基于poll实现的echo服务器

/*
poll实现的echo服务器.
Author:thinkmay
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

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

#define OPEN_MAX 512
#define BUFSIZE 1024

int main(int argc, char **argv)
{
    //判断运行格式是否正确
    if(argc != 2)
    {
        printf("usage: ./poll <port>");
        exit(-1);
    }

    int listensock, connsock;
    struct sockaddr_in servaddr;
    struct pollfd fds[OPEN_MAX];//定义pollfd结构体
    int i, count = 0, ready, reval;
    char readbuf[BUFSIZE];

    //首先对pollfd结构数组的fd都赋值为-1
    for(i = 0; i < OPEN_MAX; i++)
    {
        fds[i].fd = -1;//循环将fd赋值为-1.
    }
    
    //创建TCP套接字
    if((listensock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        perror("socket error");
        exit(-1);
    }

    memset(&servaddr, 0, sizeof(servaddr));//套接字地址变量清0
    servaddr.sin_family = AF_INET;
    servaddr.sin_family = htonl(INADDR_ANY);
    servaddr.sin_port = htons(atoi(argv[1]));
    
    //绑字套接字和套接字地址变量
    if( bind(listensock, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0)
    {
        perror("bind error");
        exit(-1);
    }
    
    //监听套接字
    if(listen(listensock, 5) < 0)
    {
        perror("listen error");
        exit(-1);
    }
    
    //将0和listensock加入到pollfd结构体中
    fds[0].fd = 0; //将标准输入添加到fd中
    fds[0].events = POLLIN;//指明触发事件状态
    count++;
    fds[1].fd = listensock;
    fds[1].events = POLLIN;
    count++;

    for(;;)
    {
        memset(readbuf, 0, BUFSIZE);
        ready = poll(fds, count, 0);//定义poll准备
        for(i = 0; i < count; i++)
        {
            //revents返回触发状态
            if(fds[i].revents & POLLIN)//判断POLLIN是否触发
            {
                    if(fds[i].fd == 0)
                    {
                        fgets(readbuf, BUFSIZE, stdin);
                        printf("read buf:%s\n", readbuf);
                    }
                    else if(fds[i].fd == listensock)
                    {
                        connsock = accept(listensock, NULL, NULL);
                        printf("client connect\n");
                        fds[count].fd = connsock;
                        fds[count].events = POLLIN;
                        count++;
                    }
                    else
                    {
                        reval = recv(fds[i].fd, readbuf, BUFSIZE, 0);
                        printf("recv buf:%s\n", readbuf);
                        send(fds[i].fd, readbuf, reval, 0);
                    }
            }
        }
    
    }
    return 0;
}