网络安全传输系统（6）-其它改进

1、改进

需要改进的地方如下：

1、输入密码时最好不回显，用*代替

2、目前数据库中保存的是明文密码，这显然是不行的，容易被窃取，可以保存密码对应的MD5摘要

3、在服务器中为每个用户创建一个文件夹，用来保存其上传的文件

4、用户选择下载文件时，最好能够列出其能够下载的所有文件

改进后的代码在：https://github.com/dayL-W/File-Transfer-with-SSL.git

1.1密码不回显

方法一：

在windows中可以使用getch函数来获取字符，且不会显，如果在Linux中使用getch()需要解压curses.h头文件的帮助，同时在编译的时候加上-lcurses.但是这个方法在我的程序中总是出现各种各样的问题，尤为麻烦，算了，放弃好了。

方法二：

Linux中的unistd.h的文件中有一个函数getpass();专门用来输入密码用的，用法是：

char *password;password = getpass("Input Password");

缺点是不能在输入密码时显示*

1.2使用OpenSSL的MD5摘要算法

头文件：

#include<openssl/md5.h>

用法：

char password_md5[33]={'\0'};char md5_tmp[33]={'\0'};

MD5(password,strlen(password),md);for(i=0; i<16; i++){sprintf(md5_tmp,"%2.2x",md[i]);strcat(password_md5,md5_tmp);}password_md5[33] = '\0';

由于MD5参数中的md返回的是16位的无符号字符型数据，一般都会把它保存成16进制的字符串类型，所以对md5进行格式化，一个unsigned char映射成2个16进制的数字，然后拼接成加密后的密码即可，最后给字符串接上结尾的符号。

1.3为用户创建文件夹

如果是新用户则需要为用户创建一个文件夹，同时线程需要保存当前的用户名，如果现在用户名已存在，则注册失败，不创建用户名。

头文件：

#include <sys/stat.h> 

实现方法：

getcwd(pwd,sizeof(pwd));strcat(pwd,"/");strcat(pwd,now_username);strcat(pwd,"/");strcat(pwd,filename);

先获取当前路径，然后把用户名和需要操作的文件名加上，构成一条路径，然后下载和上传文件都在这个目录下进行，当然也可以改变当前工作目录，但是感觉不太稳妥。

1.4列举可以下载的文件

先统计文件个数，因为这里的文件夹没有子文件，可以直接用opendir统计，

头文件：

#include <dirent.h>

统计个数及发送文件名：

int file_cnt=0;DIR *dir;struct dirent *ptr;

dir = opendir(pwd);while( (ptr = readdir(dir))!=NULL){  file_cnt++;}//发送文件个数SSL_write(ssl, &file_cnt, 4);//逐个发送文件名dir = opendir(pwd);

