目录
一、前言
二、项目功能
三、程序流程
1、客户端
2、服务器
四、代码实现
1、客户端代码
2、服务器代码
3、Makefile
本文学习自【华清远见】的一个开源嵌入式项目在线词典综合实战，涵盖了网络编程、文件I/O、并发程序设计、数据库开发等多方面知识，对想要学习嵌入式开发、锻炼提升编程能力的小伙伴来说是一个非常不错的实战项目。接下来咋们先梳理下项目要实现的具体功能，设计程序流程，最后再开始具体的编程实现
1、需要基于tcp实现一个供用户操作的客户端；在客户端中有两级菜单，一级菜单中用户可进行注册、登录、退出操作；登录后进入二级菜单，二级菜单中可进行单词查询、历史记录查询、退出操作
2、需要基于tcp实现一个多并发的服务器，用于响应客户端的注册、登录、单词查询、历史记录查询请求，同时需要将用户注册的用户信息（用户名、密码）、单词查询记录（用户名、查询时间、查询单词）分别保存到sqlite3数据库的用户表和记录表中。具体如下：
3、客户端与服务器之间的交互过程如下：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#define NAME_LEN 32
#define MSGTYPE_R 11 //user - register
#define MSGTYPE_L 22 //user - login
#define MSGTYPE_Q 33 //user - query
#define MSGTYPE_H 44 //user - history
// 通信双方的信息结构体
typedef struct {
int type;
char name[NAME_LEN];
char data[256];
}MSG_T;
/*
struct sockaddr
{
uint8_t sa_len;
sa_family_t sa_family;
char sa_data[14];
};
/* members are in network byte order */
/*
struct sockaddr_in
{
uint8_t sin_len;
sa_family_t sin_family;
in_port_t sin_port;
struct in_addr sin_addr;
#define SIN_ZERO_LEN 8
char sin_zero[SIN_ZERO_LEN];
};
struct in_addr
{
in_addr_t s_addr;
};
*/
// 注册
int do_register(int sockfd, MSG_T *msg)
{
printf("register ... \n");
memset(msg, 0, sizeof(MSG_T));
msg->type = MSGTYPE_R;
printf("input name:"); scanf("%s", msg->name); getchar();
printf("input passwd:"); scanf("%s", msg->data); getchar();
if (send(sockfd, msg, sizeof(MSG_T), 0) < 0)
{
printf("fail to send register msg.\n");
return -1;
}
if (recv(sockfd, msg, sizeof(MSG_T), 0) < 0)
{
printf("fail to register.\n");
return -1;
}
//ok ! 或者 user already exist.
printf("%s\n", msg->data);
return 1;
}
// 登录, 必服务器返回 "OK" 才表示登录成功
// 返回值：1 成功，-1 失败，0 其他
int do_login(int sockfd, MSG_T *msg)
{
printf("login ...\n");
memset(msg, 0, sizeof(MSG_T));
msg->type = MSGTYPE_L;
printf("input name:"); scanf("%s", msg->name); getchar();
printf("input passwd:"); scanf("%s", msg->data); getchar();
if (send(sockfd, msg, sizeof(MSG_T), 0) < 0)
{
printf("fail to send register msg.\n");
return -1;
}
if (recv(sockfd, msg, sizeof(MSG_T), 0) < 0)
{
printf("fail to login.\n");
return -1;
}
//登录成功
if (strncmp(msg->data, "OK", 3) == 0)
{
printf("login ok! \n");
return 1;
}
else
{
printf("%s\n", msg->data);
}
return 0;
}
// 单词查询
int do_query(int sockfd, MSG_T *msg)
{
printf("query ...\n");
msg->type = MSGTYPE_Q;
while(1)
{
printf("input word:"); scanf("%s", msg->data); getchar();
// 输入是"#"表示退出本次查询
if (strncmp(msg->data, "#", 1) == 0)
break;
//将要查询的单词发送给服务器
if (send(sockfd, msg, sizeof(MSG_T), 0) < 0)
{
printf("fail to send.\n");
return -1;
}
//等待服务器，传递回来的单次的注释信息
if (recv(sockfd, msg, sizeof(MSG_T), 0) < 0)
{
printf("fail to recv.\n");
return -1;
}
printf("%s\n", msg->data);
}
return 1;
}
// 历史记录查询
int do_history(int sockfd, MSG_T *msg)
{
printf("history ...\n");
msg->type = MSGTYPE_H;
//将消息发送给服务器
