ntp

type AuthOptions struct {
	// Type determines the cryptographic hash algorithm used to compute the
	// authentication digest or CMAC.
	Type AuthType

	// The cryptographic key used by the client to perform authentication. The
	// key may be hex-encoded or ascii-encoded. To use a hex-encoded key,
	// prefix it by "HEX:". To use an ascii-encoded key, prefix it by
	// "ASCII:". For example, "HEX:6931564b4a5a5045766c55356b30656c7666316c"
	// or "ASCII:cvuZyN4C8HX8hNcAWDWp".
	Key string

	// The identifier used by the NTP server to identify which key to use
	// for authentication purposes.
	KeyID uint16
}

type AuthType int

type Extension interface {
	// ProcessQuery is called when the client is about to send a query to the
	// NTP server. The buffer contains the NTP header. It may also contain
	// extension fields added by extensions processed prior to this one.
	ProcessQuery(buf *bytes.Buffer) error

	// ProcessResponse is called after the client has received the server's
	// NTP response. The buffer contains the entire message returned by the
	// server.
	ProcessResponse(buf []byte) error
}

type LeapIndicator uint8

type QueryOptions struct {
	// Timeout determines how long the client waits for a response from the
	// server before failing with a timeout error. Defaults to 5 seconds.
	Timeout time.Duration

	// Version of the NTP protocol to use. Defaults to 4.
	Version int

	// LocalAddress contains the local IP address to use when creating a
	// connection to the remote NTP server. This may be useful when the local
	// system has more than one IP address. This address should not contain
	// a port number.
	LocalAddress string

	// TTL specifies the maximum number of IP hops before the query datagram
	// is dropped by the network. Defaults to the local system's default value.
	TTL int

	// Auth contains the settings used to configure NTP symmetric key
	// authentication. See RFC 5905 for further details.
	Auth AuthOptions

	// Extensions may be added to modify NTP queries before they are
	// transmitted and to process NTP responses after they arrive.
	Extensions []Extension

	// Dialer is a callback used to override the default UDP network dialer.
	// The localAddress is directly copied from the LocalAddress field
	// specified in QueryOptions. It may be the empty string or a host address
	// (without port number). The remoteAddress is the "host:port" string
	// derived from the first parameter to QueryWithOptions.  The
	// remoteAddress is guaranteed to include a port number.
	Dialer func(localAddress, remoteAddress string) (net.Conn, error)

	// Dial is a callback used to override the default UDP network dialer.
	//
	// DEPRECATED. Use Dialer instead.
	Dial func(laddr string, lport int, raddr string, rport int) (net.Conn, error)

	// Port indicates the port used to reach the remote NTP server.
	//
	// DEPRECATED. Embed the port number in the query address string instead.
	Port int
}

type Response struct {
	// Time is the transmit time reported by the server just before it
	// responded to the client's NTP query. You should not use this value
	// for time synchronization purposes. Use the ClockOffset instead.
	Time time.Time

	// ClockOffset is the estimated offset of the local system clock relative
	// to the server's clock. Add this value to subsequent local system time
	// measurements in order to obtain a more accurate time.
	ClockOffset time.Duration

	// RTT is the measured round-trip-time delay estimate between the client
	// and the server.
	RTT time.Duration

	// Precision is the reported precision of the server's clock.
	Precision time.Duration

	// Stratum is the "stratum level" of the server. The smaller the number,
	// the closer the server is to the reference clock. Stratum 1 servers are
	// attached directly to the reference clock. A stratum value of 0
	// indicates the "kiss of death," which typically occurs when the client
	// issues too many requests to the server in a short period of time.
	Stratum uint8

	// ReferenceID is a 32-bit integer identifying the server or reference
	// clock. For stratum 1 servers, this is typically a meaningful
	// zero-padded ASCII-encoded string assigned to the clock. For stratum 2+
	// servers, this is a reference identifier for the server and is either
	// the server's IPv4 address or a hash of its IPv6 address. For
	// kiss-of-death responses (stratum 0), this is the ASCII-encoded "kiss
	// code".
	ReferenceID uint32

	// ReferenceTime is the time when the server's system clock was last
	// set or corrected.
	ReferenceTime time.Time

	// RootDelay is the server's estimated aggregate round-trip-time delay to
	// the stratum 1 server.
	RootDelay time.Duration

	// RootDispersion is the server's estimated maximum measurement error
	// relative to the stratum 1 server.
	RootDispersion time.Duration

	// RootDistance is an estimate of the total synchronization distance
	// between the client and the stratum 1 server.
	RootDistance time.Duration

	// Leap indicates whether a leap second should be added or removed from
	// the current month's last minute.
	Leap LeapIndicator

	// MinError is a lower bound on the error between the client and server
	// clocks. When the client and server are not synchronized to the same
	// clock, the reported timestamps may appear to violate the principle of
	// causality. In other words, the NTP server's response may indicate
	// that a message was received before it was sent. In such cases, the
	// minimum error may be useful.
	MinError time.Duration

	// KissCode is a 4-character string describing the reason for a
	// "kiss of death" response (stratum=0). For a list of standard kiss
	// codes, see https://tools.ietf.org/html/rfc5905#section-7.4.
	KissCode string

	// Poll is the maximum interval between successive NTP query messages to
	// the server.
	Poll time.Duration
	// contains filtered or unexported fields
}