Как написать клиент NTP? [закрыто]

Я ищу пример кода записи клиента NTP на C. Я нашелэтот: Fixed some things on code,and it's able to compile. But after "sending data.." it don't nothing. I have no idea how to fix this. Where is problem into code or server? Thanks in advance.

 * This code will query a ntp server for the local time and display
 * it.  it is intended to show how to use a NTP server as a time
 * source for a simple network connected device.
 * This is the C version.  The orignal was in Perl
 * For better clock management see the offical NTP info at:
 * http://www.eecis.udel.edu/~ntp/
 * written by Tim Hogard ([email protected])
 * Thu Sep 26 13:35:41 EAST 2002
 * Converted to C Fri Feb 21 21:42:49 EAST 2003
 * this code is in the public domain.
 * it can be found here http://www.abnormal.com/~thogard/ntp/
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <time.h>
#include <string.h>

void ntpdate();

int main() {
    return 0;

void ntpdate() {
char    *hostname="tick.usno.navy.mil";
int portno=123;     //NTP is port 123
int maxlen=1024;        //check our buffers
int i;          // misc var i
unsigned char msg[48]={010,0,0,0,0,0,0,0,0};    // the packet we send
unsigned long  buf[maxlen]; // the buffer we get back
//struct in_addr ipaddr;        //  
struct protoent *proto;     //
struct sockaddr_in server_addr;
int s;  // socket
int tmit;   // the time -- This is a time_t sort of

//use Socket;
//#we use the system call to open a UDP socket
//socket(SOCKET, PF_INET, SOCK_DGRAM, getprotobyname("udp")) or die "socket: $!";
s=socket(PF_INET, SOCK_DGRAM, proto->p_proto);
if(s) {
//#convert hostname to ipaddress if needed
//$ipaddr   = inet_aton($HOSTNAME);
memset( &server_addr, 0, sizeof( server_addr ));
server_addr.sin_addr.s_addr = inet_addr(hostname);
//argv[1] );
//i   = inet_aton(hostname,&server_addr.sin_addr);
//printf("ipaddr (in hex): %x\n",server_addr.sin_addr);

 * build a message.  Our message is all zeros except for a one in the
 * protocol version field
 * msg[] in binary is 00 001 000 00000000 
 * it should be a total of 48 bytes long

// send the data
printf("sending data..\n");
i=sendto(s,msg,sizeof(msg),0,(struct sockaddr *)&server_addr,sizeof(server_addr));

// get the data back
printf("recvfr: %d\n",i);

//We get 12 long words back in Network order

 * The high word of transmit time is the 10th word we get back
 * tmit is the time in seconds not accounting for network delays which
 * should be way less than a second if this is a local NTP server

tmit=ntohl((time_t)buf[10]);    //# get transmit time

 * Convert time to unix standard time NTP is number of seconds since 0000
 * UT on 1 January 1900 unix time is seconds since 0000 UT on 1 January
 * 1970 There has been a trend to add a 2 leap seconds every 3 years.
 * Leap seconds are only an issue the last second of the month in June and
 * December if you don't try to set the clock then it can be ignored but
 * this is importaint to people who coordinate times with GPS clock sources.

tmit-= 2208988800U; 
/* use unix library function to show me the local time (it takes care
 * of timezone issues for both north and south of the equator and places
 * that do Summer time/ Daylight savings time.

//#compare to system time
printf("Time: %s",ctime(&tmit));
printf("System time is %d seconds off\n",i-tmit);

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