组播测试小程序

#include <winsock2.h>
#include <stdio.h>

#define MCASTADDR	"234.5.6.101"	 //本例使用的多播组地址。
#define MCASTPORT	7000			 //绑定的本地端口号。
#define BUFSIZE		5000			 //接收数据缓冲大小。

int main( int argc,char ** argv)
{
	WSADATA wsd;

	struct sockaddr_in local;	//本地
	struct sockaddr_in remote;	//组播源
	struct sockaddr_in from;;	//实际数据来源

	SOCKET sock;
	SOCKET sockM;

	char recvbuf[BUFSIZE];

	int len = sizeof(struct sockaddr_in);
	int ret;
	
	//初始化WinSock2.2
	if(WSAStartup(MAKEWORD(2,2),&wsd) != 0 )
	{
		printf("WSAStartup() failed\n");
		
		return -1;
	}
	
	if((sock = WSASocket(AF_INET, SOCK_DGRAM, 0, NULL, 0,
				WSA_FLAG_MULTIPOINT_C_LEAF | WSA_FLAG_MULTIPOINT_D_LEAF |
				WSA_FLAG_OVERLAPPED)) == INVALID_SOCKET)
	{
		printf("socket failed with:%d\n",WSAGetLastError());
		
		WSACleanup();
		
		return -1;	
	}
	
	//将sock绑定到本机某端口上。
	local.sin_family = AF_INET;
	local.sin_port = htons(MCASTPORT);
	local.sin_ad