socket网络编程-FTP

最新推荐文章于 2025-06-11 10:40:24 发布

杨映春

最新推荐文章于 2025-06-11 10:40:24 发布

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文章标签： unix 网络

本文链接：https://blog.youkuaiyun.com/Yangyingchungood/article/details/116403902

版权

本文档展示了如何使用C语言实现一个简单的FTP服务器和客户端。服务器端通过`config.h`配置宏来处理不同类型的FTP命令，如`ls`、`pwd`、`cd`、`get`等，并通过`popen`、`chdir`、`access`等系统调用来执行相应操作。客户端则负责发送命令并接收服务器响应，处理包括文件上传、下载在内的各种请求。整个系统通过套接字进行通信。

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config.h头文件

#define LS      0
#define GET     1
#define PWD     2

#define IFGO    3

#define CD      4
#define LCD     5
#define LLS     6
#define PUT     7
#define QUIT    8
#define DOFILE  9

struct Msg{
        int type;
        char cmd[1024];
        char sendBuf[1024];
};

server服务器

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

char *getDesDir(char *cmd)  //分割传参的数据，获得可执行的命令
{
	char *p;
	p = strtok(cmd," ");   //分割函数
	p = strtok(NULL," ");
	return p;
}

int get_cmd_type(char *cmd)    //识别具体是什么执行指令，返回自定义能处理的宏
{
	if(strcmp("ls",cmd) == 0){ return LS;}
	if(strcmp("pwd",cmd) == 0){ return PWD;}
	if(strcmp("quit",cmd) == 0){ return QUIT;}
	
	if(strstr(cmd,"cd") != NULL){ return CD;}
	if(strstr(cmd,"get") != NULL){ return GET;}
	if(strstr(cmd,"put") != NULL){ return PUT;}

	return 100;
}

void msg_handler(struct Msg msg, int fd)   //具体处理传参的可执行指令的函数
{
	char *file = NULL;
	int fdfile;
	char cmdBuf[1024] = {0};

	printf("cmd:%s\n",msg.cmd);
	int ret = get_cmd_type(msg.cmd);
	switch(ret){
		case LS:
		case PWD:
			msg.type = 0;
			FILE *r = popen(msg.cmd, "r");
			fread(msg.cmd, sizeof(msg.cmd), 1, r);
			write(fd, &msg, sizeof(msg));
			pclose(r);
			break;
		case CD:
			msg.type = 1;
			char *dir = getDesDir(msg.cmd);
			printf("dir:%s\n",dir);
			chdir(dir);
			break;
		case GET:
			file = getDesDir(msg.cmd);
			if(access(file, F_OK) == -1){
				strcpy(msg.cmd, "No This File");
				write(fd, &msg, sizeof(msg));
			}else{
				msg.type = DOFILE;
				fdfile = open(file, O_RDWR);
				read(fdfile, cmdBuf, sizeof(cmdBuf));
				close(fdfile);
				strcpy(msg.cmd,cmdBuf);
				write(fd, &msg, sizeof(msg));
			}
			break;
		case PUT:
			fdfile = open(getDesDir(msg.cmd),O_RDWR|O_CREAT,0666);
			write(fdfile, msg.sendBuf, strlen(msg.sendBuf));
			close(fdfile);
			break;
		case QUIT:
			printf("client quit!");
			exit(-1);
	}
}

int main(int argc, char **argv)
{
	int s_fd;
	int c_fd;
	
	int n_read;
	struct Msg msg;

	struct sockaddr_in s_addr;
	struct sockaddr_in c_addr;
	
	if(argc !=3){
		printf("param is not good\n");
		exit(-1);
	}
	
	memset(&s_addr, 0, sizeof(struct sockaddr_in));
	memset(&c_addr, 0, sizeof(struct sockaddr_in));

	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);
	
	bind(s_fd, (struct sockaddr *)&s_addr, sizeof(struct sockaddr_in));
	
	listen(s_fd, 10);
	
	int clen = sizeof(struct sockaddr_in);

	printf("Waiting for client conneciton...\n");
	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));
		if(fork() == 0){
			while(1){
				memset(msg.cmd, 0, sizeof(msg.cmd));
				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;
}

client客户端

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

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

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

	return -1;
}

int cmd_handler(struct Msg msg, int fd)
{
	char buf[32] = {0};
	char *dir = NULL;
	int filefd;
	int ret = get_cmd_type(msg.cmd);
	
	switch(ret){
		case LS:
		case CD:
		case PWD:
			msg.type = 0;
			write(fd, &msg, sizeof(msg));
			break;
		case GET:
			msg.type = 2;
			write(fd, &msg, sizeof(msg));
			break;
		case PUT:
			strcpy(buf, msg.cmd);
			dir = getDir(buf);
			if(access(dir,F_OK) == -1){
				printf("%s not exsit\n",dir);
			}else{
				filefd = open(dir, O_RDWR);
				read(filefd, msg.sendBuf, sizeof(msg.sendBuf));
				close(filefd);
				write(fd, &msg, sizeof(msg));
			}
			break;
		case LLS:
			printf("——————————————————————————————————————\n");
			system("ls");
			printf("——————————————————————————————————————\n");
			break;
		case LCD:
			dir = getDir(msg.cmd);
			chdir(dir);
			break;
		case QUIT:
			strcpy(msg.cmd, "client quit!");
			write(fd, &msg, sizeof(msg));
			close(fd);
			exit(-1);
	}

	return ret;
}

void handler_server_message(struct Msg msg, int fd)  //  打印输入后的处理结果
{
	int n_read;
	struct Msg msgGet;
	int newfilefd;

	n_read = read(fd, &msgGet, sizeof(msgGet));
	if(n_read == 0){
		printf("server is out! quit\n");
		exit(-1);
	}else if(msgGet.type == DOFILE){
		char *p = getDir(msg.cmd);
		newfilefd = open(p, O_RDWR|O_CREAT,0600);
		write(newfilefd, msgGet.cmd, strlen(msgGet.cmd));
		putchar('>');
		fflush(stdout);
	}else{
		printf("——————————————————————————————————————\n");
		printf("\n%s\n",msgGet.cmd);
		printf("——————————————————————————————————————\n");

		putchar('>');
		fflush(stdout);
	}
}

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

	printf("connect ....\n");
	while(1){
		memset(msg.cmd, 0, sizeof(msg.cmd));
		if(mark == 0){
			printf(">");
		}
		gets(msg.cmd);
		if(strlen(msg.cmd) == 0){
			if(mark == 1){
				printf(">");
			}
			continue;
		}
		
		mark = 1;
		
		int ret = cmd_handler(msg,c_fd);
		if( ret > IFGO){
			printf(">");
			fflush(stdout);
			continue;
		}
		if( ret == -1){
			printf("command not\n");
			printf(">");
			fflush(stdout);
			continue;
		}
		handler_server_message(msg,c_fd);
	}

	close(c_fd);
	return 0;
}