用c语言实现的epoll服务器

在linux后台开发实战操作中，epoll服务器，是必备技能。

我今天就写了一个最简单的TCP server，你稍微改改就可以用于简单的数据通信。

如果要实现别的功能，比如ET，非阻塞，数据缓存，那都要围绕读写函数改了。

主要的系统API:

int epoll_create(int size);

int epoll_wait(int epfd, struct epoll_event *events,int maxevents, int timeout);

int epoll_ctl(int epfd, int op, int fd, struct epoll_event *event);

以下是代码：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

#include <sys/types.h>
#include <sys/socket.h>

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <sys/epoll.h>

#define SERVER_IPADDR "0.0.0.0"

#define SERVER_PORT "1122"

#define EV_READ EPOLLIN

#define EV_WRITE EPOLLOUT

#define MAX_EVENT_NUMS 1024

static int clifds[MAX_EVENT_NUMS];


int startListenSocket(const char *ipaddr,const char *port){
	int sck = socket(AF_INET,SOCK_STREAM,0);//IPV4
	if(sck < 0){
		perror("socket");
		exit(EXIT_FAILURE);
	}
	struct sockaddr_in addr;
	bzero(&addr,sizeof(addr));
	if(ipaddr)
		addr.sin_addr.s_addr = inet_addr(ipaddr);
	else
		addr.sin_addr.s_addr = htonl(INADDR_ANY);
	addr.sin_family = AF_INET;
	addr.sin_port = htons(atoi(port));

	int val = 1;
	setsockopt(sck,SOL_SOCKET,SO_REUSEADDR,&val,sizeof(val));
	
	if(bind(sck,(struct sockaddr*)&addr,sizeof(addr)) < 0){
		perror("bind");
		close(sck);
		exit(EXIT_FAILURE);
	}	

	if(listen(sck,20) < 0){
		perror("listen");
		close(sck);
		exit(EXIT_FAILURE);	
	}
	return sck;
}

int epoll_event_add(int epfd,int fd,int event){
	struct epoll_event ev;
	ev.data.fd = fd;
	ev.events = event;
	return epoll_ctl(epfd,EPOLL_CTL_ADD,fd,&ev);
}

int epoll_event_del(int epfd,int fd,int event){
	struct epoll_event ev;
	ev.data.fd = fd;
	ev.events = event;
	return epoll_ctl(epfd,EPOLL_CTL_DEL,fd,&ev);
}



int do_accept(int listenSocket,int epfd){
	struct sockaddr_in cliaddr;
	bzero(&cliaddr,sizeof(cliaddr));
	socklen_t addrlen = sizeof(struct sockaddr_in);
	int fd = accept(listenSocket,(struct sockaddr*)&cliaddr,&addrlen);
	if(fd < 0){
		perror("accept");
		return (-1);
	}
	printf("Accept new client <%s:%d>\n",inet_ntoa(cliaddr.sin_addr),\
	ntohs(cliaddr.sin_port));
	clifds[fd] = 1;//设置有效状态
	epoll_event_add(epfd,fd,EV_READ);
	return 0;
}

int recv_client(int epfd,struct epoll_event*evs,int i){
	char buf[1024]={0};
	bzero(buf,sizeof(buf));
	int n = read(evs[i].data.fd,buf,1024);
	if(n > 0){
		printf("Recv<fd-%d>:%s\n",evs[i].data.fd,buf);
		//处理数据,这里可以做你要做的事情
		if(strncmp(buf,"exit",4) == 0){
			return (-1);
		}
		else{
			write(evs[i].data.fd,"From server:\n",strlen("From server:\n"));
			write(evs[i].data.fd,buf,n);
		}
	}
	//客户端断开
	if(n == 0){
		printf("Client <%d> close\n",evs[i].data.fd);
		epoll_event_del(epfd,evs[i].data.fd,EPOLLIN);
		close(evs[i].data.fd);
		clifds[evs[i].data.fd] = -1;//
	}
	return 0;
}


int main(int argc,char *argv[]){
	int listSocket = startListenSocket(SERVER_IPADDR,SERVER_PORT);
	int epfd = epoll_create(1024);
	if(epfd < 0){
		perror("epoll");
		close(listSocket);
		exit(EXIT_FAILURE);
	}
	epoll_event_add(epfd,listSocket,EV_READ);
	struct epoll_event evs[MAX_EVENT_NUMS];
	int i = 0;
	memset(clifds,-1,sizeof(clifds));
	do{
		int n = epoll_wait(epfd,evs,MAX_EVENT_NUMS,-1);
		if(n == 0){
			printf("epoll_wait timeout\n");
			continue;
		}
		if(n < 0){
			perror("epoll_eait");
			if(errno == EAGAIN || errno==EINTR){
				continue;
			}
			break;			
		}
		
		//这里实际是一个reactor
		for(i=0;i < n;++i){
			if(evs[i].events & EV_READ){			
				//处理监听套接字的数据
				if(evs[i].data.fd == listSocket){
					if(do_accept(listSocket,epfd) < 0){
						perror("do_accept");
					}
				}
				else{
					//读取客户端的数据
					if(recv_client(epfd,evs,i) <0){
						goto EXIT;
					}	
				}
			}					
		}
	}while(1);
EXIT:
	for(i=0;i<MAX_EVENT_NUMS;++i){
		if(clifds[i] >= 0 ){
			printf("Close sockfd <%d>\n",i);
			close(i);
		}
	}
	close(listSocket);
	exit(EXIT_SUCCESS);
}