在同一台计算机上的两个程序之间发送和接收UDP数据包

Question

是否可以通过localhost/127 ...通过共享相同的端口#来获得两个独立的程序在同一台计算机上进行通信(仅限单向)

我们正在开展一个学生项目,我们需要在两台计算机之间发送包含遥测数据的UDP数据包.生成这些数据包的程序是专有的,但我正在使用System.Net.Sockets.UdpClient和System.Net.IPEndPoint使用C#编写接收程序.

在我们小组的会议期间,当我们连接多台计算机时,我们可以分别运行这两个程序.但是,当我回家并试图扩展遥测处理程序时它并不是很有用,因为我只有一台计算机(我需要一个用于测试处理程序的源程序).我也无法在学校的任何一台计算机上安装该程序.

当我尝试同时在我的计算机上运行这两个程序(最后开始我的程序)时,我得到一个SocketException,说通常只允许使用每个端口.这让我相信必须有一些方法来共享端口(虽然任何时候只有一个程序可以在计算机上使用端口是有意义的,我同时运行多个互联网浏览器没有问题(我假设他们使用端口80作为http)).

编辑的REEDIT:

sipwiz是对的,感谢Kalmi指向UdpClient.Client.Bind()的指针.但是,当时我们正在考虑使用另一个生成类似数据包的程序,并且我们可以使用我的第一个(虽然天真)方法在ctor中使用UDP客户端绑定在同一台计算机上共享端口.抱歉,您必须取消标记您的答案,sysrqb.

Answer 1

您可以使用ReuseAddress套接字选项多次绑定到端口.

UdpClient udpClient = new UdpClient();
udpClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);

您还需要在UDP服务器套接字上设置相同的选项.

Answer 2

我没想到这是可能的,但是..好吧.. sipwiz是对的.

它可以很容易地完成.(请投票给sipwiz的答案!)

IPEndPoint localpt = new IPEndPoint(IPAddress.Any, 6000);

//Failed try
    try
    {
        var u = new UdpClient(5000);
        u.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);

        UdpClient u2 = new UdpClient(5000);//KABOOM
        u2.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
    }
    catch (Exception)
    {
        Console.WriteLine("ERROR! You must call Bind only after setting SocketOptionName.ReuseAddress. \n And you must not pass any parameter to UdpClient's constructor or it will call Bind.");
    }

//This is how you do it (kudos to sipwiz)
    UdpClient udpServer = new UdpClient(localpt); //This is what the proprietary(see question) sender would do (nothing special) 

    //!!! The following 3 lines is what the poster needs...(and the definition of localpt (of course))
    UdpClient udpServer2 = new UdpClient();
    udpServer2.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
    udpServer2.Client.Bind(localpt);

Answer 3

以下是TarnayKálmán和sipwiz答案的完整代码:

服务器代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading.Tasks;

namespace UdpBroadcastTest
{
    class Program
    {
        static void Main(string[] args)
        {

            Console.WriteLine("Sender");
            // This constructor arbitrarily assigns the local port number.

            UdpClient udpClient = new UdpClient();
            udpClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
            udpClient.Connect("localhost", 11000);
            try
            {
                string message = String.Empty;
                do
                {
                    message = Console.ReadLine();
                    // Sends a message to the host to which you have connected.
                    Byte[] sendBytes = Encoding.ASCII.GetBytes(message);

                    udpClient.Send(sendBytes, sendBytes.Length);
                } while (message != String.Empty);

                udpClient.Close();
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }

            Console.WriteLine("Press Any Key to Continue");
            Console.ReadKey();
        }
    }
}

客户端代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading.Tasks;

namespace UdpReciever
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Receiver");
            // This constructor arbitrarily assigns the local port number.
            UdpClient udpClient = new UdpClient();
            udpClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
            udpClient.Client.Bind(new IPEndPoint(IPAddress.Any, 11000));
            try
            {
                //IPEndPoint object will allow us to read datagrams sent from any source.
                IPEndPoint RemoteIpEndPoint = new IPEndPoint(IPAddress.Any, 0);

                string message = String.Empty;
                do
                {

                    // Blocks until a message returns on this socket from a remote host.
                    Byte[] receiveBytes = udpClient.Receive(ref RemoteIpEndPoint);
                    message = Encoding.ASCII.GetString(receiveBytes);

                    // Uses the IPEndPoint object to determine which of these two hosts responded.
                    Console.WriteLine("This is the message you received: " +
                                                 message);
                    //Console.WriteLine("This message was sent from " +
                    //                            RemoteIpEndPoint.Address.ToString() +
                    //                            " on their port number " +
                    //                            RemoteIpEndPoint.Port.ToString());
                }
                while (message != "exit");
                udpClient.Close();
                //udpClientB.Close();

            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }

            Console.WriteLine("Press Any Key to Continue");
            Console.ReadKey();
        }
    }
}