UDP 广播的发送和接收

// 接收端
 
#include <iostream>
#include <stdio.h>
#include <sys/socket.h>
#include <unistd.h>
#include <sys/types.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
 
 
using namespace std;
 
int main()
{
	// 绑定地址
	struct sockaddr_in addrto;
	bzero(&addrto, sizeof(struct sockaddr_in));
	addrto.sin_family = AF_INET;
	addrto.sin_addr.s_addr = htonl(INADDR_ANY);
	addrto.sin_port = htons(6000);
	
	// 广播地址
	struct sockaddr_in from;
	bzero(&from, sizeof(struct sockaddr_in));
	from.sin_family = AF_INET;
	from.sin_addr.s_addr = htonl(INADDR_ANY);
	from.sin_port = htons(6000);
	
	int sock = -1;
	if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) 
	{   
		cout<<"socket error"<<endl;	
		return false;
	}   
 
	if(bind(sock,(struct sockaddr *)&(addrto), sizeof(struct sockaddr_in)) == -1) 
	{   
		cout<<"bind error..."<<endl;
		return false;
	}
 
	int len = sizeof(sockaddr_in);
	char smsg[100] = {0};
 
	while(1)
	{
		//从广播地址接受消息
		int ret=recvfrom(sock, smsg, 100, 0, (struct sockaddr*)&from,(socklen_t*)&len);
		if(ret<=0)
		{
			cout<<"read error...."<<sock<<endl;
		}
		else
		{		
			cout<<smsg<<endl;	
		}
 
		sleep(1);
	}
 
	return 0;
}

// 发送端

#include <iostream>
#include <stdio.h>
#include <sys/socket.h>
#include <unistd.h>
#include <sys/types.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
 
using namespace std;
 
int main()
{
	int sock = -1;
	if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) 
	{   
		cout<<"socket error"<<endl;	
		return false;
	}   
	
	const int opt = 1;
	//设置该套接字为广播类型，
	int nb = 0;
	nb = setsockopt(sock, SOL_SOCKET, SO_BROADCAST, (char *)&opt, sizeof(opt));
	if(nb == -1)
	{
		cout<<"set socket error..."<<endl;
		return false;
	}
 
	struct sockaddr_in addrto;
	bzero(&addrto, sizeof(struct sockaddr_in));
	addrto.sin_family=AF_INET;
	addrto.sin_addr.s_addr=htonl(INADDR_BROADCAST);
	addrto.sin_port=htons(6000);
	int nlen=sizeof(addrto);
 
	while(1)
	{
		sleep(1);
		//从广播地址发送消息
		char smsg[] = {"abcdef"};
		int ret=sendto(sock, smsg, strlen(smsg), 0, (sockaddr*)&addrto, nlen);
		if(ret<0)
		{
			cout<<"send error...."<<ret<<endl;
		}
		else
		{		
			cout<<"ok"<<endl;	
		}
	}
 
	return 0;
}