select.c

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

#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <unistd.h>
#include <sys/types.h>

#define IPADDRESS   "192.168.8.22"
#define PORT       12345
#define MAXLINE     1024
#define LISTENQ     5

//函数声明
//创建套接字并进行绑定
static int socket_bind(const char* ip,int port);
//IO多路复用select
static void do_select(int listenfd);
//处理多个连接
static void handle_connection(int *connfds,int num,fd_set *prset,fd_set *pallset);

int main(int argc,char *argv[])
{
    int  listenfd,connfd,sockfd;
    struct sockaddr_in cliaddr;
    socklen_t cliaddrlen;
	listenfd = socket_bind(IPADDRESS,PORT);
    listen(listenfd,LISTENQ);
	do_select(listenfd);
    return 0;
}

static int socket_bind(const char* ip,int port)
{
    int  listenfd;
    struct sockaddr_in servaddr;
    listenfd = socket(AF_INET,SOCK_STREAM,0);
    if (listenfd == -1)
    {
        perror("socket error:");
        exit(1);
    }
    bzero(&servaddr,sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    inet_pton(AF_INET,ip,&servaddr.sin_addr);
    servaddr.sin_port = htons(port);
    if (bind(listenfd,(struct sockaddr*)&servaddr,sizeof(servaddr)) == -1)
    {
        perror("bind error: ");
        exit(1);
    }
    return listenfd;
}

static void do_select(int listenfd)
{
    int  connfd,sockfd;
    struct sockaddr_in cliaddr;
    socklen_t cliaddrlen;
    fd_set  rset,allset;
    int maxfd,maxi;
    int i;
    int clientfds[FD_SETSIZE];  //保存客户连接描述符
    int nready;
    //初始化客户连接描述符
    for (i = 0;i < FD_SETSIZE;i++)
        clientfds[i] = -1;
    maxi = -1;
    FD_ZERO(&allset);
    //添加监听描述符
    FD_SET(listenfd,&allset);
    maxfd = listenfd;
    //循环处理
    for ( ; ; )
    {
        rset = allset;
        //获取可用描述符的个数
	
        nready = select(maxfd+1,&rset,NULL,NULL,NULL);
		printf("%d\n",nready);
        if (nready == -1)
        {
            perror("select error:");
            exit(1);
        }
		
        //测试监听描述符是否准备好
        if (FD_ISSET(listenfd,&rset))
        {
            cliaddrlen = sizeof(cliaddr);
            //接受新的连接
            if ((connfd = accept(listenfd,(struct sockaddr*)&cliaddr,&cliaddrlen)) == -1)
            {
                if (errno == EINTR)
                    continue;
                else
                {
                   perror("accept error:");
                   //exit(1);
                }
            }
			//printf("234234234dgfg\n");
			
            printf("accept a new client: %s:%d\n", inet_ntop(AF_INET, &cliaddr.sin_addr, NULL,4 ),ntohs(cliaddr.sin_port));
            //将新的连接描述符添加到数组中
            for (i = 0;i <FD_SETSIZE;i++)
            {
                if (clientfds[i] < 0)
                {
                    clientfds[i] = connfd;
                    break;
                }
            }
            if (i == FD_SETSIZE)
            {
                printf("too many clients.\n");
                //exit(1);
            }
            //将新的描述符添加到读描述符集合中
            FD_SET(connfd,&allset);
            //描述符个数
            maxfd = (connfd > maxfd ? connfd : maxfd);
            //记录客户连接套接字的个数
            maxi = (i > maxi ? i : maxi);
            if (--nready <= 0)
                continue;
        }
        //处理客户连接
        handle_connection(clientfds,maxi,&rset,&allset);
    }
}

static void handle_connection(int *connfds,int num,fd_set *prset,fd_set *pallset)
{
    int i,n;
    char buf[MAXLINE];
    memset(buf,0,MAXLINE);
    for (i = 0;i <= num;i++)
    {
        if (connfds[i] < 0)
            continue;
        //测试客户描述符是否准备好
        if (FD_ISSET(connfds[i],prset))
        {
            //接收客户端发送的信息
            n = read(connfds[i],buf,MAXLINE);
            if (n == 0)
            {
                close(connfds[i]);
                FD_CLR(connfds[i],pallset);
                connfds[i] = -1;
                continue;
            }
            printf("read msg is: ");
            write(STDOUT_FILENO,buf,n);
            //向客户端发送buf
            write(connfds[i],buf,n);
        }
    }
}