简单的时间/日期客户端&服务器程序

简单的时间/日期客户端&服务器程序

本文章代码根据《UNIX网络编程：卷1》修改而来，由于书中源码用于linux系统，题主在windows系统下进行模拟操作，作了部分修改。

客户端程序

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <fcntl.h>
#include <Windows.h>
#include <winsock.h>
#include <winsock2.h>
#include "my_err.h"

#define bzero(ptr,n)    memset(ptr,0,n)
#define SA  struct sockaddr

void     err_quit(const char *, ...);
void     err_sys(const char *, ...);

int main(int argc,char **argv)
{
int                 sockfd,n;
char                recvline[MAXLINE + 1];
struct sockaddr_in  servaddr;

if(argc != 2)
err_quit("usage: a.out <IPaddress>");
WSADATA wsa;
WORD wVersionRequested;
wVersionRequested = MAKEWORD(2,0);
if(WSAStartup(wVersionRequested,&wsa)!=0){
printf("Winsock Initialization failed.\n");
}
if((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0)
err_sys("socket error");
std::cout<<sockfd<<std::endl;

bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(13);
servaddr.sin_addr.s_addr = inet_addr(argv[1]);
/*
*   int inet_pton(int af,const char *sr,void *dst);
*   af:     地址簇
*   *sr:    来源地址
*   *dst:   接收转换后的数据
*/
// if(inet_ntop(AF_INET ,argv[1],&servaddr.sin_addr,sizeof(servaddr.sin_addr)) <= 0)
//  err_quit("inet_pton error for %s",argv[1]);

if(connect(sockfd,(SA *) &servaddr,sizeof(servaddr)) < 0)
err_sys("connect error");

while ( (n = read(sockfd, recvline, MAXLINE)) > 0) {
recvline
= 0;    /* null terminate */
if (fputs(recvline, stdout)r_sys("fputs error");
}
if (n < 0)

err_sys("read error");

exit(0);
}

服务器程序

#include <time.h>
#include <stdio.h>
#include <string.h>
#include <iostream>
#include <fcntl.h>
#include <Windows.h>
#include <winsock.h>
#include <winsock2.h>
#include "my_err.h"

#define bzero(ptr,n)    memset(ptr,0,n)
#define SA  struct sockaddr
#define LISTENQ     1024    /* 2nd argument to listen() */

int main(int argc,char **argv)
{
int         listenfd,connfd;
struct sockaddr_in servaddr;
char        buff[MAXLINE];
time_t      ticks;

WSADATA wsa;
WORD wVersionRequested;
wVersionRequested = MAKEWORD(2,0);
if(WSAStartup(wVersionRequested,&wsa)!=0){
printf("Winsock Initialization failed.\n"
bb00
);
}

listenfd = socket(AF_INET,SOCK_STREAM,0);
std::cout<<listenfd<<std::endl;

bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family      = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port        = htons(13);   /* daytime server */

bind(listenfd, (SA *) &servaddr, sizeof(servaddr));

listen(listenfd, LISTENQ);

for ( ; ; ) {
connfd = accept(listenfd, (SA *) NULL, NULL);

ticks = time(NULL);
snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));
write(connfd, buff, strlen(buff));

//close(connfd);
}
}

my_err.h　代码块如下：

#include <errno.h>      /* for definition of errno */
#include <stdarg.h>     /* ISO C variable aruments */

#define MAXLINE 4096

static void err_doit(int, int, const char *, va_list);

/*
* Nonfatal error related to a system call.
* Print a message and return.
*/
void
err_ret(const char *fmt, ...)
{
va_list     ap;

va_start(ap, fmt);
err_doit(1, errno, fmt, ap);
va_end(ap);
}

/*
* Fatal error related to a system call.
* Print a message and terminate.
*/
void
err_sys(const char *fmt, ...)
{
va_list     ap;

va_start(ap, fmt);
err_doit(1, errno, fmt, ap);
va_end(ap);
exit(1);
}

/*
* Fatal error unrelated to a system call.
* Error code passed as explict parameter.
* Print a message and terminate.
*/
void
err_exit(int error, const char *fmt, ...)
{
va_list     ap;

va_start(ap, fmt);
err_doit(1, error, fmt, ap);
va_end(ap);
exit(1);
}

/*
* Fatal error related to a system call.
* Print a message, dump core, and terminate.
*/
void
err_dump(const char *fmt, ...)
{
va_list     ap;

va_start(ap, fmt);
err_doit(1, errno, fmt, ap);
va_end(ap);
abort();        /* dump core and terminate */
exit(1);        /* shouldn't get here */
}

/*
* Nonfatal error unrelated to a system call.
* Print a message and return.
*/
void
err_msg(const char *fmt, ...)
{
va_list     ap;

va_start(ap, fmt);
err_doit(0, 0, fmt, ap);
va_end(ap);
}

/*
* Fatal error unrelated to a system call.
* Print a message and terminate.
*/
void
err_quit(const char *fmt, ...)
{
va_list     ap;

va_start(ap, fmt);
err_doit(0, 0, fmt, ap);
va_end(ap);
exit(1);
}

/*
* Print a message and return to caller.
* Caller specifies "errnoflag".
*/
static void
err_doit(int errnoflag, int error, const char *fmt, va_list ap)
{
char    buf[MAXLINE];
vsnprintf(buf, MAXLINE, fmt, ap);
if (errnoflag)
snprintf(buf+strlen(buf), MAXLINE-strlen(buf), ": %s",
strerror(error));
strcat(buf, "\n");
fflush(stdout);     /* in case stdout and stderr are the same */
fputs(buf, stderr);
fflush(NULL);       /* flushes all stdio output streams */
}

运行测试时，先运行服务器代码，再运行客户端代码，服务器会一直处于侦听状态，客户端连接127.0.0.1，connect成功，但是会read error,提示Bad file descriptor。

但是，把服务器和客户端中write()和read()函数相应地改成send()和recv()就可以成功进行接收数据。