玩一下linux下的IO多路复用之select-----实现多客户端访问服务器

趁着还没想睡觉，写一下io多路复用的select实现，支持多个客户端访问服务器，以下程序还有点瑕疵，等有时间再改，不说了，太困了，先睡觉。

服务器实现：

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

#define MAXMSG 1024

//处理信息接口
void handleMsg(int * clientSockFds, int maxFds, fd_set* pRset, fd_set* pAllset,const char* str)
{
    char buf[MAXMSG];
	char printBuf[MAXMSG];
	
	int i;
    for (i = 0; i< maxFds; i++) 
	{
        if (clientSockFds[i] != -1) //如果条件成立，则有连接的客户端
		{
            if (FD_ISSET(clientSockFds[i], pRset)) //判断是哪一个客户端的事件
			{
                int nread = read(clientSockFds[i], buf, MAXMSG);	//读取客户端socket流
                if (nread < 0) //对方异常。
				{
                    perror("read error");
                    close(clientSockFds[i]);
                    FD_CLR(clientSockFds[i], pAllset);
                    clientSockFds[i] = -1;
                    continue;
                }
                else if (nread == 0) //对方挂断，返回0
				{
					printf("%s",str);
                    printf(" client close the connection\n");
                    close(clientSockFds[i]);
					
					//如果对方挂断。则从文件集中清除监听该文件描述符
                    FD_CLR(clientSockFds[i], pAllset);
                    clientSockFds[i] = -1;
                    continue;
                } 
				else if (nread > 0)
				{
					sprintf(printBuf,"%s: %s",str,buf);
					printf("recv %s\n", printBuf);
				}	
                //write(clientSockFds[i], buf, nread);	
            }
        }
    }
}

int  main(int argc, char **argv)
{
    int  servPort = 6666;

    char buf[MAXMSG];
    int clientSockFds[FD_SETSIZE];
	printf("FD_SETSIZE=%d\n",FD_SETSIZE);

	//1、创建套接字
    int socketfd = socket(AF_INET, SOCK_STREAM, 0);
    if (socketfd < 0) 
	{
        perror("socket error");
        return -1;
    }
	
	//作用就是程序异常退出，再重新运行不会绑定端口失败
	int opt = 1;
    if (setsockopt(socketfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
        perror("setsockopt error");    
    }   
	
	//2、配置网络
	struct sockaddr_in clientaddr, serveraddr;
	bzero(&serveraddr, sizeof(serveraddr));
    serveraddr.sin_family = AF_INET;
    serveraddr.sin_addr.s_addr = INADDR_ANY;
    serveraddr.sin_port = htons(servPort);
	
	int socklen=sizeof(struct sockaddr_in);
	//3、绑定
	if(bind(socketfd,(struct sockaddr*)&serveraddr,socklen) == -1) 
	{
        perror("bind error");
        exit(-1);
    }
	
	//4、监听
	if (listen(socketfd, 1024) < 0) 
	{
        perror("listen error");
        return -1;
    }
	
	int i = 0;
    for (i = 0; i< FD_SETSIZE; i++) 
	{
        clientSockFds[i] = -1;  //给客户端文件描述符赋值
	}
	
	
	fd_set allset, rset; //声明文件描述符
    FD_ZERO(&allset); //把集合设置为空集 
	
	//5、将监听的socketfd 放到select集合中监听 
    FD_SET(socketfd, &allset);  
	
    int maxfd = socketfd;   
	
	printf("server port is %d\n", servPort);
    printf("max connection: %d\n", FD_SETSIZE);
	while (1) 
	{
		//因为select 每收到一次监听事件，便会从rset把相应的文件描述符从监听集合中清除 
		rset = allset; //定义两个文件集合，一个用来备份
		
		//6、select阻塞
        int nready = select(maxfd + 1, &rset, NULL, NULL, NULL);  
        if (nready < 0) 
		{
            perror("select error");
            continue;
        }
		
		//7、如果服务端的套接字有活动
        if (FD_ISSET(socketfd, &rset)) 
		{
			//8、接收连接
            int connfd = accept(socketfd, (struct sockaddr*) &clientaddr, &socklen); 
            if (connfd < 0) 
			{
                perror("accept error");
                continue;
            }

            sprintf(buf, "connect from %s:%d", inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));
            printf("%s\n",buf);
			
            for (i = 0; i< FD_SETSIZE; i++) 
			{
                if (clientSockFds[i] == -1)  //
				{
                    clientSockFds[i] = connfd; //将客户端连接的文件描述符放到clientSockFds数组
                    break;
                }
            }
			
            if (i == FD_SETSIZE) 
			{
                fprintf(stderr, "too many connection, more than %d\n", FD_SETSIZE);
                close(connfd);
                continue;
            }
			
            if (connfd > maxfd)
			{
                maxfd = connfd;
			}
				
			//添加或者删除都留着allset
            FD_SET(connfd, &allset);
            
			//超时继续
			if (--nready <= 0)
                continue;
        }
		//9、处理客户端发送的信息
        handleMsg(clientSockFds, maxfd, &rset, &allset,buf);
    }
}

客户端实现：

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

#define MAXMSG 1024

int main()
{
	int connfd=socket(AF_INET,SOCK_STREAM,0);
	if(connfd==-1)
	{
		printf("creat socket failed\n");
	}
	
	//取消端口绑定限制
	int opt = 1;
	if (setsockopt(connfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))<0)
	{
		printf("setsockopt failed\n");
		return -1;
	}
	
	struct sockaddr_in addrSrc;
	bzero(&addrSrc,sizeof(addrSrc));
	
	addrSrc.sin_family=AF_INET;
	addrSrc.sin_port=htons(6666);
	addrSrc.sin_addr.s_addr=inet_addr("127.0.0.1");
	
	if (connect(connfd, (struct sockaddr *) &addrSrc, sizeof(addrSrc)) < 0) 
	{
        printf("connect error\n");
        return -1;
    }
	
    printf("This is client\n");
    while(1)
	{
		//发送信息
		char sendBuf[100]={0};
		scanf("%s",sendBuf);
		send(connfd,sendBuf,strlen(sendBuf)+1,0);
	}		
    close(connfd);
    printf("exit\n");
	
    return 0;
}