select i/o多路复用

/* net_select.c */

#include
#include
#include
#include
#include
#include
#include
#include
#include

#define PORT    4321
#define MAX_QUE_CONN_NM   5
#define MAX_SOCK_FD   FD_SETSIZE
#define BUFFER_SIZE   1024

int main()
{
 struct sockaddr_in server_sockaddr, client_sockaddr;
 int sin_size, count;
 fd_set inset, tmp_inset;
 int sockfd, client_fd, fd;
 char buf[BUFFER_SIZE];
 
 if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
 {
  perror("socket");
  exit(1);
 }
 
 server_sockaddr.sin_family = AF_INET;
 server_sockaddr.sin_port = htons(PORT);
 server_sockaddr.sin_addr.s_addr = INADDR_ANY;
 bzero(&(server_sockaddr.sin_zero), 8);
 
 int i = 1;/* 使得重复使用本地地址与套接字进行绑定 */
 setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &i, sizeof(i));
 if (bind(sockfd, (struct sockaddr *)&server_sockaddr, sizeof(struct sockaddr)) == -1)
 {
  perror("bind");
  exit(1);
 }
 
 if(listen(sockfd, MAX_QUE_CONN_NM) == -1)
 {
  perror("listen");
  exit(1);
 }
 printf("listening....\n");
 
 /*将调用socket函数的描述符作为文件描述符*/
 FD_ZERO(&inset);
 FD_SET(sockfd, &inset);
 
 while(1)
 {
  tmp_inset = inset;
  sin_size=sizeof(struct sockaddr_in);
  memset(buf, 0, sizeof(buf));
  
  /*调用select函数*/
  if (!(select(MAX_SOCK_FD, &tmp_inset, NULL, NULL, NULL) > 0))
  {
   perror("select");
   close(sockfd);
   exit(1);
  }
  
  for (fd = 0; fd < MAX_SOCK_FD; fd++)
  {
   if (FD_ISSET(fd, &tmp_inset) > 0)
   {
    if (fd == sockfd)
    { /* 服务端接收客户端的连接请求 */
     if ((client_fd = accept(sockfd, (struct sockaddr *)&client_sockaddr, &sin_size))== -1)
     {
      perror("accept");
      exit(1);
     }
     FD_SET(client_fd, &inset);
     printf("New connection from %d(socket)\n", client_fd);
    }
    else /* 处理从客户端发来的消息 */
    {
     if ((count = recv(fd, buf, BUFFER_SIZE, 0)) > 0)
     {
      printf("Received a message from %d: %s\n", fd, buf);
     }
     else  
     {
      close(fd);
      FD_CLR(fd, &inset);
      printf("Client %d(socket) has left\n", fd);
     }      
    }  
   } /* end of if FD_ISSET*/
  } /* end of for fd*/
 } /* end if while while*/
 
 close(sockfd);
 exit(0);
}

 

 

 

附：将socket变为非阻塞方法

 int flags = fcntl(sockfd, F_GETFL, 0);
 fcntl(sockfd, F_SETFL, flags | O_NONBLOCK);