if (send(sockfd, msg, sizeof(MSG_T), 0) < 0)
{
printf("fail to send.\n");
return -1;
}
while(1)
{
//等待服务器，传递回来的单次的注释信息
if (recv(sockfd, msg, sizeof(MSG_T), 0) < 0)
{
printf("fail to recv.\n");
return -1;
}
if (msg->data[0] == '\0')
break;
//输出历史记录信息
printf("%s\n", msg->data);
}
return 1;
}
// ./client 192.168.0.107 10000
// 知识点：
// 1、在一个套接字被创建时，其默认是工作在阻塞模式下，即所有socket相关的数据发送、接收函数都会阻塞，
// 直到数据发送、接收成功，函数才继续执行
// 2、可以通过fcntl来设置成阻塞或非阻塞模式。https://blog.csdn.net/haoyu_linux/article/details/44306993
int main(int argc, const char *argv[])
{
int sockfd;
struct sockaddr_in server_addr;
int input_nbr;
MSG_T send_msg;
if (argc != 3)
{
printf("usage: %s serverip port\n", argv[0]);
return -1;
}
// 申请socket
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
perror("fail to socket\n");
return -1;
}
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = inet_addr(argv[1]);
server_addr.sin_port = htons(atoi(argv[2]));
bzero(&(server_addr.sin_zero), sizeof(server_addr.sin_zero));
/*连接到服务器*/
if (connect(sockfd, (struct sockaddr*)&server_addr, sizeof(struct sockaddr)) < 0)
{
perror("fail to connect\n");
return -1;
}
while (1)
{
printf("***********************************************\n");
printf("******* 1.register 2.login 3.quit *******\n");
printf("***********************************************\n");
printf("please choose:");
scanf("%d", &input_nbr);
getchar();//回收垃圾字符
// 一级菜单
switch (input_nbr)
{
case 1:
do_register(sockfd, &send_msg);
break;
case 2:
if (do_login(sockfd, &send_msg) == 1)
{
goto _login;
}
break;
case 3:
close(sockfd);
exit(0);
break;
default:
printf("Invalid data cmd. \n");
break;
}
}
//二级菜单,登录后进行单词查询
_login:
while(1)
{
printf("***********************************************\n");
printf("*****1.query_word 2.history_record 3.quit****\n");
printf("***********************************************\n");
printf("please choose:");
input_nbr = 0;
scanf("%d", &input_nbr);
getchar();//回收垃圾字符
switch (input_nbr)
{
case 1:
do_query(sockfd, &send_msg);
break;
case 2:
do_history(sockfd, &send_msg);
break;
case 3:
close(sockfd);
exit(0);
break;
default:
printf("Invalid data cmd. \n");
break;
}
}
return 0;
}#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <sqlite3.h>
#include <signal.h>
#include <time.h>
#define NAME_LEN 32
#define MSGTYPE_R 11 //user - register
#define MSGTYPE_L 22 //user - login
#define MSGTYPE_Q 33 //user - query
#define MSGTYPE_H 44 //user - history
#define DATABASE "my.db"
// 通信双方的信息结构体
typedef struct {
int type;
char name[NAME_LEN];
char data[256];
}MSG_T;
/*
struct sockaddr
{
uint8_t sa_len;
sa_family_t sa_family;
char sa_data[14];
};
/* members are in network byte order */
/*
struct sockaddr_in
{
uint8_t sin_len;
sa_family_t sin_family;
in_port_t sin_port;
struct in_addr sin_addr;
#define SIN_ZERO_LEN 8
