linux的小型远程FTP服务系统.doc

中北大学操作系统课程设计说 明 书学 院、系：软件学院专 业：软件工程学 生 姓 名：学 号：设 计 题 目：基于linux的小型远程FTP服务系统的设计 起 迄 日 期: 2011年12月22日- 2012年1月7日指 导 教 师:薛海丽2012 年 1月 7 日1 需求分析1.1 设计目的：用高级语言编写和调试一个简单的FTP服务系统，掌握对进程、线程、进程互斥、同步、通信、文件系统及网络编程的方法。从而加深学生对远程服务机制的理解和认识。1.2 设计要求：该系统要求有服务器端软件和客户端软件两部分组成，服务器端在指定端口接受客户连接请求，根据客户要求执行相应处理，客户端提供系统的交互界面基于套接字得客户/服务器通信模式远程登录功能要求集成linux系统的客户管理功能，对客户信息予以验证，客户发送连接请求时，提供FTP服务器软件在linux主机上的客户名及密码，请求命令格式如下：Ftps:/客户名：密码FTP服务器IP：port并发执行及管理功能采用多线程，客户通过身份请求后创建一个新线程来响应客户请求。活动客户计数功能统计当前的活动客户数，通过身份验证+1，断开连接-1文件管理功能服务器端的文件基本操作包括：mkdir、rmdir、cd、ls客户端执行的基本操作包括：创建及删除目录、切换目录、查看当前目录下的所有文件设定文件传输模式：文本模式和二进制文件传输：upload/download到指定目录。1.3 开发环境：本程序分为服务器端和客户端两部分，全部在Red Hat Enterprise Linux 5系统中使用GCC编译执行，要求系统具有vsftpd组件。1.4 程序特点：本程序主要使用套接口函数实现服务器端/客户端通信，具有较强的安全性设计和错误提示功能；采用多线程设计，可以保证多个客户端登陆同一服务器端而不冲突。程序使用命令提示符界面，在指定账户登录可实现全部功能，而在匿名账户下可实现部分功能。2. 总体设计：2.1功能模块：本程序分为套接口通信模块、登录模块、命令解析模块、文件操作模块、文件传输模块共5个模块，具体如下：A.套接口通信模块：表2-1 套接口函数列表函数名类型功能*Handle_Client_Request()void响应客户端请求do_client_work()void处理客户端动作sockaddr_in create_date_sock()struct创建数据管道send_client_info()void发送客户端信息recv_client_infoint接受客户端信息fill_host_addr()int写入服务器地址xconnect()int连接服务器与客户端ftp_send_cmd()int发送FTP指令ftp_get_reply()int接受服务器回应xconnect_ftpdata()int传输数据handle_pasv()void设定FTP工作模式B.登录模块：表2-2 登录模块函数列表函数名类型功能login()int客户端登录close_cli()void关闭客户端连接get_user()void获取账户名get_pass()void获取密码ftp_login()int登录到FTP服务器show_help()void显示帮助信息ftp_quit()void退出客户端C.命令解析模块：表2-3 命令解析模块函数列表函数名类型功能cmd_err_exit()void处理错误的命令ftp_usr_cmd()int解析用户输入的命令start_ftp_cmd()int连接到服务器的命令ftp_cmd_filename()void处理文件名的命令D.文件操作模块：表 2-4 文件操作模块函数列表函数名类型功能ftp_list()void列出服务器文件列表ftp_pwd()void显示服务器当前所在目录ftp_cd()void转到服务器指定目录del()void删除文件mkdir_srv()void新建文件夹rmdir_srv()void删除文件夹local_list()void列出客户端文件列表local_pwd()void显示客户端当前所在目录local_cd()void转到客户端指定目录handle_cwd()void处理转换目录的请求handle_rmd()void处理删除目录的请求handle_mkd()void处理新建文件夹的请求handle_list()void处理列出文件列表的请求E.文件传输模块：表2-4 文件传输模块函数列表函数名类型功能ftp_put()void上传文件ftp_get()void下载文件handle_file()void检查文件handle_del()void删除文件2.2 程序流程图图 2-1 程序流程图3详细设计3.1客户端连接服务器相关代码：函数get_user()和get_pass()得到用户输入的用户名和密码。ftp_login()函数用输入字符与缺省用户名密码、匿名用户密码相比较，如果一致则登陆成功，否则失败。void get_user()/得到输入用户名char read_buf64;printf(User(Press for anonymous): );fgets(read_buf, sizeof(read_buf), stdin);if(read_buf0=n)strncpy(user, anonymous, 9);elsestrncpy(user, read_buf, strlen(read_buf)-1);void get_pass()/得到输入密码char read_buf64;printf(Password(Press for anonymous): );echo_off();/隐藏密码fgets(read_buf, sizeof(read_buf), stdin);if(read_buf0=n)strncpy(passwd, anonymous, 9);elsestrncpy(passwd, read_buf, strlen(read_buf)-1);echo_on();/取消隐藏printf(n);int ftp_login()/登陆函数int err;get_user();if(ftp_send_cmd(USER , user, sock_control) 0)cmd_err_exit(Can not send message,1);err = ftp_get_reply(sock_control);/得到服务器返回if(err = 331)get_pass();if(ftp_send_cmd(PASS , passwd, sock_control) = 0)cmd_err_exit(Can not send message,1);elseerr = ftp_get_reply(sock_control);if(err = 230)/缺省用户return 1;else if(err = 531)/匿名用户return 2；elseprintf(Password error!n);return 0;elseprintf(User error!n);return 0;图3-1 打开服务器端和客户端函数int xconnect(struct sockaddr_in *s_addr, int type)连接到服务器。