FTP云盘项目

本文详细介绍了如何实现TCP/IP通信的服务端和客户端。服务端通过socket监听连接,接收并处理客户端请求,包括文件操作(如ls、cd、get、put等)。客户端则向服务端发送命令,进行文件传输或执行服务器端的操作。主要涉及的函数有change(命令解析)、getbehind(获取文件路径)、getmessage和putmessage(文件传输)。整个过程涉及文件读写、网络通信和系统调用。

学习参考文章:
链接: https://blog.youkuaiyun.com/qq_46518045/article/details/113482400.
ls:查看当前文件
lls:查看服务器文件
cd+空格+文件名(…),服务器进入文件夹或返回上一级
lcd+空格+文件名(…),本地进入文件夹或返回上一级
get+空格+文件名:得到服务器文件
put+空格+文件名: 发送给服务器

服务端:

#include<stdio.h>
#include<sys/types.h>          /* See NOTES */
#include<sys/socket.h>
#include<arpa/inet.h>
#include<netinet/in.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<sys/stat.h>
#include<fcntl.h>

int change(char cmd[128])//change函数负责获取发送过来的指令,将之转化为整数。strcmp,strstr
{
	if(!strcmp("lls",cmd))
	{  
		return 1;
	}
	else if(strstr(cmd,"lcd")!=NULL)
	{   return 2;
	}
	else if(!strcmp("g",cmd))
	{   return 3;
	}
	else if(!strcmp("ls",cmd))
	{   return 4;
	}
    else if(strstr(cmd,"cd")!=NULL)
    {   return 5;
    }
	else if(strstr(cmd,"get")!=NULL)
	{  
	    return 6;
	}     
	else if(strstr(cmd,"put")!=NULL)
	{   return 7;
	}

}              

char *getbehind(char cmd[128])//char *strtok(char s[], const char *delim);分解字符串为一组字符串。s为要分解的字符串,delim为分隔符字符串。
{
        char *p;
        p = (char *)malloc(128);//获取文件路径名
        p  = strtok(cmd," ");
        p = strtok(NULL," ");
        return p;

}

void getmessage(char cmd[128],int cfd)
{
	
	char readbuf[8000];
    char *p=getbehind(cmd);
	read(cfd,readbuf,8000);
	if(strlen(readbuf) != strlen("NO file")){
        int fd = open(p,O_RDWR|O_CREAT,0666);//读写文件操作,open函数 int open(const char *pathname, int flags,mode_t mode);
        write(fd,readbuf,strlen(readbuf));
	    printf("receive successfully\n");
        close(fd);
		memset(readbuf,0,8000);
	}
	else{
		printf("NO file\n");
		}

}
void putmessage(char cmd[128],int c_fd)
{
		int sfd;
	    char *p = (char *)malloc(8000);
		memset(p,0,8000);
		char *readbuf = (char *)malloc(128);
		readbuf = getbehind(cmd);
        if(access(readbuf,F_OK) == -1){
			printf("No file\n");//F_OK 值为0,判断文件是否存在
        }
        else{
            sfd = open(readbuf,O_RDWR,0666);
            read(sfd,p,8000);
            write(c_fd,p,strlen(p));
            close(sfd);
            memset(p,0,8000);
        }

}
void choosecmd(char cmd[128],int c_fd)
{
        FILE *fdb;
        int ret = change(cmd);
        char freadbuf[128];
        char *p = (char *)malloc(8000);
        switch(ret){
		case 1: 
			system("ls");
			break;
		case 2:
			p = getbehind(cmd);
            chdir(p);// int chdir(const char *path);//函数说明:chdir()用户将当前的工作目录改变成以参数路径所指的目录。
            memset(p,0,8000);
			break;
		case 3: 
			printf("unconnecting\n");
			write(c_fd,"away host",128);
			close(c_fd);
			exit(-1);
			break;
		case 4:	
			read(c_fd,p,1024);
            printf("%s\n",p);                       
            memset(p,0,1024);          
			break;
		case 5:
			printf("host folder open or exit successful\n");
			break;		
		case 6: 
			getmessage(cmd,c_fd);
            break;
		case 7:  
			putmessage(cmd,c_fd);
			break;
		}
}
int main(int argc,char **argv)
{
//socket
	struct sockaddr_in s_addr;
	struct sockaddr_in c_addr;
	char Writebuf[128];
	char Readbuf[128];
	int nread;
	int clen;
	int s_fd;
	int c_fd;
	s_fd =  socket(AF_INET, SOCK_STREAM,0);
	if(s_fd == -1){
		perror("socket");
		exit(-1);
		}
	if(argc!=3){
		perror("argc");
		exit(0);
			}
	memset(&s_addr,0,sizeof(struct sockaddr_in));
	s_addr.sin_family = AF_INET;
	s_addr.sin_port = htons(atoi(argv[2]));
	inet_aton(argv[1],&s_addr.sin_addr);
//bind
	bind(s_fd,(struct sockaddr *)&s_addr,sizeof(struct sockaddr_in));
//listen
	listen(s_fd,10);

//accept
	printf("wait connecting\n");
	memset(&c_addr,0,sizeof(struct sockaddr_in));
	clen = sizeof(struct sockaddr_in);
    while(1){
		c_fd = accept(s_fd,(struct sockaddr *)&c_addr,&clen);
		if(c_fd == -1){
			perror("accept");
			exit(-1);
		}
		printf("connect,%s\n",inet_ntoa(c_addr.sin_addr));
//read
		if(fork() == 0){					 
			while(1){
      			nread = read(c_fd, Readbuf,128);
				choosecmd(Readbuf,c_fd);
   	//	printf("nread:%d,get from IP context:%s\n",nread,Readbuf);
				memset(Readbuf,0,sizeof(Readbuf));
			}
		}		
	}
	return 0;
}

