国内常用ntp服务器ip(windows系统下向NTP服务器请求
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#ifdef _WIN32
#include <string.h>
#include<WS2tcpip.h>
#include <windows.h>
#pragma comment(lib,"ws2_32.lib")
#else
＃include "logLib.h"
＃include "socket.h"
#endif
#define DIFF 4294.967296
#define GAP 2208988800
#define NTP_VERSION 3
#define NTP_MODE_CLIENT 0x3
#define NTP_HEADER_VERSION_SET(_header, _x) (_header |= ((_x & 0x7) << 0))
#define NTP_HEADER_MODE_SET(_header, _x) (_header |= ((_x & 0x7) << 3))
typedef struct
{
unsigned int seconds;
unsigned int fraction;
} ntp_timestamp;
typedef struct
{
int header;
int root_delay;
int root_dispersion;
int reference_identifier;
ntp_timestamp reference_timestamp;
ntp_timestamp originate_timestamp;
ntp_timestamp receive_timestamp;
ntp_timestamp transmit_timestamp;
} ntp_rsp_msg;
typedef struct{
int year;
int month;
int day;
int hour;
int min;
int second;
unsigned short ms;
} QSTime;
int main()
{
const int ntp_port = 123;
const char * ntp_host = "202.120.2.101";//NTP服务器IP地址
int ntp_socket;
struct sockaddr_in server;
int xit_addrlen = sizeof(struct sockaddr_in);
ntp_rsp_msg ntp_req_msg;
int receive_len;
ntp_rsp_msg ntp_rsp_msg;
long long fraction[4]={0};
time_t second;
QSTime qsTime;
struct tm *NormTime;
#if _WIN32
WSADATA data;
WORD version = MAKEWORD(2, 2);
WSAStartup(version, &data);
ntp_socket = socket(AF_INET, SOCK_DGRAM, 0);
if (ntp_socket == -1)
{
perror("Failed to create socket");
return 0;
}
#endif
if (ntp_socket == -1)
{
perror("Failed to create socket");
return 0;
}
memset(&server, 0, sizeof(server));
server.sin_family = AF_INET;
server.sin_port = htons(ntp_port);
server.sin_addr.s_addr = inet_addr(ntp_host);
if (server.sin_addr.s_addr == INADDR_NONE)
{
fprintf(stderr, "Failed to resolve hostname %s\n", ntp_host);
return 0;
}
memset(&ntp_req_msg, 0, sizeof(ntp_req_msg));
NTP_HEADER_VERSION_SET(ntp_req_msg.header, NTP_VERSION);
NTP_HEADER_MODE_SET(ntp_req_msg.header, NTP_MODE_CLIENT);
printf("Sending NTP request to %s:%d\n", ntp_host, ntp_port);
if (sendto(ntp_socket,
(char *)&ntp_req_msg, sizeof(ntp_req_msg),
0,
(struct sockaddr *) &server, sizeof(server)) == -1)
{
perror("Failed to send NTP request");
return 0;
}
printf("Waiting for NTP response...\n");
receive_len = recvfrom(ntp_socket,
(char *)&ntp_rsp_msg, sizeof(ntp_rsp_msg),
0,
(struct sockaddr *) &server,
(socklen_t *)&xit_addrlen);
if (receive_len <= 0)
{
perror("Failed to receive NTP response");
return 0;
}
printf("Received %d bytes\n", receive_len);
fraction[1]=ntohl(ntp_rsp_msg.receive_timestamp.fraction);
fraction[2]=ntohl(ntp_rsp_msg.transmit_timestamp.fraction);
fraction[3]=fraction[2]+((fraction[2]-fraction[1]))/ 2;
second=ntohl(ntp_rsp_msg.transmit_timestamp.seconds);
NormTime = localtime (&second);
qsTime.year=NormTime->tm_year+1830;
qsTime.month=NormTime->tm_mon+1;
qsTime.day=NormTime->tm_mday;
qsTime.hour=NormTime->tm_hour;
qsTime.min=NormTime->tm_min;
qsTime.second=NormTime->tm_sec;
qsTime.ms=((fraction[3])/DIFF)/1000;
printf("TIME: %04d-%02d-%02d_%02d-%02d-%02d.%03d\n",
qsTime.year,
qsTime.month,
qsTime.day,
qsTime.hour,
qsTime.min,
qsTime.second,
qsTime.ms);
return 1;
}
运行截图：
代码运行图
可能因为算法的问题，毫秒级不能更加精确。