nazibul7/epoll-server.c

## epoll-server.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/epoll.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#define MAX_EVENTS 100
#define PORT 4000
#define BUFFER_SIZE 1024

void set_nonblocking(int fd)
{
    int flags = fcntl(fd, F_GETFL, 0);
    if (flags == -1)
    {
        perror("fcntl F_GETFL");
        return;
    }
    int updatedFlags = fcntl(fd, F_SETFL, flags | O_NONBLOCK);
    if (updatedFlags == -1)
    {
        perror("fcntl F_SETFL O_NONBLOCK");
    }
}

int main()
{
    int server_id, client_id;
    struct sockaddr_in address;
    int addlen = sizeof(address);
    server_id = socket(AF_INET, SOCK_STREAM, 0);
    if (server_id < 0)
    {
        perror("Socket creation failed");
        exit(EXIT_FAILURE);
    }
    memset(&address, 0, addlen);

    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);

    if (bind(server_id, (struct sockaddr *)&address, addlen) < 0)
    {
        perror("Failed to bind");
        close(server_id);
        exit(EXIT_FAILURE);
    }

    if (listen(server_id, 128) < 0)
    {
        perror("Listen failed");
        close(server_id);
        exit(EXIT_FAILURE);
    }

    printf("Server is listening on PORT %d\n", PORT);

    int epoll_fd = epoll_create1(0);
    if (epoll_fd == -1)
    {
        perror("epoll_create1 failed");
        close(server_id);
        exit(EXIT_FAILURE);
    }

    struct epoll_event event, events[MAX_EVENTS];

    event.events = EPOLLIN;
    event.data.fd = server_id;

    if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, server_id, &event) == -1)
    {
        perror("epoll_ctl failed");
        close(server_id);
        exit(EXIT_FAILURE);
    }

    while (1)
    {
        int nfds = epoll_wait(epoll_fd, events, MAX_EVENTS, -1);
        if (nfds == -1)
        {
            perror("epoll_wait failed");
            break;
        }

        for (int i = 0; i < nfds; i++)
        {
            if (events[i].data.fd == server_id)
            {
                client_id = accept(server_id, (struct sockaddr *)&address, (socklen_t *)&addlen);
                if (client_id == -1)
                {
                    perror("accept failed");
                    continue;
                }
                set_nonblocking(client_id);
                event.events = EPOLLIN | EPOLLET;
                event.data.fd = client_id;
                if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, client_id, &event) == -1)
                {
                    perror("epoll_ctl for client failed");
                    close(client_id);
                    continue;
                }
                printf("Accepted new connection from client: %d\n", client_id);
            }
            else
            {
                while (1)
                {
                    char buffer[BUFFER_SIZE];
                    ssize_t bytes_read = read(events[i].data.fd, buffer, sizeof(buffer) - 1);
                    if (bytes_read == 0)
                    {
                        printf("Client closed connection: %d\n", events[i].data.fd);
                        epoll_ctl(epoll_fd, EPOLL_CTL_DEL, events[i].data.fd, NULL);
                        close(events[i].data.fd);
                        break;
                    }
                    else if (bytes_read > 0)
                    {
                        buffer[bytes_read] = '\0'; // Null-terminate the buffer
                        printf("Received request: %s\n", buffer);

                        if (strncmp(buffer, "GET", 3) == 0 || strncmp(buffer, "POST", 4) == 0)
                        {
                            char http_response[] =
                                "HTTP/1.1 200 OK\r\n"
                                "Content-Type: text/html\r\n"
                                "Connection: close\r\n"
                                "Content-Length: 31\r\n"
                                "\r\n"
                                "<html><body>hello</body></html>";

                            write(events[i].data.fd, http_response, strlen(http_response));
                            printf("Sent HTTP response to client: %d\n", events[i].data.fd);
                            close(events[i].data.fd);
                            break;
                        }
                        else
                        {
                            write(events[i].data.fd, buffer, bytes_read);
                            printf("Echoed data back to client: %d\n", events[i].data.fd);
                            close(events[i].data.fd);
                            break;
                        }
                    }
                    else if (bytes_read == -1)
                    {
                        if (errno != EAGAIN && errno != EWOULDBLOCK)
                        {
                            break;
                        }
                        else
                        {
                            perror("read error");
                            close(events[i].data.fd);
                            break;
                        }
                    }
                }
            }
        }
    }

    close(server_id);
    close(epoll_fd);
    return 0;
}
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <arpa/inet.h>
	#include <sys/epoll.h>
	#include <unistd.h>
	#include <fcntl.h>
	#include <errno.h>

