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Linux系统编程——DIY编写Linux中的FTP(客户端与服务器)

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代码内容:

Linux系统编程——DIY编写Linux中的FTP(客户端与服务器)


运行环境:

Linux


编程语言:

C语言


主要语法:

函数,指针,结构体
Linux套接字,进程,多种输入输出函数,网络编程,底层调用


功能:

客户端程序连接到服务器后,可通过ls,lls,pwd,put等多种指令操作服务器端文件,打印文件路径,下载上传文件


使用演示:

// 终端1
gcc ftp_server.c -o server
./server 192.168.3.8 8000
---
// 终端2
gcc ftp_client.c -o client
./client 192.168.3.8 8000
---
//可发送指令
ls
pwd
lls
lcd
quit
get xxx
put xxx

代码


ftp_server.c 服务器程序:

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

#define LS   0
#define GET  1
#define PWD  2
#define IFGO 3
#define LCD  4
#define LLS  5
#define CD   6
#define PUT  7
#define QUIT 8
#define DOFILE  9

struct Msg
{
        int type;
        char data[1024];
        char secondBuf[128];
};

int get_cmd_type(char *cmd)
{
	if(!strcmp("ls",cmd))		return LS;
	if(!strcmp("quit",cmd))		return QUIT;
	if(!strcmp("pwd",cmd))		return PWD;
	if(strstr(cmd,"cd")!=NULL)	return CD;
	if(strstr(cmd,"get")!=NULL)	return GET;
	if(strstr(cmd,"put")!=NULL)	return PUT;
	
	return 100;
}
//分割字符串
char *getDesDir(char *cmsg)
{
	char *p;
	p = strtok(cmsg,"");
	p = strtok(NULL,"");
	return p;
}

void msg_handler(struct Msg msg,int fd)
{
	char dataBuf[1024] = {0};
	char *file = NULL;
	int fdfile;
	
	//msg.data为数组字符串类型
	printf("cmd:%s\n",msg.data);
	//将字符串转换为整型数
	int ret = get_cmd_type(msg.data);

	switch(ret)
	{
		case LS:
		//输出当前路径
		case PWD:
			msg.type = 0;
			FILE *r = popen(msg.data,"r");
			fread(msg.data, sizeof(msg.data),1,r);
			write(fd, &msg, sizeof(msg));
			break;

		case CD:
			msg.type = 1;
			//分割字符串
			char *dir = getDesDir(msg.data);
			printf("dir:%s\n",dir);
			chdir(dir);
			break;
		case GET:
			//分割字符串
			file = getDesDir(msg.data);

			if(access(file,F_OK) == -1)
			{
				strcpy(msg.data,"No this file!");
				write(fd,&msg,sizeof(msg));
			}
			else
			{
				msg.type = DOFILE;
				fdfile = open(file,O_RDWR);
				read(fdfile,dataBuf,sizeof(dataBuf));
				close(fdfile);
				
				strcpy(msg.data,dataBuf);
				write(fd,&msg,sizeof(msg));
			}
			break;
		case PUT:
			fdfile = open(getDesDir(msg.data),O_RDWR|O_CREAT,0666);
			write(fdfile, msg.secondBuf, strlen(msg.secondBuf));
			close(fdfile);
			break;
		case QUIT:
			printf("client quit!\n");
			exit(-1);
	
	}
}

int main(int argc, char **argv)
{
	int s_fd;
	int c_fd;
	int n_read;
	char readBuf[128];

	struct sockaddr_in s_addr;
	struct sockaddr_in c_addr;
	struct Msg msg;

	if(argc != 3)
	{
		printf("Unqualified parameters!\n");
		exit(-1);
	}

	memset(&s_addr,0,sizeof(struct sockaddr_in));
	memset(&c_addr,0,sizeof(struct sockaddr_in));

	//1.socket
	s_fd = socket(AF_INET, SOCK_STREAM, 0);
	if(s_fd == -1)
	{
		perror("socket");
		exit(-1);
	}

	s_addr.sin_family = AF_INET;
	s_addr.sin_port = htons(atoi(argv[2]));
	inet_aton("argv[1]",&s_addr.sin_addr);

	//2.bind
	bind(s_fd,(struct sockaddr *)&s_addr,sizeof(struct sockaddr_in));

	//3.listen
	listen(s_fd,10);

	//4.accept
	int clen = sizeof(struct sockaddr_in);
	while(1)
	{
		c_fd = accept(s_fd,(struct sockaddr *)&c_addr,&clen);
		if(c_fd == -1)
			perror("accept");
		printf("get connect:%s\n",inet_ntoa(c_addr.sin_addr));
		//当新的客户端接入的时候才创建子进程
		//一个子进程负责一条连接通道	
		if(fork() == 0)
		{
			while(1)
			{
				memset(msg.data,0,sizeof(msg.data));
				//等待输入,将所有数据都传到msg结构体中
				n_read = read(c_fd,&msg,sizeof(msg));
				if(n_read == 0)
				{
					printf("client out\n");
					break;	
				}
				else if(n_read > 0)
				{
					msg_handler(msg,c_fd);	
				}
				
