471 lines
15 KiB
C
471 lines
15 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <arpa/inet.h>
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#include <pthread.h>
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#include <signal.h>
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#define MAX_CLIENTS 10
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#define BUFFER_SIZE 1024
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#define USERNAME_LENGTH 50
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#define PASSWORD_LENGTH 50
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#define FILENAME "./users.txt"
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typedef struct {
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int socket;
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char username[USERNAME_LENGTH];
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pthread_t thread;
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int active;
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} Client;
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Client clients[MAX_CLIENTS];
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pthread_mutex_t clients_mutex = PTHREAD_MUTEX_INITIALIZER;
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int server_socket;
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// 函数声明
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void handle_signal(int sig);
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void *handle_client(void *arg);
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int find_client_index(int socket);
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int find_client_index_by_username(const char *username);
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void send_private_message(const char *sender, const char *recipient, const char *message);
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void list_users(int client_socket);
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int authenticate_user(const char *username, const char *password);
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int register_user(const char *username, const char *password);
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void save_user(const char *username, const char *password);
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int main() {
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int client_socket;
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struct sockaddr_in server_addr, client_addr;
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socklen_t client_addr_len = sizeof(client_addr);
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// 创建socket
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server_socket = socket(AF_INET, SOCK_STREAM, 0);
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if (server_socket == -1) {
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perror("Socket creation failed");
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exit(EXIT_FAILURE);
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}
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// 设置socket选项
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int opt = 1;
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if (setsockopt(server_socket, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) == -1) {
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perror("Setsockopt failed");
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exit(EXIT_FAILURE);
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}
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// 准备服务器地址
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memset(&server_addr, 0, sizeof(server_addr));
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server_addr.sin_family = AF_INET;
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server_addr.sin_addr.s_addr = INADDR_ANY;
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server_addr.sin_port = htons(8888);
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// 绑定socket
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if (bind(server_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
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perror("Bind failed");
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exit(EXIT_FAILURE);
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}
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// 监听连接
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if (listen(server_socket, 5) == -1) {
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perror("Listen failed");
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exit(EXIT_FAILURE);
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}
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printf("Server started. Waiting for connections...\n");
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// 初始化客户端数组
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for (int i = 0; i < MAX_CLIENTS; i++) {
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clients[i].socket = -1;
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clients[i].active = 0;
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}
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// 设置信号处理
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signal(SIGINT, handle_signal);
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// 接受客户端连接
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while (1) {
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client_socket = accept(server_socket, (struct sockaddr *)&client_addr, &client_addr_len);
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if (client_socket == -1) {
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perror("Accept failed");
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continue;
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}
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// 查找空闲位置
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int i;
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for (i = 0; i < MAX_CLIENTS; i++) {
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if (clients[i].socket == -1) {
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pthread_mutex_lock(&clients_mutex);
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clients[i].socket = client_socket;
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clients[i].active = 1;
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pthread_mutex_unlock(&clients_mutex);
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// 创建线程处理客户端
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if (pthread_create(&clients[i].thread, NULL, handle_client, &clients[i]) != 0) {
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perror("Thread creation failed");
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pthread_mutex_lock(&clients_mutex);
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clients[i].socket = -1;
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clients[i].active = 0;
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pthread_mutex_unlock(&clients_mutex);
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close(client_socket);
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}
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pthread_detach(clients[i].thread);
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break;
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}
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}
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if (i == MAX_CLIENTS) {
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// 服务器已满
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char response[] = "Server is full. Try again later.\n";
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send(client_socket, response, strlen(response), 0);
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close(client_socket);
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}
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}
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// 关闭服务器socket
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close(server_socket);
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return 0;
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}
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void handle_signal(int sig) {
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printf("\nShutting down server...\n");
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// 关闭所有客户端socket
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pthread_mutex_lock(&clients_mutex);
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (clients[i].socket != -1) {
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close(clients[i].socket);
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clients[i].socket = -1;
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clients[i].active = 0;
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}
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}
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pthread_mutex_unlock(&clients_mutex);
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// 关闭服务器socket
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close(server_socket);
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exit(EXIT_SUCCESS);
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}
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void *handle_client(void *arg) {
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Client *client = (Client *)arg;
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char buffer[BUFFER_SIZE];
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int bytes_received;
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// 登录/注册流程
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while (1) {
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// 发送菜单
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char menu[] = "1. Login\n2. Register\nEnter choice: ";
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send(client->socket, menu, strlen(menu), 0);
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// 接收选择
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memset(buffer, 0, BUFFER_SIZE);
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bytes_received = recv(client->socket, buffer, BUFFER_SIZE - 1, 0);
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if (bytes_received <= 0) {
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pthread_mutex_lock(&clients_mutex);
