Implementation of the Serializer API of the coreSNTP library. More...

#include <string.h>
#include <stdbool.h>
#include <assert.h>
#include "core_sntp_serializer.h"
#include "core_sntp_config_defaults.h"

Data Structures
struct	SntpPacket_t
	Structure representing an SNTP packet header. For more information on SNTP packet format, refer to RFC 4330 Section 4. More...

Macros
#define	SNTP_VERSION ( 4U )
	The version of SNTP supported by the coreSNTP library by complying with the SNTPv4 specification defined in RFC 4330.

#define	SNTP_MODE_BITS_MASK ( 0x07U )
	The bit mask for the "Mode" information in the first byte of an SNTP packet. The "Mode" field occupies bits 0-2 of the byte.

#define	SNTP_MODE_CLIENT ( 3U )
	The value indicating a "client" in the "Mode" field of an SNTP packet.

#define	SNTP_MODE_SERVER ( 4U )
	The value indicating a "server" in the "Mode" field of an SNTP packet.

#define	SNTP_LEAP_INDICATOR_LSB_POSITION ( 6 )
	The position of the least significant bit of the "Leap Indicator" field in first byte of an SNTP packet. The "Leap Indicator" field occupies bits 6-7 of the byte.

#define	SNTP_KISS_OF_DEATH_STRATUM ( 0U )
	Value of Stratum field in SNTP packet representing a Kiss-o'-Death message from server.

#define	SNTP_VERSION_LSB_POSITION ( 3 )
	The position of least significant bit of the "Version" information in the first byte of an SNTP packet. "Version" field occupies bits 3-5 of the byte.

#define	KOD_CODE_DENY_UINT_VALUE ( 0x44454e59U )
	The integer value of the Kiss-o'-Death ASCII code, "DENY", used for comparison with data in an SNTP response.

#define	KOD_CODE_RSTR_UINT_VALUE ( 0x52535452U )
	The integer value of the Kiss-o'-Death ASCII code, "RSTR", used for comparison with data in an SNTP response.

#define	KOD_CODE_RATE_UINT_VALUE ( 0x52415445U )
	The integer value of the Kiss-o'-Death ASCII code, "RATE", used for comparison with data in an SNTP response.

#define	CLOCK_OFFSET_MAX_TIME_DIFFERENCE ( ( ( ( int64_t ) INT32_MAX + 1 ) * 1000 ) )
	Macro to represent exactly half of the total number of seconds in an NTP era. As 32 bits are used to represent the "seconds" part of an SNTP timestamp, the half of the total range of seconds in an NTP era is 2^31 seconds, which represents ~68 years.

#define	TOTAL_MILLISECONDS_IN_NTP_ERA ( ( ( int64_t ) UINT32_MAX + 1 ) * 1000 )
	Macro to represent the total number of milliseconds that are represented in an NTP era period. This macro represents a duration of ~136 years.

Functions
static void	fillWordMemoryInNetworkOrder (uint32_t *pWordMemory, uint32_t data)
	Utility macro to fill 32-bit integer in word-sized memory in network byte (or Big Endian) order.

static uint32_t	readWordFromNetworkByteOrderMemory (const uint32_t *ptr)
	Utility macro to generate a 32-bit integer from memory containing integer in network (or Big Endian) byte order.

static int64_t	absoluteOf (int64_t value)
	Utility to return absolute (or positively signed) value of an signed 64 bit integer.

static bool	isZeroTimestamp (const SntpTimestamp_t *pTime)
	Utility to determine whether a timestamp represents a zero timestamp value.

static uint32_t	fractionsToMs (uint32_t fractions)
	Utility to convert the "fractions" part of an SNTP timestamp to milliseconds duration of time.

static int64_t	safeTimeDifference (const SntpTimestamp_t pServerTime, const SntpTimestamp_t pClientTime)
	Utility to safely calculate difference between server and client timestamps and return the difference in the resolution of milliseconds as a signed 64 bit integer. The calculated value represents the effective subtraction as ( `serverTimeSec` - `clientTimeSec` ).

static void	calculateClockOffset (const SntpTimestamp_t pClientTxTime, const SntpTimestamp_t pServerRxTime, const SntpTimestamp_t pServerTxTime, const SntpTimestamp_t pClientRxTime, int64_t *pClockOffset)
	Utility to calculate clock offset of system relative to the server using the on-wire protocol specified in the NTPv4 specification. For more information on on-wire protocol, refer to RFC 5905 Section 8.

static SntpStatus_t	parseValidSntpResponse (const SntpPacket_t pResponsePacket, const SntpTimestamp_t pRequestTxTime, const SntpTimestamp_t pResponseRxTime, SntpResponseData_t pParsedResponse)
	Parse a SNTP response packet by determining whether it is a rejected or accepted response to an SNTP request, and accordingly, populate the `pParsedResponse` parameter with the parsed data.

