Enum ReferenceIdentifier 

pub enum ReferenceIdentifier {
    PrimarySource(PrimarySource),
    SecondaryOrClient([u8; 4]),
    KissOfDeath(KissOfDeath),
    Unknown([u8; 4]),
}

A 32-bit code identifying the particular server or reference clock.

The interpretation depends on the value in the stratum field:

• For packet stratum 0 (unspecified or invalid), this is a four-character ASCII [RFC1345] string, called the “kiss code”, used for debugging and monitoring purposes.
• For stratum 1 (reference clock), this is a four-octet, left-justified, zero-padded ASCII string assigned to the reference clock.

The authoritative list of Reference Identifiers is maintained by IANA; however, any string beginning with the ASCII character “X” is reserved for unregistered experimentation and development.

Variants

PrimarySource(PrimarySource)

Primary reference source (stratum 1) identifier.

SecondaryOrClient([u8; 4])

The reference identifier of the secondary or client server. Can be used to detect timing loops.

If using the IPv4 address family, the identifier is the four-octet IPv4 address.

If using the IPv6 address family, it is the first four octets of the MD5 hash of the IPv6 address. Note that when using the IPv6 address family on a NTPv4 server with a NTPv3 client, the Reference Identifier field appears to be a random value and a timing loop might not be detected.

KissOfDeath(KissOfDeath)

Kiss-o’-Death packet code (stratum 0).

Unknown([u8; 4])

An unrecognized 4-byte reference identifier.

Used for stratum 0 packets with non-standard kiss codes, stratum 1 packets with unrecognized reference source identifiers, and stratum 16+ (unsynchronized/reserved) packets.

Implementations

impl ReferenceIdentifier

pub fn from_bytes_with_stratum( bytes: [u8; 4], stratum: Stratum, ) -> ReferenceIdentifier

Parse a reference identifier from 4 bytes, using stratum for disambiguation.

The interpretation of the reference identifier depends on the stratum:

• Stratum 0: Kiss-o’-Death code
• Stratum 1: Primary source identifier
• Stratum 2-15: Secondary/client reference (IPv4 or IPv6 hash)
• Stratum 16+: Unknown

impl ReferenceIdentifier

pub fn as_bytes(&self) -> [u8; 4]

Returns the raw 4-byte representation of the reference identifier.

pub fn is_kiss_of_death(&self) -> bool

Returns true if this is a Kiss-o’-Death reference identifier.

pub fn from_ipv4(addr: Ipv4Addr) -> ReferenceIdentifier

Construct a reference identifier from an IPv4 address.

For stratum 2+ servers, the reference identifier is the upstream server’s IPv4 address (RFC 5905 Section 7.3).

pub fn from_ipv6(addr: Ipv6Addr) -> ReferenceIdentifier

Construct a reference identifier from an IPv6 address.

Per RFC 5905, the reference identifier for IPv6 peers is the first 4 bytes of MD5(IPv6_address).

Collision Risk

This 4-byte hash may coincidentally match an IPv4 address, causing false positive loop detection. draft-ietf-ntp-refid-updates-05 proposes a fix but is stalled. NTPv5’s 120-bit Bloom filter Reference IDs eliminate this problem entirely.

pub fn matches_ipv4(&self, addr: Ipv4Addr) -> bool

Check if this reference identifier matches an IPv4 address.

Used for loop detection: if the upstream server’s reference ID matches our own IPv4 address, a timing loop exists.

Trait Implementations

impl Clone for ReferenceIdentifier

fn clone(&self) -> ReferenceIdentifier

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl ConstPackedSizeBytes for ReferenceIdentifier

const PACKED_SIZE_BYTES: usize = 4

The constant size in bytes when this type is packed for network transmission.

impl Debug for ReferenceIdentifier

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for ReferenceIdentifier

fn default() -> ReferenceIdentifier

Defaults to Unknown([0; 4]) (unset reference identifier).

impl Hash for ReferenceIdentifier

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ReferenceIdentifier

fn eq(&self, other: &ReferenceIdentifier) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl ToBytes for ReferenceIdentifier

fn to_bytes(&self, buf: &mut [u8]) -> Result<usize, ParseError>

Write this value into the given byte slice. Returns the number of bytes written. Fails with ParseError::BufferTooShort if buf is too short.

impl WriteToBytes for ReferenceIdentifier

fn write_to_bytes<W>(&self, writer: W) -> Result<(), Error>

where W: WriteBytesExt,

Write the command to bytes.

impl Copy for ReferenceIdentifier

impl Eq for ReferenceIdentifier

impl StructuralPartialEq for ReferenceIdentifier