/*客戶程序client.c*/
#include <stdio.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/socket.h>
#include <unistd.h>
#include <netinet/in.h>
//#include <unp.h>
#define MYPORT 4950
#define MAXSIZE 80

void str_cli1(FILE *fp,int sockfd,struct sockaddr_in *addr,int addrlen);
int main(int argc,char *argv[])
{
  	int sockfd,ret,len;
	struct sockaddr_in ser_addr;
	char *myname;
	struct hostent *sh;
	struct sockaddr_in their_addr;
	struct in_addr **addrs;
	if(argc!=2){
		printf("parameters not match.");
		exit(0);
	}
		/* 判斷參數是否匹配*/

	if((sh=gethostbyname(argv[1]))==NULL){
		printf("error when gethostbyname");
		exit(0);
	}
		/*根據服務器名獲得詳細消息*/
	sockfd=socket(AF_INET,SOCK_STREAM,0	);
  	if(sockfd<0){
		printf("error in socket");
		exit(1);
	}
		/*創建套接口 */

	their_addr.sin_family=AF_INET;
	their_addr.sin_port=htons(MYPORT);
	their_addr.sin_addr=*((struct in_addr *)sh->h_addr);
	bzero(&(their_addr.sin_zero),8);
	str_cli1(stdin,sockfd,&their_addr,sizeof(struct sockaddr_in));
		/*數據傳輸處理 */
	close(sockfd);
	exit(0);
}

void str_cli1(FILE *fp,int sockfd,struct sockaddr_in *addr,int addrlen)
{
	char sends[MAXSIZE],recvs[MAXSIZE];
	int n=0;

	while(fgets(sends,MAXSIZE,	fp)!=NULL)
	{
		sendto(sockfd,sends,strlen(sends),0,addr,addrlen);
		if((n=recvfrom(sockfd,recvs,MAXSIZE,0,NULL,NULL))==0){
			printf("error receiving data");
			exit(1);
		}
		recvs[n]=0;
			/*加上字符串結束標記 */
		fputs(recvs,stdout);
	}
}

/*服務器程序server.c如下*/

#include <stdio.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <unistd.h>
//#include "unp.h"
#define MYPORT 4950
#define MAXSIZE 80
#define SA struct sockaddr

void str_ser1(int sockfd);
main1()
{
	int sockfd;
	struct sockaddr_in my_addr;
	struct sockaddr_in their_addr;
	int addr_len;

	if((sockfd=socket(AF_INET,SOCK_DGRAM,0))==-1){
		printf("error in socket");
		exit(1);
	}
		/*創建UDP套接口 */
	my_addr.sin_family=AF_INET;
	my_addr.sin_port=htons(MYPORT);
	my_addr.sin_addr.s_addr=INADDR_ANY;
	bzero(&(my_addr.sin_zero),8);
	if(bind(sockfd,(SA *)&my_addr,sizeof(struct sockaddr))==-1)
	{
		printf("error in binding");
		exit(1);
	}
		/*綁定套接口 */

	str_ser1(sockfd);
		/*數據傳輸處理 */
	close(sockfd);
	exit(1);
}
#define true 1
void str_ser1(int sockfd)
{
	char recvs[MAXSIZE];
	int n=0,len;
	struct sockaddr *addr;

	while(true)
	{
		len=sizeof(struct sockaddr_in);
		if((n=recvfrom(sockfd,recvs,MAXSIZE,	0,addr,&len))== -1){
			printf("error receiving");
			exit(1);
		}
		sendto(sockfd,recvs,n,0,addr,len);
  	}
}