1.server.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.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, F_GETFL)");
exit(1);
}
opts = opts | O_NONBLOCK;
if(fcntl(sock, F_SETFL, opts) < 0)
{
perror("fcntl(sock, F_SETFL, opts)");
exit(1);
}
}
int main()
{
int listenfd, connfd, sockfd, epfd, nfds, maxi, i;
ssize_t n;
char line[MAXLINE];
socklen_t clilen = sizeof(struct sockaddr);
struct epoll_event ev, events[20];
struct sockaddr_in clientaddr;
struct sockaddr_in serveraddr;
epfd = epoll_create(256);
listenfd = socket(AF_INET, SOCK_STREAM, 0);
if(listenfd < 0)
{
perror("socket create\n");
exit(-1);
}
setnonblocking(listenfd);
ev.data.fd = listenfd;
ev.events = EPOLLIN | EPOLLET;
epoll_ctl(epfd, EPOLL_CTL_ADD, listenfd, &ev);
bzero(&serveraddr, sizeof(serveraddr));
bzero(&clientaddr, sizeof(clientaddr));
serveraddr.sin_family = AF_INET;
serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
serveraddr.sin_port = htons(SERV_PORT);
bind(listenfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr));
if(listen(listenfd, LISTENQ) < 0)
{
perror("listen");
exit(-1);
}
printf("listen successful\n");
maxi = 0;
while(1)
{
nfds = epoll_wait(epfd, events, 20, 500);
/*处理发生的所有事件*/
for(i=0; i<nfds; i++)
{
if(events[i].data.fd == listenfd)
{
connfd = accept(listenfd, (struct sockaddr *)&clientaddr, &clilen);
if(connfd < 0)
{
perror("accept");
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
{
perror("read line error");
}
}
else if(n == 0)
{
close(sockfd);
events[i].data.fd = -1;
}
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);
ev.data.fd = sockfd;
ev.events = EPOLLIN | EPOLLET;
epoll_ctl(epfd, EPOLL_CTL_MOD, sockfd, &ev);
}
}
}
return 0;
}
2.client.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <errno.h>
int main()
{
struct sockaddr_in address;
char ch = 'A';
int cli_fd;
int len;
int ret;
cli_fd = socket(AF_INET, SOCK_STREAM, 0);
address.sin_family = AF_INET;
address.sin_addr.s_addr = inet_addr("127.0.0.1");
address.sin_port = htons(5555);
len = sizeof(address);
ret = connect(cli_fd, (struct sockaddr *)&address, len);
if(ret == -1)
{
perror("oops: client 2");
exit(-1);
}
/*第一次读写*/
write(cli_fd, &ch, 1);
ch = 0x00;
read(cli_fd, &ch, 1);
printf("the first time: char from server = %c\n", ch);
sleep(5);
/*第二次读写*/
ch = 'B';
write(cli_fd, &ch, 1);
ch = 0x00;
read(cli_fd, &ch, 1);
printf("the second time: char from server = %c\n", ch);
close(cli_fd);
return 0;
}
3.编译程序
$ gcc -o server server.c
$ gcc -o client client.c
4.运行及其结果
$ ./server
listen successful
connect from 127.0.0.1
$ ./client
the first time: char from server = A
the second time: char from server = B
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