server.c

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
#include <sys/types.h>
#include <signal.h>
#define MAX_CLIENTS 5
#define BUFFER_SZ 2048
static _Atomic unsigned int cli_count = 0;
static int uid = 10;
typedef struct
{
	struct sockaddr_in address;
	int sockfd, uid;
	char name[32];
} client_t;
client_t *clients[MAX_CLIENTS];
pthread_mutex_t clients_mutex = PTHREAD_MUTEX_INITIALIZER;
void str_overwrite_stdout()
{
	printf("\r%s", "> ");
	fflush(stdout);
}
void str_trim_lf(char *arr, int length)
{
	for (int i = 0; i < length; i++)
	{
		if (arr[i] == '\n')
		{
			arr[i] = '\0';
			break;
		}
	}
}
void print_client_addr(struct sockaddr_in addr)
{
	printf("%d.%d.%d.%d",
		   addr.sin_addr.s_addr & 0xff,
		   (addr.sin_addr.s_addr & 0xff00) >> 8,
		   (addr.sin_addr.s_addr & 0xff0000) >> 16,
		   (addr.sin_addr.s_addr & 0xff000000) >> 24);
}
void queue_add(client_t *cl)
{
	pthread_mutex_lock(&clients_mutex);
	for (int i = 0; i < MAX_CLIENTS; ++i)
	{
		if (!clients[i])
		{
			clients[i] = cl;
			break;
		}
	}
	pthread_mutex_unlock(&clients_mutex);
}
void queue_remove(int uid)
{
	pthread_mutex_lock(&clients_mutex);
	for (int i = 0; i < MAX_CLIENTS; ++i)
	{
		if (clients[i])
		{
			if (clients[i]->uid == uid)
			{
				clients[i] = NULL;
				break;
			}
		}
	}
	pthread_mutex_unlock(&clients_mutex);
}
void send_message(char *s, int uid)
{
	pthread_mutex_lock(&clients_mutex);
	for (int i = 0; i < MAX_CLIENTS; ++i)
	{
		if (clients[i])
		{
			if (clients[i]->uid != uid)
			{
				if (write(clients[i]->sockfd, s, strlen(s)) < 0)
				{
					perror("ERROR: Write To Descriptor Failed");
					break;
				}
			}
		}
	}
	pthread_mutex_unlock(&clients_mutex);
}
void *handle_client(void *arg)
{
	char buff_out[BUFFER_SZ];
	char name[32];
	int leave_flag = 0;
	cli_count++;
	client_t *cli = (client_t *)arg;
	if (recv(cli->sockfd, name, 32, 0) <= 0 || strlen(name) < 2 || strlen(name) >= 32 - 1)
	{
		printf("Didn't Enter The Name.\n");
		leave_flag = 1;
	}
	else
	{
		strcpy(cli->name, name);
		sprintf(buff_out, "%s Has Joined\n", cli->name);
		printf("%s", buff_out);
		send_message(buff_out, cli->uid);
	}
	bzero(buff_out, BUFFER_SZ);
	while (1)
	{
		if (leave_flag)
		{
			break;
		}
		int receive = recv(cli->sockfd, buff_out, BUFFER_SZ, 0);
		if (receive > 0)
		{
			if (strlen(buff_out) > 0)
			{
				send_message(buff_out, cli->uid);
				str_trim_lf(buff_out, strlen(buff_out));
				printf("%s -> %s\n", buff_out, cli->name);
			}
		}
		else if (receive == 0 || strcmp(buff_out, "Exit") == 0)
		{
			sprintf(buff_out, "%s Has Left\n", cli->name);
			printf("%s", buff_out);
			send_message(buff_out, cli->uid);
			leave_flag = 1;
		}
		else
		{
			printf("ERROR: -1\n");
			leave_flag = 1;
		}
		bzero(buff_out, BUFFER_SZ);
	}
	close(cli->sockfd);
	queue_remove(cli->uid);
	free(cli);
	cli_count--;
	pthread_detach(pthread_self());
	return NULL;
}
int main(int argc, char **argv)
{
	if (argc != 2)
	{
		printf("Usage: %s <port>\n", argv[0]);
		return EXIT_FAILURE;
	}
	char *ip = "127.0.0.1";
	int port = atoi(argv[1]);
	int option = 1;
	int listenfd = 0, connfd = 0;
	struct sockaddr_in serv_addr;
	struct sockaddr_in cli_addr;
	pthread_t tid;
	listenfd = socket(AF_INET, SOCK_STREAM, 0);
	serv_addr.sin_family = AF_INET;
	serv_addr.sin_addr.s_addr = inet_addr(ip);
	serv_addr.sin_port = htons(port);
	signal(SIGPIPE, SIG_IGN);
	if (setsockopt(listenfd, SOL_SOCKET, (SO_REUSEPORT | SO_REUSEADDR), (char *)&option, sizeof(option)) < 0)
	{
		perror("ERROR: setsockopt Failed");
		return EXIT_FAILURE;
	}
	if (bind(listenfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
	{
		perror("ERROR: Socket Binding Failed");
		return EXIT_FAILURE;
	}
	if (listen(listenfd, 10) < 0)
	{
		perror("ERROR: Socket Listening Failed");
		return EXIT_FAILURE;
	}
	printf("XXX Chat Server Online XXX\n");
	while (1)
	{
		socklen_t clilen = sizeof(cli_addr);
		connfd = accept(listenfd, (struct sockaddr *)&cli_addr, &clilen);
		if ((cli_count + 1) == MAX_CLIENTS)
		{
			printf("Max clients Reached. Rejected: ");
			print_client_addr(cli_addr);
			printf(":%d\n", cli_addr.sin_port);
			close(connfd);
			continue;
		}
		client_t *cli = (client_t *)malloc(sizeof(client_t));
		cli->address = cli_addr;
		cli->sockfd = connfd;
		cli->uid = uid++;
		queue_add(cli);
		pthread_create(&tid, NULL, &handle_client, (void *)cli);
		sleep(1);
	}
	return EXIT_SUCCESS;
}