UDP组播服务端与客户端代码实例

1.组播服务端代码（数据发送端）

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
 
#define BUF_SIZE 		128
#define PORT     		50001
#define ADDR     		"192.168.1.100"
#define MUNICASTADDR    "235.3.3.3"
 
int main(int argc, char *argv[])
{
    //建立套接字
    int sock_fd = socket(AF_INET, SOCK_DGRAM, 0);           //IPV4,数据报套接字类型,不指定协议
 
    struct sockaddr_in  group_addr;
    memset(&group_addr, 0, sizeof(group_addr));
	group_addr.sin_family = AF_INET,                              //协议类型IPV4
	group_addr.sin_port = htons(PORT),                            //端口号-网络字节序
	group_addr.sin_addr.s_addr = inet_addr(MUNICASTADDR);                 //IP地址-字符串转IP
 
    //发送数据
    char buf[BUF_SIZE] = { 0 };
	int count = 0;
    while (1)
    {
        memset(buf,0, BUF_SIZE);
        sprintf(buf, "%d",count);
		printf("udp client send:[%s - %d]:%s\n",ADDR,PORT,buf);
        sendto(sock_fd, buf, strlen(buf), 0, (const struct sockaddr*)&group_addr, sizeof(group_addr));
		count++;
		sleep(1);
    }
 
    //关闭套接字
    close(sock_fd);
 
    return 0;
}

2.客户端代码

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <iostream>
#include <fcntl.h>

using namespace std;
 
#define BUF_SIZE 		128
#define MULTICASTPROT     		50001
#define ADDR     		"192.168.1.100"
#define MUNICASTADDR    "235.3.3.3"
#define RCV_BUF_SIZE 65535

void print_err(string str)
{
    static char log_buf[1024];
    sprintf(log_buf,"%d:%s",__LINE__,str.c_str());
    cout<<log_buf<<endl;
}
 
int main(int argc, char *argv[])
{
    //建立套接字
    int sock_fd = socket(AF_INET, SOCK_DGRAM, 0);           //IPV4,数据报套接字类型,不指定协议
    if(sock_fd==-1)
    {
        print_err("creat socket failed!");
    }

    //socket可以重新使用一个本地地址
    int flag=1;
    if(setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, (const char*)&flag, sizeof(flag)) != 0)
    {
        print_err("setsockopt failed!");
    }

    int options = fcntl(sock_fd, F_GETFL);
    if(options < 0)
    {
        print_err("get fcntl failed!");
    }
    options = options | O_NONBLOCK;
    int i_ret = fcntl(sock_fd, F_SETFL, options);
    if(i_ret < 0)
    {
        print_err("get non-block failed!");
    }
 
    //声明将连接地址
    struct sockaddr_in  group_addr;
    memset(&group_addr, 0, sizeof(group_addr));
	group_addr.sin_family = AF_INET,                              //协议类型IPV4
	group_addr.sin_port = htons(MULTICASTPROT),                            //端口号-网络字节序
	group_addr.sin_addr.s_addr = inet_addr(MUNICASTADDR);                 //IP地址-字符串转IP
    if (bind(sock_fd, (struct sockaddr*)&group_addr, sizeof(group_addr)) < 0)   //bind multicast addr
    {
        print_err("bond socket failed!");
    }
	
	struct ip_mreq	ipMreq;

	ipMreq.imr_interface.s_addr = inet_addr(ADDR);
	ipMreq.imr_multiaddr.s_addr = inet_addr(MUNICASTADDR);
	if(setsockopt(sock_fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &ipMreq, sizeof(ipMreq))!=0)
    {
        print_err("add multicast membership failed!");
    }
    
    //接收数据
    char buf[BUF_SIZE] = { 0 };
    struct sockaddr_in cliaddr;
    socklen_t cliaddrlen = sizeof(cliaddr);
    while (1)
    {
        bzero(buf, BUF_SIZE);
        bzero(&cliaddr, cliaddrlen);
        recvfrom(sock_fd, buf, BUF_SIZE, 0, (struct sockaddr *)&cliaddr, &cliaddrlen);
        printf("udp server from [%s - %hu]:%s\n",inet_ntoa(cliaddr.sin_addr),ntohs(cliaddr.sin_port),buf);
        sleep(1);
    }
 
    //关闭套接字
    close(sock_fd);
 
    return 0;
}