基本套接字编程（3）

#include 
#include 

int select(int maxfdp1,fd_set *readset,fd_set *writeset,fd_set *exceptset,const struct timeval *timeout)
返回值：就绪描述符的数目，超时返回0，出错返回-1

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 


#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) 得到监听描述符*/
listenfd = socket(AF_INET , SOCK_STREAM , 0);

/*(2) 绑定套接字*/
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) 监听*/
listen(listenfd , LISTENQ);

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

/*(5) 进入服务器接收请求死循环*/
while(1)
{
rset = allset;
nready = select(maxfd+1 , &rset , NULL , NULL , NULL);

if(FD_ISSET(listenfd , &rset))
{
/*接收客户端的请求*/
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);

/*将客户链接套接字描述符添加到数组*/
for(i=0 ; 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))
{
/*处理客户请求*/
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
}

3.2 client.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define PORT 8888
#define MAX_LINE 2048

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

/*readline函数实现*/
ssize_t readline(int fd, char *vptr, size_t maxlen)
{
ssize_tn, rc;
charc, *ptr;

ptr = vptr;
for (n = 1; 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);
}

/*普通客户端消息处理函数*/
void str_cli(int sockfd)
{
/*发送和接收缓冲区*/
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
}

/*采用select的客户端消息处理函数*/
void str_cli2(FILE* fp , int sockfd)
{
int maxfd;
fd_set rset;
/*发送和接收缓冲区*/
char sendline[MAX_LINE] , recvline[MAX_LINE];

FD_ZERO(&rset);
while(1)
{
/*将文件描述符和套接字描述符添加到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)
{
/*声明套接字和链接服务器地址*/
    int sockfd;
    struct sockaddr_in servaddr;

    /*判断是否为合法输入*/
    if(argc != 2)
    {
        perror("usage:tcpcli ");
        exit(1);
    }//if

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

    /*(2) 设置链接服务器地址结构*/
    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) 发送链接服务器请求*/
    if(connect(sockfd , (struct sockaddr *)&servaddr , sizeof(servaddr)) <0)
    {
        perror("connect error");
        exit(1);
    }//if

/*调用普通消息处理函数*/
str_cli(sockfd);
/*调用采用select技术的消息处理函数*/
//str_cli2(stdin , sockfd);
exit(0);
}

3.3 运行结果