使用c++ 写一个远程控制代码，要求，多并发，实现功能，打开文件，关闭文件，上传文件，下载文件，远程监控，

下面是一个简单的远程控制代码实现，使用了多线程实现多并发：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <pthread.h>
#include <unistd.h>

#define MAX_CLIENTS 10
#define FILE_BUFFER_SIZE 1024

struct client_info {
    int sock_fd;
    struct sockaddr_in client_addr;
};

void *handle_client(void *arg) {
    struct client_info *info = (struct client_info *) arg;
    char buffer[1024];
    int recv_len;
    char filename[256];
    FILE *fp;
    int filesize;
    char file_buffer[FILE_BUFFER_SIZE];
    int sent_size;
    int read_size;

    printf("New client connected: %s:%d\n", inet_ntoa(info->client_addr.sin_addr), ntohs(info->client_addr.sin_port));

    while (1) {
        // 接收客户端发送的命令
        recv_len = recv(info->sock_fd, buffer, sizeof(buffer), 0);
        if (recv_len == 0) {
            // 客户端关闭了连接
            printf("Client disconnected: %s:%d\n", inet_ntoa(info->client_addr.sin_addr), ntohs(info->client_addr.sin_port));
            close(info->sock_fd);
            free(info);
            pthread_exit(NULL);
        } else if (recv_len < 0) {
            // 接收数据失败
            printf("Failed to receive data from client: %s:%d\n", inet_ntoa(info->client_addr.sin_addr), ntohs(info->client_addr.sin_port));
            close(info->sock_fd);
            free(info);
            pthread_exit(NULL);
        }

        // 处理客户端发送的命令
        if (strncmp(buffer, "open", 4) == 0) {
            // 打开文件
            sscanf(buffer + 5, "%s", filename);
            fp = fopen(filename, "r");
            if (fp == NULL) {
                send(info->sock_fd, "Failed to open file", strlen("Failed to open file"), 0);
            } else {
                send(info->sock_fd, "File opened", strlen("File opened"), 0);
                fclose(fp);
            }
        } else if (strncmp(buffer, "close", 5) == 0) {
            // 关闭文件
            sscanf(buffer + 6, "%s", filename);
            fp = fopen(filename, "r");
            if (fp == NULL) {
                send(info->sock_fd, "Failed to close file", strlen("Failed to close file"), 0);
            } else {
                send(info->sock_fd, "File closed", strlen("File closed"), 0);
                fclose(fp);
            }
        } else if (strncmp(buffer, "upload", 6) == 0) {
            // 上传文件
            sscanf(buffer + 7, "%s %d", filename, &filesize);
            fp = fopen(filename, "w");
            if (fp == NULL) {
                send(info->sock_fd, "Failed to create file", strlen("Failed to create file"), 0);
            } else {
                send(info->sock_fd, "Ready to receive file", strlen("Ready to receive file"), 0);
                sent_size = 0;
                while (sent_size < filesize) {
                    read_size = recv(info->sock_fd, file_buffer, FILE_BUFFER_SIZE, 0);
                    if (read_size < 0) {
                        printf("Failed to receive file from client: %s:%d\n", inet_ntoa(info->client_addr.sin_addr), ntohs(info->client_addr.sin_port));
                        fclose(fp);
                        remove(filename);
                        break;
                    }
                    fwrite(file_buffer, 1, read_size, fp);
                    sent_size += read_size;
                }
                fclose(fp);
            }
        } else if (strncmp(buffer, "download", 8) == 0) {
            // 下载文件
            sscanf(buffer + 9, "%s", filename);
            fp = fopen(filename, "r");
            if (fp == NULL) {
                send(info->sock_fd, "Failed to open file", strlen("Failed to open file"), 0);
            } else {
                fseek(fp, 0, SEEK_END);
                filesize = ftell(fp);
                fseek(fp, 0, SEEK_SET);
                sprintf(buffer, "Ready to send file %d", filesize);
                send(info->sock_fd, buffer, strlen(buffer), 0);
                sent_size = 0;
                while (sent_size < filesize) {
                    read_size = fread(file_buffer, 1, FILE_BUFFER_SIZE, fp);
                    if (read_size < 0) {
                        printf("Failed to read file: %s\n", filename);
                        break;
                    }
                    send(info->sock_fd, file_buffer, read_size, 0);
                    sent_size += read_size;
                }
                fclose(fp);
            }
        } else if (strncmp(buffer, "monitor", 7) == 0) {
            // 远程监控
            printf("Start monitoring client: %s:%d\n", inet_ntoa(info->client_addr.sin_addr), ntohs(info->client_addr.sin_port));
            while (1) {
                // 接收客户端发送的数据
                recv_len = recv(info->sock_fd, buffer, sizeof(buffer), 0);
                if (recv_len == 0) {
                    // 客户端关闭了连接
                    printf("Client disconnected: %s:%d\n", inet_ntoa(info->client_addr.sin_addr), ntohs(info->client_addr.sin_port));
                    close(info->sock_fd);
                    free(info);
                    pthread_exit(NULL);
                } else if (recv_len < 0) {
                    // 接收数据失败
                    printf("Failed to receive data from client: %s:%d\n", inet_ntoa(info->client_addr.sin_addr), ntohs(info->client_addr.sin_port));
                    close(info->sock_fd);
                    free(info);
                    pthread_exit(NULL);
                }

