Linux Socket C語言網路程式設計：Select Socket

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


#define PORT 8888
#define MAX_LINE 2048
#define LISTENQ 20


int main(int argc , char **argv)
{
	int i, maxi, maxfd, listenfd, connfd, sockfd;

	int nready , client[FD_SETSIZE];
	
	ssize_t n, ret;
		
	fd_set rset , allset;

	char buf[MAX_LINE];

	socklen_t clilen;

	struct sockaddr_in servaddr , cliaddr;

	/*(1) 得到監聽描述符*/
	listenfd = socket(AF_INET , SOCK_STREAM , 0);

	/*(2) 繫結套接字*/
	bzero(&servaddr , sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	servaddr.sin_port = htons(PORT);

	bind(listenfd , (struct sockaddr *)&servaddr , sizeof(servaddr));

	/*(3) 監聽*/
	listen(listenfd , LISTENQ);

	/*(4) 設定select*/
	maxfd = listenfd;
	maxi = -1;
	for(i=0 ; i<FD_SETSIZE ; ++i)
	{
		client[i] = -1;
	}//for
	FD_ZERO(&allset);
	FD_SET(listenfd , &allset);

	/*(5) 進入伺服器接收請求死迴圈*/
	while(1)
	{
		rset = allset;
		nready = select(maxfd+1 , &rset , NULL , NULL , NULL);
		
		if(FD_ISSET(listenfd , &rset))
		{
			/*接收客戶端的請求*/
			clilen = sizeof(cliaddr);

			printf("\naccpet connection~\n");

			if((connfd = accept(listenfd , (struct sockaddr *)&cliaddr , &clilen)) < 0)
			{
				perror("accept error.\n");
				exit(1);
			}//if		

			printf("accpet a new client: %s:%d\n", inet_ntoa(cliaddr.sin_addr) , cliaddr.sin_port);

			/*將客戶連結套接字描述符新增到陣列*/
			for(i=0 ; i<FD_SETSIZE ; ++i)
			{
				if(client[i] < 0)
				{
					client[i] = connfd;
					break;
				}//if
			}//for

			if(FD_SETSIZE == i)
			{
				perror("too many connection.\n");
				exit(1);
			}//if

			FD_SET(connfd , &allset);
			if(connfd > maxfd)
				maxfd = connfd;
			if(i > maxi)
				maxi = i;

			if(--nready < 0)
				continue;
		}//if

		for(i=0; i<=maxi ; ++i)
		{
			if((sockfd = client[i]) < 0)
				continue;
			if(FD_ISSET(sockfd , &rset))
			{
				/*處理客戶請求*/
				printf("\nreading the socket~~~ \n");
				
				bzero(buf , MAX_LINE);
				if((n = read(sockfd , buf , MAX_LINE)) <= 0)
				{
					close(sockfd);
					FD_CLR(sockfd , &allset);
					client[i] = -1;
				}//if
				else{
					printf("clint[%d] send message: %s\n", i , buf);
					if((ret = write(sockfd , buf , n)) != n)
	
					{
						printf("error writing to the sockfd!\n");
						break;
					}//if
				}//else
				if(--nready <= 0)
					break;
			}//if
		}//for
	}//while
}

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

#define PORT 8888
#define MAX_LINE 2048

int max(int a , int b)
{
	return a > b ? a : b;
}

/*readline函式實現*/
ssize_t readline(int fd, char *vptr, size_t maxlen)
{
	ssize_t	n, rc;
	char	c, *ptr;

	ptr = vptr;
	for (n = 1; n < maxlen; n++) {
		if ( (rc = read(fd, &c,1)) == 1) {
			*ptr++ = c;
			if (c == '\n')
				break;	/* newline is stored, like fgets() */
		} else if (rc == 0) {
			*ptr = 0;
			return(n - 1);	/* EOF, n - 1 bytes were read */
		} else
			return(-1);		/* error, errno set by read() */
	}

	*ptr = 0;	/* null terminate like fgets() */
	return(n);
}

/*普通客戶端訊息處理函式*/
void str_cli(int sockfd)
{
	/*傳送和接收緩衝區*/
	char sendline[MAX_LINE] , recvline[MAX_LINE];
	while(fgets(sendline , MAX_LINE , stdin) != NULL)	
	{
		write(sockfd , sendline , strlen(sendline));

		bzero(recvline , MAX_LINE);
		if(readline(sockfd , recvline , MAX_LINE) == 0)
		{
			perror("server terminated prematurely");
			exit(1);
		}//if

		if(fputs(recvline , stdout) == EOF)
		{
			perror("fputs error");
			exit(1);
		}//if

		bzero(sendline , MAX_LINE);
	}//while
}

/*採用select的客戶端訊息處理函式*/
void str_cli2(FILE* fp , int sockfd)
{
	int maxfd;
	fd_set rset;
	/*傳送和接收緩衝區*/
	char sendline[MAX_LINE] , recvline[MAX_LINE];

	FD_ZERO(&rset);
	while(1)
	{
		/*將檔案描述符和套接字描述符新增到rset描述符集*/
		FD_SET(fileno(fp) , &rset);	
		FD_SET(sockfd , &rset);
		maxfd = max(fileno(fp) , sockfd) + 1;
		select(maxfd , &rset , NULL , NULL , NULL);
		
		if(FD_ISSET(fileno(fp) , &rset))
		{
			if(fgets(sendline , MAX_LINE , fp) == NULL)
			{
				printf("read nothing~\n");
				close(sockfd); /*all done*/
				return ;
			}//if
			sendline[strlen(sendline) - 1] = '\0';
			write(sockfd , sendline , strlen(sendline));
		}//if

		if(FD_ISSET(sockfd , &rset))
		{
			if(readline(sockfd , recvline , MAX_LINE) == 0)
			{
				
				perror("handleMsg: server terminated prematurely.\n");
				exit(1);			
			}//if
			
			if(fputs(recvline , stdout) == EOF)
			{
				perror("fputs error");
				exit(1);
			}//if
		}//if	
	}//while
}

int main(int argc , char **argv)
{
	/*宣告套接字和連結伺服器地址*/
    int sockfd;
    struct sockaddr_in servaddr;

    /*判斷是否為合法輸入*/
    if(argc != 2)
    {
        perror("usage:tcpcli <IPaddress>");
        exit(1);
    }//if

    /*(1) 建立套接字*/
    if((sockfd = socket(AF_INET , SOCK_STREAM , 0)) == -1)
    {
        perror("socket error");
        exit(1);
    }//if

    /*(2) 設定連結伺服器地址結構*/
    bzero(&servaddr , sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(PORT);
    if(inet_pton(AF_INET , argv[1] , &servaddr.sin_addr) < 0)
    {
        printf("inet_pton error for %s\n",argv[1]);
        exit(1);
    }//if

    /*(3) 傳送連結伺服器請求*/
    if(connect(sockfd , (struct sockaddr *)&servaddr , sizeof(servaddr)) < 0)
    {
        perror("connect error");
        exit(1);
    }//if

	/*呼叫普通訊息處理函式*/
	str_cli(sockfd);	
	/*呼叫採用select技術的訊息處理函式*/
	//str_cli2(stdin , sockfd);
	exit(0);
}