根据您提供的《linux远程终端管理系统
.doc》文档内容，我将帮助您概述如何完成该项目的主要部分。由于代码量较大，这里仅提供关键部分的示例代码和指导，您可以在此基础上进一步开发和完善。
### 1
. 服务器与客户端的基本框架
#### 1
.1 服务器端
(server
.c
)
```c
#include <stdio
.h>
#include <stdlib
.h>
#include <string
.h>
#include <unistd
.h>
#include <arpa/inet
.h>
#include <sys/socket
.h>
#include <pthread
.h>
#define PORT 8888
#define MAX_CLIENTS 10
#define BUFFER_SIZE 1024
typedef struct {
int data_type;
char name[
20];
char data[BUFFER_SIZE];
} Protocol;
int client_sockets[MAX_CLIENTS];
int client_count = 0;
void *handle_client
(void *client_socket
) {
int sock = *
(int *
)client_socket;
Protocol packet;
while
(1
) {
int bytes_received = read
(sock, &packet, sizeof
(packet
));
if
(bytes_received <= 0
) break;
switch
(packet
.data_type
) {
case 0: // 登录
printf
("Login request from %s\n", packet
.name
);
// 处理登录逻辑
break;
case 1: // 注册
printf
("Register request from %s\n", packet
.name
);
// 处理注册逻辑
break;
case 2: // 消息
printf
("Message from %s: %s\n", packet
.name, packet
.data
);
// 处理消息逻辑
break;
case 3: // 心跳
printf
("Heartbeat from %s\n", packet
.name
);
// 处理心跳逻辑
break;
case 4: // 命令
printf
("Command from %s: %s\n", packet
.name, packet
.data
);
// 处理命令逻辑
break;
default:
printf
("Unknown packet type\n"
);
break;
}
}
close
(sock
);
for
(int i = 0; i < client_count; i++
) {
if
(client_sockets[i] == sock
) {
client_sockets[i] = client_sockets[--client_count];
break;
}
}
pthread_exit
(NULL
);
}
int main
() {
int server_fd, new_socket;
struct sockaddr_in address;
int addrlen = sizeof
(address
);
if
((server_fd = socket
(AF_INET, SOCK_STREAM, 0
)) == 0
) {
perror
("Socket creation failed"
);
exit
(EXIT_FAILURE
);
}
memset
(&address, 0, sizeof
(address
));
address
.sin_family = AF_INET;
address
.sin_addr
.s_addr = INADDR_ANY;
address
.sin_port = htons
(PORT
);
if
(bind
(server_fd,
(struct sockaddr *
)&address, sizeof
(address
)) < 0
) {
perror
("Bind failed"
);
exit
(EXIT_FAILURE
);
}
if
(listen
(server_fd, 3
) < 0
) {
perror
("Listen failed"
);
exit
(EXIT_FAILURE
);
}
while
(1
) {
if
((new_socket = accept
(server_fd,
(struct sockaddr *
)&address,
(socklen_t*
)&addrlen
)) < 0
) {
perror
("Accept failed"
);
continue;
}
if
(client_count >= MAX_CLIENTS
) {
close
(new_socket
);
continue;
}
client_sockets[client_count++] = new_socket;
pthread_t thread_id;
pthread_create
(&thread_id, NULL, handle_client,
(void *
)&new_socket
);
}
return 0;
}
```
#### 1
.2 客户端
(client
.c
)
```c
#include <stdio
.h>
#include <stdlib
.h>
#include <string
.h>
#include <unistd
.h>
#include <arpa/inet
.h>
#include <sys/socket
.h>
#define SERVER_IP "127
.0
.0
.1"
#define PORT 8888
#define BUFFER_SIZE 1024
typedef struct {
int data_type;
char name[
20];
char data[BUFFER_SIZE];
} Protocol;
int main
() {
int sock = socket
(AF_INET, SOCK_STREAM, 0
);
if
(sock < 0
) {
perror
("Socket creation failed"
);
exit
(EXIT_FAILURE
);
}
struct sockaddr_in server_address;
memset
(&server_address, 0, sizeof
(server_address
));
server_address
.sin_family = AF_INET;
server_address
