linux服务器开发三(网络编程)
/* server.c */ #include <stdio.h>#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "wrap.h"
#define MAXLINE 80
#define SERV_PORT 6666
int main(int argc, char *argv[])
{
int i, maxi, maxfd, listenfd, connfd, sockfd;
int nready, client; /* FD_SETSIZE 默认为 1024 */
ssize_t n;
fd_set rset, allset;
char buf;
char str; /* #define INET_ADDRSTRLEN 16 */
socklen_t cliaddr_len;
struct sockaddr_in cliaddr, servaddr;
listenfd = Socket(AF_INET, SOCK_STREAM, 0);
bzero(&servaddr,> servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);
Bind(listenfd, (struct sockaddr *)&servaddr,> Listen(listenfd, 20); /* 默认最大128 */
maxfd = listenfd; /* 初始化 */
maxi = -1; /* client[]的下标 */
for (i = 0; i < FD_SETSIZE; i++)
client = -1; /* 用-1初始化client[] */
FD_ZERO(&allset);
FD_SET(listenfd, &allset); /* 构造select监控文件描述符集 */
for ( ; ; ) {
rset = allset; /* 每次循环时都从新设置select监控信号集 */
nready = select(maxfd+1, &rset, NULL, NULL, NULL);
if (nready < 0)
perr_exit("select error");
if (FD_ISSET(listenfd, &rset)) { /* new client connection */
cliaddr_len => connfd = Accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);
printf("received from %s at PORT %d\n",
inet_ntop(AF_INET, &cliaddr.sin_addr, str,> ntohs(cliaddr.sin_port));
for (i = 0; i < FD_SETSIZE; i++) {
if (client < 0) {
client = connfd; /* 保存accept返回的文件描述符到client[]里 */
break;
}
}
/* 达到select能监控的文件个数上限 1024 */
if (i == FD_SETSIZE) {
fputs("too many clients\n", stderr);
exit(1);
}
FD_SET(connfd, &allset); /* 添加一个新的文件描述符到监控信号集里 */
if (connfd > maxfd)
maxfd = connfd; /* select第一个参数需要 */
if (i > maxi)
maxi = i; /* 更新client[]最大下标值 */
if (--nready == 0)
continue; /* 如果没有更多的就绪文件描述符继续回到上面select阻塞监听,
负责处理未处理完的就绪文件描述符 */
}
for (i = 0; i <= maxi; i++) { /* 检测哪个clients 有数据就绪 */
if ( (sockfd = client) < 0)
continue;
if (FD_ISSET(sockfd, &rset)) {
if ( (n = Read(sockfd, buf, MAXLINE)) == 0) {
Close(sockfd); /* 当client关闭链接时，服务器端也关闭对应链接 */
FD_CLR(sockfd, &allset); /* 解除select监控此文件描述符 */
client = -1;
} else {
int j;
for (j = 0; j < n; j++)
buf = toupper(buf);
Write(sockfd, buf, n);
}
if (--nready == 0)
break;
}
}
}
close(listenfd);
return 0;
} 谢谢分享
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