使用新的 QUdpSocket 重新绑定

发布于 2024-10-12 05:16:01 字数 1041 浏览 1 评论 0原文

我有一个网络应用程序，它使用 UDP 广播进行设备发现，但一次只接受一个连接。因此，当建立新的 TCP 连接时，我删除用于发现的 QUdpSocket。

但是，当远程设备断开连接时，我想创建一个新的 QUdpSocket 并再次开始监听：

    // Set up a UDP server to respond to any "discovery" messages:
    udpServer = new QUdpSocket(this);
    if (udpServer -> bind(QHostAddress::Any, DISCOVERY_PORT))
        connect(udpServer, SIGNAL(readyRead()),
                this,      SLOT(beDiscovered()));
    else
    {
        fprintf(stderr, "UDP port not bound successfully: %d, ", udpServer ->error());
        fprintf(stderr, udpServer ->errorString().toLocal8Bit());
        fprintf(stderr, "\r\n");
        fflush(stderr);
#ifdef WIN32
        _commit(_fileno(stderr));
#else
        fsync(_fileno(stderr));
#endif
    }

但是，重新绑定失败，代码为 8，“绑定地址已在使用中”。

那么，我如何确保当“旧”QUdpSocket 被删除时，它完全释放它所绑定的地址？

或者，我应该与 QUdpSocket::ShareAddress 或 QUdpSocket::ReuseAddressHint 绑定吗？这似乎不对，因为两者都没有真正描述我想要的行为，即我的 QUdpSocket 在其生命周期内的独占绑定，并且无论如何 QUdpSocket::ShareAddress 应该是 Windows 上的默认设置。

谢谢，史蒂芬.

原文

I have a network application which uses UDP broadcasts for device discovery, but only accepts one connection at a time. So, when a new TCP connection is made, I delete the QUdpSocket that was used for discovery.

However, when the remote device is disconnected, I want to create a new QUdpSocket and start listening again:

    // Set up a UDP server to respond to any "discovery" messages:
    udpServer = new QUdpSocket(this);
    if (udpServer -> bind(QHostAddress::Any, DISCOVERY_PORT))
        connect(udpServer, SIGNAL(readyRead()),
                this,      SLOT(beDiscovered()));
    else
    {
        fprintf(stderr, "UDP port not bound successfully: %d, ", udpServer ->error());
        fprintf(stderr, udpServer ->errorString().toLocal8Bit());
        fprintf(stderr, "\r\n");
        fflush(stderr);
#ifdef WIN32
        _commit(_fileno(stderr));
#else
        fsync(_fileno(stderr));
#endif
    }

The re-bind fails, however, with code 8, "The bound address is already in use".

So, how can I make sure that when the 'old' QUdpSocket was deleted, it fully releases the address(es) it was bound to?

Alternatievly, should I be binding with QUdpSocket::ShareAddress or QUdpSocket::ReuseAddressHint? This doesn't seem right, as neither really describe the behaviour I want, namely an exclusive binding for my QUdpSocket during its lifetime, and in any case QUdpSocket::ShareAddress is supposed to be the default on Windows.

Thanks,
Stephen.

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