436 lines
13 KiB
C
436 lines
13 KiB
C
/*
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Реализовать приложение сетевой чат. Сервер должен
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использовать неблокирующие сокеты, как способ параллельной
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обработки и передачи данных клиентам. Сетевой сервер
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должен быть реализован ввиде демона, с контролем и
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журналированием ошибок через syslog. Сервер должен
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обеспечивать одноадресную и широковещательную отправку
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текстовых сообщений, одному или всем участникам соответственно.
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*/
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#include "daemon.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <netinet/in.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <sys/syslog.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include <time.h>
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#include <unistd.h>
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#define MAX_CLIENTS 100
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#define BUFFER_SIZE 1024
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#define NAME_SIZE 32
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typedef struct {
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int socket;
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char name[NAME_SIZE];
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int has_name;
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} Client;
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static int stop = 0;
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static Client clients[MAX_CLIENTS];
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static int client_count = 0;
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void signal_handler(int sig) {
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switch (sig) {
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case SIGTERM:
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case SIGINT:
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syslog(LOG_INFO, "Terminate signal catched. Stopping chat server...");
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stop = 1;
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break;
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}
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}
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void get_timestamp(char *buffer, size_t size) {
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time_t now = time(NULL);
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struct tm *tm_info = localtime(&now);
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strftime(buffer, size, "%H:%M:%S", tm_info);
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}
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void send_user_list(int client_socket) {
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char list[BUFFER_SIZE * 2];
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int offset = 0;
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int count = 0;
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offset += snprintf(list + offset, sizeof(list) - offset,
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"=== Online users (%d) ===\n", client_count);
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (clients[i].socket != -1 && clients[i].has_name) {
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offset += snprintf(list + offset, sizeof(list) - offset, " - %s\n",
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clients[i].name);
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count++;
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}
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}
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if (count == 0) {
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offset += snprintf(list + offset, sizeof(list) - offset,
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" (no other users yet)\n");
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}
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offset += snprintf(list + offset, sizeof(list) - offset,
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"========================\n");
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send(client_socket, list, strlen(list), 0);
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}
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void init_clients() {
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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].has_name = 0;
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memset(clients[i].name, 0, NAME_SIZE);
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}
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client_count = 0;
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}
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int add_client(int sock) {
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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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clients[i].socket = sock;
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clients[i].has_name = 0;
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client_count++;
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syslog(LOG_INFO, "New client connected (slot %d, total: %d)", i,
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client_count);
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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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void remove_client(int index) {
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if (clients[index].socket != -1) {
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syslog(LOG_INFO, "Client '%s' disconnected (slot %d)", clients[index].name,
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index);
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// Уведомляем других пользователей об отключении
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if (clients[index].has_name) {
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char notification[256];
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snprintf(notification, sizeof(notification), "*** %s left the chat ***\n",
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clients[index].name);
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (clients[i].socket != -1 && i != index && clients[i].has_name) {
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send(clients[i].socket, notification, strlen(notification), 0);
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}
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}
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}
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close(clients[index].socket);
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clients[index].socket = -1;
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clients[index].has_name = 0;
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memset(clients[index].name, 0, NAME_SIZE);
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client_count--;
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}
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}
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Client *find_client_by_name(const char *name) {
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (clients[i].socket != -1 && clients[i].has_name &&
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strcmp(clients[i].name, name) == 0) {
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return &clients[i];
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}
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}
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return NULL;
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}
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void broadcast_message(const char *message, int sender_index) {
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char timestamp[16];
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char formatted[BUFFER_SIZE + NAME_SIZE + 32];
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get_timestamp(timestamp, sizeof(timestamp));
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snprintf(formatted, sizeof(formatted), "[%s] %s: %s\n", timestamp,
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clients[sender_index].name, message);
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (clients[i].socket != -1 && i != sender_index && clients[i].has_name) {
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send(clients[i].socket, formatted, strlen(formatted), 0);
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}
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}
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syslog(LOG_INFO, "Broadcast from '%s': %s", clients[sender_index].name,
