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QUdpSocket bind problem

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  • J JulsPower

    Ok I changed the init function to be more like it should be

        ui->setupUi(this);
        m_UdpSocket = new QUdpSocket(this);
        bool b;
        b = m_UdpSocket->bind(QHostAddress::Any, 55555);
        auto state = m_UdpSocket->state();
        QMessageBox::information(this, "info", QString(b?"true ":"false ") + QString::number(state));
        connect(m_UdpSocket, &QUdpSocket::readyRead, this, &MainWindow::readPendingDatagrams);
        connect(m_UdpSocket, &QUdpSocket::errorOccurred, this, &MainWindow::errorOccurred);
    
    

    if I debug the message box show false 0 (which is unconnected)
    and if I run the debug version it shows true 4

    errorOccurred is never called

    HansonH Offline
    HansonH Offline
    Hanson
    wrote last edited by
    #10

    @JulsPower
    You can now use error() or errorString() to see the actual error message.
    https://doc.qt.io/qt-6/qabstractsocket.html#error
    https://doc.qt.io/qt-6/qiodevice.html#errorString

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    • J Offline
      J Offline
      JulsPower
      wrote last edited by
      #11

      indeed
      QMessageBox::information(this, "info", QString(b?"true ":"false ") + QString::number(state) + m_UdpSocket->errorString());
      return unknow error :(

      1 Reply Last reply
      0
      • HansonH Offline
        HansonH Offline
        Hanson
        wrote last edited by
        #12

        @JulsPower What is return value of error().

        J 1 Reply Last reply
        0
        • HansonH Hanson

          @JulsPower What is return value of error().

          J Offline
          J Offline
          JulsPower
          wrote last edited by
          #13

          @Hanson said in QUdpSocket bind problem:

          @JulsPower What is return value of error().

          -1

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          • HansonH Offline
            HansonH Offline
            Hanson
            wrote last edited by
            #14

            @JulsPower
            I checked the relevant source code and I can see that the error code without an error message could be WSANOTINITIALISED, which stands for WSAStartup failed. I guess it could be a mismatch or missing winsock library in the debug environment.
            https://learn.microsoft.com/zh-cn/windows/win32/winsock/windows-sockets-error-codes-2

            bool QNativeSocketEnginePrivate::nativeBind(const QHostAddress &a, quint16 port)
            {
                QHostAddress address = a;
                if (address.protocol() == QAbstractSocket::IPv4Protocol) {
                    if ((address.toIPv4Address() & 0xffff0000) == 0xefff0000) {
                        // binding to a multicast address
                        address = QHostAddress(QHostAddress::AnyIPv4);
                    }
                }
            
                qt_sockaddr aa;
                QT_SOCKLEN_T sockAddrSize = 0;
                setPortAndAddress(port, address, &aa, &sockAddrSize);
            
                if (aa.a.sa_family == AF_INET6) {
                    // The default may change in future, so set it explicitly
                    int ipv6only = 0;
                    if (address.protocol() == QAbstractSocket::IPv6Protocol)
                        ipv6only = 1;
                    ::setsockopt(socketDescriptor, IPPROTO_IPV6, IPV6_V6ONLY, (char*)&ipv6only, sizeof(ipv6only) );
                }
            
            
                int bindResult = ::bind(socketDescriptor, &aa.a, sockAddrSize);
                if (bindResult == SOCKET_ERROR && WSAGetLastError() == WSAEAFNOSUPPORT
                        && address.protocol() == QAbstractSocket::AnyIPProtocol) {
                    // retry with v4
                    aa.a4.sin_family = AF_INET;
                    aa.a4.sin_port = htons(port);
                    aa.a4.sin_addr.s_addr = htonl(address.toIPv4Address());
                    sockAddrSize = sizeof(aa.a4);
                    bindResult = ::bind(socketDescriptor, &aa.a, sockAddrSize);
                }
                if (bindResult == SOCKET_ERROR) {
                    int err = WSAGetLastError();
                    WS_ERROR_DEBUG(err);
                    switch (err) {
                    case WSANOTINITIALISED:
                        //###
                        break;
                    case WSAEADDRINUSE:
                    case WSAEINVAL:
                        setError(QAbstractSocket::AddressInUseError, AddressInuseErrorString);
                        break;
                    case WSAEACCES:
                        setError(QAbstractSocket::SocketAccessError, AddressProtectedErrorString);
                        break;
                    case WSAEADDRNOTAVAIL:
                        setError(QAbstractSocket::SocketAddressNotAvailableError, AddressNotAvailableErrorString);
                        break;
                    default:
                        break;
                    }
            
            #if defined (QNATIVESOCKETENGINE_DEBUG)
                    qDebug("QNativeSocketEnginePrivate::nativeBind(%s, %i) == false (%s)",
                           address.toString().toLatin1().constData(), port, socketErrorString.toLatin1().constData());
            #endif
            
                    return false;
                }
            
            #if defined (QNATIVESOCKETENGINE_DEBUG)
                qDebug("QNativeSocketEnginePrivate::nativeBind(%s, %i) == true",
                       address.toString().toLatin1().constData(), port);
            #endif
                socketState = QAbstractSocket::BoundState;
                return true;
            }
            
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            • J Offline
              J Offline
              JulsPower
              wrote last edited by
              #15

              Interesting
              would you know a way to confirm this? and even more fix it?