.sin_port = htons
(PORT
);
inet_pton
(AF_INET, SERVER_IP, &server_address
.sin_addr
);
if
(connect
(sock,
(struct sockaddr *
)&server_address, sizeof
(server_address
)) < 0
) {
perror
("Connection failed"
);
exit
(EXIT_FAILURE
);
}
Protocol packet;
packet
.data_type = 0; // 示例：登录请求
strcpy
(packet
.name, "username"
);
strcpy
(packet
.data, "
password"
);
send
(sock, &packet, sizeof
(packet
), 0
);
char buffer[BUFFER_SIZE];
int bytes_received = recv
(sock, buffer, BUFFER_SIZE, 0
);
if
(bytes_received > 0
) {
buffer[bytes_received] = '\0';
printf
("Server response: %s\n", buffer
);
}
close
(sock
);
return 0;
}
```
### 2
. 主要功能实现
#### 2
.1 注册功能
在 `handle_client` 函数中添加注册逻辑：
```c
case 1: // 注册
printf
("Register request from %s\n", packet
.name
);
// 检查用户名是否已存在
// 如果不存在，保存到用户链表和文件中
// 发送注册成功或失败的消息给客户端
break;
```
#### 2
.2 登录功能
在 `handle_client` 函数中添加登录逻辑：
```c
case 0: // 登录
printf
("Login request from %s\n", packet
.name
);
// 检查用户名和密码是否正确
// 如果正确，添加到在线链表
// 发送登录成功或失败的消息给客户端
break;
```
#### 2
.3 远程命令功能
在 `handle_client` 函数中添加命令执行逻辑：
```c
case 4: // 命令
printf
("Command from %s: %s\n", packet
.name, packet
.data
);
FILE *fp;
char path[
1035];
fp = popen
(packet
.data, "r"
);
if
(fp == NULL
) {
printf
("Failed to run command\n"
);
break;
}
while
(fgets
(path, sizeof
(path
)-1, fp
) != NULL
) {
write
(client_socket, path, strlen
(path
));
}
pclose
(fp
);
break;
```
#### 2
.4 心跳机制
在客户端中添加心跳发送逻辑：
```c
void send_heartbeat
(int sock
) {
Protocol packet;
packet
.data_type = 3; // 心跳包
strcpy
(packet
.name, "username"
);
strcpy
(packet
.data, ""
);
while
(1
) {
send
(sock, &packet, sizeof
(packet
), 0
);
sleep
(3
);
}
}
int main
() {
//
... (之前的代码
)
pthread_t heartbeat_thread;
pthread_create
(&heartbeat_thread, NULL,
(void*
)send_heartbeat,
(void*
)sock
);
//
... (主逻辑
)
pthread_join
(heartbeat_thread, NULL
);
return 0;
}
```
#### 2
.5 聊天功能
在 `handle_client` 函数中添加聊天逻辑：
```c
case 2: // 消息
printf
("Message from %s: %s\n", packet
.name, packet
.data
);
// 遍历在线链表找到聊天对象
// 将消息发送给聊天对象
break;
```
### 3
. 日志记录
在服务器端添加日志记录功能：
```c
void log_message
(const char *message
) {
FILE *log_file = fopen
("server
.log", "a"
);
if
(log_file == NULL
) {
perror
("Log file open failed"
);
return;
}
fprintf
(log_file, "%s\n", message
);
fclose
(log_file
);
}
// 在适当的地方调用 log_message 函数
```
### 4
. 异常处理
在服务器端添加心跳异常处理逻辑：
```c
void check_heartbeats
() {
time_t current_time = time
(NULL
);
for
(int i = 0; i < client_count; i++
) {
if
(difftime
(current_time, last_heartbeat_times[i]
) > 15
) {
printf
("Client %d disconnected due to heartbeat timeout\n", client_sockets[i]
);
close
(client_sockets[i]
);
// 从在线链表中移除该客户端
for
(int j = i; j < client_count - 1; j++
) {
client_sockets[j] = client_sockets[j + 1];
}
client_count--;
}
}
}
// 在主线程中定期调用 check_heartbeats 函数
```
以上代码提供了项目的基架和一些关键功能的实现示例。您可以在此基础上继续完善其他功能和细节。如果有更具体的需求或问题，请随时告知。
本文展示了一个使用C++进行字符串处理的例子，具体为修改特定字符以增强密码强度的方法。通过对输入的用户名和密码进行检查，并将某些字符替换为特殊符号来实现密码的安全变更。
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