Udp广播消息

#include<stdio.h>

#include <winsock2.h>

#pragma comment (lib,"ws2_32")

#include "stdafx.h"

#define PORT 51654

#include <windows.h>

#include <stdlib.h>#include<sys/scoket.h>

//8750_2.html

int main(int argc,char* argv[])

{

int sockfd;

struct sockaddr_in their_addr;

struct in_addr addr;

struct hostent *he;

int broadcast = 1;

int num = 0;

if(argc != 3)

{

fprintf(stderr,"Usage: broadcase hostname message/n");

exit(1);

}

if( inet_aton(argv[1],&addr) == 0)

{

he = gethostbyname(argv[1]); //Domain

addr.s_addr = (*(unsigned int *)*he->h_addr_list[0]);

}

if( (sockfd = socket(AF_INET,SOCK_DGRAM,0)) == -1 )

{

perror("socket function!/n");

exit(1);

}

if( setsockopt(sockfd,SOL_SOCKET,SO_BROADCAST,&broadcast,sizeof(broadcast)) == -1)

{

perror("setsockopt function!/n");

exit(1);

}

their_addr.sin_family = AF_INET;

their_addr.sin_port = htons(PORT);

their_addr.sin_addr = addr;

if( (num = sendto( sockfd,argv[2],strlen(argv[2]),0,(struct sockaddr *)&their_addr,sizeof(struct sockaddr) )) == -1)

{

perror("sendto function!/n");

exit(1);

}

printf("Send %d bytes to %s/n",num,inet_ntoa(their_addr.sin_addr) );

close(sockfd);

return 0;

}