 0)
  24.             {
  25.                 // client
  26.                 printf("starting client\n");
  27.                 if(argc > 2)
  28.                 {
  29.                     int port = atoi((const char *)argv[1]);
  30.                     ipcomm.client(port);
  31.                     // not sure if this is correct, seems
  32.                     // to be the only way for this func
  33.                     // to get called.
  34.                     ipcomm.requestNewData();
  35.                 }
  36.                 else
  37.                     printf("Must supply port for client\n");
  38.             }
  39.         }
  40.     }
  41.     return a.exec();
  42. }
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ipcomm.h:
Qt Code: 
  1. #pragma once
  2.  
  3. #include <QtCore/QCoreApplication>
  4. #include <QtNetwork>
  5. #include <QTcpSocket>
  6. #include <QHostAddress>
  7.  
  8. class    QTcpServer;
  9. class    QTcpSocket;
  11.  
  12.  
  13. enum {
  14.     TCP_NONE = 0,
  15.     TCP_SERVER,
  16.     TCP_CLIENT
  17. };
  18.  
  19. class IPComm : public QObject
  20. {
  21.  
  22.     Q_OBJECT
  23.  
  24. public:
  25.     IPComm(void);
  26.     ~IPComm(void);
  27.  
  28.  
  29.     QTcpServer      *tcpServer;
  30.     QStringList     fortunes;
  31.  
  32.     QTcpSocket      *tcpClient;
  33.     QString         currentFortune;
  34.     quint16         blockSize;
  35.  
  36.  
  37.     int             tcpType;
  38.     quint16         tcpPort;
  39.  
  40.     void            init(void);
  41.  
  42.     void            server(void);
  43.     void            client(int port);
  44.  
  45. public slots:
  46.     void            requestNewData(void);
  47.  
  48. private slots:
  49.     void            sendData(void);
  50.     void            readData(void);
  51.     void            displayError(QAbstractSocket::SocketError socketError);
  52.  
  53. };
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ipcomm.cpp:
Qt Code: 
  1. include "IPComm.h"
  2. #include <string>
  3.  
  4. IPComm::IPComm(void)
  5. {
  6. }
  7.  
  8. IPComm::~IPComm(void)
  9. {
  10. }
  11.  
  12. void                    IPComm::init(void)
  13. {
  14.     tcpServer = NULL;
  15.     tcpClient = NULL;
  16.     tcpType   = TCP_NONE;
  17.  
  18.     // testing data
  19.     fortunes << tr("You've been leading a dog's life. Stay off the furniture.")
  20.              << tr("You've got to think about tomorrow.")
  21.              << tr("You will be surprised by a loud noise.")
  22.              << tr("You will feel hungry again in another hour.")
  23.              << tr("You might have mail.")
  24.              << tr("You cannot kill time without injuring eternity.")
  25.              << tr("Computers are not intelligent. They only think they are.");
  26. }
  27.  
  28. void                    IPComm::server(void)
  29. {
  30.     if(tcpType == TCP_NONE)
  31.     {
  32.         tcpServer = new QTcpServer(this);
  33.         tcpType   = TCP_SERVER;
  34.  
  35.         // trying out different methods for setting the address
  36. //        if(!tcpServer->listen(QHostAddress::LocalHost))
  37.         QHostAddress qhl("10.3.23.27");
  38.         if(!tcpServer->listen(qhl)) 
  39.             printf("Unable to start the server: %s", tcpServer->errorString());
  40.         else
  41.         {
  42.             if(tcpServer->isListening())
  43.             {
  44.                 QHostAddress qhost = tcpServer->serverAddress();
  45.                 std::string qh = qhost.toString().toStdString();
  46.                 printf("The server address is %s\n", (char *)qh.c_str());
  47.                 printf("The server port is    %d\n", tcpServer->serverPort());
  48.  
  49.                 connect(tcpServer, SIGNAL(newConnection()), this, SLOT(sendData()));
  50.             }
  51.             else
  52.                 printf("we're NOT listening!!\n");
  53.         }
  54.         printf("server() - done\n");
  55.     }
  56. }
  57.  