while( (ptr = readdir(dir))!=NULL){SSL_write(ssl, ptr->d_name, 20);}

2、实例代码

经过这个多的改进，这里贴出所以代码

客户机：

#include <stdio.h>#include <string.h>#include <curses.h>#include <sys/socket.h>#include <sys/types.h>#include <netinet/in.h>#include <sys/stat.h>#include <errno.h>#include <fcntl.h>#include <unistd.h>#include <stdlib.h>#include <openssl/err.h>#include <openssl/ssl.h>#include <openssl/md5.h>#define port 3333char ipaddr[15];int sockfd;struct sockaddr_in sockaddr;//声明SSL套接字SSL_CTX *ctx;SSL *ssl;int login(){char username[20];char *password;char ch;int  cnt_ch=0;int login_or_create;char temp[100];char buf[10];int  i=0,login_flag=0;unsigned char md[15];char password_md5[33]={'\0'};char md5_tmp[33]={'\0'};printf("please input your selection: 1 to login 2 to create\n");printf("selection:");scanf("%d",&login_or_create);if(login_or_create != 1 && login_or_create != 2){return 0;}printf("username:");scanf("%s",username);password = getpass("password:");MD5(password,strlen(password),md);for(i=0; i<16; i++){sprintf(md5_tmp,"%2.2x",md[i]);strcat(password_md5,md5_tmp);}password_md5[33] = '\0';printf("password:%s\n",password);printf("md5:%s\n",password_md5);sprintf(temp,"log:%d username:%s password:%s",login_or_create,username,password_md5);SSL_write(ssl,temp,100);SSL_read(ssl,buf,10);sscanf(buf,"login:%d",&login_flag);if(login_flag == 0){printf("-----wrong username or password!-------\n");}else if(login_or_create == 1){printf("----------login successufl!------------\n");}else{printf("----------create successufl!------------\n");}//0失败1成功return login_flag;}int linkS(){//创建socketif((sockfd = socket(AF_INET,SOCK_STREAM,0)) == -1){perror("socket\n");_exit(0);}//连接memset(&sockaddr,0, sizeof(sockaddr));sockaddr.sin_family = AF_INET;sockaddr.sin_port = htons(port);sockaddr.sin_addr.s_addr = inet_addr(ipaddr);if(connect(sockfd,(struct sockaddr *)&sockaddr,sizeof(sockaddr)) == -1){perror("connect\n");_exit(0);}ssl = SSL_new(ctx);SSL_set_fd(ssl,sockfd);if(SSL_connect(ssl) == -1){printf("SSL connect error!\n");_exit(0);}return login();}void upload_file(char *filename){int fd;char cmd = 'U';int FileNameSize = strlen(filename);char buf[1024];int count=0;struct stat fstat;//打开文件fd = open(filename,O_RDONLY);//发送命令SSL_write(ssl,&cmd,1);//发送文件名SSL_write(ssl,(void *)&FileNameSize,4);SSL_write(ssl,filename, FileNameSize);//发送文件长度if((stat(filename,&fstat)) == -1)return;SSL_write(ssl,(void *)&fstat.st_size,4);//发送文件数据while((count = read(fd,(void *)buf,1024)) > 0){SSL_write(ssl,buf,count);}//关闭文件close(fd);}void download_file(){int fd;char cmd = 'D';char buf[1024];int FileNameSize;int filesize=0,count=0,totalrecv=0;int file_num=0;char file_name_temp[20];char file_d[20];char c;//发送命令SSL_write(ssl,&cmd,1);//接收文件总个数和文件名SSL_read(ssl,&file_num,4);printf("Total file:%d\n",file_num);while(file_num--){SSL_read(ssl,file_name_temp,20);printf("%s\n",file_name_temp);}printf("Download Files:");//输入文件名while((c = getchar()) != '\n' && c != EOF);fgets(file_d, 30, stdin);file_d[strlen(file_d)-1] = '\0';//发送文件名FileNameSize = strlen(file_d);SSL_write(ssl,(void *)&FileNameSize,4);SSL_write(ssl,file_d,FileNameSize);//打开并创建文件if((fd = open(file_d,O_RDWR|O_CREAT)) == -1){perror("open:");_exit(0);}//接收数据SSL_read(ssl,&filesize,4);while((count = SSL_read(ssl,(void *)buf,1024)) > 0){write(fd,buf,count);totalrecv += count;if(totalrecv == filesize)break;}//关闭文件close(fd);}void quit(){char cmd = 'Q';//发送命令SSL_write(ssl,(void *)&cmd,1);//关闭及释放SSL连接SSL_shutdown(ssl);SSL_free(ssl);//退出_exit(0);}void menu(){char cmd;char c;char file_u[30];char file_d[30];while(1){printf("----------1.Upload Files---------------\n");printf("----------2.Download Files-------------\n");printf("----------3.Exit-----------------------\n");printf("Please input the Client command:");scanf("%c",&cmd);switch(cmd){case '1':{printf("Upload Files:");//输入文件名while((c = getchar()) != '\n' && c != EOF);fgets(file_u, 30, stdin);file_u[strlen(file_u)-1] = '\0';//上传文件upload_file(file_u);}break;case '2':{//下载文件download_file();}break;case '3':{//退出quit();break;}break;default:{printf("Please input right command!\n");}break;}}}int main(int argc, char *args[]){if(argc != 2){printf("format error: you mast enter ipaddr like this : client 192.168.0.6\n");    _exit(0);}strcpy(ipaddr,args[1]);//初始化SSlSSL_library_init();OpenSSL_add_all_algorithms();SSL_load_error_strings();//创建SSL套接字，参数表明支持版本和客户机ctx = SSL_CTX_new(SSLv23_client_method());if(ctx == NULL){printf("Creat CTX error!!!");}//建立连接if(linkS() == 0){printf("user name or password error!\n");//关闭及释放SSL连接SSL_shutdown(ssl);SSL_free(ssl);//清屏system("clear");_exit(0);}//打印菜单menu();//结尾操作close(sockfd);//释放CTXSSL_CTX_free(ctx);return 0;}

