epoll.c

#include <sys/socket.h>
#include <sys/epoll.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#define MAXLINE		10
#define OPEN_MAX	100
#define LISTENQ		20
#define SERV_PORT	5555
#define INFTIM		1000

void setnonblocking(int sock)
{
	int opts;
	opts = fcntl(sock, F_GETFL);

	if(opts < 0) {
		perror("fcntl(sock, GETFL)");
		exit(1);
	}

	opts = opts | O_NONBLOCK;

	if(fcntl(sock, F_SETFL, opts) < 0) {
		perror("fcntl(sock, SETFL, opts)");
		exit(1);
	}
}

int main(int argc, char *argv[])
{
	printf("epoll socket begins.\n");
	int i, maxi, listenfd, connfd, sockfd, epfd, nfds;
	ssize_t n;
	char line[MAXLINE];
	socklen_t clilen;

	struct epoll_event ev, events[20];

	epfd = epoll_create(256);

	struct sockaddr_in clientaddr;
	struct sockaddr_in serveraddr;

	listenfd = socket(AF_INET, SOCK_STREAM, 0);

	setnonblocking(listenfd);

	ev.data.fd = listenfd;
	ev.events = EPOLLIN | EPOLLET;

	epoll_ctl(epfd, EPOLL_CTL_ADD, listenfd, &ev);

	bzero(&serveraddr, sizeof(serveraddr));
	serveraddr.sin_family = AF_INET;
	char *local_addr = "192.168.199.8";
	inet_aton(local_addr, &(serveraddr.sin_addr));
	serveraddr.sin_port = htons(SERV_PORT);

	bind(listenfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr));

	listen(listenfd, LISTENQ);

	maxi = 0;

	for(; ;) {
		nfds = epoll_wait(epfd, events, 20, 500);

		for(i = 0; i < nfds; ++i) {
			if(events[i].data.fd == listenfd) {
				printf("accept connection, fd is %d\n", listenfd);
				connfd = accept(listenfd, (struct sockaddr *)&clientaddr, &clilen);
				if(connfd < 0) {
					perror("connfd < 0");
					exit(1);
				}

				setnonblocking(connfd);

				char *str = inet_ntoa(clientaddr.sin_addr);
				printf("connect from %s\n", str);

				ev.data.fd = connfd;
				ev.events = EPOLLIN | EPOLLET;
				epoll_ctl(epfd, EPOLL_CTL_ADD, connfd, &ev);
			}
			else if(events[i].events & EPOLLIN) {
				if((sockfd = events[i].data.fd) < 0) continue;
				if((n = read(sockfd, line, MAXLINE)) < 0) {
					if(errno == ECONNRESET) {
						close(sockfd);
						events[i].data.fd = -1;
					} else {
						printf("readline error");
					}
				} else if(n == 0) {
					close(sockfd);
					events[i].data.fd = -1;
				}
				
				printf("received data: %s\n", line);

				ev.data.fd = sockfd;
				ev.events = EPOLLOUT | EPOLLET;
				epoll_ctl(epfd, EPOLL_CTL_MOD, sockfd, &ev);
			}
			else if(events[i].events & EPOLLOUT) {
				sockfd = events[i].data.fd;
				write(sockfd, line, n);

				printf("written data: %s\n", line);

				ev.data.fd = sockfd;
				ev.events = EPOLLIN | EPOLLET;
				epoll_ctl(epfd, EPOLL_CTL_MOD, sockfd, &ev);
			}
		}
	}
}