int xconnect(struct sockaddr_in *s_addr, int type)struct timeval outtime;int set;int s = socket(AF_INET, SOCK_STREAM, 0);if(s 0)cmd_err_exit(creat socket error!, 249);set = setsockopt(s, SOL_SOCKET,SO_RCVTIMEO, &outtime,sizeof(outtime);if(set !=0)printf(set socket %s errno:%dn,strerror(errno),errno);cmd_err_exit(set socket, 1);/connect to the serverif (connect(s,(struct sockaddr *)s_addr,sizeof(struct sockaddr_in) sin_addr),ntohs(ftp_server.sin_port);exit(252);return s;fgets(read_buf, sizeof(read_buf), stdin);得到用户名和密码的关键函数。读入数据。int s = socket(AF_INET, SOCK_STREAM, 0);if(s 0)cmd_err_exit(creat socket error!, 249);图 3-2 用户登录创建套接字，如创建成功，socket函数返回非负值。/connect to the serverif (connect(s,(struct sockaddr *)s_addr,sizeof(struct sockaddr_in) sin_addr),ntohs(ftp_server.sin_port);exit(252);连接到服务器，如果连接成功，connect函数返回0，如果不成功，返回-1。int ftp_send_cmd(const char *s1, const char *s2, int sock_fd)向服务器发送客户端的命令的函数。int ftp_send_cmd(const char *s1, const char *s2, int sock_fd)char send_buf256;int send_err, len;if(s1) strcpy(send_buf,s1);if(s2)strcat(send_buf, s2);strcat(send_buf,rn);len = strlen(send_buf);send_err = send(sock_fd, send_buf, len, 0);else strcat(send_buf,rn);len = strlen(send_buf);send_err = send(sock_fd, send_buf, len, 0); if(send_err 0)reply_code = atoi(rcv_buf);elsereturn 0;while(1)if(count );fgets(usr_cmd,510,stdin);fflush(stdin);if(usr_cmd0 = n)continue;usr_cmdstrlen(usr_cmd)-1 = 0;cmd_flag = ftp_usr_cmd(usr_cmd);if(cmd_flag = 15)char *cmd = strchr(usr_cmd, );char dress_ftp1024;if(cmd = NULL)printf(command error!n);show_help();return;elsewhile(*cmd = )cmd+;if(cmd = NULL|cmd = 0)printf(command error!n);return;elsechar * dr = ;strncpy(dress_ftp,cmd,strlen(cmd);dress_ftpstrlen(cmd) = 0;printf(%s,dress_ftp);if(dress_ftp = )printf(Connect Seccessed!n);start_ftp_cmd(dr,DEFAULT_FTP_PORT);/open成功则调用该函数，该函数与open_ftpsrv()很相似。elseprintf(Inviable Server Dress!n);else/如果open不成功，则只能进行客户端上的操作，不能进行有关服务器操作switch(cmd_flag)case 11:local_list();memset(usr_cmd,0,sizeof(usr_cmd);break;case 12:local_pwd();memset(usr_cmd,0,sizeof(usr_cmd);break;case 13:local_cd(usr_cmd);memset(usr_cmd,0,sizeof(usr_cmd);break;case 6:/quitprintf(BYE TO WEILIQI FTP!n);exit(0);break;default:printf(command error!n);show_help();memset(usr_cmd,0,sizeof(usr_cmd);break;图3-3 退出与服务器的连接3.2客户端目录文件操作相关代码：void ftp_list()显示服务器当前目录下文件的函数。图3-4 文件列表功能int list_sock_data = xconnect_ftpdata();创建一个新套接字，表示是否连接上服务器的数据。ftp_send_cmd(LIST, NULL, sock_control);ftp_get_reply(sock_control);向服务器发送命令，得到服务器的响应答复。new_sock = accept(list_sock_data, (struct sockaddr *)&local_host, (socklen_t *)&set);从服务器接收数据（文件信息）。void ftp_cmd_filename(char * usr_cmd, char * src_file, char * dst_file)此函数读取客户端命令后的文件名字。在很多命令中，如get，put后要加入上传或下载的文件名字，这个函数解析文件名字信息。void local_pwd()显示客户端目录函数。/print local current directoryvoid local_pwd()char curr_dir512;int size = sizeof(curr_dir);if(getcwd(curr_dir, size) = NULL)printf(getcwd failedn);elseprintf(Current local directory: %sn, curr_dir);getcwd(curr_dir, size)得到客户端目录。void ftp_cd(char * usr_cmd)转换服务器目录函数。void ftp_cd(char * usr_cmd)char *cmd = strchr(usr_cmd, );char path1024;if(cmd = NULL)printf(command error!n);return;elsewhile(*cmd = )cmd +;if(cmd = NULL | cmd = 0)printf(command error!n);return;elsestrncpy(path, cmd, strlen(cmd);pathstrlen(cmd)=0;ftp_send_cmd(CWD , path, sock_control);ftp_get_reply(sock_control);ftp_send_cmd(CWD , path, sock_control);ftp_get_reply(sock_control);发送转换目录命令给服务器，服务器完成该功能。