搭建广播，组播

广播发送端

#include <stdio.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <string.h>
#include <unistd.h>

#define ERR_MSG(msg) do{\
    fprintf(stderr, "__%d__:", __LINE__);\
    perror(msg);\
}while(0)

#define PORT 8888
#define IP  "192.168.43.255"

int main(int argc, const char *argv[])
{
	//创建报式套接字
	int sfd = socket(AF_INET, SOCK_DGRAM, 0);
	if(sfd < 0)
	{
		ERR_MSG("socket");
		return -1;
	}

	//填充地址信息结构体,真是的地址信息结构体根据地址族制定
	//AF_INET :  man 7 ip
	struct sockaddr_in sin;
	sin.sin_family      = AF_INET;      //必须填AF_INET;
	sin.sin_port        = htons(PORT);  //端口号的网络字节序;1024~49151
	sin.sin_addr.s_addr = inet_addr(IP); //本机IP，ifconfig查看;
	//注意，切换网络环境后，IP地址是会改变的


	//绑定址信息结构体到套接字文件描述符上，必须绑定
	if(bind(sfd, (struct sockaddr*)&sin, sizeof(sin)) < 0)
	{
		ERR_MSG("bind");
		return -1;
	}
	printf("bind success\n");

	ssize_t res = 0;
	char buf[128] = "";

	struct sockaddr_in cin; 	//存储数据包的来源
	socklen_t addrlen = sizeof(cin);
	
	while(1)
	{
		bzero(buf, sizeof(buf));
		//接收, 接收信息的同时，接收该数据包从谁哪里来
		res = recvfrom(sfd, buf, sizeof(buf), 0, (struct sockaddr*)&cin, &addrlen);
		if(res < 0)
		{
			ERR_MSG("recvfrom");
			return -1;
		}
		printf("[%s:%d] : %s\n", inet_ntoa(cin.sin_addr), ntohs(cin.sin_port), buf);

		}
	//关闭文件描述符
	close(sfd);
	return 0;
}

广播接收端

#include <stdio.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <string.h>
#include <unistd.h>

#define ERR_MSG(msg) do{\
    fprintf(stderr, "__%d__:", __LINE__);\
    perror(msg);\
}while(0)

#define PORT 8888
#define IP  "192.168.43.255" 

int main(int argc, const char *argv[])
{
	//创建报式套接字
	int sfd = socket(AF_INET, SOCK_DGRAM, 0);
	if(sfd < 0)
	{
		ERR_MSG("socket");
		return -1;
	}
	//设置允许广播
	int broad = 1;
	if(setsockopt(sfd,SOL_SOCKET,SO_BROADCAST,&broad,sizeof(broad))<0)
	{
		ERR_MSG("setsockopt");
		return -1;
	}


	//填充服务器地址信息结构体
	//供给下面的sendto函数使用;
	struct sockaddr_in sin;
	sin.sin_family      = AF_INET;      //必须填AF_INET;
	sin.sin_port        = htons(PORT);  
	sin.sin_addr.s_addr = inet_addr(IP); 
	//注意，切换网络环境后，IP地址是会改变的

	char buf[128] = "";

	while(1)
	{
		bzero(buf, sizeof(buf));
		//发送,数据给服务器
		printf("请输入>>>");
		fgets(buf, sizeof(buf), stdin);
		buf[strlen(buf)-1] = 0;

		if(sendto(sfd, buf, sizeof(buf), 0, (struct sockaddr*)&sin, sizeof(sin)) < 0)
		{
			ERR_MSG("sendto");
			return -1;
		}
		printf("sendto success\n");
	}
	//关闭文件描述符
	close(sfd);
	return 0;
}

组播发送方

#include <stdio.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <string.h>
#include <unistd.h>

#define ERR_MSG(msg) do{\
    fprintf(stderr, "__%d__:", __LINE__);\
    perror(msg);\
}while(0)

#define PORT 8888
#define IP  "224.6.6.6" 

int main(int argc, const char *argv[])
{
	//创建报式套接字
	int sfd = socket(AF_INET, SOCK_DGRAM, 0);
	if(sfd < 0)
	{
		ERR_MSG("socket");
		return -1;
	}

	//填充服务器地址信息结构体
	//供给下面的sendto函数使用;
	struct sockaddr_in sin;
	sin.sin_family      = AF_INET;      //必须填AF_INET;
	sin.sin_port        = htons(PORT);  
	sin.sin_addr.s_addr = inet_addr(IP); 
	//注意，切换网络环境后，IP地址是会改变的

	char buf[128] = "";

	while(1)
	{
		bzero(buf, sizeof(buf));
		//发送,数据给服务器
		printf("请输入>>>");
		fgets(buf, sizeof(buf), stdin);
		buf[strlen(buf)-1] = 0;

		if(sendto(sfd, buf, sizeof(buf), 0, (struct sockaddr*)&sin, sizeof(sin)) < 0)
		{
			ERR_MSG("sendto");
			return -1;
		}
		printf("sendto success\n");
	}
	//关闭文件描述符
	close(sfd);
	return 0;
}

组播接收方

#include <stdio.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <string.h>
#include <unistd.h>
#include <net/if.h>
#define ERR_MSG(msg) do{\
    fprintf(stderr, "__%d__:", __LINE__);\
    perror(msg);\
}while(0)

#define PORT 8888
#define IP  "192.168.43.161"

#define GRP_IP "224.6.6.6"

int main(int argc, const char *argv[])
{
	//创建报式套接字
	int sfd = socket(AF_INET, SOCK_DGRAM, 0);
	if(sfd < 0)
	{
		ERR_MSG("socket");
		return -1;
	}

	//加入多播组
	struct ip_mreqn mq;
	mq.imr_multiaddr.s_addr = inet_addr(GRP_IP);//组播IP
	mq.imr_address.s_addr = inet_addr(IP);//本机IP
	mq.imr_ifindex = if_nametoindex("ens33");//设备索引号

	if(setsockopt(sfd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mq,sizeof(mq))<0)
	{
		ERR_MSG("setsockopt");
		return -1;
	}
	printf("加入多播组成功\n");

	//填充地址信息结构体,真是的地址信息结构体根据地址族制定
	//AF_INET :  man 7 ip
	struct sockaddr_in sin;
	sin.sin_family      = AF_INET;      //必须填AF_INET;
	sin.sin_port        = htons(PORT);  //端口号的网络字节序;1024~49151
	sin.sin_addr.s_addr = inet_addr(GRP_IP); //本机IP，ifconfig查看;
	//注意，切换网络环境后，IP地址是会改变的


	//绑定址信息结构体到套接字文件描述符上，必须绑定
	if(bind(sfd, (struct sockaddr*)&sin, sizeof(sin)) < 0)
	{
		ERR_MSG("bind");
		return -1;
	}
	printf("bind success\n");

	ssize_t res = 0;
	char buf[128] = "";

	struct sockaddr_in cin; 	//存储数据包的来源
	socklen_t addrlen = sizeof(cin);
	
	while(1)
	{
		bzero(buf, sizeof(buf));
		//接收, 接收信息的同时，接收该数据包从谁哪里来
		res = recvfrom(sfd, buf, sizeof(buf), 0, (struct sockaddr*)&cin, &addrlen);
		if(res < 0)
		{
			ERR_MSG("recvfrom");
			return -1;
		}
		printf("[%s:%d] : %s\n", inet_ntoa(cin.sin_addr), ntohs(cin.sin_port), buf);

		}
	//关闭文件描述符
	close(sfd);
	return 0;
}

搭建广播，组播

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