C language implements broadcasting (udp protocol)

16469129:

Broadcast: As the name implies, you can send your own data to everyone within a specific range; the broadcast in our network programming generally sends your own data to the currently online client in the LAN through a specific broadcast address

We can use the command to view our current broadcast address under Linux: ifconfig

We only need to send data to this broadcast address, and other online clients in the current LAN can receive this information

code:

/*
	使用udp实现广播功能：当我们执行代码时：
				./file send----》执行发送广播代码
				./file recv----》执行接收广播代码
	默认端口为：9999
*/
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>

int broadcast_send(int port)
{
    
    
	//1.创建udp套接字
	int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
	if(sockfd < 0)
	{
    
    
		perror("socket error");
		return  -1;
	}
	//2.开启广播
	int on=1;
	int ret = setsockopt(sockfd,  SOL_SOCKET, SO_BROADCAST, &on, sizeof(on));
	if(ret < 0)
	{
    
    
		perror("setsockopt error");
		goto err;
	}

	//3.发送数据到广播地址
	char buffer[]="hello world";
	struct sockaddr_in dest_addr;
	memset(&dest_addr, 0, sizeof(dest_addr));
	dest_addr.sin_family = AF_INET;//地址族IPV4
	dest_addr.sin_port = htons(port);//设置端口号
	dest_addr.sin_addr.s_addr = inet_addr("192.168.19.255");//设置广播地址
	
	//把数据发往广播地址
	ret = sendto(sockfd, buffer, sizeof(buffer), 0, (struct sockaddr*)&dest_addr, sizeof(dest_addr));
	if(ret < 0)
	{
    
    
		perror("sendto error");
		goto err;
	}
err:
	//4.关闭套接字
	close(sockfd);
	return 0;
}

int broadcast_recv(int port)
{
    
    
	
	//1.创建udp套接字
	int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
	if(sockfd < 0)
	{
    
    
		perror("socket error");
		return -1;
	}
	//设置端口地址复用
	int on=1;
	int rt = setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
	if(rt < 0)
	{
    
    
		perror("setsockopt error");
		goto recverr;
	}



	//2.绑定地址
	struct sockaddr_in src_addr;
	memset(&src_addr, 0, sizeof(src_addr));
	src_addr.sin_family = AF_INET;//地址族IPV4
	src_addr.sin_port = htons(port);//设置端口号
	src_addr.sin_addr.s_addr = htonl(INADDR_ANY);

	int ret = bind(sockfd, (struct sockaddr*)&src_addr, sizeof(src_addr));
	if(ret < 0)
	{
    
    
		perror("bind error");
		goto recverr;
	}


	//3.接收数据
	char buffer[128]={
    
    0};
	struct sockaddr_in sendaddr;
	socklen_t len = sizeof(sendaddr);

	ret  = recvfrom(sockfd, buffer, sizeof(buffer), 0, (struct sockaddr*)&sendaddr, &len);
	if(ret < 0)
	{
    
    
		perror("recvfrom error");
		goto recverr;
	}
	printf("接到数据:%s\n", buffer);
recverr:
	//4.关闭套接字
	close(sockfd);
	return 0;
}

//主函数入口
int main(int argc, char **argv)
{
    
    
	if(argc >= 2 && strcmp(argv[1],"send")==0)
		broadcast_send(9999);
		
	if(argc >= 2 && strcmp(argv[1],"recv")==0)
		broadcast_recv(9999);
	return 0;
}