求助高手，如何使用双网卡进行UDP多播？

[chxywm]

局域网中每台机器都有两块网卡，如何指定网卡进行通信呢？（UDP多播）
经实验发现系统总是选择默认的那个网卡发送数据包，而另一个网卡闲着，如何能让两块网卡分工呢？请高手们帮忙解答！！

[chxywm]

绑定IP肯定是不行的，跟绑定网卡是两码事，我试试xlzxlich(阳光)的方法

[xlzxlich]

struct ip_mreq MulticastIp;

// Setup the im_req structure to indicate what group we want to join as well as the interface

//MulticastIp.imr_interface.s_addr =INADDR_ANY;

MulticastIp.imr_interface.s_addr =IPPROTO_IP;

MulticastIp.imr_multiaddr.s_addr =dwMulticastGroup;

if(!SetSockOpt(IP_ADD_MEMBERSHIP, (char *)&MulticastIp, sizeof(MulticastIp), IPPROTO_IP))
{
int err = WSAGetLastError();
sprintf(text, "setsockopt(IP_ADD_MEMBERSHIP) Error !(%d)", err);
MessageBox(NULL, text, "Error", 0);

return(-err);
}

[xlzxlich]

MulticastIp.imr_interface.s_addr = mdLocalIP;//网卡的IP地址

[oyljerry]

指定网卡IP地址来

[AntonlioX]

帮 up

[rotus]

//将套接字绑定到用户指定端口及默认的接口
memset(&m_sockaddr,0,sizeof(m_sockaddr));
m_sockaddr.sin_family=AF_INET;
m_sockaddr.sin_port=htons((USHORT)m_nPort);
m_sockaddr.sin_addr.s_addr= inet_addr( m_strLocalIP );//htonl(INADDR_ANY);//
bind(m_hSocket,(struct sockaddr FAR *)&m_sockaddr,sizeof(m_sockaddr));

[菲斯可儿]

可以枚举网卡的吧？

[huyansoft]

void main()
{
//初始化Winsock
WSADATA wsadata;
int ret=WSAStartup(WAVERS,&wsadata);
if(ret!=0) Error("initialize winsock error");

char* multiaddr="234.5.6.7";//多播组地址
char* localaddr="192.168.1.88";

//创建UDP类型套接字
SOCKET sock=socket(AF_INET,SOCK_DGRAM,0);

//使套接字监听本地端口
sockaddr_in local;
local.sin_family=AF_INET;
local.sin_port=htons(3333);
local.sin_addr.s_addr=htonl(INADDR_ANY);//不须具体指定IP

ret=bind(sock,(sockaddr*)&local,sizeof(local));
if(ret==SOCKET_ERROR) Error("bind error");

//加入多播组
ip_mreq ipmr;
ipmr.imr_multiaddr.s_addr=inet_addr(multiaddr);
ipmr.imr_interface.s_addr=inet_addr(localaddr);//因本机有两个网卡(两个IP)，其中只有一个能收到多播数据，这里指定是哪一个
ret=setsockopt(sock,IPPROTO_IP,IP_ADD_MEMBERSHIP,(char*)&ipmr,sizeof(ipmr));
if(ret==SOCKET_ERROR) Error("setsockopt error");

//接收数据
char buf[256];
sockaddr_in from;
int len=sizeof(from);
while(true)
{
ret=recvfrom(sock,buf,256,0,(sockaddr*)&from,&len);
if(ret==0)
Error("recv len=0");
else if(ret==SOCKET_ERROR)
Error("recvfrom error");
else
{
buf[ret]='\0';
printf("%s[%d]发来:%s\n",inet_ntoa(from.sin_addr),ntohs(from.sin_port),buf);
}
}

//离开多播组
setsockopt(sock,IPPROTO_IP,IP_DROP_MEMBERSHIP,(char*)&ipmr,sizeof(ipmr));

//关闭套接字
closesocket(sock);
}

[alexmayer]

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