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message);
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}
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void send_private_message(const char *message, int sender_index,
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const char *recipient_name) {
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Client *recipient = find_client_by_name(recipient_name);
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if (recipient == NULL) {
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char error_msg[BUFFER_SIZE];
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snprintf(error_msg, sizeof(error_msg), "Error: User '%s' not found\n",
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recipient_name);
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send(clients[sender_index].socket, error_msg, strlen(error_msg), 0);
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return;
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}
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char timestamp[16];
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char formatted[BUFFER_SIZE + NAME_SIZE + 32];
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get_timestamp(timestamp, sizeof(timestamp));
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snprintf(formatted, sizeof(formatted), "[%s] %s -> you: %s\n", timestamp,
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clients[sender_index].name, message);
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send(recipient->socket, formatted, strlen(formatted), 0);
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// Отправляем подтверждение отправителю
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snprintf(formatted, sizeof(formatted), "[%s] you -> %s: %s\n", timestamp,
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recipient_name, message);
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send(clients[sender_index].socket, formatted, strlen(formatted), 0);
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syslog(LOG_INFO, "Private message from '%s' to '%s': %s",
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clients[sender_index].name, recipient_name, message);
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}
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void send_group_message(const char *message, int sender_index,
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const char *recipients_list) {
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char recipients_copy[BUFFER_SIZE];
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strncpy(recipients_copy, recipients_list, BUFFER_SIZE - 1);
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recipients_copy[BUFFER_SIZE - 1] = '\0';
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char *token = strtok(recipients_copy, ",");
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while (token != NULL) {
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while (*token == ' ')
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token++;
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char *end = token + strlen(token) - 1;
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while (end > token && *end == ' ') {
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*end = '\0';
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end--;
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}
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if (strlen(token) > 0) {
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send_private_message(message, sender_index, token);
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}
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token = strtok(NULL, ",");
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}
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}
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void handle_message(int client_index, char *message) {
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// Убираем перевод строки
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char *newline = strchr(message, '\n');
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if (newline)
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*newline = '\0';
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newline = strchr(message, '\r');
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if (newline)
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*newline = '\0';
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if (strlen(message) == 0)
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return;
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// Если у клиента еще нет имени, первое сообщение - это его имя
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if (!clients[client_index].has_name) {
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// Проверяем, не занято ли это имя
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (clients[i].socket != -1 && clients[i].has_name && i != client_index &&
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strcmp(clients[i].name, message) == 0) {
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// Имя уже занято
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char error_msg[256];
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snprintf(
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error_msg, sizeof(error_msg),
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"Error: Name '%s' is already taken. Please choose another name:\n",
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message);
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send(clients[client_index].socket, error_msg, strlen(error_msg), 0);
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syslog(LOG_WARNING, "Client in slot %d tried to use taken name: %s",
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client_index, message);
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return;
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}
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}
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strncpy(clients[client_index].name, message, NAME_SIZE - 1);
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clients[client_index].has_name = 1;
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char welcome[256];
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snprintf(welcome, sizeof(welcome), "Welcome to chat, %s! Total users: %d\n",
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message, client_count);
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send(clients[client_index].socket, welcome, strlen(welcome), 0);
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// Отправляем список пользователей
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send_user_list(clients[client_index].socket);
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// Уведомляем других о новом пользователе
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char notification[256];
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snprintf(notification, sizeof(notification), "*** %s joined the chat ***\n",
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message);
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for (int i = 0; i < MAX_CLIENTS; i++) {
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if (clients[i].socket != -1 && i != client_index && clients[i].has_name) {
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send(clients[i].socket, notification, strlen(notification), 0);
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}
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}
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syslog(LOG_INFO, "Client in slot %d set name: %s", client_index, message);
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return;
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}
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// Проверяем, не является ли это личным сообщением (@username: message)
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if (message[0] == '@') {
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char *colon = strchr(message, ':');
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if (colon != NULL) {
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*colon = '\0';
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char *recipients = message + 1; // Пропускаем '@'
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char *msg_text = colon + 1;
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/* Пропускаем пробелы после двоеточия */
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while (*msg_text == ' ')
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msg_text++;
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// Групповые сообщения
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if (strchr(recipients, ',') != NULL) {
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send_group_message(msg_text, client_index, recipients);
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} else {
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send_private_message(msg_text, client_index, recipients);
