使用 IPAddress.Any 获取客户端的 IP

Question

我目前正在开发一个简单的 udp client/server 系统，我偶然发现了以下内容：当我尝试在程序中获取 IPEndPoint 的 IP（我使用 IPAdress.Any 获取）时使用 UdpClient 它有效，我得到以下结果（最上面的一个）：

但是当我使用普通套接字而不是 UdpClient 时，它无法区分 clients/IPs（底部）。下面列出了两者的代码。我想使用套接字的原因是因为使用相同的 class 发送和接收（不是同一个实例）很方便并且使代码更容易理解。

第一个

bool messageReceived = false;
bool done = false;
const int listenPort = 11000;
UdpClient listener = new UdpClient(listenPort);
IPEndPoint receiveEP = new IPEndPoint(IPAddress.Any, listenPort);
string[] adresses = new string[2];
public void ReceiveCallback(IAsyncResult ar)
{
    int id = 0;
    Byte[] receiveBytes = listener.EndReceive(ar, ref receiveEP);
    for (int i = 0; i < adresses.Length; i++)
    {
        if (adresses[i] == receiveEP.Address.ToString())
        {
            id = i;
            break;
        }
        else if (adresses[i] == null)
        {
            id = i;
            adresses[i] = receiveEP.Address.ToString();
            break;
        }
    }
    byte[] a= Encoding.ASCII.GetBytes("Is anybody there?");
    listener.Send(a, a.Length, receiveEP);
    Console.WriteLine("Received message from {0} (client {1}):",    adresses[id],id);
    string receiveString = Encoding.ASCII.GetString(receiveBytes);
    if (receiveString == "stop")
    {
        done = true;
    }
    Console.WriteLine("Received: {0}", receiveString);
    messageReceived = true;
}
public void ReceiveMessages()
{
    Console.WriteLine("listening for messages");
    while(!done){
        try
        {
            messageReceived = false;
            if (!messageReceived)
            {
                listener.BeginReceive(new AsyncCallback(ReceiveCallback),  null);
            }
            while (!messageReceived)
            {
            }

        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }
    Console.WriteLine("Done receiving messages...");
    for (int i = 0; i < adresses.Length; i++)
    {
        if (adresses[i] != null)
        {
            Console.WriteLine(adresses[i]);
        }
    }
    Console.ReadLine();
    listener.Close();
}'

第二

bool messageReceived = false;
bool done = false;
const int listenPort = 11000;
Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,  ProtocolType.Udp);
IPEndPoint receiveEP = new IPEndPoint(IPAddress.Any, listenPort);
string[] adresses = new string[2];
byte[] buffer = new byte[1024];
public void ReceiveMessages()
{
    listener.Bind(receiveEP);
    Console.WriteLine("listening for messages");
    while (!done)
    {
        try
        {
            messageReceived = false;
            if (!messageReceived)
            {
                listener.BeginReceive(buffer, 0,1024,SocketFlags.None,new AsyncCallback(ReceiveCallback), null);
            }
            while (!messageReceived)
            {
            }

        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }
    Console.WriteLine("Done receiving messages...");
    for (int i = 0; i < adresses.Length; i++)
    {
        if (adresses[i] != null)
        {
            Console.WriteLine(adresses[i]);
        }
    }
    Console.ReadLine();
    listener.Close();
}
public void ReceiveCallback(IAsyncResult ar)
{
    int id = 0;
    int read = listener.EndReceive(ar);
    for (int i = 0; i < adresses.Length; i++)
    {
        if (adresses[i] == receiveEP.Address.ToString())
        {
            id = i;
            break;
        }
        else if (adresses[i] == null)
        {
            id = i;
            adresses[i] = receiveEP.Address.ToString();
            break;
        }
    }
    Console.WriteLine("Received message from {0} (client {1}):", adresses[id], id);
    string receiveString = Encoding.ASCII.GetString(buffer,0,read);
    if (receiveString == "stop")
    {
        done = true;
    }
    Console.WriteLine("Received: {0}", receiveString);
    messageReceived = true;
}'

我已经尝试过 Socket.ReceiveMessageFrom() 并使用它返回的数据包信息，但即使我从另一台机器发送，我最终也得到了服务器的 ip4。有人可以帮我吗？

Answer 1

尽管这从来不应该是 Q/A 类型的问题，但我找到了一种让它工作的方法，这意味着 receive() 将 groupEP 更改为数据包的 IP发件人，只需使用 Socket 而不是 UdpClient（我模仿了 UdpClient 的工作方式）。目前，它仍然是同步的（listener.Receive() 是一个阻塞调用）但在不久的将来会改变：

    private const int listenPort = 11000;
    public static int Main()
    {
        bool done = false;
        Listener listener = new Listener(listenPort);
        IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, listenPort);
        byte[] buffer = new byte[2048];
        string received_data;
        try
        {
            while (!done)
            {
                Console.WriteLine("Waiting for broadcast");
                buffer=listener.Receive(ref groupEP);
                received_data = Encoding.ASCII.GetString(buffer);
                Console.WriteLine("Received a broadcast from {0}: {1}", groupEP.ToString(), received_data);
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
        return 0;
    }
}
public class Listener
{
    public Socket client;
    public AddressFamily adressFamily;
    byte[] byte_buffer = new byte[2048];
    public int port;
    public Listener(int p) 
    {
        port=p;
        adressFamily = AddressFamily.InterNetwork;
        IPEndPoint localEP;
        localEP = new IPEndPoint(IPAddress.Any, port);
        client = new Socket(this.adressFamily, SocketType.Dgram, ProtocolType.Udp);
        client.Bind(localEP);
    }
    public byte[] Receive(ref IPEndPoint remoteEP)
    {
        IPEndPoint ipEndPoint=new IPEndPoint(IPAddress.Any,port);
        EndPoint endPoint = (EndPoint)ipEndPoint;

        int num = client.ReceiveFrom(byte_buffer, 2048, SocketFlags.None, ref endPoint);
        remoteEP = (IPEndPoint)endPoint;
        if (num < 2048)
        {
            byte[] array = new byte[num];
            Buffer.BlockCopy(byte_buffer, 0, array, 0, num);
            return array;
        }
        return byte_buffer;
    }

使用 IPAddress.Any 获取客户端的 IP

Acquiring client's IP using IPAddress.Any

.net

c#

sockets

networking

udp