SntpStatus_t	Sntp_SerializeRequest (SntpTimestamp_t pRequestTime, uint32_t randomNumber, void pBuffer, size_t bufferSize)
	Serializes an SNTP request packet to use for querying a time server.

SntpStatus_t	Sntp_DeserializeResponse (const SntpTimestamp_t pRequestTime, const SntpTimestamp_t pResponseRxTime, const void pResponseBuffer, size_t bufferSize, SntpResponseData_t pParsedResponse)
	De-serializes an SNTP packet received from a server as a response to a SNTP request.

SntpStatus_t	Sntp_CalculatePollInterval (uint16_t clockFreqTolerance, uint16_t desiredAccuracy, uint32_t *pPollInterval)
	Utility to calculate the poll interval of sending periodic time queries to servers to achieve a desired system clock accuracy for a given frequency tolerance of the system clock.

SntpStatus_t	Sntp_ConvertToUnixTime (const SntpTimestamp_t pSntpTime, uint32_t pUnixTimeSecs, uint32_t *pUnixTimeMicrosecs)
	Utility to convert SNTP timestamp (that uses 1st Jan 1900 as the epoch) to UNIX timestamp (that uses 1st Jan 1970 as the epoch).

Detailed Description

Implementation of the Serializer API of the coreSNTP library.

Macro Definition Documentation

◆ SNTP_MODE_BITS_MASK

#define SNTP_MODE_BITS_MASK ( 0x07U )

The bit mask for the "Mode" information in the first byte of an SNTP packet. The "Mode" field occupies bits 0-2 of the byte.

Note: Refer to the RFC 4330 Section 4 for more information.

◆ SNTP_MODE_CLIENT

#define SNTP_MODE_CLIENT ( 3U )

The value indicating a "client" in the "Mode" field of an SNTP packet.

Note: Refer to the RFC 4330 Section 4 for more information.

◆ SNTP_MODE_SERVER

#define SNTP_MODE_SERVER ( 4U )

The value indicating a "server" in the "Mode" field of an SNTP packet.

Note: Refer to the RFC 4330 Section 4 for more information.

◆ SNTP_LEAP_INDICATOR_LSB_POSITION

#define SNTP_LEAP_INDICATOR_LSB_POSITION ( 6 )

The position of the least significant bit of the "Leap Indicator" field in first byte of an SNTP packet. The "Leap Indicator" field occupies bits 6-7 of the byte.

Note: Refer to the RFC 4330 Section 4 for more information.

◆ SNTP_VERSION_LSB_POSITION

#define SNTP_VERSION_LSB_POSITION ( 3 )

The position of least significant bit of the "Version" information in the first byte of an SNTP packet. "Version" field occupies bits 3-5 of the byte.

Note: Refer to the RFC 4330 Section 4 for more information.

◆ KOD_CODE_DENY_UINT_VALUE

#define KOD_CODE_DENY_UINT_VALUE ( 0x44454e59U )

The integer value of the Kiss-o'-Death ASCII code, "DENY", used for comparison with data in an SNTP response.

Note: Refer to RFC 4330 Section 8 for more information.

◆ KOD_CODE_RSTR_UINT_VALUE

#define KOD_CODE_RSTR_UINT_VALUE ( 0x52535452U )

The integer value of the Kiss-o'-Death ASCII code, "RSTR", used for comparison with data in an SNTP response.

Note: Refer to RFC 4330 Section 8 for more information.

◆ KOD_CODE_RATE_UINT_VALUE

#define KOD_CODE_RATE_UINT_VALUE ( 0x52415445U )

The integer value of the Kiss-o'-Death ASCII code, "RATE", used for comparison with data in an SNTP response.

Note: Refer to RFC 4330 Section 8 for more information.

◆ CLOCK_OFFSET_MAX_TIME_DIFFERENCE

#define CLOCK_OFFSET_MAX_TIME_DIFFERENCE ( ( ( ( int64_t ) INT32_MAX + 1 ) * 1000 ) )

Macro to represent exactly half of the total number of seconds in an NTP era. As 32 bits are used to represent the "seconds" part of an SNTP timestamp, the half of the total range of seconds in an NTP era is 2^31 seconds, which represents ~68 years.

