epoll - Kernel 2.6 기반

#include <pthread.h>
#include <stdio.h>
#include <sys/timeb.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/epoll.h>
#include <netinet/in.h>
#include <string.h>
#include <fcntl.h>
#include <signal.h>
#include <errno.h>

#include <stdlib.h>
#include <unistd.h>

#define MAX_CLIENT 101 
#define PORT 3355 
#define MAX_LINE 1024
#define DEBUG 

int listenfd;

// nonblock 소켓생성 
void nonblock(int sockfd)
{
    int opts;
    opts = fcntl(sockfd, F_GETFL);
    if(opts < 0)
    {
        perror("fcntl(F_GETFL)\n");
        exit(1);
    }
    opts = (opts | O_NONBLOCK);
    if(fcntl(sockfd, F_SETFL, opts) < 0)
    {
        perror("fcntl(F_SETFL)\n");
        exit(1);
    }
}


int main(int argc, char **argv)
{
    int epfd;
    struct epoll_event *events;
    struct epoll_event ev;

    struct sockaddr_in srv;
    int clifd;
    int i;
    int n;
    int res;
    char buffer[MAX_LINE];

    if( (listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        perror("sockfd\n");
        exit(1);
    }

    events = malloc(sizeof(struct epoll_event) * MAX_CLIENT);

    bzero(&srv, sizeof(srv));
    srv.sin_family = AF_INET;
    srv.sin_addr.s_addr = INADDR_ANY;
    srv.sin_port = htons(PORT);

    if( bind(listenfd, (struct sockaddr *) &srv, sizeof(srv)) < 0)
    {
        perror("bind\n");
        exit(1);
    }

    listen(listenfd, 5);

    epfd = epoll_create(MAX_CLIENT);
    if(!epfd)
    {
        perror("epoll_create\n");
        exit(1);
    }
    ev.events = EPOLLIN | EPOLLHUP | EPOLLET;
    ev.data.fd = listenfd;
    if(epoll_ctl(epfd, EPOLL_CTL_ADD, listenfd, &ev) < 0)
    {
        perror("epoll_ctl, adding listenfd\n");
        exit(1);
    }
    for( ; ; )
    {
        res = epoll_wait(epfd, events, MAX_CLIENT, 0);
        for(i = 0; i < res; i++)
        {
            if(events[i].data.fd == listenfd)
            {
                clifd = accept(listenfd, NULL, NULL);
                if(clifd > 0)
                {
                    nonblock(clifd);
                    ev.events = EPOLLIN | EPOLLET;
                    ev.data.fd = clifd;
                    if(epoll_ctl(epfd, EPOLL_CTL_ADD, clifd, &ev) < 0)
                    {
                        perror("epoll_ctl ADD\n");
                        exit(1);
                    }
                }
            }
            else {
                memset(buffer, 0x00, MAX_LINE);
                n = recv(events[i].data.fd, buffer, MAX_LINE-1, 0);
                if(n == 0)
                {
#ifdef DEBUG 
                    printf("%d closed connection\n", events[i].data.fd);
                    epoll_ctl(epfd, EPOLL_CTL_DEL, events[i].data.fd, NULL);
#endif
                }
                else if(n < 0)
                {
#ifdef DEBUG 
                    printf("%d error occured, errno: %d\n",
                            events[i].data.fd, errno);
#endif
                }
                else {
#ifdef DEBUG 
                    printf("%d data received: %s",
                            events[i].data.fd, buffer);
                    bzero(&buffer, strlen(buffer));
#endif
                    send(events[i].data.fd, buffer, strlen(buffer), 0);
                }
            }
        }
    }

    return 0;
}