¿Hay alguna biblioteca C/C++ para conectarse con un servidor NTP remoto?

Question

Estoy creando un software C++ que necesita sincronizar el reloj del sistema con el servidor NTP remoto. Por ahora, uso el comando "sistema" para llamar al comando "ntpdate" de la consola.

.. Pero creo que es una forma fea de hacer eso.

¿Conoces alguna biblioteca que me permita conectarme al servidor NTP remoto? Gracias.

Answer 1

¿No sería una mejor solución que acaba ejecutando ntpd en dicho sistema para garantizar que el reloj sea correcto en lugar de tener su software emitiendo sincronización manualmente y posiblemente causando problemas con otras aplicaciones que no disfrutan de saltos de tiempo repentinos, especialmente al revés.

Dicho esto, hay libntp, creo.

Voy a agregar más cosas, ya que Google las encuentra para mí.

Answer 2

esto funciona en C++ (adaptado de c). obtendrá tiempo UTC de pool.ntp.br (DEBE usar IP). Si logra averiguar cómo obtener DAYTIME (horario de verano - horario verao), informe. i se puede obtener de los servidores de pastillas de la UFRJ, pero UFRJ no es fiable, lo que con ellos estar en huelga de la mitad del año ...

/* 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 (thogard@abnormal.com) 
* 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> 
#include <iostream> 

void ntpdate(); 

int main() { 
    ntpdate(); 
    return 0; 
} 

void ntpdate() { 
//char *hostname=(char *)"163.117.202.33"; 
//char *hostname=(char *)"pool.ntp.br"; 
char *hostname=(char *)"200.20.186.76"; 
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 
long 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: $!"; 
proto=getprotobyname("udp"); 
s=socket(PF_INET, SOCK_DGRAM, proto->p_proto); 
perror("socket"); 
// 
//#convert hostname to ipaddress if needed 
//$ipaddr = inet_aton($HOSTNAME); 
memset(&server_addr, 0, sizeof(server_addr)); 
server_addr.sin_family=AF_INET; 
server_addr.sin_addr.s_addr = inet_addr(hostname); 
//argv[1]); 
//i = inet_aton(hostname,&server_addr.sin_addr); 
server_addr.sin_port=htons(portno); 
//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)); 
perror("sendto"); 
// get the data back 
struct sockaddr saddr; 
socklen_t saddr_l = sizeof (saddr); 
i=recvfrom(s,buf,48,0,&saddr,&saddr_l); 
perror("recvfr:"); 

//We get 12 long words back in Network order 
/* 
for(i=0;i<12;i++) { 
    //printf("%d\t%-8x\n",i,ntohl(buf[i])); 
    long tmit2=ntohl((time_t)buf[i]); 
    std::cout << "Round number " << i << " time is " << ctime(&tmit2) << std::endl; 
} 
*/ 
/* 
* 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 
tmit=ntohl((time_t)buf[4]); //# get transmit time 
//printf("tmit=%d\n",tmit); 

/* 
* 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; 
//printf("tmit=%d\n",tmit); 
/* 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)); 

std::cout << "time is " << ctime(&tmit) << std::endl; 
i=time(0); 
//printf("%d-%d=%d\n",i,tmit,i-tmit); 
//printf("System time is %d seconds off\n",(i-tmit)); 
std::cout << "System time is " << (i-tmit) << " seconds off" << std::endl; 
}