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}
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return;
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}
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}
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/* Обычное широковещательное сообщение */
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broadcast_message(message, client_index);
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}
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int create_server_socket(int port) {
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struct sockaddr_in addr;
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int listener = socket(AF_INET, SOCK_STREAM, 0);
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if (listener < 0) {
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syslog(LOG_ERR, "Unable to create server socket");
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exit(1);
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}
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// Устанавливаем неблокирующий режим
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if (fcntl(listener, F_SETFL, O_NONBLOCK) < 0) {
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syslog(LOG_ERR, "Unable to set non-blocking mode");
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exit(1);
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}
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int opt = 1;
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if (setsockopt(listener, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
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syslog(LOG_WARNING, "Unable to set SO_REUSEADDR");
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}
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addr.sin_family = AF_INET;
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addr.sin_port = htons(port);
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addr.sin_addr.s_addr = INADDR_ANY;
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if (bind(listener, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
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syslog(LOG_ERR, "Unable to bind socket to port %d", port);
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exit(1);
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}
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if (listen(listener, 10) < 0) {
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syslog(LOG_ERR, "Unable to listen");
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exit(1);
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}
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return listener;
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}
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int chat_server(int port) {
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openlog("CHAT-SERVER", 0, LOG_DAEMON);
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daemonize();
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signal(SIGTERM, signal_handler);
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signal(SIGINT, signal_handler);
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init_clients();
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int listener = create_server_socket(port);
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syslog(LOG_INFO, "Chat server started on port %d", port);
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while (!stop) {
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fd_set readset;
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FD_ZERO(&readset);
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FD_SET(listener, &readset);
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int max_fd = listener;
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// Добавляем все активные клиентские сокеты
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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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FD_SET(clients[i].socket, &readset);
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if (clients[i].socket > max_fd) {
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max_fd = clients[i].socket;
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}
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}
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}
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// Устанавливаем таймаут для периодической проверки флага stop
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struct timeval timeout;
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timeout.tv_sec = 1;
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timeout.tv_usec = 0;
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int activity = select(max_fd + 1, &readset, NULL, NULL, &timeout);
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if (activity < 0 && errno != EINTR) {
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syslog(LOG_ERR, "Select error: %s", strerror(errno));
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continue;
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}
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if (activity == 0) {
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// Таймаут, просто продолжаем
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continue;
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}
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// Проверяем, есть ли новое подключение
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if (FD_ISSET(listener, &readset)) {
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int new_socket = accept(listener, NULL, NULL);
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if (new_socket >= 0) {
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// Устанавливаем неблокирующий режим для клиентского сокета
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if (fcntl(new_socket, F_SETFL, O_NONBLOCK) < 0) {
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syslog(LOG_WARNING, "Unable to set non-blocking mode for client");
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}
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int index = add_client(new_socket);
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if (index == -1) {
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syslog(LOG_WARNING, "Maximum clients reached, rejecting connection");
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const char *msg = "Server full, please try again later\n";
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send(new_socket, msg, strlen(msg), 0);
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close(new_socket);
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} else {
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const char *greeting = "Connected to chat server. Please enter your "
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"name:\n";
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send(new_socket, greeting, strlen(greeting), 0);
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}
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}
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}
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// Проверяем данные от клиентов
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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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continue;
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if (FD_ISSET(clients[i].socket, &readset)) {
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char buffer[BUFFER_SIZE];
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int bytes_read = recv(clients[i].socket, buffer, BUFFER_SIZE - 1, 0);
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if (bytes_read <= 0) {
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// Клиент отключился
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remove_client(i);
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} else {
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buffer[bytes_read] = '\0';
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handle_message(i, buffer);
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}
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}
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}
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}
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// Закрываем все соединения
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close(listener);
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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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}
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}
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syslog(LOG_INFO, "Chat server stopped");
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closelog();
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return 0;
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}
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