udp_recv_netparam.c

使用udp的broadcast方式写的c程序

/*************本程序用于创建服务端程序*****************/

#include <sys/types.h> 

#include <sys/socket.h> 

#include <netinet/in.h> 

#include <stdio.h> 

#include <errno.h> 

#include "msgstruct.h"

nettype *upd_receive_ip()

{ 

	int sockfd,n,addrlen,loop; 

	struct sockaddr_in server_addr;  /*服务器地址信息*/

	struct sockaddr_in client_addr;   /*客户端地址信息*/
	
	static nettype init;
	nettype * getmsg;
	getmsg = (nettype *)&init;

	sockfd=socket(AF_INET,SOCK_DGRAM,0); /*创建数据报套接字*/

	if(sockfd<0) { 
		printf("Socket Error:%s\n",strerror(errno)); 
		return NULL; 
	} 
	loop = 1;
	if(setsockopt(sockfd,SOL_SOCKET, SO_REUSEADDR,&loop, sizeof(loop)) < 0) { 
		perror("setsockopt:SO_REUSEADDR");
		exit(-1);
	}
	/* 服务器端填充 sockaddr_in结构 */
	bzero(&server_addr,sizeof(struct sockaddr_in)); 

	server_addr.sin_family=AF_INET; 
	server_addr.sin_addr.s_addr=htonl(INADDR_ANY); 

	server_addr.sin_port=htons(UDP_PORT); 

	/*绑定套接字*/
	if(bind(sockfd,(struct sockaddr *)&server_addr,sizeof(struct sockaddr))<0) { 
		printf("Bind Error:%s\n",strerror(errno)); 
		return NULL;	
	}

	addrlen=sizeof(struct sockaddr);
	n=recvfrom(sockfd,getmsg,sizeof(nettype),0,(struct sockaddr *)&client_addr,&addrlen); 
	//printf("Got packet from %s\n The Num. of packet is:%d\n",inet_ntoa(client_addr.sin_addr),n);
	close(sockfd);
	return getmsg;
}