boradcast_sample.c

linux下udp实现广播的一个小程序

#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <stdio.h>
#include <errno.h>
#include <signal.h>

void sig_handle(int signum)
{
	return;
}

int main(int argc,char *argv[])
{
	
	char buffer[512];
	int bordcast_socket;
	int read_count=0;
	int addr_len=sizeof(struct sockaddr);
	struct sockaddr_in  addr_info,addr_net;
	int opt=1;
	if(argc!=2)
	{
		printf("Use page boradcast <ip address>\n");
		return -1;
	}
	addr_info.sin_family=AF_INET;
	addr_info.sin_addr.s_addr=inet_addr(argv[1]);
	addr_info.sin_port=htons(5555);
	bordcast_socket=socket(AF_INET,SOCK_DGRAM,0);
	if(bordcast_socket<0)
	{
		perror("bordcast_socket");
		return -1;
	}
	signal(SIGALRM,sig_handle);
	setsockopt(bordcast_socket,SOL_SOCKET,SO_BROADCAST,&opt,sizeof(opt));
	while(fgets(buffer,sizeof(buffer),stdin)!=NULL)
	{
		sendto(bordcast_socket,buffer,strlen(buffer),0,(struct sockaddr *)&addr_info,addr_len);
		alarm(5);
		memset(buffer,0,sizeof(buffer));
		for (; ; )
		{
			read_count=recvfrom(bordcast_socket,buffer,sizeof(buffer),0,(struct sockaddr *)&addr_net,&addr_len);
			if(read_count<0 && errno==EINTR)
			{
				continue;
			}
			else
			{
				printf("from %s\n",inet_ntoa(addr_net.sin_addr));
			}
		}		
	}
	return 0;
}