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              • J Offline
                J Offline
                JulsPower
                wrote last edited by
                #16

                I did update to qt creator 17 with all debug symbol, issue remain

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                • HansonH Offline
                  HansonH Offline
                  Hanson
                  wrote last edited by Hanson
                  #17

                  @JulsPower
                  You can try the following code before executing the bind() function

                  #include <winsock2.h>
                  #include <ws2tcpip.h>
                  #pragma comment(lib, "ws2_32.lib")
                  
                  ....
                  WSAData wsadata;
                  int err = WSAStartup(MAKEWORD(2,0), &wsadata);
                  if (err != 0) {
                          qWarning("QTcpSocketAPI: WinSock v2.0 initialization failed.");
                      } 
                  ....
                  
                  J 1 Reply Last reply
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                  • HansonH Hanson

                    @JulsPower
                    You can try the following code before executing the bind() function

                    #include <winsock2.h>
                    #include <ws2tcpip.h>
                    #pragma comment(lib, "ws2_32.lib")
                    
                    ....
                    WSAData wsadata;
                    int err = WSAStartup(MAKEWORD(2,0), &wsadata);
                    if (err != 0) {
                            qWarning("QTcpSocketAPI: WinSock v2.0 initialization failed.");
                        } 
                    ....
                    
                    J Offline
                    J Offline
                    JulsPower
                    wrote last edited by
                    #18

                    @Hanson said in QUdpSocket bind problem:

                    @JulsPower
                    You can try the following code before executing the bind() function

                    #include <winsock2.h>
                    #include <ws2tcpip.h>
                    #pragma comment(lib, "ws2_32.lib")
                    
                    ....
                    WSAData wsadata;
                    int err = WSAStartup(MAKEWORD(2,0), &wsadata);
                    if (err != 0) {
                            qWarning("QTcpSocketAPI: WinSock v2.0 initialization failed.");
                        } 
                    ....
                    

                    WSAStartup return 0 so no error there
                    but the bind function continue to return false

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                    • HansonH Offline
                      HansonH Offline
                      Hanson
                      wrote last edited by
                      #19

                      @JulsPower
                      emmm... I can't figure it out anymore :)
                      Or you can download the qt source code and debug it.

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                      • J Offline
                        J Offline
                        JulsPower
                        wrote last edited by
                        #20

                        WSAGetLastError return error 10106 (WSAEPROVIDERFAILEDINIT)
                        gives you an idea??

                        HansonH 1 Reply Last reply
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                        • J JulsPower

                          WSAGetLastError return error 10106 (WSAEPROVIDERFAILEDINIT)
                          gives you an idea??

                          HansonH Offline
                          HansonH Offline
                          Hanson
                          wrote last edited by
                          #21

                          @JulsPower
                          Can you show me where in your code calling WSAGetLastError()?

                          J 1 Reply Last reply
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                          • HansonH Hanson

                            @JulsPower
                            Can you show me where in your code calling WSAGetLastError()?

                            J Offline
                            J Offline
                            JulsPower
                            wrote last edited by
                            #22

                            @Hanson said in QUdpSocket bind problem:

                            @JulsPower
                            Can you show me where in your code calling WSAGetLastError()?

                            b = m_UdpSocket->bind(QHostAddress::Any, 55555);
                            auto state = m_UdpSocket->state();
                            QMessageBox::information(this, "info", QString(b?"true ":"false ") + QString::number(state) + QString::number(WSAGetLastError()));
                            

                            show while debugging it shows false 010106

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                            • J Offline
                              J Offline
                              JulsPower
                              wrote last edited by JulsPower
                              #23

                              I replicated the samething in a new project using qmake instead of cmake. lo and behold it works in debugging mode...
                              seem ill be using qmake

                              HansonH 1 Reply Last reply
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                              • J JulsPower

                                I replicated the samething in a new project using qmake instead of cmake. lo and behold it works in debugging mode...
                                seem ill be using qmake

                                HansonH Offline
                                HansonH Offline
                                Hanson
                                wrote last edited by Hanson
                                #24

                                @JulsPower
                                Maybe same as this question
                                https://stackoverflow.com/questions/48597996/qtcpserver-return-unknown-error-on-listen-function-only-under-debugger
                                https://developercommunity.visualstudio.com/t/native-cmake-support-application-debug-launch-is-b/562174

                                So the reason could be that when debugging the program with cmake project, the environment variables were cleared and the SystemRoot variable was missing, which caused WSASocket to fail to load the related components.

                                1 Reply Last reply
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                                • HansonH Offline
                                  HansonH Offline
                                  Hanson
                                  wrote last edited by
                                  #25
                                  This post is deleted!
                                  1 Reply Last reply
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                                  • J Offline
                                    J Offline
                                    JulsPower
                                    wrote last edited by
                                    #26

                                    seems like it
                                    thank you

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                                    • J JulsPower has marked this topic as solved
                                    • Kent-DorfmanK Offline
                                      Kent-DorfmanK Offline
                                      Kent-Dorfman
                                      wrote last edited by Kent-Dorfman
                                      #27

                                      @JulsPower I understand you probably lack the motivation and time to do it, but it would be interesting to see the differences in the build between cmake generated makefile an qmake generated makfile. Obviously the two are building/linking differently. Smells like a build flag isn't the same in cmake debug

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