socket_select demo

#include <sys/types.h> #include <sys/socket.h> #include <stdio.h> #include <netinet/in.h> #include <sys/time.h> #include <sys/ioctl.h> #include <unistd.h> #include <stdlib.h> int main() { int server_sockfd, client_sockfd; int server_len, client_len; struct sockaddr_in server_address; struct sockaddr_in client_address; int result; fd_set readfds, testfds; server_sockfd = socket(AF_INET, SOCK_STREAM, 0);//建立服务器端socket server_address.sin_family = AF_INET; server_address.sin_addr.s_addr = htonl(INADDR_ANY); server_address.sin_port = htons(8888); server_len = sizeof(server_address); bind(server_sockfd, (struct sockaddr *)&server_address, server_len); listen(server_sockfd, 5); //监听队列最多容纳5个 FD_ZERO(&readfds); FD_SET(server_sockfd, &readfds);//将服务器端socket加入到集合中 while(1) { char ch; int fd; int nread; testfds = readfds;//将需要监视的描述符集copy到select查询队列中，select会对其修改，所以一定要分开使用变量 printf("server waiting\n"); /*无限期阻塞，并测试文件描述符变动 */ result = select(FD_SETSIZE, &testfds, (fd_set *)0,(fd_set *)0, (struct timeval *) 0); //FD_SETSIZE：系统默认的最大文件描述符 if(result < 1) { perror("server5"); exit(1); } /*扫描所有的文件描述符*/ for(fd = 0; fd < FD_SETSIZE; fd++) { /*找到相关文件描述符*/ if(FD_ISSET(fd,&testfds)) { /*判断是否为服务器套接字，是则表示为客户请求连接。*/ if(fd == server_sockfd) { client_len = sizeof(client_address); client_sockfd = accept(server_sockfd, (struct sockaddr *)&client_address, (socklen_t*) &client_len); FD_SET(client_sockfd, &readfds);//将客户端socket加入到集合中 printf("adding client on fd %d\n", client_sockfd); } /*客户端socket中有数据请求时*/ else { ioctl(fd, FIONREAD, &nread);//取得数据量交给nread /*客户数据请求完毕，关闭套接字，从集合中清除相应描述符 */ if(nread == 0) { close(fd); FD_CLR(fd, &readfds); //去掉关闭的fd printf("removing client on fd %d\n", fd); } /*处理客户数据请求*/ else { read(fd, &ch, 1); sleep(5); printf("serving client on fd %d\n", fd); ch++; write(fd, &ch, 1); } } } } } return 0; }