图3-5 下载文件创建目录函数void mkdir_srv(char * usr_cmd) 和删除目录函数void rmdir_srv(char * usr_cmd)与void ftp_cd(char * usr_cmd)函数相似，在此不做解释。图3-6 列出本地文件目录函数void local_list()列出客户端文件列表。void local_list()DIR * dp;struct dirent *dirp;if(dp = opendir(./) = NULL)printf(opendir() error!n);return;printf(Local file list:n);while(dirp = readdir(dp) != NULL)if(strcmp(dirp-d_name, .) = 0 | strcmp(dirp-d_name, .) = 0)continue;printf(%sn, dirp-d_name);转换客户端目录函数void local_cd(char * usr_cmd)char *cmd = strchr(usr_cmd, );char path1024;if(cmd = NULL)printf(command error!n);return;elsewhile(*cmd = )cmd +;if(cmd = NULL | cmd = 0)printf(command error!n);return;elsestrncpy(path, cmd, strlen(cmd);pathstrlen(cmd)=0;if(chdir(path) client_sock,info-client)函数与客户端交互。void *Handle_Client_Request(void* arg)struct ARG*info;info=(struct ARG*)arg;printf(You got a connection from %sn,inet_ntoa(info-client.sin_addr);do_client_work(info-client_sock,info-client);close(info-client_sock);pthread_exit(NULL);函数do_client_work(int client_sock,struct sockaddr_in client)处理FTP各种命令。void do_client_work(int client_sock,struct sockaddr_in client)int login_flag;login_flag=login(client_sock);while(recv_client_info(client_sock)&login_flag=1)/缺省用户操作响应if(strncmp(quit, client_Control_Info, 4) = 0)|(strncmp(QUIT, client_Control_Info, 4) = 0)send_client_info(client_sock, serverInfo221, strlen(serverInfo221);break;else if(strncmp(close,client_Control_Info,5) = 0)|(strncmp(CLOSE,client_Control_Info,5) = 0)printf(Client Quit!n);shutdown(client_sock,SHUT_WR);/关闭连接服务器，只关闭写操作。此时仍可进行客户端相关操作。else if(strncmp(pwd, client_Control_Info, 3) = 0|(strncmp(PWD, client_Control_Info, 3) = 0)char pwd_infoMSG_INFO; char tmp_dirDIR_INFO; snprintf(pwd_info, MSG_INFO, 257 %s is current location.rn, getcwd(tmp_dir, DIR_INFO);send_client_info(client_sock, pwd_info, strlen(pwd_info);else if(strncmp(cwd, client_Control_Info, 3) = 0|(strncmp(CWD, client_Control_Info, 3) = 0)handle_cwd(client_sock);else if(strncmp(mkd, client_Control_Info, 3) = 0|(strncmp(MKD, client_Control_Info, 3) = 0)handle_mkd(client_sock);else if(strncmp(rmd, client_Control_Info, 3) = 0|(strncmp(RMD, client_Control_Info, 3) = 0)handle_rmd(client_sock);else if(strncmp(dele, client_Control_Info, 4) = 0|(strncmp(DELE, client_Control_Info, 4) = 0)handle_del(client_sock);else if(strncmp(pasv, client_Control_Info, 4) = 0|(strncmp(PASV, client_Control_Info, 4) = 0) handle_pasv(client_sock,client);else if(strncmp(list, client_Control_Info, 4) = 0|(strncmp(LIST, client_Control_Info, 4) = 0) handle_list(client_sock); send_client_info(client_sock,serverInfo226, strlen(serverInfo226);else if(strncmp(type, client_Control_Info, 4) = 0|(strncmp(TYPE, client_Control_Info, 4) = 0)if(strncmp(type I, client_Control_Info, 6) = 0|(strncmp(TYPE I, client_Control_Info, 6) = 0) translate_data_mode=FILE_TRANS_MODE_BIN; send_client_info(client_sock, serverInfo200, strlen(serverInfo200);else if(strncmp(retr, client_Control_Info, 4) = 0|(strncmp(RETR, client_Control_Info, 