	#define MAX_EVENTS 100
	#define PORT 4000
	#define BUFFER_SIZE 1024

	void set_nonblocking(int fd)
	{
	int flags = fcntl(fd, F_GETFL, 0);
	if (flags == -1)
	{
	perror("fcntl F_GETFL");
	return;
	}
	int updatedFlags = fcntl(fd, F_SETFL, flags \| O_NONBLOCK);
	if (updatedFlags == -1)
	{
	perror("fcntl F_SETFL O_NONBLOCK");
	}
	}

	int main()
	{
	int server_id, client_id;
	struct sockaddr_in address;
	int addlen = sizeof(address);
	server_id = socket(AF_INET, SOCK_STREAM, 0);
	if (server_id < 0)
	{
	perror("Socket creation failed");
	exit(EXIT_FAILURE);
	}
	memset(&address, 0, addlen);

	address.sin_family = AF_INET;
	address.sin_addr.s_addr = INADDR_ANY;
	address.sin_port = htons(PORT);

	if (bind(server_id, (struct sockaddr *)&address, addlen) < 0)
	{
	perror("Failed to bind");
	close(server_id);
	exit(EXIT_FAILURE);
	}

	if (listen(server_id, 128) < 0)
	{
	perror("Listen failed");
	close(server_id);
	exit(EXIT_FAILURE);
	}

	printf("Server is listening on PORT %d\n", PORT);

	int epoll_fd = epoll_create1(0);
	if (epoll_fd == -1)
	{
	perror("epoll_create1 failed");
	close(server_id);
	exit(EXIT_FAILURE);
	}

	struct epoll_event event, events[MAX_EVENTS];

	event.events = EPOLLIN;
	event.data.fd = server_id;

	if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, server_id, &event) == -1)
	{
	perror("epoll_ctl failed");
	close(server_id);
	exit(EXIT_FAILURE);
	}

	while (1)
	{
	int nfds = epoll_wait(epoll_fd, events, MAX_EVENTS, -1);
	if (nfds == -1)
	{
	perror("epoll_wait failed");
	break;
	}

	for (int i = 0; i < nfds; i++)
	{
	if (events[i].data.fd == server_id)
	{
	client_id = accept(server_id, (struct sockaddr )&address, (socklen_t )&addlen);
	if (client_id == -1)
	{
	perror("accept failed");
	continue;
	}
	set_nonblocking(client_id);
	event.events = EPOLLIN \| EPOLLET;
	event.data.fd = client_id;
	if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, client_id, &event) == -1)
	{
	perror("epoll_ctl for client failed");
	close(client_id);
	continue;
	}
	printf("Accepted new connection from client: %d\n", client_id);
	}
	else
	{
	while (1)
	{
	char buffer[BUFFER_SIZE];
	ssize_t bytes_read = read(events[i].data.fd, buffer, sizeof(buffer) - 1);
	if (bytes_read == 0)
	{
	printf("Client closed connection: %d\n", events[i].data.fd);
	epoll_ctl(epoll_fd, EPOLL_CTL_DEL, events[i].data.fd, NULL);
	close(events[i].data.fd);
	break;
	}
	else if (bytes_read > 0)
	{
	buffer[bytes_read] = '\0'; // Null-terminate the buffer
	printf("Received request: %s\n", buffer);

	if (strncmp(buffer, "GET", 3) == 0 \|\| strncmp(buffer, "POST", 4) == 0)
	{
	char http_response[] =
	"HTTP/1.1 200 OK\r\n"
	"Content-Type: text/html\r\n"
	"Connection: close\r\n"
	"Content-Length: 31\r\n"
	"\r\n"
	"<html><body>hello</body></html>";

	write(events[i].data.fd, http_response, strlen(http_response));
	printf("Sent HTTP response to client: %d\n", events[i].data.fd);
	close(events[i].data.fd);
	break;
	}
	else
	{
	write(events[i].data.fd, buffer, bytes_read);
	printf("Echoed data back to client: %d\n", events[i].data.fd);
	close(events[i].data.fd);
	break;
	}
	}
	else if (bytes_read == -1)
	{
	if (errno != EAGAIN && errno != EWOULDBLOCK)
	{
	break;
	}
	else
	{
	perror("read error");
	close(events[i].data.fd);
	break;
	}
	}
	}
	}
	}
	}

	close(server_id);
	close(epoll_fd);
	return 0;
	}