QUpdSocket and setsockopt()

[bob2oneil]

I need to set the DSCP fields for UDP frames transmitted using a QUdpSocket. This socket will transmit to a range of IP addresses, and is not bound to a particular port.

I need to get the socket descriptor for the socket in a cross platform manner (although I can use conditional compilation)

The problem is, the socketDescriptor() API returns -1 unless the socket is connected. If I bind to any port as shown, the ::setsockopt() API continues to fail

Here is my code segment. Anybody have any ideas or tried to do similar things?

// Create thread local storage
    m_udpTxSocket = new QUdpSocket();
 
    // Bind to any socket 
    m_updTxSocket->bind());
 
    // Set DSCP field of socket to high priority setting
    DWORD DSCPValue = 0x07; 
    if (::setsockopt(m_udpTxSocket->socketDescriptor(), // Socket descriptor
        IPPROTO_IP,                                     // Socket level
        IP_TOS,                                         // Socket option (type of service)
        (char *)&DSCPValue,                             // Option value buffer
        sizeof(DWORD)))
    {
        FILE_LOG(logERROR) << "TDMA: failed to set transmit socket DSCP value";
    }

// Create thread local storage
    m_udpTxSocket = new QUdpSocket();

    // Bind to any socket 
    m_updTxSocket->bind());

    // Set DSCP field of socket to high priority setting
    DWORD DSCPValue = 0x07; 
    if (::setsockopt(m_udpTxSocket->socketDescriptor(), // Socket descriptor
        IPPROTO_IP,                                     // Socket level
        IP_TOS,                                         // Socket option (type of service)
        (char *)&DSCPValue,                             // Option value buffer
        sizeof(DWORD)))
    {
        FILE_LOG(logERROR) << "TDMA: failed to set transmit socket DSCP value";
    }

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