#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; 
}