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client->active = 0;
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pthread_mutex_unlock(&clients_mutex);
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close(client->socket);
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pthread_exit(NULL);
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}
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int choice = atoi(buffer);
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// 处理登录
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if (choice == 1) {
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// 请求用户名
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char username_prompt[] = "Username: ";
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send(client->socket, username_prompt, strlen(username_prompt), 0);
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// 接收用户名
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memset(buffer, 0, BUFFER_SIZE);
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bytes_received = recv(client->socket, buffer, BUFFER_SIZE - 1, 0);
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if (bytes_received <= 0) {
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pthread_mutex_lock(&clients_mutex);
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client->active = 0;
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pthread_mutex_unlock(&clients_mutex);
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close(client->socket);
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pthread_exit(NULL);
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}
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char username[USERNAME_LENGTH];
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strncpy(username, buffer, USERNAME_LENGTH - 1);
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// 请求密码
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char password_prompt[] = "Password: ";
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send(client->socket, password_prompt, strlen(password_prompt), 0);
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// 接收密码
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memset(buffer, 0, BUFFER_SIZE);
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bytes_received = recv(client->socket, buffer, BUFFER_SIZE - 1, 0);
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if (bytes_received <= 0) {
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pthread_mutex_lock(&clients_mutex);
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client->active = 0;
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pthread_mutex_unlock(&clients_mutex);
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close(client->socket);
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pthread_exit(NULL);
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}
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char password[PASSWORD_LENGTH];
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strncpy(password, buffer, PASSWORD_LENGTH - 1);
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// 验证用户
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if (authenticate_user(username, password)) {
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// 检查用户名是否已被使用
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int username_in_use = 0;
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pthread_mutex_lock(&clients_mutex);
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (i != find_client_index(client->socket) && clients[i].active &&
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strcmp(clients[i].username, username) == 0) {
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username_in_use = 1;
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break;
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}
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}
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pthread_mutex_unlock(&clients_mutex);
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if (username_in_use) {
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char response[] = "Username already in use. Please try again.\n";
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send(client->socket, response, strlen(response), 0);
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} else {
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// 登录成功
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strcpy(client->username, username);
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char success[] = "Login successful. Welcome to the chat!\n";
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send(client->socket, success, strlen(success), 0);
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// 通知用户可用命令
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char help[] = "Available commands:\n/private <username> <message> - Send private message\n/list - List online users\n/quit - Exit chat\n";
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send(client->socket, help, strlen(help), 0);
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break;
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}
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} else {
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char response[] = "Authentication failed. Please try again.\n";
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send(client->socket, response, strlen(response), 0);
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}
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}
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// 处理注册
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else if (choice == 2) {
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// 请求用户名
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char username_prompt[] = "Enter username: ";
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send(client->socket, username_prompt, strlen(username_prompt), 0);
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// 接收用户名
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memset(buffer, 0, BUFFER_SIZE);
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bytes_received = recv(client->socket, buffer, BUFFER_SIZE - 1, 0);
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if (bytes_received <= 0) {
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pthread_mutex_lock(&clients_mutex);
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client->active = 0;
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pthread_mutex_unlock(&clients_mutex);
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close(client->socket);
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pthread_exit(NULL);
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}
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char username[USERNAME_LENGTH];
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strncpy(username, buffer, USERNAME_LENGTH - 1);
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// 请求密码
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char password_prompt[] = "Enter password: ";
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send(client->socket, password_prompt, strlen(password_prompt), 0);
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// 接收密码
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memset(buffer, 0, BUFFER_SIZE);
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bytes_received = recv(client->socket, buffer, BUFFER_SIZE - 1, 0);
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if (bytes_received <= 0) {
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pthread_mutex_lock(&clients_mutex);
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client->active = 0;
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pthread_mutex_unlock(&clients_mutex);
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close(client->socket);
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pthread_exit(NULL);
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}
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char password[PASSWORD_LENGTH];
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strncpy(password, buffer, PASSWORD_LENGTH - 1);
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// 注册用户
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if (register_user(username, password)) {
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char success[] = "Registration successful. You can now login.\n";
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send(client->socket, success, strlen(success), 0);
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} else {
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char response[] = "Registration failed. Username already exists.\n";
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send(client->socket, response, strlen(response), 0);
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}
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}
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else {
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char response[] = "Invalid choice. Please try again.\n";
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send(client->socket, response, strlen(response), 0);
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}
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}
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// 聊天循环
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while (1) {
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memset(buffer, 0, BUFFER_SIZE);
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bytes_received = recv(client->socket, buffer, BUFFER_SIZE - 1, 0);
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if (bytes_received <= 0) {
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// 客户端断开连接
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break;
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}
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// 检查是否是退出命令
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if (strncmp(buffer, "/quit", 5) == 0) {
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break;
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}
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// 检查是否是列出用户命令
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if (strncmp(buffer, "/list", 5) == 0) {
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list_users(client->socket);
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continue;
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}