  58. void                    IPComm::client(int port)
  59. {
  60.     if(tcpType == TCP_NONE)
  61.     {
  62.         tcpClient = new QTcpSocket(this);
  63.         tcpType   = TCP_CLIENT;
  64.  
  65.         tcpPort   = port;
  66.  
  67.         connect(tcpClient, SIGNAL(readyRead()), this, SLOT(readData()));
  68.         connect(tcpClient, SIGNAL(error(QAbstractSocket::SocketError)),
  69.                 this, SLOT(displayError(QAbstractSocket::SocketError)));
  70.  
  71.         printf("client() - done\n");
  72.     }
  73. }
  74.  
  75.  void                   IPComm::readData()
  76.  {
  77.     printf("readData() - begin\n");
  78.  
  79.     QDataStream in(tcpClient);
  80.     //in.setVersion(QDataStream::Qt_4_0);
  81.  
  82.     if (blockSize == 0) 
  83.     {
  84.         if (tcpClient->bytesAvailable() < (int)sizeof(quint16))
  85.             return;
  86.  
  87.         in >> blockSize;
  88.     }
  89.  
  90.     if (tcpClient->bytesAvailable() < blockSize)
  91.         return;
  92.  
  93.     QString nextFortune;
  94.     in >> nextFortune;
  95.  
  96.     if (nextFortune == currentFortune) 
  97.     {
  98.         printf("readData() - requestNewData\n");
  99.         QTimer::singleShot(0, this, SLOT(requestNewData()));
  100.         return;
  101.     }
  102.  
  103.     currentFortune = nextFortune;
  104.     std::string tmp = currentFortune.toStdString();
  105.     printf("readData(): %s\n", (char *)(tmp.c_str()));
  106.  }
  107.  
  108.  void                   IPComm::requestNewData()
  109.  {
  110.     printf("requestNewData() - begin\n");
  111.  
  112.     blockSize = 0;
  113.     tcpClient->abort();
  114.  
  115.     QString servIP = "10.3.23.27";
  116.     int      servPO = tcpPort;
  117.  
  118.     tcpClient->connectToHost(servIP, servPO);
  119.  
  120.     printf("requestNewData() - done\n");
  121.  }
  122.  
  123.  
  124.  void                   IPComm::sendData()
  125.  {
  126.     printf("sendData() - begin\n");
  127.  
  128.     QByteArray block;
  129.     QDataStream out(&block, QIODevice::WriteOnly);
  130.     out.setVersion(QDataStream::Qt_4_0);
  131.     out << (quint16)0;
  132.     out << fortunes.at(qrand() % fortunes.size());
  133.     out.device()->seek(0);
  134.     out << (quint16)(block.size() - sizeof(quint16));
  135.  
  136.     QTcpSocket *clientConnection = tcpServer->nextPendingConnection();
  137.     connect(clientConnection, SIGNAL(disconnected()),
  138.             clientConnection, SLOT(deleteLater()));
  139.  
  140.     clientConnection->write(block);
  141.     clientConnection->disconnectFromHost();
  142.  
  143.     printf("sendData() - done\n");
  144.  }
  145.  
  146.  
  147. void                    IPComm::displayError(QAbstractSocket::SocketError socketError)
  148. {
  149.     switch (socketError) 
  150.     {
  151.         case QAbstractSocket::RemoteHostClosedError:
  152.             printf("The connection was closed by the host.\n");
  153.             break;
  154.  
  155.         case QAbstractSocket::HostNotFoundError:
  156.             printf("The host was not found. Please check the host name and port settings.\n");
  157.             break;
  158.  
  159.         case QAbstractSocket::ConnectionRefusedError:
  160.             printf("The connection was refused by the peer.\n");
  161.             break;
  162.  
  163.         default:
  164.             std::string err = tcpServer->errorString().toStdString();
  165.             printf("the following error occurred: %s\n", (char *)err.c_str());
  166.             break;
  167.     }
  168. }
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