《UNIX网络编程》 1

1、安装 daytime 服务：

apt-get install xinetd

chmod 777 /etc/xinetd.d/daytime

vim /etc/xinetd.d/daytime

把两个 disable = yes ,改成 disable = no

/etc/init.d/xinetd restart

2、timeserver.cpp:

#include <time.h>
#include <netinet/in.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>

#define LISTENQ 1024
int main(int argc, char** argv)
{
    int listenfd,connfd;
    sockaddr_in servaddr;
    char buff[1024];
    time_t ticks;

    listenfd = socket(AF_INET,SOCK_STREAM,0);
    bzero(&servaddr,sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(2013);

    bind(listenfd,(sockaddr*)&servaddr,sizeof(servaddr));
    listen(listenfd,LISTENQ);
    for(;;)
    {   
        connfd = accept(listenfd,(sockaddr*)NULL,NULL);
        ticks = time(NULL);
        snprintf(buff,sizeof(buff),"%.24s\r\n",ctime(&ticks));
        write(connfd,buff,strlen(buff));    //#include <unistd.h>
        close(connfd);
    }   
}

3、timeclient.cpp:

#include <iostream>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
#include <stdio.h>

int main(int argc, char **argv)
{
    int     sockfd,n;
    char    recvline[1024];
    sockaddr_in servaddr;       //#include <netinet/in.h>

    if(argc != 2)
    {   
        std::cout<<"usage: a.out <IP>"<<std::endl;
        return -1; 
    }   
    if((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0)    //#include <sys/socket.h>
    {   
        std::cout<<"socket error."<<std::endl;
        return -1; 
    }   
    bzero(&servaddr, sizeof(servaddr)); //#include <cstring>
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(2013);
    if(inet_pton(AF_INET,argv[1],&servaddr.sin_addr) <= 0)  // #include <arpa/inet.h>
    {   
        std::cout<<"inet_pton error"<<std::endl;
        return -1; 
    }   
    if(connect(sockfd, (sockaddr*)&servaddr,sizeof(servaddr)) < 0)  
    {   
        std::cout<<"connect error"<<std::endl;
        return -1; 
    }   
    while( (n = read(sockfd, recvline, 1023)) > 0)
    {   
        recvline[n] = 0;
        if(fputs(recvline, stdout) == EOF)  //#include <stdio.h>
        {   
            std::cout<<"fputs error"<<std::endl;
        }   
    }   
    if(n < 0)
    {   
        std::cout<<"read error"<<std::endl;
    }  
}