代码： 全选
/* timeserv.c - a socket-based time of day server
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <time.h>
#include <strings.h>
#define PORTNUM 0 /* our time service random phone number */
#define HOSTLEN 256
#define oops(msg) { perror(msg) ; exit(1) ; }
int main(int ac, char *av[])
{
struct sockaddr_in saddr; /* build our address here */
struct hostent *hp; /* this is part of our */
char hostname[HOSTLEN]; /* address */
int sock_id,sock_fd; /* line id, file desc */
FILE *sock_fp; /* use socket as stream */
char *ctime(); /* convert secs to string */
time_t thetime; /* the time we report */
/*
* Step 1: ask kernel for a socket
*/
sock_id = socket( AF_INET, SOCK_STREAM, 0 ); /* get a socket */
if ( sock_id == -1 )
oops( "socket" );
/*
* Step 2: bind address to socket. Address is host,port
*/
bzero( (void *)&saddr, sizeof(saddr) ); /* clear out struct */
gethostname( hostname, HOSTLEN ); /* where am I ? */
hp = gethostbyname( hostname ); /* get info about host */
/* fill in host part */
bcopy( (void *)hp->h_addr, (void *)&saddr.sin_addr, hp->h_length);
saddr.sin_port = htons(PORTNUM); /* fill in socket port */
saddr.sin_family = AF_INET ; /* fill in addr family */
if ( bind(sock_id, (struct sockaddr *)&saddr, sizeof(saddr)) != 0 )
oops( "bind" );
/* 服务器程序获得一个随机端口后，请问怎样得到这个随机端口的具体值? */
/*
* Step 3: allow incoming calls with Qsize=1 on socket
*/
if ( listen(sock_id, 1) != 0 )
oops( "listen" );
/*
* main loop: accept(), write(), close()
*/
while ( 1 ){
sock_fd = accept(sock_id, NULL, NULL); /* wait for call */
printf("Wow! got a call!\n");
if ( sock_fd == -1 )
oops( "accept" ); /* error getting calls */
sock_fp = fdopen(sock_fd,"w"); /* we'll write to the */
if ( sock_fp == NULL ) /* socket as a stream */
oops( "fdopen" ); /* unless we can't */
thetime = time(NULL); /* get time */
/* and convert to strng */
fprintf( sock_fp, "The time here is .." );
fprintf( sock_fp, "%s", ctime(&thetime) );
fclose( sock_fp ); /* release connection */
}
}