客户端:

#include<stdio.h>
#include<sys/types.h>          /* See NOTES */
#include<sys/socket.h>
#include<arpa/inet.h>
#include<netinet/in.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<sys/stat.h>
#include<fcntl.h>

//lls,lcd分别命令服务端测ls,cd指令。
int change(char cmd[128])//change函数负责获取发送过来的指令,将之转化为整数。strcmp,strstr
{
	if(!strcmp("lls",cmd))	
	{  
	    return 1;
	}
	else if(strstr(cmd,"lcd")!=NULL)	
	{  
		return 2;
	}
	else if(!strcmp("g",cmd))
	{   
		return 3;
	}
	else if(!strcmp("ls",cmd))             
	{   
		return 4;
	}
    else if(strstr(cmd,"cd")!=NULL)
    {   
    	return 5;
    }
	else if(strstr(cmd,"get")!=NULL)	
	{ 
	    return 6;
	}     
	else if(strstr(cmd,"put")!=NULL) 
	{   
		return 7;
	}


}              

char *getbehind(char cmd[128])//char *strtok(char s[], const char *delim);分解字符串为一组字符串。s为要分解的字符串,delim为分隔符字符串。
{
        char *p;
        p = (char *)malloc(128);//获取文件路径名
        p  = strtok(cmd," ");
        p = strtok(NULL," ");
        return p;

}

void getmessage(char cmd[128],int cfd)
{
	
	char readbuf[8000];
    char *p=getbehind(cmd);
	read(cfd,readbuf,8000);
	if(strlen(readbuf) != strlen("NO file")){
        int fd = open(p,O_RDWR|O_CREAT,0666);//读写文件操作,open函数 int open(const char *pathname, int flags,mode_t mode);
        write(fd,readbuf,strlen(readbuf));
	    printf("receive successfully\n");
        close(fd);
		memset(readbuf,0,8000);
	}
	else{
		printf("NO file\n");
		}

}
void putmessage(char cmd[128],int c_fd)
{
		int sfd;
	    char *p = (char *)malloc(8000);
		memset(p,0,8000);
		char *readbuf = (char *)malloc(128);
		readbuf = getbehind(cmd);
        if(access(readbuf,F_OK) == -1){
			printf("No file\n");
        }
        else{
            sfd = open(readbuf,O_RDWR,0666);
            read(sfd,p,8000);
            write(c_fd,p,strlen(p));
            close(sfd);
            memset(p,0,8000);
        }

}
void choosecmd(char cmd[128],int c_fd)
{
        FILE *fdb;
        int ret = change(cmd);
        char freadbuf[128];
        char *p = (char *)malloc(8000);
        switch(ret){
		case 1: 
			system("ls");
			break;
		case 2:
			p = getbehind(cmd);
            chdir(p);// int chdir(const char *path);
            memset(p,0,8000);
			break;
		case 3: 
			printf("unconnecting\n");
			write(c_fd,"away host",128);
			close(c_fd);
			exit(-1);
			break;
		case 4:	
			read(c_fd,p,1024);
            printf("%s\n",p);                       
            memset(p,0,1024);          
			break;
		case 5:
			printf("host folder open or exit successful\n");
			break;		
		case 6: 
			getmessage(cmd,c_fd);
            break;
		case 7:  
			putmessage(cmd,c_fd);
			break;
		}
}

//       int socket(int domain, int type, int protocol);
int main(int argc,char **argv)
{
//socket
	char Readbuf[1024];
	char Writebuf[128];
	struct sockaddr_in c_addr;
	int clent;
	int c_fd;
	int nread;
	char buf[256];
	if(argc != 3){
		perror("argc");
		exit(1);
	}
	c_fd =  socket(AF_INET, SOCK_STREAM,0);
	if(c_fd == -1){
		perror("socket");
		exit(-1);
	}
	memset(&c_addr,0,sizeof(struct sockaddr_in));
	c_addr.sin_family = AF_INET;
	c_addr.sin_port = htons(atoi(argv[2]));
	inet_aton(argv[1],&c_addr.sin_addr);
//connect
//	int connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
	clent = sizeof(struct sockaddr_in);
	if(connect(c_fd,(struct sockaddr *)&c_addr,clent)){
		perror("connect");
		exit(-1);
	}
//write send
	printf("connect...\n");
	while(1){
		gets(Writebuf);
        printf("cmd:%s\n",Writebuf);
		write(c_fd,Writebuf,strlen(Writebuf));
		choosecmd(Writebuf,c_fd);
		printf("*cmd*\n");	
		memset(Writebuf,0,strlen(Writebuf));
	}
	return 0;
}

代码讲解:
1.首先change函数将各种命令(字符串形式转化为整形数字,方便choosecmd函数使用)
2.char*函数getbehind获取文件的路径名,如"cd /GYJ"命令,该函数获取到"/GYJ"路径名
3.getmessage函数,从cfd标识符对应的文件中读取内容,
4.putmessage函数,先判断文件是否存在,将读到的p写入c_fd中,
5.choose函数根据change函数转化为的整形,执行相应的命令。
Main函数中,传ip地址,端口号。
首先根据上几节的内容,搭建服务端和客户端,服务端,while(1)不断收到连接请求,一旦收到请求,立刻创建一个子进程去执行choosecmd函数。
客户端不断向服务端发送请求。

(师上官可编程)
(参考kpler)

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