ntp_packet.h

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/*
 * Copyright (C) 2016 Luminița Lăzărescu <cluminita.lazarescu@gmail.com>
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 */
 
#pragma once
 
#include <stdint.h>
#include "byteorder.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
#define NTP_PACKET_LI_POS    (6U)
#define NTP_PACKET_LI_MASK   (0xc0)     
#define NTP_PACKET_VN_POS    (3U)       
#define NTP_PACKET_VN_MASK   (0x38)     
#define NTP_PACKET_MODE_MASK (0x07)     
#define NTP_VERSION          (4U)       
#define NTP_PORT             (123U)     
#define NTP_UNIX_OFFSET      (2208988800)
 
typedef enum {
    NTP_MODE_RESERVED = 0,  
    NTP_MODE_SYM_ACTIVE,    
    NTP_MODE_SYM_PASSIVE,   
    NTP_MODE_CLIENT,        
    NTP_MODE_SERVER,        
    NTP_MODE_BROADCAST,     
    NTP_MODE_PRIV           
} ntp_mode_t;
 
typedef struct __attribute__((packed)) {
    network_uint32_t seconds;           
    network_uint32_t fraction;          
} ntp_timestamp_t;
 
typedef struct __attribute__((packed)) {
    uint8_t li_vn_mode;                 
    uint8_t stratum;                    
    uint8_t poll;                       
    uint8_t precision;                  
    network_uint32_t root_delay;        
    network_uint32_t root_dispersion;   
    network_uint32_t reference_id;      
    ntp_timestamp_t reference;          
    ntp_timestamp_t origin;             
    ntp_timestamp_t receive;            
    ntp_timestamp_t transmit;           
} ntp_packet_t;
 
static inline void ntp_packet_set_li(ntp_packet_t *packet, uint8_t li)
{
    packet->li_vn_mode &= ~NTP_PACKET_LI_MASK;
    packet->li_vn_mode |= li << NTP_PACKET_LI_POS;
}
 
static inline void ntp_packet_set_vn(ntp_packet_t *packet)
{
    packet->li_vn_mode &= ~NTP_PACKET_VN_MASK;
    packet->li_vn_mode |= (NTP_VERSION << NTP_PACKET_VN_POS) & NTP_PACKET_VN_MASK;
}
 
static inline void ntp_packet_set_mode(ntp_packet_t *packet, ntp_mode_t mode)
{
    packet->li_vn_mode &= ~NTP_PACKET_MODE_MASK;
    packet->li_vn_mode |= mode & NTP_PACKET_MODE_MASK;
}
 
static inline uint8_t ntp_packet_get_li(ntp_packet_t *packet)
{
    return (packet->li_vn_mode & NTP_PACKET_LI_MASK) >> NTP_PACKET_LI_POS;
}
 
static inline uint8_t ntp_packet_get_vn(ntp_packet_t *packet)
{
    return (packet->li_vn_mode & NTP_PACKET_VN_MASK) >> NTP_PACKET_VN_POS;
}
 
static inline ntp_mode_t ntp_packet_get_mode(ntp_packet_t *packet)
{
    return (packet->li_vn_mode & NTP_PACKET_MODE_MASK);
}
 
#ifdef __cplusplus
}
#endif