服务器：

#include <stdio.h>#include <string.h>#include <sys/socket.h>#include <sys/types.h>#include <netinet/in.h>#include <errno.h>#include <fcntl.h>#include <unistd.h>#include <dirent.h>#include <openssl/err.h>#include <openssl/ssl.h>#include <pthread.h> #include <sqlite3.h> #define port 3333typedef struct task {     void *(*process) (int newfd, char *now_username);     int newfd;    char *now_username;    struct task *next; } Cthread_task; /*线程池结构*/ typedef struct {     pthread_mutex_t queue_lock;     pthread_cond_t queue_ready;     /*链表结构，线程池中所有等待任务*/     Cthread_task *queue_head;     /*是否销毁线程池*/     int shutdown;     pthread_t *threadid;         /*线程池中线程数目*/     int max_thread_num;         /*当前等待的任务数*/     int cur_task_size; } Cthread_pool; static Cthread_pool *pool = NULL; void *thread_routine (void *arg); int sockfd;struct sockaddr_in sockaddr;struct sockaddr_in client_addr;int sin_size;char passwd_d[33];SSL_CTX *ctx;sqlite3 *db; char now_username[20]; //存放当前线程执行任务的用户名void pool_init (int max_thread_num) {     int i = 0;        pool = (Cthread_pool *) malloc (sizeof (Cthread_pool));     pthread_mutex_init (&(pool->queue_lock), NULL);     /*初始化条件变量*/    pthread_cond_init (&(pool->queue_ready), NULL);     pool->queue_head = NULL;     pool->max_thread_num = max_thread_num;     pool->cur_task_size = 0;     pool->shutdown = 0;     pool->threadid = (pthread_t *) malloc (max_thread_num * sizeof (pthread_t));     for (i = 0; i < max_thread_num; i++)     {          pthread_create (&(pool->threadid[i]), NULL, thread_routine, NULL);     } } void * thread_routine (void *arg) {     printf ("starting thread 0x%x\n", pthread_self ());     while (1)     {         pthread_mutex_lock (&(pool->queue_lock));         while (pool->cur_task_size == 0 && !pool->shutdown)         {             printf ("thread 0x%x is waiting\n", pthread_self ());             pthread_cond_wait (&(pool->queue_ready), &(pool->queue_lock));         }         /*线程池要销毁了*/         if (pool->shutdown)         {             /*遇到break,continue,return等跳转语句，千万不要忘记先解锁*/             pthread_mutex_unlock (&(pool->queue_lock));             printf ("thread 0x%x will exit\n", pthread_self ());             pthread_exit (NULL);         }         printf ("thread 0x%x is starting to work\n", pthread_self ());                  /*待处理任务减1，并取出链表中的头元素*/         pool->cur_task_size--;         Cthread_task *task = pool->queue_head;         pool->queue_head = task->next;         pthread_mutex_unlock (&(pool->queue_lock));         /*调用回调函数，执行任务*/         (*(task->process)) (task->newfd,task->now_username);         free (task);         task = NULL;     }     /*这一句应该是不可达的*/     pthread_exit (NULL); }/*向线程池中加入任务*/ int pool_add_task (void *(*process) (int newfd, char *now_username), int newfd, char *now_username) {     /*构造一个新任务*/     Cthread_task *task = (Cthread_task *) malloc (sizeof (Cthread_task));     task->process = process;     task->newfd = newfd;    task->now_username = now_username;     task->next = NULL;    pthread_mutex_lock (&(pool->queue_lock));     /*将任务加入到等待队列中*/     Cthread_task *member = pool->queue_head;     if (member != NULL)     {         while (member->next != NULL)             member = member->next;         member->next = task;     }     else     {         pool->queue_head = task;     }     pool->cur_task_size++;     pthread_mutex_unlock (&(pool->queue_lock));     //唤醒一个线程    //加入    pthread_cond_signal (&(pool->queue_ready));         return 0; } void handle(char cmd,SSL *ssl,char *now_username){char filename[30]={0};int FileNameSize=0;int fd;int filesize=0;int count=0,totalrecv=0;char pwd[100];char buf[1024];struct stat fstat;int file_cnt=0;DIR *dir;struct dirent *ptr;  switch(cmd){case 'U':{//接收文件名SSL_read(ssl, &FileNameSize, 4);SSL_read(ssl, (void *)filename, FileNameSize);filename[FileNameSize]='\0';//strcat(pwd,"./");getcwd(pwd,sizeof(pwd));strcat(pwd,"/");strcat(pwd,now_username);strcat(pwd,"/");strcat(pwd,filename);//创建文件if((fd = open(pwd,O_RDWR|O_CREAT)) == -1){perror("creat:");_exit(0);}//接收文件长度SSL_read(ssl, &filesize, 4);//接收文件while((count = SSL_read(ssl,(void *)buf,1024)) > 0){write(fd,&buf,count);totalrecv += count;if(totalrecv == filesize)break;}//关闭文件close(fd);}break;case 'D':{//统计用户文件夹的个数getcwd(pwd,sizeof(pwd));strcat(pwd,"/");strcat(pwd,now_username);dir = opendir(pwd);while( (ptr = readdir(dir))!