Question

我正在尝试从网络中的UPnP设备接收UPnP NOTIFY消息。但是当我发送M-SEARCH消息时，我有时会得不到答案。我的代码看起来像这样：

public bool StartListener()
{
  if (this.ssdpSocket == null)
  {
    IPAddress localIpAddress = IPAddress.Any; 
    IPEndPoint localIpEndpoint = new IPEndPoint(localIpAddress, SsdpPort);

    try
    {
      this.ssdpSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
      this.ssdpSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, 1);

      this.ssdpSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveBuffer, 16384); 

      this.ssdpSocket.Bind(localIpEndpoint);
      this.ssdpSocket.SetSocketOption(
        SocketOptionLevel.IP,
        SocketOptionName.AddMembership,
        new MulticastOption(IPAddress.Parse(SsdpMulticastAddress), localIpAddress));

      this.ssdpSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastTimeToLive, 2);
      this.ssdpSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastLoopback, true);

      this.culture = Thread.CurrentThread.CurrentUICulture;
      this.workerThreadListener = new WorkerThread(this.ssdpSocket, this.HandleSsdpMessage);
      this.workerThreadListener.Start();

      Log.InfoFormat("SSDP server bind successful [{0}]", localIpEndpoint);

      return true;
    }
    catch (Exception exception)
    {
      Log.Info(string.Format("SSDP server bind failed [{0}]", localIpEndpoint), exception);
      throw;
    }
  }

  return false;
}

我找到了以下答案，但对我来说无法更改端口。有替代解决方案吗？

UPnP Multicast

Answer 1

这对你来说是一个纯粹的运气 - 相反，它的工作原因与预期不同。

您收到了NOTIFY消息，因为您开始收听多播作为该组的成员 - UPnP定期在1900年将其存在多播到邻居，没有搜索请求。

另一方面，当您发送M-SEARCH（多播，大概是）时，您应该留在并暂时监听短暂的端口，因为单播响应将会到达那里。

SSDP组播缺少来自M-SEARCH - Discovery - UPnP的答案

1 个答案: