《Linux网络编程》课程设计班级：姓名：指导老师：一、设计背景Linux操作系统作为一个开源的操作系统被越来越多的人所应用，它的好处在于操作系统源代码的公开化！只要是基于GNU公约的软件你都可以任意使用并修改它的源代码。

通过这次课程设计能更好的学习网络编程知识和掌握LINUX平台上应用程序设计开发的过程，将大学四年所学知识综合运用，为未来的工作学习打下基础。

二、设计目的1、学习epoll 跟FTP被动模式2、掌握linux基本命令，例如ls、cd、login；3、学会如何编译、运行三、环境要求1、centos 64位操作系统2、gcc编译器四、设计原理4．1客户端客户端程序的主要任务有以下3个：（1）、分析用户输入的命令。

（2）、根据命令向服务器发出请求（3）、接受服务器返回请求的结果客户端为用户提供了3种命令：（1）、get:从服务器下载文件（2）、list:列出客户端当前目录的内容（3）、quit离开4.2 服务器端（1）、分析请求代码。

（2）、根据请求代码做相应的处理（3）、等待返回结果或者应答信息五、软件测试结果六、部分主代码#include "ftserve.h"int main(int argc, char *argv[]){int sock_listen, sock_control, port, pid;if (argc != 2) {printf("usage: ./ftserve port\n");exit(0);}port = atoi(argv[1]);// create socketif ((sock_listen = socket_create(port)) < 0 ) { perror("Error creating socket");exit(1);}while(1) { // wait for client request// create new socket for control connectionif ((sock_control = socket_accept(sock_listen)) < 0 )break;// create child process to do actual file transferif ((pid = fork()) < 0) {perror("Error forking child process");} else if (pid == 0) {close(sock_listen);ftserve_process(sock_control);close(sock_control);exit(0);}close(sock_control);}close(sock_listen);return 0;}/*** Send file specified in filename over data connection, sending * control message over control connection* Handles case of null or invalid filename*/void ftserve_retr(int sock_control, int sock_data, char* filename) {FILE* fd = NULL;char data[MAXSIZE];size_t num_read;fd = fopen(filename, "r");if (!fd) {// send error code (550 Requested action not taken)send_response(sock_control, 550);} else {// send okay (150 File status okay)send_response(sock_control, 150);do {num_read = fread(data, 1, MAXSIZE, fd);if (num_read < 0) {printf("error in fread()\n");}// send blockif (send(sock_data, data, num_read, 0) < 0)perror("error sending file\n");} while (num_read > 0);// send message: 226: closing conn, file transfer successfulsend_response(sock_control, 226);fclose(fd);}}/*** Send list of files in current directory* over data connection* Return -1 on error, 0 on success*/int ftserve_list(int sock_data, int sock_control){char data[MAXSIZE];size_t num_read;FILE* fd;int rs = system("ls -l | tail -n+2 > tmp.txt");if ( rs < 0) {exit(1);}fd = fopen("tmp.txt", "r");if (!fd) {exit(1);}/* Seek to the beginning of the file */fseek(fd, SEEK_SET, 0);send_response(sock_control, 1); //startingmemset(data, 0, MAXSIZE);while ((num_read = fread(data, 1, MAXSIZE, fd)) > 0) { if (send(sock_data, data, num_read, 0) < 0) {perror("err");}memset(data, 0, MAXSIZE);}fclose(fd);send_response(sock_control, 226); // send 226return 0;}/*** Open data connection to client* Returns: socket for data connection* or -1 on error*/int ftserve_start_data_conn(int sock_control){char buf[1024];int wait, sock_data;// Wait for go-ahead on control connif (recv(sock_control, &wait, sizeof wait, 0) < 0 ) { perror("Error while waiting");return -1;}// Get client addressstruct sockaddr_in client_addr;socklen_t len = sizeof client_addr;getpeername(sock_control, (struct sockaddr*)&client_addr, &len);inet_ntop(AF_INET, &client_addr.sin_addr, buf, sizeof(buf));// Initiate data connection