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// 检查是否是私聊命令
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if (strncmp(buffer, "/private", 7) == 0) {
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char recipient[USERNAME_LENGTH];
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char message[BUFFER_SIZE - USERNAME_LENGTH - 8];
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// 解析命令
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sscanf(buffer, "/private %s %[^\n]", recipient, message);
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// 发送私聊消息
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send_private_message(client->username, recipient, message);
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continue;
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}
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// 发送帮助信息
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char help[] = "Invalid command. Available commands:\n/private <username> <message> - Send private message\n/list - List online users\n/quit - Exit chat\n";
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send(client->socket, help, strlen(help), 0);
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}
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// 客户端断开连接
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char leave_message[BUFFER_SIZE];
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snprintf(leave_message, BUFFER_SIZE, "%s has left the chat.\n", client->username);
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pthread_mutex_lock(&clients_mutex);
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (i != find_client_index(client->socket) && clients[i].active) {
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send(clients[i].socket, leave_message, strlen(leave_message), 0);
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}
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}
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pthread_mutex_unlock(&clients_mutex);
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// 关闭客户端socket
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pthread_mutex_lock(&clients_mutex);
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close(client->socket);
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client->socket = -1;
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client->active = 0;
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pthread_mutex_unlock(&clients_mutex);
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pthread_exit(NULL);
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}
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int find_client_index(int socket) {
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (clients[i].socket == socket) {
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return i;
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}
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}
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return -1;
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}
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int find_client_index_by_username(const char *username) {
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pthread_mutex_lock(&clients_mutex);
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (clients[i].active && strcmp(clients[i].username, username) == 0) {
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pthread_mutex_unlock(&clients_mutex);
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return i;
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}
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}
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pthread_mutex_unlock(&clients_mutex);
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return -1;
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}
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void send_private_message(const char *sender, const char *recipient, const char *message) {
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int recipient_index = find_client_index_by_username(recipient);
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if (recipient_index == -1) {
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char error[BUFFER_SIZE];
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snprintf(error, BUFFER_SIZE, "Error: User '%s' not found or offline.\n", recipient);
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int sender_index = find_client_index_by_username(sender);
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if (sender_index != -1) {
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send(clients[sender_index].socket, error, strlen(error), 0);
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}
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return;
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}
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// 发送消息给接收者
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char private_message[BUFFER_SIZE];
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snprintf(private_message, BUFFER_SIZE, "[Private from %s]: %s\n", sender, message);
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send(clients[recipient_index].socket, private_message, strlen(private_message), 0);
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// 发送确认给发送者
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char confirmation[BUFFER_SIZE];
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snprintf(confirmation, BUFFER_SIZE, "[Private to %s]: %s\n", recipient, message);
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int sender_index = find_client_index_by_username(sender);
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if (sender_index != -1) {
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send(clients[sender_index].socket, confirmation, strlen(confirmation), 0);
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}
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}
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void list_users(int client_socket) {
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char response[BUFFER_SIZE] = "Online users:\n";
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pthread_mutex_lock(&clients_mutex);
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (clients[i].active) {
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strncat(response, clients[i].username, USERNAME_LENGTH - strlen(response) - 2);
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strcat(response, "\n");
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}
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}
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pthread_mutex_unlock(&clients_mutex);
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send(client_socket, response, strlen(response), 0);
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}
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int authenticate_user(const char *username, const char *password) {
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FILE *file = fopen(FILENAME, "r");
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if (file == NULL) {
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return 0;
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}
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char stored_username[USERNAME_LENGTH];
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char stored_password[PASSWORD_LENGTH];
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int found = 0;
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while (fscanf(file, "%s %s", stored_username, stored_password) != EOF) {
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if (strcmp(username, stored_username) == 0 && strcmp(password, stored_password) == 0) {
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found = 1;
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break;
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}
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}
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fclose(file);
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return found;
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}
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int register_user(const char *username, const char *password) {
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FILE *file = fopen(FILENAME, "r");
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if (file == NULL) {
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file = fopen(FILENAME, "w");
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if (file == NULL) {
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return 0;
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}
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fclose(file);
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file = fopen(FILENAME, "r");
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}
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char stored_username[USERNAME_LENGTH];
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while (fscanf(file, "%s", stored_username) != EOF) {
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if (strcmp(username, stored_username) == 0) {
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fclose(file);
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return 0; // 用户名已存在
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}
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// 跳过密码
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fscanf(file, "%*s");
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}
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fclose(file);
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// 添加新用户
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save_user(username, password);
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return 1;
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}
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void save_user(const char *username, const char *password) {
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FILE *file = fopen(FILENAME, "a");
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if (file != NULL) {
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fprintf(file, "%s %s\n", username, password);
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fclose(file);
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}
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}
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