从github 中找到的一份代码进行的修改
板卡是0区,手动加了8个时区

#include <iostream>
#include <netdb.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#define NTP_TIMESTAMP_DELTA 2208988800ull#define LI(packet)                                                             \(uint8_t)((packet.li_vn_mode & 0xC0) >> 6) // (li   & 11 000 000) >> 6
#define VN(packet)                                                             \(uint8_t)((packet.li_vn_mode & 0x38) >> 3) // (vn   & 00 111 000) >> 3
#define MODE(packet)                                                           \(uint8_t)((packet.li_vn_mode & 0x07) >> 0) // (mode & 00 000 111) >> 0void error(const char *msg) {perror(msg); // Print the error message to stderr.exit(0);     // Quit the process.
}int main(int argc, char *argv[]) {if (argc != 2) {printf("%s [ ntp server]\n", argv[0]);return 0;}int sockfd, n; // Socket file descriptor and the n return result from// writing/reading from the socket.int portno = 123; // NTP UDP port number.const char *host_name = argv[1]; // NTP server host-name.std::cout << "NTP: " << host_name << std::endl;// Structure that defines the 48 byte NTP packet protocol.typedef struct {uint8_t li_vn_mode; // Eight bits. li, vn, and mode.// li.   Two bits.   Leap indicator.// vn.   Three bits. Version number of the protocol.// mode. Three bits. Client will pick mode 3 for client.uint8_t stratum; // Eight bits. Stratum level of the local clock.uint8_t poll; // Eight bits. Maximum interval between successive messages.uint8_t precision; // Eight bits. Precision of the local clock.uint32_t rootDelay; // 32 bits. Total round trip delay time.uint32_trootDispersion; // 32 bits. Max error aloud from primary clock source.uint32_t refId;     // 32 bits. Reference clock identifier.uint32_t refTm_s; // 32 bits. Reference time-stamp seconds.uint32_t refTm_f; // 32 bits. Reference time-stamp fraction of a second.uint32_t origTm_s; // 32 bits. Originate time-stamp seconds.uint32_t origTm_f; // 32 bits. Originate time-stamp fraction of a second.uint32_t rxTm_s; // 32 bits. Received time-stamp seconds.uint32_t rxTm_f; // 32 bits. Received time-stamp fraction of a second.uint32_t txTm_s; // 32 bits and the most important field the client cares// about. Transmit time-stamp seconds.uint32_t txTm_f; // 32 bits. Transmit time-stamp fraction of a second.} ntp_packet; // Total: 384 bits or 48 bytes.// Create and zero out the packet. All 48 bytes worth.ntp_packet packet = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};memset(&packet, 0, sizeof(ntp_packet));// Set the first byte's bits to 00,011,011 for li = 0, vn = 3, and mode = 3.// The rest will be left set to zero.*((char *)&packet + 0) =0x1b; // Represents 27 in base 10 or 00011011 in base 2.// Create a UDP socket, convert the host-name to an IP address, set the port// number, connect to the server, send the packet, and then read in the return// packet.struct sockaddr_in serv_addr; // Server address data structure.struct hostent *server;       // Server data structure.sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); // Create a UDP socket.if (sockfd < 0)error("ERROR opening socket");server = gethostbyname(host_name); // Convert URL to IP.if (server == NULL)error("ERROR, no such host");// Zero out the server address structure.bzero((char *)&serv_addr, sizeof(serv_addr));serv_addr.sin_family = AF_INET;// Copy the server's IP address to the server address structure.bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr,server->h_length);// Convert the port number integer to network big-endian style and save it to// the server address structure.serv_addr.sin_port = htons(portno);// Call up the server using its IP address and port number.if (connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)error("ERROR connecting");// Send it the NTP packet it wants. If n == -1, it failed.n = write(sockfd, (char *)&packet, sizeof(ntp_packet));if (n < 0)error("ERROR writing to socket");// Wait and receive the packet back from the server. If n == -1, it failed.n = read(sockfd, (char *)&packet, sizeof(ntp_packet));if (n < 0)error("ERROR reading from socket");// These two fields contain the time-stamp seconds as the packet left the NTP// server. The number of seconds correspond to the seconds passed since 1900.// ntohl() converts the bit/byte order from the network's to host's// "endianness".packet.txTm_s = ntohl(packet.txTm_s); // Time-stamp seconds.packet.txTm_f = ntohl(packet.txTm_f); // Time-stamp fraction of a second.// Extract the 32 bits that represent the time-stamp seconds (since NTP epoch)// from when the packet left the server. Subtract 70 years worth of seconds// from the seconds since 1900. This leaves the seconds since the UNIX epoch// of 1970.// (1900)------------------(1970)**************************************(Time// Packet Left the Server)time_t txTm = (time_t)(packet.txTm_s - NTP_TIMESTAMP_DELTA);// Print the time we got from the server, accounting for local timezone and// conversion from UTC time.struct timeval tv = {tv.tv_sec = txTm + 8 * 3600};settimeofday(&tv, NULL);txTm+=8*3600;std::cout << "date:" << ctime(&txTm) << std::endl;return 0;
}