前一篇文章是介绍的select一个极为简单的用法,这篇将select和socket结合使用,完成单线程多用户连接,用户退出后,可用连接自动+1,。
客户端同http://blog.youkuaiyun.com/xluren/article/details/8043484 中的客户端
服务器端代码如下:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define MYPORT 6666 // the port users will be connecting to
#define BACKLOG 5 // how many pending connections queue will hold
#define BUF_SIZE 1024
#define MAXCLIENT 5
int fd_access[BACKLOG]; // accepted connection fd
int conn_amount; // current connection amount
void showclient()
{
int i;
printf("client amount: %d\n", conn_amount);
printf("\n");
}
int main(void)
{
int sock_fd, new_fd; // listen on sock_fd, new connection on new_fd
struct sockaddr_in server_addr; // server address information
struct sockaddr_in client_addr; // connector's address information
socklen_t sin_size;
char buf[BUF_SIZE];
int ret;
int i;
if ((sock_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
perror("socket");
exit(1);
}
server_addr.sin_family = AF_INET; // host byte order
server_addr.sin_port = htons(MYPORT); // short, network byte order
server_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP
memset(server_addr.sin_zero, '\0', sizeof(server_addr.sin_zero));
if (bind(sock_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1)
{
perror("bind");
exit(1);
}
if (listen(sock_fd, BACKLOG) == -1)
{
perror("listen");
exit(1);
}
printf("listen port %d\n", MYPORT);
fd_set fdsr;
int maxsock;
struct timeval tv;
conn_amount = 0;
sin_size = sizeof(client_addr);
maxsock = MAXCLIENT;
FD_ZERO(&fdsr);
while (1)
{
FD_SET(sock_fd, &fdsr);
tv.tv_sec = 3;
tv.tv_usec = 0;
for (i = 0; i < BACKLOG; i++)
{
printf("fd---%d\n",fd_access[i]);
if (fd_access[i] != 0)
{
FD_SET(fd_access[i], &fdsr);
}
}
ret = select(maxsock + 1, &fdsr, NULL, NULL, &tv);
if (ret < 0)
{
perror("select");
break;
}
else if (ret == 0)
{
printf("timeout\n");
continue;
}
printf("select----ret%d",ret);
// check every fd in the set
for (i = 0; i < MAXCLIENT; i++)
{
if (FD_ISSET(fd_access[i], &fdsr))
{
ret = recv(fd_access[i], buf, sizeof(buf), 0);
if (ret <= 0)
{
printf("client[%d] close\n", i);
close(fd_access[i]);
FD_CLR(fd_access[i], &fdsr);
fd_access[i] = 0;
conn_amount--;
}
else
{
if (ret < BUF_SIZE)
memset(&buf[ret], '\0', 1);
printf("client[%d] send:%s\n", i, buf);
}
}
}
// check whether a new connection comes
if (FD_ISSET(sock_fd, &fdsr))
{
new_fd = accept(sock_fd, (struct sockaddr *)&client_addr, &sin_size);
if (new_fd <= 0)
{
perror("accept");
continue;
}
// add to fd queue
if (conn_amount < BACKLOG)
{
for(i = 0;i < MAXCLIENT;i++)
{
if(fd_access[i] == 0)
{
fd_access[i] = new_fd;
break;
}
}//for
conn_amount++;
printf("new connection client[%d] %s:%d\n",
conn_amount,inet_ntoa(client_addr.sin_addr),
ntohs(client_addr.sin_port));
if (new_fd > maxsock)
maxsock = new_fd;
}//if
else
{
printf("max connections arrive, exit\n");
send(new_fd, "bye", 4, 0);
continue;
}
}//if (FD_ISSET(sock_fd, &fdsr))
showclient();
}//while
// close other connections
for (i = 0; i < BACKLOG; i++)
{
if (fd_access[i] != 0)
{
close(fd_access[i]);
}
}
exit(0);
}
(END)
代码借鉴了很多牛人的博客,最后形成了这个服务器的代码,衷心的感谢各位技术牛人无私的奉献,谢谢~~·