echo_EPETserv.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <fcntl.h>
#include <errno.h>
#define BUF_SIZE 4
#define EPOLL_SIZE 50
void error_handling(char *buf)
{
	fputs(buf, stderr);
	fputc('\n',stderr);
	exit(1);
}

void setnonblockingmode(int fd)
{
	int flag = fcntl(fd, F_GETFL, 0);
	fcntl(fd, F_SETFL, flag|O_NONBLOCK);
}

int main(int argc, char const *argv[])
{
	int serv_sock, clnt_sock;
	struct sockaddr_in serv_adr, clnt_adr;
	socklen_t adr_sz;
	int str_len, i;
	char buf[BUF_SIZE];

	int opt = 1;

	struct epoll_event *ep_events;
	struct epoll_event event;
	int epfd, event_cnt;

	if (argc != 2)
	{
		printf("Usage : %s <port>\n", argv[0]);
		exit(1);
	}

	serv_sock = socket(PF_INET, SOCK_STREAM, 0);
	memset(&serv_adr, 0, sizeof(serv_adr));
	serv_adr.sin_family = AF_INET;
	serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
	serv_adr.sin_port = htons(atoi(argv[1]));

	setsockopt(serv_sock, SOL_SOCKET, SO_REUSEADDR,(void*)&opt,sizeof(opt));

	if (bind(serv_sock, (struct sockaddr *)&serv_adr, sizeof(serv_adr)) == -1)
		error_handling("bind error");
	if (listen(serv_sock,5) == -1)
		error_handling("listen error");

	epfd = epoll_create(EPOLL_SIZE);
	ep_events = malloc(sizeof(struct epoll_event)*EPOLL_SIZE);

	setnonblockingmode(serv_sock);
	event.events = EPOLLIN;
	event.data.fd = serv_sock;
	epoll_ctl(epfd, EPOLL_CTL_ADD, serv_sock, &event);

	while(1)
	{
		event_cnt = epoll_wait(epfd, ep_events, EPOLL_SIZE, -1);
		
		if (event_cnt == -1)
		{
			puts("epoll_wait error");
			break;
		}

		puts("return epoll_wait");
		for (i = 0; i < event_cnt; ++i)
		{
			if (ep_events[i].data.fd == serv_sock)
			{
				adr_sz = sizeof(clnt_adr);
				clnt_sock = accept(serv_sock, (struct sockaddr *)&clnt_adr, &adr_sz);
				setnonblockingmode(clnt_sock);
				event.events = EPOLLIN|EPOLLET;
				event.data.fd = clnt_sock;
				epoll_ctl(epfd, EPOLL_CTL_ADD, clnt_sock, &event);
				printf("connect client : %d \n", clnt_sock);
			}
			else
				while(1)
			{
				str_len = read(ep_events[i].data.fd, buf, BUF_SIZE);
				if (str_len == 0)
				{
					epoll_ctl(epfd, EPOLL_CTL_DEL, ep_events[i].data.fd, NULL);
					close(ep_events[i].data.fd);//shutdown(ep_events[i].data.fd, SHUT_WR);
					printf("close client :%d \n", ep_events[i].data.fd);
					break;
				}
				else if(str_len<0)
				{
					if(errno == EAGAIN)
						break;
				}
				else
				{
					write(ep_events[i].data.fd, buf, str_len);
					//buf[str_len]=0;
					//printf("close client :%s \n", buf);
				}
			}
		}
	}
	close(serv_sock);
	close(epfd);
	return 0;
}