Linux/Unix IO多路复用之poll网络编程(含源码)

本章节是用基本的Linux/Unix基本函数加上poll调用编写一个完整的服务器和客户端例子，可在Linux(ubuntu)和Unix(freebsd)上运行，客户端和服务端的功能如下:

客户端从标准输入读入一行，发送到服务端

服务端从网络读取一行，然后输出到客户端

客户端收到服务端的响应，输出这一行到标准输出

#include
#include /* basic system data types */
#include /* basic socket definitions */
#include in.h> /* sockaddr_in{} and other Internet defns */
#include /* inet(3) functions */

#include
#include
#include
#include <string.h>


#include /* poll function */
#include

#define MAXLINE 10240

#ifndef OPEN_MAX
#define OPEN_MAX 40960
#endif

void handle(struct pollfd* clients, int maxClient, int readyClient);

int main(int argc, char **argv)
{
int servPort = 6888;
int listenq = 1024;
int listenfd, connfd;
struct pollfd clients[OPEN_MAX];
int maxi;
socklen_t socklen = sizeof(struct sockaddr_in);
struct sockaddr_in cliaddr, servaddr;
char buf[MAXLINE];
int nready;

bzero(&servaddr, socklen);
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(servPort);

listenfd = socket(AF_INET, SOCK_STREAM, 0);
if (listenfd < 0) {
perror("socket error");
}

int opt = 1;
if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
perror("setsockopt error");
}

if(bind(listenfd, (struct sockaddr *) &servaddr, socklen) == -1) {
perror("bind error");
exit(-1);
}
if (listen(listenfd, listenq) < 0) {
perror("listen error");
}

clients[0].fd = listenfd;
clients[0].events = POLLIN;
int i;
for (i = 1; i< OPEN_MAX; i++)
clients[i].fd = -1;
maxi = listenfd + 1;

printf("pollechoserver startup, listen on port:%d\n", servPort);
printf("max connection is %d\n", OPEN_MAX);

for ( ; ; ) {
nready = poll(clients, maxi + 1, -1);
//printf("nready is %d\n", nready);
if (nready == -1) {
perror("poll error");
}
if (clients[0].revents & POLLIN) {
connfd = accept(listenfd, (struct sockaddr *) &cliaddr, &socklen);
sprintf(buf, "accept form %s:%d\n", inet_ntoa(cliaddr.sin_addr), cliaddr.sin_port);
printf(buf, "");

for (i = 0; i < OPEN_MAX; i++) {
if (clients[i].fd == -1) {
clients[i].fd = connfd;
clients[i].events = POLLIN;
break;
}
}

if (i == OPEN_MAX) {
fprintf(stderr, "too many connection, more than %d\n", OPEN_MAX);
close(connfd);
continue;
}

if (i > maxi)
maxi = i;

--nready;
}

handle(clients, maxi, nready);
}
}

void handle(struct pollfd* clients, int maxClient, int nready) {
int connfd;
int i, nread;
char buf[MAXLINE];

if (nready == 0)
return;

for (i = 1; i< maxClient; i++) {
connfd = clients[i].fd;
if (connfd == -1)
continue;
if (clients[i].revents & (POLLIN | POLLERR)) {
nread = read(connfd, buf, MAXLINE);//读取客户端socket流
if (nread < 0) {
perror("read error");
close(connfd);
clients[i].fd = -1;
continue;
}
if (nread == 0) {
printf("client close the connection");
close(connfd);
clients[i].fd = -1;
continue;
}

write(connfd, buf, nread);//响应客户端
if (--nready <= 0)//没有连接需要处理，退出循环
break;
}
}
}