char sin_zero[SIN_ZERO_LEN];
};
struct in_addr
{
in_addr_t s_addr;
};
*/
// 注册
int do_register(int sockfd, MSG_T *msg, sqlite3 *db)
{
char sql[128] = {0};
char *errmsg = NULL;
//sprintf(sql, "create table if not exists user(name text primary key, passwd text);");
sprintf(sql, "insert into user values('%s', '%s');", msg->name, msg->data);
if (sqlite3_exec(db, sql, NULL, NULL, &errmsg) != SQLITE_OK)
{
printf("%s\n", errmsg);
memset(msg->data, 0, strlen(msg->data));
sprintf(msg->data, "user(%s) already exist.!", msg->name);
}
else
{
printf("client user(%s) register success\n", msg->name);
memset(msg->data, 0, strlen(msg->data));
strcpy(msg->data, "register ok !");
}
//返回应答
if (send(sockfd, msg, sizeof(MSG_T), 0) < 0)
{
printf("fail to send\n");
return 0;
}
return 1;
}
// 登录, 必服务器返回 "OK" 才表示登录成功
// 返回值：1 成功，-1 失败，0 其他
int do_login(int sockfd, MSG_T *msg, sqlite3 *db)
{
char sql[128] = {0};
char *errmsg = NULL, **result = NULL;
int nrow, ncolumn;
//sprintf(sql, "create table if not exists user(name text primary key, passwd text);");
//sprintf(sql, "insert into user values('%s', '%s');", msg->name, msg->data);
sprintf(sql, "select * from user where name='%s' and passwd='%s';", msg->name, msg->data);
if (sqlite3_get_table(db, sql, &result, &nrow, &ncolumn, &errmsg) != SQLITE_OK)
{
printf("%s\n", errmsg);
}
else
{
printf("sqlite3 get table ok! \n");
}
//查询成功，数据库中拥有此用户
if (nrow == 1)
{
printf("client user(%s) login success\n", msg->name);
memset(msg->data, 0, strlen(msg->data));
strcpy(msg->data, "OK");
}
else //用户名或密码错误
{
printf("client user(%s) login fail! \n", msg->name);
memset(msg->data, 0, strlen(msg->data));
strcpy(msg->data, "user or passwd wrong! \n");
}
//返回应答
if (send(sockfd, msg, sizeof(MSG_T), 0) < 0)
{
printf("fail to send\n");
return 0;
}
return 1;
}
//根据单词从dirt.txt文本中查找对应的注释信息
//返回值: -1 文件打开失败; 0 单词未找到; 1 查找成功
int do_searchword(MSG_T *msg, char *word)
{
FILE *fp = NULL;
int word_len = strlen(word);
char row_data[512] = {'\0'};
int res = 0;
char *p; //指向注释
//打开文件
if ((fp = fopen("dict.txt", "r")) == NULL)
{
perror("fail to open dict.txt.\n");
return -1;
}
//打印客户端要查询的单词
word_len = strlen(word);
printf("%s, len = %d\n", word, word_len );
//读取文件 行数据(一行一行读取),对比要查询的单词
//如果成功，该函数返回相同的 str 参数。
//如果到达文件末尾或者没有读取到任何字符，str 的内容保持不变，并返回一个空指针。
//如果发生错误，返回一个空指针。
while (fgets(row_data, 512, fp) != NULL)
{
res = strncmp(row_data, word, word_len);//每行对比前word_len个字节
if (res != 0)
continue;
if (row_data[word_len] != ' ') //单词跟注释之间没有空格
goto _end;
// 找到了单词,跳过所有的空格
p = row_data + word_len;
while (*p == ' ')
{
p++;
}
strcpy(msg->data, p);
fclose(fp);
return 1;
}
_end:
fclose(fp);
return 0; //文件对比完,单词未找到
}
//获取系统时间
void get_date(char *data)
{
time_t rowtime; //typedef long time_t;
// struct tm {
// int tm_sec; /* Seconds (0-60) */
// int tm_min; /* Minutes (0-59) */