Note: This macro represents the edge case of calculating the client system clock-offset relative to server time as the library ASSUMES that the client and server times are within 2^31 seconds apart in duration. This is done to support calculating clock-offset for the cases when server and client systems are in adjacent NTP eras, which can occur when NTP time wraps around in 2036, and the relative NTP era presence of client and server times is determined based on comparing first order difference values between all possible NTP era configurations of the systems.

◆ TOTAL_MILLISECONDS_IN_NTP_ERA

#define TOTAL_MILLISECONDS_IN_NTP_ERA ( ( ( int64_t ) UINT32_MAX + 1 ) * 1000 )

Macro to represent the total number of milliseconds that are represented in an NTP era period. This macro represents a duration of ~136 years.

Note: Rationale for calculation: The "seconds" part of an NTP timestamp is represented in unsigned 32 bit width, thus, the total range of seconds it represents is 2^32, i.e. (UINT32_MAX + 1).

Function Documentation

◆ fillWordMemoryInNetworkOrder()

static void fillWordMemoryInNetworkOrder	(	uint32_t *	pWordMemory,
		uint32_t	data
	)

static

Utility macro to fill 32-bit integer in word-sized memory in network byte (or Big Endian) order.

Parameters

[out]	pWordMemory	Pointer to the word-sized memory in which the 32-bit integer will be filled.
[in]	data	The 32-bit integer to fill in the `wordMemory` in network byte order.

Note: This utility ensures that data is filled in memory in expected network byte order, as an assignment operation (like *pWordMemory = word) can cause undesired side-effect of network-byte ordering getting reversed on Little Endian platforms.

◆ readWordFromNetworkByteOrderMemory()

static uint32_t readWordFromNetworkByteOrderMemory ( const uint32_t * ptr )

static

Utility macro to generate a 32-bit integer from memory containing integer in network (or Big Endian) byte order.

Parameters

[in] ptr Pointer to the memory containing 32-bit integer in network byte order.

Returns: The host representation of the 32-bit integer in the passed word memory.

◆ absoluteOf()

static int64_t absoluteOf ( int64_t value )

static

Utility to return absolute (or positively signed) value of an signed 64 bit integer.

Parameters

[in] value The integer to return the absolute value of.

Returns: The absolute value of value.

◆ isZeroTimestamp()

static bool isZeroTimestamp ( const SntpTimestamp_t * pTime )

static

Utility to determine whether a timestamp represents a zero timestamp value.

Note: This utility is used to determine whether a timestamp value is invalid. According to the SNTPv4 specification, a zero timestamp value is considered invalid.

Parameters

[in] pTime The timestamp whose value is to be inspected for zero value.

Returns: true if the timestamp is zero; otherwise false.

◆ fractionsToMs()

static uint32_t fractionsToMs ( uint32_t fractions )

static

Utility to convert the "fractions" part of an SNTP timestamp to milliseconds duration of time.

Parameters

[in] fractions The fractions value.

Returns: The milliseconds equivalent of the fractions value.

◆ safeTimeDifference()

static int64_t safeTimeDifference	(	const SntpTimestamp_t *	pServerTime,
		const SntpTimestamp_t *	pClientTime
	)

static

Utility to safely calculate difference between server and client timestamps and return the difference in the resolution of milliseconds as a signed 64 bit integer. The calculated value represents the effective subtraction as ( serverTimeSec - clientTimeSec ).

Note

This utility SUPPORTS the cases of server and client timestamps being in different NTP eras, and ASSUMES that the server and client systems are within 68 years of each other. To handle the case of different NTP eras, this function calculates difference values for all possible combinations of NTP eras of server and client times (i.e. 1. both timestamps in same era,

server timestamp one era ahead, and 3. client timestamp being one era ahead), and determines the NTP era configuration by choosing the difference value of the smallest absolute value.

Parameters

[in]	pServerTime	The server timestamp.
[in]	pClientTime	The client timestamp.

Returns: The calculated difference between server and client times as a signed 64 bit integer.

◆ calculateClockOffset()

static void calculateClockOffset	(	const SntpTimestamp_t *	pClientTxTime,
		const SntpTimestamp_t *	pServerRxTime,
		const SntpTimestamp_t *	pServerTxTime,
		const SntpTimestamp_t *	pClientRxTime,
		int64_t *	pClockOffset
	)

static

Utility to calculate clock offset of system relative to the server using the on-wire protocol specified in the NTPv4 specification. For more information on on-wire protocol, refer to RFC 5905 Section 8.

