UNIX网络编程daytime服务端和客户端的实现过程

Server.c

#include "unp.h"
//solid for server
#include <time.h>

int main(int argc,char **argv)
{
int listenfd,connfd;
struct sockaddr_in servaddr;
//header file contain the struct sockaddr_in
/*
struct sockaddr_in{
short sin_family; //2bytes e.g AF_INET AF_INET6
unsigned short sin_port;2bytes for short
struct in_addr sin_addr;
char sin_zero[8]; // 8bytes zero this if you want to
};

struct in_addr{
unsigned long s_addr;//4 bytes load with inet_pton()
}
*/
char buff[MAXLINE];

time_t ticks;

listenfd = socket(AF_INET,SOCK_STREAM,0);
//listenfd is token as a desicribale symbol
//SOCK_STREAM used for reliable communications
//third parameter is the implicitly 0 based on what you choose the previous two parameters or explicitly IPPROTO_TCP/IPPROTO_UDP
bzero(&servaddr,sizeof(servaddr));
// set the n bits to zero in the memory

servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr=htonl(INADDR_ANY);
//host to network long conversion to the net long from host long 32 bits data
//listen to the any port and receive the default port.0.0.0.0
//daytime 13 reserved port for the client requested for the daytime
servaddr.sin_port = htonl(13);
/*daytime server*/
//bind listenfd with the servaddr
for ( ; ; )
{
connfd = accept(listenfd,(SA*)NULL,NULL);
ticks = time(NULL);
snprintf(buff,sizeof(buff),"%.24s ",ctime(&ticks));
//convert the parameters to the string with the format "%.24s "
//char* ctime(const time_t *time);----->gelinweizhi standard time
write(connfd,buff,strlen(buff));
//write(int fd,const void*buf,size_t count)--->fd need to describe the key words/buf----->the buffer/count---->the number of the maxium
close(connfd);
}
}

这个是客户端代码，和注释，Ubuntu下sublime 的中文注释配起来好烦，干脆练习了英语，哈哈哈哈哈！

这个是服务端代码。

//echo server
#include "unp.h"
#include "my_err.h"

int main(int argc,char ** argv)
//argc 是 argv[]的参数
{
int sockfd,n;
//?scheme for what
char recvline[MAXLINE+1];
//MAXLINE is a #define?
struct sockaddr_in servaddr;
if (argc!=2)
err_quit("usage:a.out<IP address>");
if((sockfd = socket(AF_INET,SOCK_STREAM,0))<0)
err_sys("socket error");
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(13);

if( inet_pton(AF_INET,argv[1], &servaddr.sin_addr) <= 0 )//inet_pton(addr,点分十进制，二进制整数)
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[n] = 0; //fputS()没有自动写入字符串结束'',补上recvline[n]=''因为0转换为char
if(fputs(recvline,stdout) == EOF)//EOF==-1
err_sys("fputs error");
}
if(n<0)
err_sys("read error");
exit(0);
}

配置时，注意如下引入这个头文件，下载unpv13e这个文件夹并且按步骤配置好，网上搜教程

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

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, " ");
fflush(stdout); /* in case stdout and stderr are the same */
fputs(buf, stderr);
fflush(NULL); /* flushes all stdio output streams */
}