向所有可用网卡广播 UDP 消息

Question

我需要向特定的 IP 和端口发送 UDP 消息。

由于有 3 个网卡，

10.1.x.x
10.2.x.x
10.4.x.x

当我发送 UDP 消息时，我仅在一个网络适配器中接收该消息...其余 ip 未接收。

我想在发送消息时检查网络适配器。 我怎样才能做到这一点？

---

目前我正在使用以下内容：

IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Parse(LocalIP), 0);
IPEndPoint targetEndPoint = new IPEndPoint(TargetIP, iTargetPort);
UdpClient sendUdpClient = new UdpClient(localEndPoint);
int numBytesSent = sendUdpClient.Send(CombineHeaderBody, CombineHeaderBody.Length, targetEndPoint);

Answer 1

这实际上比听起来更棘手，因为如果您有多个接口，广播并不总是会发送到所有接口。 为了解决这个问题，我创建了这个类。

public class MyUdpClient : UdpClient
{
   public MyUdpClient() : base()
   {
      //Calls the protected Client property belonging to the UdpClient base class.
      Socket s = this.Client;
      //Uses the Socket returned by Client to set an option that is not available using UdpClient.
      s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);
      s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.DontRoute, 1);
   }

   public MyUdpClient(IPEndPoint ipLocalEndPoint) : base(ipLocalEndPoint)
   {
      //Calls the protected Client property belonging to the UdpClient base class.
      Socket s = this.Client;
      //Uses the Socket returned by Client to set an option that is not available using UdpClient.
      s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);
      s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.DontRoute, 1);
   }

}

然后，为了通过广播发送 UDP 数据包，我使用如下所示的内容。 我正在使用 IPAddress.Broadcast 和 MyUdpClient，这与您的代码不同。

IPEndPoint  localEndPoint  = new IPEndPoint(IPAddress.Parse(LocalIP), 0);
IPEndPoint  targetEndPoint = new IPEndPoint(IPAddress.Broadcast, iTargetPort);
MyUdpClient sendUdpClient  = new MyUdpClient(localEndPoint);
int numBytesSent = sendUdpClient.Send(CombineHeaderBody, CombineHeaderBody.Length, targetEndPoint);

另外，您应该注意，当您使用特定的ipaddress而不是广播时，路由表只会将其发送到与该地址匹配的接口。

因此，在您的示例中，使用单播。 您需要将 LocalIP 设置为要发送到的本地接口的 IP。 如果有三个接口，您将拥有三个本地 IP，并且您需要选择正确的一个来使用。

IPEndPoint  localEndPoint  = new IPEndPoint(IPAddress.Parse(LocalIP), 0);
IPEndPoint  targetEndPoint = new IPEndPoint(TargetIP, iTargetPort);
MyUdpClient sendUdpClient  = new MyUdpClient(localEndPoint);
int numBytesSent = sendUdpClient.Send(CombineHeaderBody, CombineHeaderBody.Length, targetEndPoint);

由于路由已关闭，您可能会在所有接口上看到它，但您需要针对单播情况进行测试。

如果您不关心发送 IP 或端口，可以使用以下代码。

IPEndPoint  targetEndPoint = new IPEndPoint(TargetIP, iTargetPort);
MyUdpClient sendUdpClient  = new MyUdpClient();
int numBytesSent = sendUdpClient.Send(CombineHeaderBody, CombineHeaderBody.Length, targetEndPoint);

或者对于广播

IPEndPoint  targetEndPoint = new IPEndPoint(IPAddress.Broadcast, iTargetPort);
MyUdpClient sendUdpClient  = new MyUdpClient();
int numBytesSent = sendUdpClient.Send(CombineHeaderBody, CombineHeaderBody.Length, targetEndPoint);

IPAddress.Broadcast 的问题是它们不会通过任何网关进行路由。 为了解决这个问题，您可以创建一个 IPAddresses 列表，然后循环并发送。 此外，由于发送可能会因您无法控制的网络问题而失败，因此您还应该有一个 try/catch 块。

ArrayList ip_addr_acq = new ArrayList();

ip_addr_acq.Add(IPAddress.Parse("10.1.1.1")); // add to list of address to send to

try
{
   foreach (IPAddress curAdd in ip_addr_acq) 
   {
       IPEndPoint  targetEndPoint = new IPEndPoint(curAdd , iTargetPort);
       MyUdpClient sendUdpClient  = new MyUdpClient();
       int numBytesSent = sendUdpClient.Send(CombineHeaderBody, CombineHeaderBody.Length, targetEndPoint);