Note

The following diagram explains the calculation of the clock offset:

            T2      T3
 ---------------------------------   <-----   *SNTP/NTP server*
          /\         \
          /           \
Request* /             \ *Response*
        /              \/
 ---------------------------------   <-----   *SNTP client*
      T1                T4

The four most recent timestamps, T1 through T4, are used to compute the clock offset of SNTP client relative to the server where:

T1 = Client Request Transmit Time T2 = Server Receive Time (of client request) T3 = Server Response Transmit Time T4 = Client Receive Time (of server response)

Clock Offset = T(NTP/SNTP server) - T(SNTP client)

= [( T2 - T1 ) + ( T3 - T4 )]

2

Note: Both NTPv4 and SNTPv4 specifications suggest calculating the clock offset value, if possible. As the timestamp format uses 64 bit integer and there exist 2 orders of arithmetic calculations on the timestamp values (subtraction followed by addition as shown in the diagram above), the clock offset for the system can be calculated ONLY if the value can be represented in 62 significant bits and 2 sign bits i.e. if the system clock is within 34 years (in the future or past) of the server time.

Parameters

[in]	pClientTxTime	The system time of sending the SNTP request. This is the same as "T1" in the above diagram.
[in]	pServerRxTime	The server time of receiving the SNTP request packet from the client. This is the same as "T2" in the above diagram.
[in]	pServerTxTime	The server time of sending the SNTP response packet. This is the same as "T3" in the above diagram.
[in]	pClientRxTime	The system time of receiving the SNTP response from the server. This is the same as "T4" in the above diagram.
[out]	pClockOffset	This will be filled with the calculated offset value of the system clock relative to the server time with the assumption that the system clock is within 68 years of server time.

◆ parseValidSntpResponse()

static SntpStatus_t parseValidSntpResponse	(	const SntpPacket_t *	pResponsePacket,
		const SntpTimestamp_t *	pRequestTxTime,
		const SntpTimestamp_t *	pResponseRxTime,
		SntpResponseData_t *	pParsedResponse
	)

static

Parse a SNTP response packet by determining whether it is a rejected or accepted response to an SNTP request, and accordingly, populate the pParsedResponse parameter with the parsed data.

Note: If the server has rejected the request with the a Kiss-o'-Death message, then this function will set the associated rejection code in the output parameter while setting the remaining members to zero. If the server has accepted the time request, then the function will set the rejectedResponseCode member of the output parameter to SNTP_KISS_OF_DEATH_CODE_NONE, and set the other the members with appropriate data extracted from the response packet.

Parameters

[in]	pResponsePacket	The SNTP response packet from server to parse.
[in]	pRequestTxTime	The system time (in SNTP timestamp format) of sending the SNTP request to server.
[in]	pResponseRxTime	The system time (in SNTP timestamp format) of receiving the SNTP response from server.
[out]	pParsedResponse	The parameter that will be populated with data parsed from the response packet, `pResponsePacket`.

Returns

This function returns one of the following:

SntpSuccess if the server response does not represent a Kiss-o'-Death message.
SntpRejectedResponseChangeServer if the server rejected with a code indicating that client cannot be retry requests to it.
SntpRejectedResponseRetryWithBackoff if the server rejected with a code indicating that client should back-off before retrying request.
SntpRejectedResponseOtherCode if the server rejected with a code other than "DENY", "RSTR" and "RATE".

◆ Sntp_SerializeRequest()

SntpStatus_t Sntp_SerializeRequest	(	SntpTimestamp_t *	pRequestTime,
		uint32_t	randomNumber,
		void *	pBuffer,
		size_t	bufferSize
	)

Serializes an SNTP request packet to use for querying a time server.

This function will fill only SNTP_PACKET_BASE_SIZE bytes of data in the passed buffer.

Parameters

[in,out]	pRequestTime	The current time of the system, expressed as time since the SNTP epoch (i.e. 0h of 1st Jan 1900 ). This time will be serialized in the SNTP request packet. The function will use this parameter to return the timestamp serialized in the SNTP request. To protect against attacks spoofing server responses, the timestamp MUST NOT be zero in value.
[in]	randomNumber	A random number (generated by a True Random Generator) for use in the SNTP request packet to protect against replay attacks as suggested by SNTPv4 specification. For more information, refer to RFC 4330 Section 3.
[out]	pBuffer	The buffer that will be populated with the serialized SNTP request packet.
[in]	bufferSize	The size of the `pBuffer` buffer. It should be at least SNTP_PACKET_BASE_SIZE bytes in size.

