unix网络编程笔记---4.时间获取server与client

第1章1.5节一个简单的时间获取服务器程序
下面的demo既有server端又有client端，两者互相通信
1. server端

cong@msi:/work/test/tcpip$ cat 2timeserv/timeserv.c
#include "utils.h"

#define TIME_SERV_ADDR "192.168.4.98"
//#define TIME_SERV_ADDR "127.0.0.1"

#define LISTENQ 10

int main ( int argc, char *argv[] )
{
    int listenfd, connfd;
    struct sockaddr_in servaddr;
    char buff[1024];
    time_t ticks;
    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    if(listenfd< 0)
        return -1;
    dbmsg("socket created");
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(13999);               //绑定端口13999,htons将主机字节转为网络字节序
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);   //区别:client端必须是一个固定的ip,server端是INADDR_ANY
    //inet_pton(AF_INET, TIME_SERV_ADDR, &servaddr.sin_addr);

    dbmsg("next bind&listen");
    bind(listenfd, (const struct sockaddr*)&servaddr, sizeof(servaddr));
    listen(listenfd, LISTENQ);
    dbmsg("bind&listen success");
    while(1)
    {
        //int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);
        connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);
        dbmsg("accept success");
        ticks = time(NULL);
        snprintf(buff, sizeof(buff), "%.24s\n", ctime(&ticks));
        write(connfd, buff, strlen(buff));
        close(connfd);
    }

    return EXIT_SUCCESS;
}

2. client端

#include "utils.h"

//#define TIME_SERV_ADDR "192.168.4.98"
#define TIME_SERV_ADDR "127.0.0.1"

int main ( int argc, char *argv[] )
{
    dbmsg();
    int sockfd, n;
    struct sockaddr_in servaddr;
    char recvline[1024];
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if(sockfd < 0)
        return -1;
    dbmsg("socket created");
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    //这儿修改端口为13999，不修改在主机上运行就会访问系统的daytime而不访问自己写的server了
    servaddr.sin_port = htons(13999);      //绑定端口13999,htons将主机字节转为网络字节序
    inet_pton(AF_INET, TIME_SERV_ADDR, &servaddr.sin_addr);  //将字符串(presentation)转为数值(numeric)
    dbmsg("next connect");
    connect(sockfd, (const struct sockaddr*)&servaddr, sizeof(servaddr));
    dbmsg("connect success");
    while((n=read(sockfd, recvline, MAXLINE)) > 0)
    {
        recvline[n] = '\0';
        dbmsg("read over");
        fputs(recvline, stdout);
    }

    return EXIT_SUCCESS;
}

3.查看本要端口占用情况
a.netstat默认，是不显示listen状态的socket

cong@msi:/work/test/tcpip$ netstat
tcp        0      1 192.168.4.98:37985      58.215.118.34:http      FIN_WAIT1
unix  3 [ ] STREAM     CONNECTED     19484

b. -l 显示处于listen状态的socket
    -a 显示所有状态的socket,包括listen connect等
c. -n 将host与port name显示为数字

cong@msi:/work/test/tcpip$ netstat -lp
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 *:daytime *:* LISTEN -

cong@msi:/work/test/tcpip$ netstat -lnp
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:13 0.0.0.0:* LISTEN -    //将daytime服务变为数字13

d. -p显示使用socket的程序

cong@msi:/work/test/tcpip$ netstat -lp
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 *:daytime *:* LISTEN -

cong@msi:/work/test/tcpip$ netstat -lnp
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:13              0.0.0.0:* LISTEN -

附源码:
client端,下载后改名为1echo.tar.gz
1echo.rar
server端,下载后改名为2timeserv.tar.gz
2timeserv.rar