       Thread.Sleep(40); //small delay between each message
    }
 }
 catch
 {
 // handle any exceptions
 }

编辑：请参阅上面对具有多个接口的单播的更改以及 尝试将数据包单播到可用网络时出现问题。

Answer 2

雷克斯答案的扩展。 这使您不必对要广播的 IP 地址进行硬编码。 循环遍历所有接口，检查它们是否已启动，确保其具有 IPv4 信息以及与其关联的 IPv4 地址。 只需将“数据”变量更改为您想要广播的任何数据，并将“目标”端口更改为您想要的端口即可。 小缺点是，如果一个接口有多个与其关联的 IP 地址，它将从每个地址进行广播。 注意：这还将尝试通过任何 VPN 适配器发送广播（通过网络和共享中心/网络连接，Win 7+ 验证），如果您想接收响应，则必须保存所有客户端。 您也不需要中学课程。

    foreach( NetworkInterface ni in NetworkInterface.GetAllNetworkInterfaces() ) {
        if( ni.OperationalStatus == OperationalStatus.Up && ni.SupportsMulticast && ni.GetIPProperties().GetIPv4Properties() != null ) {
            int id = ni.GetIPProperties().GetIPv4Properties().Index;
            if( NetworkInterface.LoopbackInterfaceIndex != id ) {
                foreach(UnicastIPAddressInformation uip in ni.GetIPProperties().UnicastAddresses ) {
                    if( uip.Address.AddressFamily == AddressFamily.InterNetwork ) {
                        IPEndPoint local = new IPEndPoint(uip.Address.Address, 0);
                        UdpClient udpc = new UdpClient(local);
                        udpc.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);
                        udpc.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.DontRoute, 1);
                        byte[] data = new byte[10]{1,2,3,4,5,6,7,8,9,10};
                        IPEndPoint target = new IPEndPoint(IPAddress.Broadcast, 48888);
                        udpc.Send(data,data.Length, target);
                    }
                }
            }
        }
    }

Answer 3

我通过从每个适配器发送 UDP 广播（使用绑定）解决了这个问题：

public static void SNCT_SendBroadcast(out List<MyDevice> DevicesList)
{
DevicesList = new List<MyDevice>();
byte[] data = new byte[2]; //broadcast data
data[0] = 0x0A;
data[1] = 0x60;

IPEndPoint ip = new IPEndPoint(IPAddress.Broadcast, 45000); //braodcast IP address, and corresponding port

NetworkInterface[] nics = System.Net.NetworkInformation.NetworkInterface.GetAllNetworkInterfaces(); //get all network interfaces of the computer

foreach (NetworkInterface adapter in nics)
{
// Only select interfaces that are Ethernet type and support IPv4 (important to minimize waiting time)
if (adapter.NetworkInterfaceType != NetworkInterfaceType.Ethernet) { continue; }
if (adapter.Supports(NetworkInterfaceComponent.IPv4) == false) { continue; }
try
{
    IPInterfaceProperties adapterProperties = adapter.GetIPProperties();    
    foreach (var ua in adapterProperties.UnicastAddresses)
    {
        if (ua.Address.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)
        {
         //SEND BROADCAST IN THE ADAPTER
            //1) Set the socket as UDP Client
            Socket bcSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); //broadcast socket
            //2) Set socker options
            bcSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);
            bcSocket.ReceiveTimeout = 200; //receive timout 200ms
            //3) Bind to the current selected adapter
            IPEndPoint myLocalEndPoint = new IPEndPoint(ua.Address, 45000);
            bcSocket.Bind(myLocalEndPoint);
            //4) Send the broadcast data
            bcSocket.SendTo(data, ip);

        //RECEIVE BROADCAST IN THE ADAPTER
            int BUFFER_SIZE_ANSWER = 1024;
            byte[] bufferAnswer = new byte[BUFFER_SIZE_ANSWER];
            do
            {
                try
                {
                    bcSocket.Receive(bufferAnswer);
                    DevicesList.Add(GetMyDevice(bufferAnswer)); //Corresponding functions to get the devices information. Depends on the application.
                }
                catch { break; }

            } while (bcSocket.ReceiveTimeout != 0); //fixed receive timeout for each adapter that supports our broadcast
            bcSocket.Close();
        }
    }
  }
  catch { }
}
return;
}

Answer 4

如果您发送到特定的 IP 地址，那么您是单播，而不是广播。