SmartPDCode/ip/src/ntpclient.c

#include "ntpclient.h"
  
#define NTP_PORT 123  
#define NTP_PACKET_SIZE 48  
  
// 发送NTP请求  
static int sendNTPRequest(NTPClient* client) {  
    client->ntp_packet[0] = 0x1B; // LI = 0, VN = 3, Mode = 3 (client)  
    ssize_t sentBytes = sendto(client->sockfd, client->ntp_packet, NTP_PACKET_SIZE, 0,  
                               (struct sockaddr *)&client->server_addr, sizeof(client->server_addr));  
    if (sentBytes < 0) {  
        perror("sendto failed");  
        return -1;  
    }  
    return 0;  
}  
  
// 接收NTP响应  
static int receiveNTPResponse(NTPClient* client) {  
    socklen_t len = sizeof(client->server_addr);  
    ssize_t receivedBytes = recvfrom(client->sockfd, client->ntp_packet, NTP_PACKET_SIZE, 0,  
                              (struct sockaddr *)&client->server_addr, &len);  
    if (receivedBytes < 0) {  
        perror("recvfrom failed");  
        return -1;  
    }  
    return 0;  
}  
  
// 解析NTP响应中的时间  
static time_t parseNTPResponse(const char* ntp_packet) {  
    unsigned int sec_since_1900 = ntohl(((unsigned int *)ntp_packet)[10]);  
    unsigned int frac_sec = ntohl(((unsigned int *)ntp_packet)[11]);  
    double frac = frac_sec * 2.0e-32;  
    return (time_t)(sec_since_1900 - 2208988800U) + (time_t)frac;  
}  
  
// 创建NTP客户端实例  
NTPClient* createNTPClient(const char* ntp_server, int port) {  
    NTPClient* client = (NTPClient*)malloc(sizeof(NTPClient));  
    if (!client) {  
        perror("malloc failed");  
        return NULL;  
    }  
  
    // 创建UDP套接字  
    if ((client->sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {  
        perror("socket creation failed");  
        free(client);  
        return NULL;  
    }  
  
    // 设置NTP服务器地址  
    memset(&client->server_addr, 0, sizeof(client->server_addr));  
    client->server_addr.sin_family = AF_INET;  
    client->server_addr.sin_port = htons(port);  
    if (inet_aton(ntp_server, &client->server_addr.sin_addr) == 0) {  
        fprintf(stderr, "Invalid address/Address not supported\n");  
        close(client->sockfd);  
        free(client);  
        return NULL;  
    }  
  
    return client;  
}  
  
// 销毁NTP客户端实例  
void destroyNTPClient(NTPClient* client) {  
    if (client) {  
        close(client->sockfd);  
        free(client);  
    }  
}  
  
// 从NTP服务器获取当前时间  
int getCurrentTimeFromNTP(NTPClient* client, time_t* current_time) {  
    if (sendNTPRequest(client) < 0) {  
        return -1;  
    }  
  
    if (receiveNTPResponse(client) < 0) {  
        return -1;  
    }  
  
    *current_time = parseNTPResponse(client->ntp_packet);  
    return 0;  
}  
  
  
// 根据时间获取星期信息
int getCurrentWeekday(time_t  current_time,char *weekday) {  
    struct tm * timeinfo;  
    timeinfo = localtime(&current_time);  
    if (timeinfo == NULL) {  
        return -1;  
    }  
    
    // 格式化星期几  
    strftime(weekday, 20, "%A", timeinfo); // %A 代表完整的星期名，例如：Sunday 
    
    return 0;
}