			}
		}
	
	}
	close(c_fd);
	close(s_fd);
	return 0;
}

ftp_client.c 客户端程序:

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

#define LS   0
#define GET  1
#define PWD  2
#define IFGO 3
#define LCD  4
#define LLS  5
#define CD   6
#define PUT  7
#define QUIT 8
#define DOFILE  9


struct Msg
{
        int type;
        char data[1024];
        char secondBuf[128];
};


char *getdir(char *cmd)
{
	char *p;
	p = strtok(cmd," ");
	p = strtok(NULL," ");
	return p;
}

int get_cmd_type(char *cmd)
{
	if(strstr(cmd,"lcd"))		return LCD;
	
	if(!strcmp("quit",cmd))		return QUIT;
	if(!strcmp("ls",cmd))		return LS;
	if(!strcmp("lls",cmd))		return LLS;
	if(!strcmp("pwd",cmd))		return LS;
		
	if(strstr(cmd,"cd"))		return CD;
	if(strstr(cmd,"get"))		return GET;
	if(strstr(cmd,"put"))		return PUT;

	return -1;
}

int cmd_handler(struct Msg msg, int fd)
{
	char *dir = NULL;
	char buf[32];
	int ret;
	int filefd;

	//将字符串转换为宏
	ret = get_cmd_type(msg.data);

	switch(ret)
	{
		case LS:
		case CD:
		case PWD:
			msg.type = 0;
			//发送给宏
			write(fd, &msg, sizeof(msg));
			break;
		case GET:
			msg.type = 2;
			write(fd, &msg,sizeof(msg));
			break;
		case PUT:
			strcpy(buf, msg.data);
			dir = getdir(buf);
			if(access(dir, F_OK) == -1)
			{
				printf("%s not exsit\n",dir);
			}
			else
			{
				filefd = open(dir, O_RDWR);
				read(filefd,msg.secondBuf,sizeof(msg.secondBuf));
				close(filefd);

				write(fd, &msg,sizeof(msg));
			}
			break;
		case LLS:
			system("ls");
			break;
		case LCD:
			dir = getdir(msg.data);
			chdir(dir);
			break;
		case QUIT:
			strcpy(msg.data,"quit");
			write(fd,&msg,sizeof(msg));
			close(fd);
			exit(-1);
	
	}
	return ret;
}

void handler_server_message(int c_fd,struct Msg msg)
{
	int n_read;
	struct Msg msgget;
	int newfilefd;

	//读取服务器数据
	n_read = read(c_fd, &msgget,sizeof(msgget));

	//连接断开
	if(n_read == 0)
	{
		printf("server is out,quit\n");
		exit(-1);
	}
	else if(msgget.type == DOFILE)
	{
		char *p = getdir(msg.data);
		newfilefd = open(p,O_RDWR|O_CREAT,0600);
		write(newfilefd,msgget.data,strlen(msgget.data));
		putchar('>');
		fflush(stdout);
	}
	else 
	{
		printf("--------------------------------------\n");
		printf("\n%s\n",msgget.data);
		printf("--------------------------------------\n");
		putchar('>');
		fflush(stdout);
	}
}

int main(int argc, char **argv)
{
	int c_fd;
	struct sockaddr_in c_addr;
	struct Msg msg;
	
	memset(&c_addr, 0, sizeof(struct sockaddr_in));
	
	if(argc != 3)
	{
		printf("param is not good\n");
		exit(-1);
	}

	//1.socket
	c_fd = socket(AF_INET, SOCK_STREAM, 0);
	if(c_fd == -1)
	{
		perror("socket");
		exit(-1);
	}

	c_addr.sin_family = AF_INET;
	c_addr.sin_port = htons(atoi(argv[2]));
	inet_aton("argv[1]", &c_addr.sin_addr);

	//2.connect
	if(connect(c_fd, (struct sockaddr *)&c_addr, sizeof(struct sockaddr)) == -1)
	{
		perror("connect");
		exit(-1);
	}
	printf("connect ...\n");
	int mark = 0;
	while(1)
	{
		memset(msg.data, 0, sizeof(msg.data));
		if(mark == 0) printf(">");
		
		//接收用户输入
		gets(msg.data);
		//规范格式
		if(strlen(msg.data) == 0)
		{
			if(mark == 1)
			{
				printf(">");
			}
			continue;
		}

		mark = 1;
	
		//调用处理
		int ret = cmd_handler(msg,c_fd);
		if(ret >IFGO)
		{
			putchar('>');
			fflush(stdout);
			continue;
		}
		if(ret == -1)
		{
			printf("command not \n");
			printf(">");
			fflush(stdout);
			continue;
		}
		handler_server_message(c_fd, msg);
	}
	return 0;

}

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