请教组播问题！！！！！

[wiresharker]

#include "stdafx.h"
#pragma comment(lib, "ws2_32.lib")

#include <WinSock2.h>
#include <WS2tcpip.h>
#include <windows.h>

#define GROUP_IP "239.255.255.254"
#define GROUP_PORT 1900

WORD wVersionRequested;
WSADATA wsaData;

void main()
{
WSAStartup(MAKEWORD(2,2),(LPWSADATA)&wsaData);

SOCKET s = ::socket(AF_INET, SOCK_DGRAM, 0);

// 允许其它进程使用绑定的地址
BOOL bReuse = TRUE;
int s1 =::setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char*)&bReuse, sizeof(BOOL));
printf("s1 = %d\n", s1 );

// 绑定到端口
sockaddr_in si;
memset(&si, 0, sizeof(si));
si.sin_family = AF_INET;
si.sin_port = ::htons(GROUP_PORT);
//si.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
si.sin_addr.s_addr = htonl(INADDR_ANY);

s1 = ::bind(s, (struct sockaddr*)&si, sizeof(si));
printf("s1 = %d\n", s1 );

// 加入多播组
ip_mreq mcast;
//mcast.imr_interface.S_un.S_addr = htonl(INADDR_ANY);
//mcast.imr_multiaddr.S_un.S_addr = ::inet_addr(GROUP_IP);
mcast.imr_interface.s_addr = htonl(INADDR_ANY);
mcast.imr_multiaddr.s_addr = ::inet_addr(GROUP_IP);
s1 = ::setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char*)&mcast, sizeof(mcast));
printf("s1 = %d\n", s1);

// 发送多播数据
sockaddr_in to;
memset(&to, 0, sizeof(to));
to.sin_family = AF_INET;
to.sin_port = htons(GROUP_PORT);
//to.sin_addr.S_un.S_addr = ::inet_addr(GROUP_IP);
to.sin_addr.s_addr = ::inet_addr(GROUP_IP);

for(int i=0; i<3; i++ )
{
getchar();
int slen;
slen=sendto(s, "hello", 5, 0, (struct sockaddr*)&to, sizeof(to));
printf("slen=%d, to %s\n", slen, inet_ntoa(to.sin_addr));


char buf[1280];
int len;
sockaddr_in other;
int nRet = ::recvfrom(s, buf, sizeof(buf), 0, (sockaddr*)&other, &len);
printf("nRet = %d\n", nRet);
if(nRet != SOCKET_ERROR)
{
buf[nRet] = '\0';
printf("recv: %s from %s\n", buf, inet_ntoa(si.sin_addr));
}
}



::setsockopt(s, IPPROTO_IP, IP_DROP_MEMBERSHIP, (char*)&mcast, sizeof(mcast));
::closesocket(s);
printf("exit success!\n");
getchar();
}
上面的windows程序是向一个组发送数据包，但接收端始终收不到，同样的代码移植到linux上去发送，接收端可以收到。
这个代码哪里有问题啊。。

[无趣]

有难度，帮你顶下。

[wiresharker]

我也顶下。。。。。

[5t4rk]

linux下可以 windows下不可以

[5t4rk]

//这个是C#写的多播 没有任何问题 通过测试正确

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;

namespace UDP同步组播
{
    public partial class Form1 : Form
    {
        EndPoint GroupEP;
        IPAddress LocalIP, GroupIP;
        Socket LocalSocket;
        byte[] ReceiveBuffer = new byte[1024];
        /// <summary>
        /// 绑定事件
        /// </summary>
        public Form1()
        {
            InitializeComponent();
        //定义本地接口
             IPAddress[]   IPS = Dns.GetHostAddresses(Dns.GetHostName());
            foreach (IPAddress myhost_ip in IPS)
            {
                if (myhost_ip.AddressFamily == AddressFamily.InterNetwork)
                {
                    LocalIP = myhost_ip;
                    break;
                }
            }
            //创建本地套接字并绑定本地接口
            LocalSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
            LocalSocket.Bind((EndPoint)new IPEndPoint(LocalIP,5033));
            //指定远端接口
              GroupIP = IPAddress.Parse("224.168.101.2");  
            //制定组播地址接口
            GroupEP = (EndPoint)new IPEndPoint(GroupIP,5033);
        }

        #region 发送事件
        private void SendBtn_Click(object sender, EventArgs e)
        {
            //配置组播选项
            MulticastOption MO = new MulticastOption(GroupIP, LocalIP);

            //预定组播地址
            LocalSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, MO);
            LocalSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastInterface, 
                (int)IPAddress.HostToNetworkOrder(0));
            //发送数据
            LocalSocket.SendTo(Encoding.UTF8.GetBytes(ContentBox.Text), GroupEP);
            //退出组播地址
            LocalSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.DropMembership, MO);

            //信息显示
            MsgList.Items.Add(string.Format("发送：{0}({1})",ContentBox.Text,
                DateTime.Now.ToString("yy-MM-dd h:m:s")));
        }
        #endregion

        #region 接收事件
        private void ReceiveBtn_Click(object sender, EventArgs e)
        {
            //配置组播选项
            MulticastOption MO = new MulticastOption(GroupIP, LocalIP);

            //预定组播地址
            LocalSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, MO);
            LocalSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastInterface,
                (int)IPAddress.NetworkToHostOrder(0));

            //接收数据
            IPEndPoint remoteIEP = new IPEndPoint(IPAddress.Any, 0);
            EndPoint remoteEP = (EndPoint)remoteIEP;
            int rf = LocalSocket.ReceiveFrom(ReceiveBuffer, ref remoteEP);

            //退出组播地址
            LocalSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.DropMembership, MO);

            //信息显示
            MsgList.Items.Add(string.Format("接受：{0}({1})",Encoding.UTF8.GetString(ReceiveBuffer,0,rf).Trim(),
    DateTime.Now.ToString("yyyy-MM-dd h:m:s")));
        }
        #endregion

        private void Form1_Load(object sender, EventArgs e)
        {

        }

    }
}

楼主还是单步跟踪吧

[wiresharker]

谢谢楼上的回复。
今天下载了个组播发送与接收的代码，发现在同一个系统（即同一个pc）里运行没有问题。
但分别运行在两个pc时就收不到了。google了下好像是说需要交换机支持组播才行。
难道实现组播技术需要在每个交换机上做组播配置吗。。

[Julien_Lion]

请问楼主是从哪里下载的组播发送与接收代码？请不吝指导一下，谢谢！
ps：代码是基于mfc界面的吗？