// int tm_hour; /* Hours (0-23) */
// int tm_mday; /* Day of the month (1-31) */
// int tm_mon; /* Month (0-11) */
// int tm_year; /* Year - 1900 */
// int tm_wday; /* Day of the week (0-6, Sunday = 0) */
// int tm_yday; /* Day in the year (0-365, 1 Jan = 0) */
// int tm_isdst; /* Daylight saving time */
// };
struct tm *info;
// rowtime = the number of seconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC)
time(&rowtime);
//进行时间格式转换
info = localtime(&rowtime);
sprintf(data, "%d-%d-%d %d:%d:%d", info->tm_year + 1900, info->tm_mon + 1, info->tm_mday,
info->tm_hour, info->tm_min, info->tm_sec);
printf("get date is : %s\n", data);
}
// 单词查询
int do_query(int sockfd, MSG_T *msg, sqlite3 *db)
{
char sql[128] = {0};
char word[64] = {0};
int found = 0;
char date[128] = {0};
char *errmsg;
printf("\n");//显示换行
//单词查找
strcpy(word, msg->data);
found = do_searchword(msg, word);
if (found == 1)// 找到了单词，需要将 name,date,word 插入到历史记录表中去
{
get_date(date);//获取系统时间
//sprintf(sql, "insert into user values('%s', '%s');", msg->name, msg->data);
sprintf(sql, "insert into record values('%s', '%s', '%s')", msg->name, date, word);
if (sqlite3_exec(db, sql, NULL, NULL, &errmsg) != SQLITE_OK)
{
printf("%s\n", errmsg);
return -1;
}
else
{
printf("sqlite3 insert record done.\n");
}
}
else if (found == 0)//没有找到
{
memset(msg->data, 0, strlen(msg->data));
strcpy(msg->data, "Not found!\n");
}
else if (found == -1)//dict.txt代开失败
{
memset(msg->data, 0, strlen(msg->data));
strcpy(msg->data, "fail to open dict.txt.");
}
//将查询的结果发送给客户端
send(sockfd, msg, sizeof(MSG_T), 0);
return 0;
}
// 得到查询结果，并且需要将历史记录发送给客户端
int history_callback(void* arg,int colCount,char** colValue,char** colName)
{
// record : name, date, word
int acceptfd;
MSG_T msg;
acceptfd = *((int *)arg);
sprintf(msg.data, "%s , %s", colValue[1], colValue[2]);
send(acceptfd, &msg, sizeof(MSG_T), 0);
return 0;
}
// 历史记录查询
int do_history(int sockfd, MSG_T *msg, sqlite3 *db)
{
char sql[128] = {0};
char *errmsg;
//查询数据库
//会先执行*sql对应的功能命令，然后将结果传递给回调函数，回调函数根据结果再进一步执行
//关于回调函数详细可参考https://blog.csdn.net/u012351051/article/details/90382391
sprintf(sql, "select * from record where name = '%s'", msg->name);
if(sqlite3_exec(db, sql, history_callback,(void *)&sockfd, &errmsg)!= SQLITE_OK)
{
printf("%s\n", errmsg);
}
else
{
printf("sqlite3 query record done.\n");
}
// 所有的记录查询发送完毕之后，给客户端发出一个结束信息
msg->data[0] = '\0';
send(sockfd, msg, sizeof(MSG_T), 0);
return 0;
}
int do_client(int acceptfd, sqlite3 *db)
{
MSG_T recv_msg;
// 默认是阻塞式接收
// 如果客户端断开连接 或是 主动发送close关闭连接,recv会返回0
// recv的返回值：<0 出错; =0 连接关闭; >0 接收到数据大小
while (recv(acceptfd, &recv_msg, sizeof(MSG_T), 0) > 0)
{
switch(recv_msg.type)
{
case MSGTYPE_R:
do_register(acceptfd, &recv_msg, db);
break;
case MSGTYPE_L:
do_login(acceptfd, &recv_msg, db);