with clientif ((sock_data = socket_connect(CLIENT_PORT_ID, buf)) < 0) return -1;return sock_data;}/*** Authenticate a user's credentials* Return 1 if authenticated, 0 if not*/int ftserve_check_user(char*user, char*pass){char username[MAXSIZE];char password[MAXSIZE];char *pch;char buf[MAXSIZE];char *line = NULL;size_t num_read;size_t len = 0;FILE* fd;int auth = 0;fd = fopen(".auth", "r");if (fd == NULL) {perror("file not found");exit(1);}while ((num_read = getline(&line, &len, fd)) != -1) {memset(buf, 0, MAXSIZE);strcpy(buf, line);pch = strtok (buf," ");strcpy(username, pch);if (pch != NULL) {pch = strtok (NULL, " ");strcpy(password, pch);}// remove end of line and whitespacetrimstr(password, (int)strlen(password));if ((strcmp(user,username)==0) && (strcmp(pass,password)==0)) { auth = 1;break;}}free(line);fclose(fd);return auth;}/*** Log in connected client*/int ftserve_login(int sock_control){char buf[MAXSIZE];char user[MAXSIZE];char pass[MAXSIZE];memset(user, 0, MAXSIZE);memset(pass, 0, MAXSIZE);memset(buf, 0, MAXSIZE);// Wait to recieve usernameif ( (recv_data(sock_control, buf, sizeof(buf)) ) == -1) { perror("recv error\n");exit(1);}int i = 5;int n = 0;while (buf[i] != 0)user[n++] = buf[i++];// tell client we're ready for passwordsend_response(sock_control, 331);// Wait to recieve passwordmemset(buf, 0, MAXSIZE);if ( (recv_data(sock_control, buf, sizeof(buf)) ) == -1) { perror("recv error\n");exit(1);}i = 5;n = 0;while (buf[i] != 0) {pass[n++] = buf[i++];}return (ftserve_check_user(user, pass));}/*** Wait for command from client and* send response* Returns response code*/int ftserve_recv_cmd(int sock_control, char*cmd, char*arg){int rc = 200;char buffer[MAXSIZE];memset(buffer, 0, MAXSIZE);memset(cmd, 0, 5);memset(arg, 0, MAXSIZE);// Wait to recieve commandif ((recv_data(sock_control, buffer, sizeof(buffer)) ) == -1) { perror("recv error\n");return -1;}strncpy(cmd, buffer, 4);char *tmp = buffer + 5;strcpy(arg, tmp);if (strcmp(cmd, "QUIT")==0) {rc = 221;} else if((strcmp(cmd, "USER")==0) || (strcmp(cmd, "PASS")==0) || (strcmp(cmd, "LIST")==0) || (strcmp(cmd, "RETR")==0)) { rc = 200;} else { //invalid commandrc = 502;}send_response(sock_control, rc);return rc;}/*** Child process handles connection to client*/void ftserve_process(int sock_control){int sock_data;char cmd[5];char arg[MAXSIZE];// Send welcome messagesend_response(sock_control, 220);// Authenticate userif (ftserve_login(sock_control) == 1) {send_response(sock_control, 230);} else {send_response(sock_control, 430);exit(0);}while (1) {// Wait for commandint rc = ftserve_recv_cmd(sock_control, cmd, arg);if ((rc < 0) || (rc == 221)) {break;}if (rc == 200 ) {// Open data connection with clientif ((sock_data = ftserve_start_data_conn(sock_control)) < 0) {close(sock_control);exit(1);}// Execute commandif (strcmp(cmd, "LIST")==0) { // Do listftserve_list(sock_data, sock_control);} else if (strcmp(cmd, "RETR")==0) { // Do get <filename>ftserve_retr(sock_control, sock_data, arg);}// Close data connectionclose(sock_data);}}}七、设计总结通过本次的linux程序与设计课程设计让我们学会使用linux系统和socket，极大的丰富了linux系统下编程和网络方面的知识，锻炼了动手能力，为以后的工作学习打下了坚实的基础。