Linux网络编程——UDP通信（文件传输）
实验二 UDP数据发送与接收
【实验目的】
1、熟练掌握套接字函数的使用方法。
2、应用套接字函数完成基本UDP通讯，实现服务器与客户端的文件传送
【实验学时】
4学时
【实验内容】
要求：
（1）客户可以从服务器下载文件、或向服务器上传文件。
（2）客户可向服务器发送多种指令：DOWNLOAD、UPLOAD、YES、NO、START、END、SHUTDOWN、CONTENT、OKDOWLOAD格式：DOWLOAD [filename]表示从服务器下载filename文件，如果服务器存在该文件，返回YES，否则返回NO；客户接收如果是YES，可发送START表示开始下载，之后，服务器将文件传送给客户，客户接收并保存；UPLOAD格式：UPLOAD [filename]表示向服务器上传filename文件，服务器发送NO表示拒绝接收。服务器发送START表示开始传送，之后向服务器传输文件；END:表示文件传送结束SHUTDOWN:表示通讯结束，双方退出。
实验流程如下：
protocol.h:
#ifndef _protocol
#define _protocol
#define INFOLEN 1000
#define SHUTDOWN 0
#define DOWNLOAD 1
#define UPLOAD 2
#define YES 3
#define NO 4
#define START 5
#define END 6
#define CONTENT 7
#define OK 8
struct protocol
{
int command;
int len; //length of buf
int no;
char buf[INFOLEN];
};
#endif
server:
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<unistd.h>
#include"protocol.h"
int main()
{
int sockfd;
struct sockaddr_in server;
struct sockaddr_in client;
int len=sizeof(client);
int port;
char ip[20];
//sock
sockfd=socket(AF_INET, SOCK_DGRAM, 0);
printf("client ip: ");
scanf("%s", ip);
printf("server port: ");
scanf("%d", &port);
bzero(&server, sizeof(server));
server.sin_family=AF_INET;
server.sin_port=htons(port);
server.sin_addr.s_addr=inet_addr(ip);
//bind
bind(sockfd, (struct sockaddr *)&server, sizeof(server));
//sendto/recvfrom
struct protocol pro;
while(1)
{
int a;
int num=recvfrom(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server,&len);
printf("command= %d\n",pro.command);
int i=pro.command;
switch(i)
{
case 1:
a=access(pro.buf,F_OK);
if(a!=-1)
{
pro.command=3;
sendto(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server ,sizeof(server));
num=recvfrom(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server,&len);
if(pro.command==5)
{
FILE *fd;
pro.no=0;
fd=fopen(pro.buf,"r+");
if(fd==NULL)
{
perror("create file error");
exit(1);
}
else
{
int f;
while((f=fread(pro.buf,1,1000,fd)) !=0)
{
pro.command = 7;
pro.len=f;
sendto(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server ,sizeof(server));
pro.no++;
bzero(&pro.buf,1000);
}
bzero(&pro.buf,1000);
pro.command = 6;
sendto(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server ,sizeof(server));
}
}
}
else
{
printf("no such file!\n");
}
case 2:
num=recvfrom(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server,&len);
pro.command=3;
int no=0;
sendto(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server ,sizeof(server));
FILE *fd;
fd=fopen(pro.buf,"w+");
if(fd==NULL)
{
perror("create file error");
exit(1);
}
else{
while((num=recvfrom(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server,&len))>0)
{
if(pro.command==7&&pro.no==no)
{
fwrite(pro.buf,1,pro.len,fd);
no++;
}
else if(pro.command==6)
{
break;
}
bzero(&pro.buf,1000);
}
}
fclose(fd);
break;
}
}
//close
close(sockfd);
return 0;
}
client:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
#include "protocol.h"
int main()
{
int sockfd;
struct sockaddr_in server;
int len=sizeof(server);
int port;
char ip[20];
//sock
if((sockfd=socket(AF_INET,SOCK_DGRAM,0))==-1)
{
perror("socket error");
exit(1);
}
printf("server ip:");
scanf("%s",ip);
printf("server port:");
scanf("%d",&port);
bzero(&server,sizeof(server));
server.sin_family=AF_INET;
server.sin_port=htons(port);
server.sin_addr.s_addr=inet_addr(ip);
//sendto/recvfrom
char buf[100];
int num;
while(1)
{
printf("------------------------------\n");
printf("--------input a number--------\n");
printf("--------1:DOWNLOAD------------\n");
printf("--------2:UPLOAD--------------\n");
printf("--------3:SHUTDOWN------------\n");
printf("------------------------------\n");
int s;
char p[10];
printf("input you switch :");
scanf("%d",&s);
int shut=0;
struct protocol pro;
switch(s)
{
case 1:
printf("input download filename:");
scanf("%s",pro.buf);
pro.command=1;
sendto(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server ,sizeof(server));
num=recvfrom(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server,&len);
if(pro.command==3)
{
pro.command=5;
sendto(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server ,sizeof(server));
FILE *fd;
fd=fopen(pro.buf,"w+");
int no=0;
if(fd==NULL)
{
perror("create file error");
exit(1);
}
else
{
bzero(&pro.buf,1000);
while((num=recvfrom(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server,&len))>0)
{
if(pro.command==7&&pro.no==no)
{
fwrite(pro.buf,1,pro.len,fd);
}
else if(pro.command==6)
{
printf("file downover\n");
break;
}
no++;
}
}
fclose(fd);
}
else
printf("from server:no file\n");
break;
case 2:
len=sizeof(server);
bzero(&pro.buf,1000);
printf("input Upload filename:");
scanf("%s",pro.buf);
pro.command=2;
sendto(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server ,sizeof(server));
num=recvfrom(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server,&len);
printf("command %d\n",pro.command);
if(pro.command==3)
{
FILE *fd;
pro.no=0;
fd=fopen(pro.buf,"r+");
if(fd==NULL)
{
perror("create file error");
exit(1);
}
else
{
int f;
bzero(&pro.buf,1000);
while((f=fread(pro.buf,1,1000,fd))!=0)
{
pro.command=7;
pro.len=f;
sendto(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server ,sizeof(server));
pro.no++;
}
pro.command=6;
sendto(sockfd,(struct protocol *)&pro,sizeof(struct protocol),0,(struct sockaddr *)&server ,sizeof(server));
}
fclose(fd);
}
break;
case 3:
exit(1);
break;
default:
printf("input a right number\n");
}
}
close(sockfd);
return 0;
}版权声明：本文为博主原创文章，未经博主允许不得转载。
