I/O复用实现单线程并发服务器

/*
 * =====================================================================================
 *
 *       Filename:  select.c
 *
 *    Description:  
 *
 *        Version:  1.0
 *        Created:  2012年02月22日 22时18分07秒
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  MaZheng (blog.csdn.net/mazheng1989), [e-mail]
 *        Company:  Dalian University Of Technology
 *
 * =====================================================================================
 */


#include	<stdio.h>
#include	<string.h>
#include	<unistd.h>
#include	<sys/types.h>
#include	<sys/socket.h>
#include	<netinet/in.h>
#include	<stdlib.h>
#include	<arpa/inet.h>
#include	<sys/time.h>
#define	PORT 1234			/* port that will be opened */
#define	BACKLOG 5			/* number of allowed connections */
#define	MAXDATASIZE 1000			/*  */

 struct Client{
	int fd;
	char *name;
	struct sockaddr_in addr;/*client's address information*/
	char *data;
};
typedef struct Client CLIENT;
void process_cli(CLIENT *client,char *recvbuf,int len);
void savedata(char * recvbuf,int len,char *data);

int main()
{
	int i,maxi,maxfd,sockfd;
	int nready;
	ssize_t n;
	fd_set rset,allset;
	int listenfd,connectfd; /*socket descriptors*/
	struct sockaddr_in server;/*server's address information*/
	/*client's information*/
	CLIENT client[FD_SETSIZE];
	char recvbuf[MAXDATASIZE];
	int sin_size;

	/*create tcp socket*/
	if((listenfd=socket(AF_INET,SOCK_STREAM,0))==-1)
	{
		/*handle exception*/
		perror("creating socket failed.");
		exit(1);
	}
	int opt=SO_REUSEADDR;
	setsockopt(listenfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));

	bzero(&server,sizeof(server));
	server.sin_family=AF_INET;
	server.sin_port=htons(PORT);
	server.sin_addr.s_addr=htonl(INADDR_ANY);
	if(bind(listenfd,(struct sockaddr *)&server,sizeof(struct sockaddr))==-1)
	{
		/*handle exception*/
		perror("bind() error.");
		exit(1);
	}
	if(listen(listenfd,BACKLOG)==-1)
	{
		perror("listen() error\n");
		exit(1);
	}
	sin_size=sizeof(struct sockaddr_in);
	/*initialize for select*/
	maxfd=listenfd;
	maxi=-1;
	for(i=0;i<FD_SETSIZE;i++)
	{
		client[i].fd=-1;
	}
	FD_ZERO(&allset);
	FD_SET(listenfd,&allset);
	while(1)
	{
		struct sockaddr_in addr;
		rset=allset;
		nready=select(maxfd+1,&rset,NULL,NULL,NULL);
		if(FD_ISSET(listenfd,&rset))
		{
			/*new client connection */
			/*accept connection*/
			if((connectfd=accept(listenfd,(struct sockaddr*)&addr,&sin_size))==-1)
			{
				perror("accept() error.\n");
				continue;
			}
			/*put new fd to client*/
			for(i=0;i<FD_SETSIZE;i++)
			{
				if(client[i].fd<0)
				{
					client[i].fd=connectfd;//save descriptor
					client[i].name=(char *)malloc(MAXDATASIZE);
					client[i].addr=addr;
					client[i].data=(char *)malloc(MAXDATASIZE);
					client[i].name[0]='\0';
					client[i].data[0]='\0';
					printf("You got a connection from %s.",inet_ntoa(client[i].addr.sin_addr));
					break;
				}
			}
			if(i==FD_SETSIZE)
				printf("too many clients.\n");
			FD_SET(connectfd,&allset);//add new descriptor to set
			if(connectfd>maxfd)
				maxfd=connectfd;
			if(i>maxi)
				maxi=i;
			if(--nready<=0)
				continue;/*no more readable descriptors*/
			for(i=0;i<=maxi;i++)
			{
				/*check all clients for data*/
				if((sockfd=client[i].fd)<0)
					continue;
				if(FD_ISSET(sockfd,&rset))
				{
					if((n=recv(sockfd,recvbuf,MAXDATASIZE,0))==0)
					{
						/*connection closed by client*/
						close(sockfd);
						printf("client( %s )closed connection.User's data:%s\n",client[i].name,client[i].data);
						FD_CLR(sockfd,&allset);
						client[i].fd=-1;
						free(client[i].name);
						free(client[i].data);
					}
					else
					{
						process_cli(&client[i],recvbuf,n);
					}
					if(--nready<=0)
						break;//no more readable descriptors
				}
			}
		}
		close(listenfd);
	}
	return 0;
}

void process_cli(CLIENT *client,char *recvbuf,int len)
{
	char sendbuf[MAXDATASIZE];
	recvbuf[len-1]='\0';
	if(strlen(client->name)==0)
	{
		//get client's name from client
		memcpy(client->name,recvbuf,len);
		printf("client's name is %s.\n",client->name);
		return ;
	}
	/*save client's data*/
	printf("received client ( %s )message:%s\n",client->name,recvbuf);
	/*save user's data*/
	savedata(recvbuf,len,client->data);
	int i1;
	for( i1=0;i1<len-1;i1++)
	{
		sendbuf[i1]=recvbuf[len-i1-2];
	}
	sendbuf[len-1]='\0';
	send(client->fd,sendbuf,strlen(sendbuf),0);
}
void savedata(char *recvbuf,int len,char *data)
{
	int start=strlen(data);
	int i;
	for( i=0;i<len;i++)
	{
		data[start+i]=recvbuf[i];
	}
}