                printf("Received data from client: %s:%d\n", inet_ntoa(info->client_addr.sin_addr), ntohs(info->client_addr.sin_port));
                printf("%s", buffer);
            }
        }
    }
}

int main(int argc, char *argv[]) {
    int server_fd, client_fd;
    struct sockaddr_in server_addr, client_addr;
    socklen_t client_addr_len;
    pthread_t threads[MAX_CLIENTS];
    int i = 0;

    // 创建服务器套接字
    server_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (server_fd < 0) {
        perror("Failed to create socket");
        exit(EXIT_FAILURE);
    }

    // 绑定服务器地址和端口号
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(atoi(argv[1]));
    if (bind(server_fd, (struct sockaddr *) &server_addr, sizeof(server_addr)) < 0) {
        perror("Failed to bind socket");
        exit(EXIT_FAILURE);
    }

    // 监听来自客户端的连接请求
    if (listen(server_fd, MAX_CLIENTS) < 0) {
        perror("Failed to listen on socket");
        exit(EXIT_FAILURE);
    }

    printf("Server started at port %d\n", atoi(argv[1]));

    while (1) {
        // 接收来自客户端的连接请求
        client_addr_len = sizeof(client_addr);
        client_fd = accept(server_fd, (struct sockaddr *) &client_addr, &client_addr_len);
        if (client_fd < 0) {
            perror("Failed to accept client connection");
            continue;
        }

        // 创建线程处理客户端连接
        struct client_info *info = (struct client_info *) malloc(sizeof(struct client_info));
        info->sock_fd = client_fd;
        info->client_addr = client_addr;
        pthread_create(&threads[i++], NULL, handle_client, info);
        if (i == MAX_CLIENTS) {
            i = 0;
            while (i < MAX_CLIENTS) {
                pthread_join(threads[i++], NULL);
            }
            i = 0;
        }
    }

    return 0;
}

这个程序实现了以下功能：

- 打开文件：客户端发送 `open filename` 命令，服务器会尝试打开指定的文件，如果打开成功，会向客户端发送 "File opened" 消息，否则会向客户端发送 "Failed to open file" 消息。
- 关闭文件：客户端发送 `close filename` 命令，服务器会尝试关闭指定的文件，如果关闭成功，会向客户端发送 "File closed" 消息，否则会向客户端发送 "Failed to close file" 消息。
- 上传文件：客户端发送 `upload filename filesize` 命令，服务器会尝试创建指定的文件并准备接收客户端发送的数据。如果创建文件失败，会向客户端发送 "Failed to create file" 消息，否则会向客户端发送 "Ready to receive file" 消息，并开始接收客户端发送的数据，直到接收完整个文件。
- 下载文件：客户端发送 `download filename` 命令，服务器会尝试打开指定的文件并获取文件大小。如果打开文件失败，会向客户端发送 "Failed to open file" 消息，否则会向客户端发送 "Ready to send file filesize" 消息，并开始发送文件数据，直到发送完整个文件。
- 远程监控：客户端发送 `monitor` 命令，服务器会进入远程监控模式，接收客户端发送的数据并打印到控制台上。客户端可以随时关闭连接来结束监控模式。