当有多个服务器广播时，客户端如何接收多个广播消息？

Posted 2023-02-16

【中文标题】当有多个服务器广播时，客户端如何接收多个广播消息？

【英文标题】：how can a client receive more than one broadcast messages when there is more than one server broadcasting?

【发布时间】：2012-09-18 06:46:47

【问题描述】：

我正在使用 system.Net.Socket 从服务器向客户端发送和接收消息。但是当多个服务器广播消息然后接收程序突然关闭时遇到问题。

我的广播服务器代码如下..

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;

public class Broadcst

    public static void Main()
    
        Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
        IPEndPoint iep1 = new IPEndPoint(IPAddress.Broadcast, 9050);
        IPEndPoint iep2 = new IPEndPoint(IPAddress.Parse("192.168.1.255"), 9050);

        string hostname = Dns.GetHostName();
        byte[] data = Encoding.ASCII.GetBytes(hostname);

        sock.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);
        sock.SendTo(data, iep1);
        sock.SendTo(data, iep2);
        sock.Close();
    

我的客户接收代码如下...

  using System;
    using System.Net;
    using System.Net.Sockets;
    using System.Text;

    public class RecvBroadcst
    
        public static void Main()
        
            Socket sock = new Socket(AddressFamily.InterNetwork,
                            SocketType.Dgram, ProtocolType.Udp);

While(true)
  IPEndPoint iep = new IPEndPoint(IPAddress.Any, 9050);
            sock.Bind(iep);
            EndPoint ep = (EndPoint)iep;
            Console.WriteLine("Ready to receive...");

            byte[] data = new byte[1024];
            int recv = sock.ReceiveFrom(data, ref ep);
            string stringData = Encoding.ASCII.GetString(data, 0, recv);
            Console.WriteLine("received: 0  from: 1",
                                  stringData, ep.ToString());

            data = new byte[1024];
            recv = sock.ReceiveFrom(data, ref ep);
            stringData = Encoding.ASCII.GetString(data, 0, recv);
            Console.WriteLine("received: 0  from: 1",
                                  stringData, ep.ToString());


            sock.Close();
        
    

那么当有多个服务器广播时，客户端如何接收多个广播消息呢？

当我再次从服务器发送消息时，它会抛出错误，例如“每个套接字地址（协议/网络地址/端口）通常只允许使用一次”

【问题讨论】：

您的接收程序在收到一条消息后立即“退出”，因为您就是这样写的。如果您希望它接收多条消息，请相应地调整代码。这里有什么问题？

我已经将该代码放入，但当从服务器发送下一条消息时，它应该有任何消息。请参阅我更新的问题

程序不只是被“关闭”。由于未处理的异常而失败。解释该异常很重要。

【参考方案1】：

您在同一个 Socket 实例上使用相同的参数多次调用Bind（每次迭代一个）。你应该打电话给Bind一次。

【参考方案2】：

我已经解决了上面代码中的更改问题，并在接收端进行了以下操作。我每次都只是绑定套接字，所以我现在只绑定一次，并且每次只从指定的端口迭代传入的数据。

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;

public class RecvBroadcst

    public static void Main()
    
       Socket sock = new Socket(AddressFamily.InterNetwork,
                           SocketType.Dgram, ProtocolType.Udp);
     //  int port_no=Convert.ToInt32(sock.RemoteEndPoint);


         int portnumber = 9050;

            sock = new Socket(AddressFamily.InterNetwork,
                           SocketType.Dgram, ProtocolType.Udp);
            IPEndPoint iep = new IPEndPoint(IPAddress.Any,portnumber);
            sock.Bind(iep);
            EndPoint ep = (EndPoint)iep;
            Console.WriteLine("Ready to receive...");
          // int port_no = Convert.ToInt32(sock.RemoteEndPoint);
            while (true)
            

                byte[] data = new byte[1024];
                int recv = sock.ReceiveFrom(data, ref ep);
                string stringData = Encoding.ASCII.GetString(data, 0, recv);
                Console.WriteLine("received: 0  from: 1",
                                      stringData, ep.ToString());

                //data = new byte[1024];
                //recv = sock.ReceiveFrom(data, ref ep);
                //stringData = Encoding.ASCII.GetString(data, 0, recv);
                //Console.WriteLine("received: 0  from: 1",
                //                      stringData, ep.ToString());

                data = null;
            
            //portnumber--;


        sock.Close();
    

我刚刚成功了。感谢您的回复。这很有帮助。