4) = 0)handle_file(client_sock);send_client_info(client_sock,serverInfo226, strlen(serverInfo226);else if(strncmp(stor, client_Control_Info, 4) = 0|(strncmp(STOR, client_Control_Info, 4) = 0)handle_file(client_sock);send_client_info(client_sock,serverInfo226, strlen(serverInfo226);else if(strncmp(syst, client_Control_Info, 4) = 0|(strncmp(SYST, client_Control_Info, 4) = 0)send_client_info(client_sock, serverInfo215, strlen(serverInfo215);else if(strncmp(size, client_Control_Info, 4) = 0|(strncmp(SIZE, client_Control_Info, 4) = 0)send_client_info(client_sock, serverInfo213, strlen(serverInfo213);else if(strncmp(feat, client_Control_Info, 4) = 0|(strncmp(FEAT, client_Control_Info, 4) = 0)send_client_info(client_sock, serverInfo211, strlen(serverInfo211);else if(strncmp(rest, client_Control_Info, 4) = 0|(strncmp(REST, client_Control_Info, 4) = 0)send_client_info(client_sock, serverInfo350, strlen(serverInfo350);else send_client_info(client_sock, serverInfo, strlen(serverInfo);while(recv_client_info(client_sock)&(login_flag = 2)/匿名用户操作响应/省略代码函数int login(int client_sock)为登陆函数。处理客户端登录请求，与已定义的权限用户密码进行匹配，成功则为ROOT用户，失败则匹配匿名用户，匿名用户只能进行简单服务。if(strncmp(format_client_Info, default_user, 4) = 0)flag=1;if(strncmp(format_client_Info, anony_user, 9) = 0) flag=2;函数void handle_cwd(int client_sock)处理转换目录功能。关键代码：if (chdir(client_dir) = 0) snprintf(cwd_info, MSG_INFO, 257 %s is current location.rn, getcwd(tmp_dir, DIR_INFO); send_client_info(client_sock, cwd_info, strlen(cwd_info); else snprintf(cwd_info, MSG_INFO, 550 %s :%srn,client_dir,strerror(errno); perror(chdir():); send_client_info(client_sock, cwd_info, strlen(cwd_info); 上述代码表示当转换目录存在则把当前目录更改为转换目录，否则报错。创建目录与删除目录关键代码与之类似。函数void handle_mkd(int client_sock)处理创建目录功能。关键代码：if (mkdir(client_dir) = 0) printf( %s is created successfully.rn, client_dir); send_client_info(client_sock, mkd_info, strlen(mkd_info); else snprintf(mkd_info, MSG_INFO, 550 %s :%srn,client_dir,strerror(errno); perror(mkdir():); send_client_info(client_sock, mkd_info, strlen(mkd_info); 上述代码表示创建client_dir目录，成功输出消息，否则报错。图3-7 创建目录函数void handle_rmd(int client_sock)处理删除目录功能。关键代码：if (rmdir(client_dir) = 0) printf( %s is deleted successfully.rn, client_dir); send_client_info(client_sock, rmd_info, strlen(rmd_info); else snprintf(rmd_info, MSG_INFO, 550 %s :%srn,client_dir,strerror(errno); perror(rmdir():); send_client_info(client_sock, rmd_info, strlen(rmd_info); 上述代码表示删除client_dir目录，成功输出消息，否则报错。函数handle_list(int client_sock)处理list命令。FILE *pipe_fp;/建立管道以传输数据char t_dirDIR_INFO;char list_cmd_infoDIR_INFO;snprintf(list_cmd_info, DIR_INFO, ls -l %s, getcwd(t_dir, DIR_INFO);/得到当前目录 if (pipe_fp = popen(list_cmd_info, r) = NULL)/打开管道 printf(pipe open error in cmd_listn);return ; printf(pipe open successfully!, cmd is %sn, list_cmd_info);char t_char; while (t_char = fgetc(pipe_fp) != EOF) printf(%c, t_char);write(t_data_sock, &t_char, 1); /得到当前目录文件列表 pclose(pipe_fp);/关闭管道 printf(close pipe successfully!n); close(t_data_sock);printf(%s close data successfully!n,serverInfo226);close(ftp_data_sock);函数struct sockaddr_in create_date_sock()创建数据sock。struct sockaddr_in create_date_sock()int t_client_sock;struct