=NULL){file_cnt++;}//发送文件个数SSL_write(ssl, &file_cnt, 4);//逐个发送文件名dir = opendir(pwd);while( (ptr = readdir(dir))!=NULL){SSL_write(ssl, ptr->d_name, 20);}//接收文件名SSL_read(ssl, &FileNameSize, 4);SSL_read(ssl, filename, FileNameSize);filename[FileNameSize]='\0';//strcat(pwd,"./");strcat(pwd,"/");strcat(pwd,filename);//打开文件if((fd = open(pwd,O_RDONLY)) == -1){perror("open:");_exit(0);}//发送文件长度和文件名if((stat(pwd,&fstat)) == -1)return;SSL_write(ssl,&fstat.st_size,4);while((count = read(fd,(void *)buf,1024)) > 0){SSL_write(ssl,&buf,count);}close(fd);}break;default:break;}}static int callback(void *NotUsed, int argc, char **argv, char **azColName) {      int i;      for(i=0; i<argc; i++)      {               strcpy(passwd_d,argv[i]);     }     return 0;} int login(SSL *ssl){char username[20];char password[33];int login_or_create;char temp[100];char buf[10];int  login_flag=0;char sql[100];int rc;char pwd[100];sqlite3_open("user.db",&db);SSL_read(ssl,temp,100);sscanf(temp,"log:%d username:%s password:%s",&login_or_create,username,password);strcpy(now_username,username);//注册if(login_or_create == 2){sprintf(sql,"insert into stu(username,password) values('%s','%s');",username,password);printf("username:%s password:%s\n",username,password);rc = sqlite3_exec(db, sql, callback, 0, NULL);strcat(pwd,"./");strcat(pwd,now_username);mkdir(pwd,S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);if(rc == SQLITE_OK){ login_flag = 1;} else{login_flag = 0;printf("insert to database error!\n");}}//登录else{sprintf(sql, "select password from stu where username='%s';",username); sqlite3_exec(db, sql, callback, 0, NULL);printf("username:%s password:%s\n",username,passwd_d);if(strcmp(password,passwd_d) == 0){login_flag = 1;}else{login_flag = 0;return 0;}}sqlite3_close(db);sprintf(buf,"login:%d",login_flag);SSL_write(ssl,buf,10);return login_flag;}void *myprocess(int newfd, char *now_username){SSL *ssl;int tmp_fd = newfd;char cmd;int first=1;//产生新的SSLssl = SSL_new(ctx);SSL_set_fd(ssl,tmp_fd);SSL_accept(ssl);//处理事件while(1){if(first == 1 && login(ssl) == 0 ){SSL_shutdown(ssl);SSL_free(ssl);close(tmp_fd);break;}first = 0;SSL_read(ssl,&cmd,1);if(cmd == 'Q'){SSL_shutdown(ssl);SSL_free(ssl);close(tmp_fd);break;}else{handle(cmd,ssl,now_username);}}return NULL;}int main(){int newfd;char sql[100];int rc;//初始化线程池pool_init(5);//创建数据库rc = sqlite3_open("user.db",&db);if(rc){printf("Can't open database: %s\n", sqlite3_errmsg(db));         sqlite3_close(db); }sprintf(sql,"create table stu(username char(20), password char(40));");rc = sqlite3_exec(db, sql, callback, 0, NULL); if(rc != SQLITE_OK){printf("create tables error!\n");}//建立连接//SSL连接SSL_library_init();OpenSSL_add_all_algorithms();SSL_load_error_strings();ctx = SSL_CTX_new(SSLv23_server_method());//载入数字证书SSL_CTX_use_certificate_file(ctx,"./cacert.pem",SSL_FILETYPE_PEM);//载入私钥SSL_CTX_use_PrivateKey_file(ctx,"./privkey.pem",SSL_FILETYPE_PEM);SSL_CTX_check_private_key(ctx);//创建socketif((sockfd = socket(AF_INET,SOCK_STREAM,0)) == -1){perror("socket:");_exit(0);}memset(&sockaddr,0, sizeof(sockaddr));sockaddr.sin_family = AF_INET;sockaddr.sin_port = htons(port);sockaddr.sin_addr.s_addr = htonl(INADDR_ANY);//绑定地址if(bind(sockfd,(struct sockaddr *)&sockaddr,sizeof(sockaddr)) == -1){perror("bind:");_exit(0);}//监听if(listen(sockfd,10) == -1){perror("listen");}while(1){//连接if((newfd = accept(sockfd, (struct sockaddr *)(&client_addr),&sin_size)) == -1){perror("accept:");_exit(0);}//给线程池添加任务pool_add_task(myprocess,newfd,now_username);}close(sockfd);SSL_CTX_free(ctx);return 0;}