Note: It is recommended to use a True Random Generator (TRNG) to generate the random number.; The application MUST save the pRequestTime value for de-serializing the server response with Sntp_DeserializeResponse API.

Returns

This function returns one of the following:

SntpSuccess when serialization operation is successful.
SntpErrorBadParameter if an invalid parameter is passed.
SntpErrorBufferTooSmall if the buffer does not have the minimum size for serializing an SNTP request packet.

◆ Sntp_DeserializeResponse()

SntpStatus_t Sntp_DeserializeResponse	(	const SntpTimestamp_t *	pRequestTime,
		const SntpTimestamp_t *	pResponseRxTime,
		const void *	pResponseBuffer,
		size_t	bufferSize,
		SntpResponseData_t *	pParsedResponse
	)

De-serializes an SNTP packet received from a server as a response to a SNTP request.

This function will parse only the SNTP_PACKET_BASE_SIZE bytes of data in the passed buffer.

Note: If the server has sent a Kiss-o'-Death message to reject the associated time request, the API function will return the appropriate return code and, also, provide the ASCII code (of fixed length, SNTP_KISS_OF_DEATH_CODE_LENGTH bytes) in the SntpResponseData_t.rejectedResponseCode member of pParsedResponse parameter, parsed from the response packet. The application SHOULD respect the server rejection and take appropriate action based on the rejection code. If the server response represents an accepted SNTP client request, then the API function will set the SntpResponseData_t.rejectedResponseCode member of pParsedResponse parameter to SNTP_KISS_OF_DEATH_CODE_NONE.; If the server has positively responded with its clock time, then this API function will calculate the clock-offset. For the clock-offset to be correctly calculated, the system clock MUST be within ~68 years (or 2^31 seconds) of the server time mentioned. This function supports clock-offset calculation when server and client timestamps are in adjacent NTP eras, with one system is in NTP era 0 (i.e. before 7 Feb 2036 6h:28m:14s UTC) and another system in NTP era 1 (on or after 7 Feb 2036 6h:28m:14s UTC).; In the special case when the server and client times are exactly 2^31 seconds apart, the library ASSUMES that the server time is ahead of the client time, and returns the positive clock-offset value of INT32_MAX seconds.

Parameters

[in]	pRequestTime	The system time used in the SNTP request packet that is associated with the server response. This MUST be the same as the time returned by the Sntp_SerializeRequest API. To protect against attacks spoofing server responses, this timestamp MUST NOT be zero in value.
[in]	pResponseRxTime	The time of the system, expressed as time since the SNTP epoch (i.e. 0h of 1st Jan 1900 ), at receiving SNTP response from server. This time will be used to calculate system clock offset relative to server.
[in]	pResponseBuffer	The buffer containing the SNTP response from the server.
[in]	bufferSize	The size of the `pResponseBuffer` containing the SNTP response. It MUST be at least SNTP_PACKET_BASE_SIZE bytes long for a valid SNTP response.
[out]	pParsedResponse	The information parsed from the SNTP response packet. If possible to calculate without overflow, it also contains the system clock offset relative to the server time.

Returns

This function returns one of the following:

SntpSuccess if the de-serialization operation is successful.
SntpErrorBadParameter if an invalid parameter is passed.
SntpErrorBufferTooSmall if the buffer does not have the minimum size required for a valid SNTP response packet.
SntpInvalidResponse if the response fails sanity checks expected in an SNTP response.
SntpRejectedResponseChangeServer if the server rejected with a code indicating that client cannot be retry requests to it.
SntpRejectedResponseRetryWithBackoff if the server rejected with a code indicating that client should back-off before retrying request.
SntpRejectedResponseOtherCode if the server rejected with a code that application can inspect in the pParsedResponse parameter.

◆ Sntp_CalculatePollInterval()

SntpStatus_t Sntp_CalculatePollInterval	(	uint16_t	clockFreqTolerance,
		uint16_t	desiredAccuracy,
		uint32_t *	pPollInterval
	)

Utility to calculate the poll interval of sending periodic time queries to servers to achieve a desired system clock accuracy for a given frequency tolerance of the system clock.