break;
case MSGTYPE_Q:
do_query(acceptfd, &recv_msg, db);
break;
case MSGTYPE_H:
do_history(acceptfd, &recv_msg, db);
break;
default:
printf("invalid data msg.\n");
}
}
printf("client exit.\n");
close(acceptfd);
exit(0);
return 0;
}
// ./server 192.168.0.107 10000
// 知识点：
// 1、在一个套接字被创建时，其默认是工作在阻塞模式下，即所有socket相关的数据发送、接收函数都会阻塞，
// 直到数据发送、接收成功，函数才继续执行
// 2、可以通过fcntl来设置成阻塞或非阻塞模式。https://blog.csdn.net/haoyu_linux/article/details/44306993
int main(int argc, const char *argv[])
{
int sockfd, acceptfd;
struct sockaddr_in server_addr;
struct sockaddr_in client_addr;
socklen_t addrlen = sizeof(client_addr);
char ipv4_addr[16];//存放电分格式的ip地址
sqlite3 *db = NULL;
char *errmsg = NULL;
char sql[128] = {0};
pid_t pid;
if (argc != 3)
{
printf("usage: %s serverip port\n", argv[0]);
return -1;
}
/*********************数据库操作*********************/
if (sqlite3_open(DATABASE, &db) != SQLITE_OK) //打开数据库
{
printf("%s\n", sqlite3_errmsg(db));
return -1;
}
printf("sqlite3 open %s success.\n", DATABASE);
sprintf(sql, "create table if not exists user(name text primary key, passwd text);");
if (sqlite3_exec(db, sql, NULL, NULL, &errmsg) != SQLITE_OK) //创建用户表
{
printf("%s\n", errmsg);
return -1;
}
memset(sql, 0, sizeof(sql));
sprintf(sql, "create table if not exists record(name text, date text, word text);");
if (sqlite3_exec(db, sql, NULL, NULL, &errmsg) != SQLITE_OK)//创建记录表
{
printf("%s\n", errmsg);
return -1;
}
/*********************tcp server操作*********************/
// 申请socket
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
perror("fail to socket\n");
return -1;
}
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = inet_addr(argv[1]);
server_addr.sin_port = htons(atoi(argv[2]));
bzero(&(server_addr.sin_zero), sizeof(server_addr.sin_zero));
//绑定套接字
if (bind(sockfd, (struct sockaddr*)&server_addr, sizeof(struct sockaddr)) < 0)
{
perror("fail to bind.\n");
return -1;
}
//将套接字设为监听模式
if (listen(sockfd, 5) < 0)
{
perror("fail to listen.\n");
exit(1);
}
printf("listen success.\n");
//处理僵尸进程
signal(SIGCHLD, SIG_IGN);
while (1)
{
//接收客户端的连接请求
if ((acceptfd = accept(sockfd, (struct sockaddr *)&client_addr, &addrlen)) < 0)
{
perror("fail to accept\n");
return -1;
}
if (inet_ntop(AF_INET, &client_addr.sin_addr, ipv4_addr, addrlen) < 0)
{
perror("fail to inet_ntop\n");
return -1;
}
printf("client(%s:%d) is connected!\n", ipv4_addr, htons(client_addr.sin_port));
//创建子进程
if ((pid = fork()) < 0)
{
perror("fail to fork!\n");
return -1;
}
else if (pid == 0) //子进程,处理客服端具体的消息
{
close(sockfd);
do_client(acceptfd, db);
}
else //父进程,用来接收客户端的连接请求
{
close(acceptfd);//父进程不需要子进程的套接字
}
}
return 0;
}all:client server
.PHONY : all
cc = gcc
client : client.c
$(cc) client.c -o client
server : server.c
$(cc) server.c -o server -lsqlite3
.PHONY : clean
clean:
rm client server