UNP卷1：第一章（简介）
最后更新于：2022-04-01 14:48:51
1. 时间获取程序
服务端：srv.c
~~~
#include <time.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <fcntl.h>
#define SA struct sockaddr
#define MAXLINE 1024
int main( void )
{
int listenfd, connfd;
struct sockaddr_in servaddr;
char buff[ MAXLINE ];
time_t ticks;
pid_t pid;
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(7777);
bind(listenfd, ( SA * )&servaddr, sizeof(servaddr));
listen( listenfd, 5 );
for( ; ; ){
connfd = accept( listenfd, ( SA * )NULL, NULL);
pid = fork();
if ( 0 == pid ){
ticks = time( NULL );
snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));
write( connfd, buff, strlen(buff));
exit(1);
}
if ( waitpid(pid, NULL,0 ) != pid ){
printf("waitpid error");
exit(1);
}
close( connfd );
}
return 0;
}
~~~
客户端：cli.c
~~~
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#define SA struct sockaddr
#define MAXLINE 1024
int main( int argc, char **argv )
{
int sockfd, n;
char recvline[ MAXLINE + 1 ];
struct sockaddr_in servaddr;
if ( argc != 2 ){
printf("usage:a.out <IPaddress>");
exit(1);
}
if ( ( sockfd = socket( AF_INET, SOCK_STREAM, 0 ) ) < 0 ){
printf("socket error\n");
exit(1);
}
bzero( &servaddr, sizeof( servaddr ) );
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons( 7777 );
if ( inet_pton( AF_INET, argv[ 1 ], &servaddr.sin_addr ) <= 0 ){
printf("inet_pton error for %s", argv[1]);
exit(1);
}
if ( connect( sockfd, ( SA * )&servaddr, sizeof( servaddr ) ) < 0 ){
printf("connect error\n");
exit(1);
}
while ( ( n = read( sockfd, recvline, MAXLINE )) > 0){
recvline[n] = 0;
if (fputs(recvline, stdout) == EOF){
printf("fputs error\n");
exit(1);
}
}
if (n < 0){
printf("read error\n");
exit(1);
}
exit(0);
}
~~~
运行结果如下：
服务端：
~~~
root@ThinkPad-T430i:/home/leichaojian# lsof -i:7777
root@ThinkPad-T430i:/home/leichaojian# cc srv.c
root@ThinkPad-T430i:/home/leichaojian# ./a.out
~~~
客户端：
~~~
leichaojian@ThinkPad-T430i:~$ ./a.out 127.0.0.1
Fri Sep 5 00:14:14 2014
~~~
**这里lsof -i:7777是必要的，否则端口会被占用，导致connect失败！**
对于习题1.5，修改代码如下：
~~~
for ( count = 0; count < strlen( buff ); count++ )
write( connfd, &buff[ count ], 1 );
~~~
但是客户端依旧只返回1，即虽然服务端是分字符write，但实际上还是一次性的发送所有的数据。