For example, from the SNTPv4 specification, "if the frequency tolerance is 200 parts per million (PPM) and the required accuracy is one minute, the maximum timeout is about 3.5 days". In this example, the system clock frequency tolerance is 200 PPM and the desired accuracy is 60000 milliseconds (or 1 minute) for which this API function will return the maximum poll interval value as 2^18 seconds (or ~3 days).

Note: The poll interval returned is a power of 2, which is the standard way to represent the value. According to the SNTPv4 specification Best Practices, an SNTP client SHOULD NOT have a poll interval less than 15 seconds. https://tools.ietf.org/html/rfc4330#section-10. This API function DOES NOT support poll interval calculation less than 1 second.

Parameters

[in]	clockFreqTolerance	The frequency tolerance of system clock in parts per million (PPM) units. This parameter MUST be non-zero.
[in]	desiredAccuracy	The acceptable maximum drift, in milliseconds, for the system clock. The maximum value (0xFFFF) represents ~1 minute of desired clock accuracy. This parameter MUST be non-zero.
[out]	pPollInterval	This is filled with the poll interval, in seconds calculated as the closest power of 2 value that will achieve either the exact desired or higher clock accuracy `desiredAccuracy`, for the given clock frequency tolerance, `clockFreqTolerance`.

Returns

Returns one of the following:

SntpSuccess if calculation is successful.
SntpErrorBadParameter for an invalid parameter passed to the function.
SntpZeroPollInterval if calculated poll interval is less than 1 second.

◆ Sntp_ConvertToUnixTime()

SntpStatus_t Sntp_ConvertToUnixTime	(	const SntpTimestamp_t *	pSntpTime,
		uint32_t *	pUnixTimeSecs,
		uint32_t *	pUnixTimeMicrosecs
	)

Utility to convert SNTP timestamp (that uses 1st Jan 1900 as the epoch) to UNIX timestamp (that uses 1st Jan 1970 as the epoch).

Note: This function can ONLY handle conversions of SNTP timestamps that lie in the range from 1st Jan 1970 0h 0m 0s, the UNIX epoch time, to 19th Jan 2038 3h 14m 7s, the maximum UNIX time that can be represented in a signed 32 bit integer. (The limitation is to support systems that use signed 32-bit integer to represent the seconds part of the UNIX time.); This function supports overflow of the SNTP timestamp (from the 7 Feb 2036 6h 28m 16s time, i.e. SNTP era 1) by treating the timestamps with seconds part in the range [0, 61,505,152] seconds where the upper limit represents the UNIX overflow time (i.e. 19 Jan 2038 3h 14m 7s) for systems that use signed 32-bit integer to represent time.

Parameters

[in]	pSntpTime	The SNTP timestamp to convert to UNIX time.
[out]	pUnixTimeSecs	This will be filled with the seconds part of the UNIX time equivalent of the SNTP time, `pSntpTime`.
[out]	pUnixTimeMicrosecs	This will be filled with the microseconds part of the UNIX time equivalent of the SNTP time, `pSntpTime`.

Returns

Returns one of the following:

SntpSuccess if conversion to UNIX time is successful
SntpErrorBadParameter if any of the passed parameters are NULL.
SntpErrorTimeNotSupported if the passed SNTP time does not lie in the supported time range.

Data Structures

Macros

Functions

Detailed Description

Macro Definition Documentation

◆ SNTP_MODE_BITS_MASK

◆ SNTP_MODE_CLIENT

◆ SNTP_MODE_SERVER

◆ SNTP_LEAP_INDICATOR_LSB_POSITION

◆ SNTP_VERSION_LSB_POSITION

◆ KOD_CODE_DENY_UINT_VALUE

◆ KOD_CODE_RSTR_UINT_VALUE

◆ KOD_CODE_RATE_UINT_VALUE

◆ CLOCK_OFFSET_MAX_TIME_DIFFERENCE

◆ TOTAL_MILLISECONDS_IN_NTP_ERA

Function Documentation

◆ fillWordMemoryInNetworkOrder()

◆ readWordFromNetworkByteOrderMemory()

◆ absoluteOf()

◆ isZeroTimestamp()

◆ fractionsToMs()

◆ safeTimeDifference()

◆ calculateClockOffset()

= [( T2 - T1 ) + ( T3 - T4 )]

◆ parseValidSntpResponse()

◆ Sntp_SerializeRequest()

◆ Sntp_DeserializeResponse()

◆ Sntp_CalculatePollInterval()

◆ Sntp_ConvertToUnixTime()