c语言实现-socket之select

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本文介绍如何使用Linux Socket和Select函数结合实现一个简单的HTTP服务器，通过Socket监听客户端连接并使用Select进行高效的数据读取和处理。

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#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <errno.h>
#include <netinet/in.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <stdlib.h>

#define LISTENQ 5 
#define OPEN_MAX 1024
#define SERV_PORT  60088
#define MAX_LINE 1024
#define INFTIM -1

#define MAXEVENTS 1000

char szHtmlBuf[] = "HTTP/1.1 200 OK\r\n"
"Date: Mon, 02 Feb 2015 03:44:06 GMT \r\n"
"Expires:0 \r\n"
"Vary: Accept-Encoding\r\n"
"Content-Type: text/html; charset=gb2312\r\n"
"Content-Length: 46\r\n"
"\r\n"
"<html> <head>Welcome !!!</head> <body>LINUX SELECT</body></html>";

fd_set fds;

void echo_srv(int clientFd)
{
	char line[MAX_LINE];
	printf(" starting read data ... \n");
	int n = read(clientFd, line, sizeof(line));
	if(n < 0) {
		if(errno == ECONNRESET)
		{
			close(clientFd);
			FD_CLR(clientFd, &fds);
			printf(" network error! \n ");
		}
		else
		{
			printf(" network exception! \n ");
			exit(-1);
		}
	}
	else if(n == 0)
	{
		close(clientFd);
		FD_CLR(clientFd, &fds);
		printf( " normal return! \n " );
	}
	else
	{
		line[n] = 0;
		printf("receive data  %s \n ", line);

		write(clientFd, szHtmlBuf, sizeof(szHtmlBuf));
	}
}

int main()
{
	struct sockaddr_in cliaddr, servaddr;
	int listenFd = socket(AF_INET, SOCK_STREAM, 0);
	if( listenFd < 0)
	{
		printf(" socket function exec fail! \n ");
		return 1;
	}

	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);

	servaddr.sin_port = htons(SERV_PORT);
	if(bind(listenFd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0)
	{
		printf("bind function exec fail! \n ");
		return 1;
	}

	if(listen(listenFd, LISTENQ) < 0)
	{
		printf("listen function exec fail! \n");
		return 1;
	}
	printf("listen function exec success! \n");

	int maxfd;
	FD_ZERO(&fds);

	do{
		FD_SET(listenFd, &fds);
		maxfd = listenFd + 1;
		int nRead = 0;
		if( (nRead = select(maxfd + 1, &fds, NULL, NULL, NULL)) < 0)
		{
			printf("select fail! \n");
			exit(-1);
		}
		printf("select find data Change\n");

		int i;
		for( i = 0; i <= maxfd && nRead > 0; i++)
		{
			if(!FD_ISSET(i, &fds))
			{
				continue;
			}
			--nRead;
			if(i == listenFd)
			{
				socklen_t clilen = sizeof(cliaddr);
				int connfd = accept(listenFd, (struct sockaddr*)&cliaddr, &clilen);
				if(connfd < 0)
				{
					if ((errno != EAGAIN) && (errno != EWOULDBLOCK)) 
					{
						printf( "fail to accept new client \n");
						continue;
					}
				}
				printf("Ip: %s come here !\n", inet_ntoa(cliaddr.sin_addr));
				FD_SET(connfd, &fds);
				maxfd = (connfd > maxfd ? connfd : maxfd);
			}
			else
			{
				echo_srv(i);
			}
		}

	}while(1);

	return 0;
}

编译：gcc -o select_socket select_socket_linux.c
启动：./select_socket
服务器打印：
listen function exec success!

在浏览器中访问：http://{IP}:60088
返回：

<html> <head>Welcome !!!</head> <body>LINUX SE

服务器打印：
select find data Change
Ip: {C-IP} come here !
select find data Change
starting read data ...
receive data GET / HTTP/1.1
Host: {IP}:60088
Connection: keep-alive
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36
Accept-Encoding: gzip, deflate, sdch
Accept-Language: zh-CN,zh;q=0.8