Reorganize errors

Author: beevik

auth_test.go

@@ -118,8 +118,8 @@ func TestOnlineAuthenticatedQuery(t *testing.T) {
 			}
 			r, err := QueryWithOptions(host, opt)
 			if c.ExpectedErr == errAuthFail {
-				// With old NTP servers, failed authentication leads to Crypto-NAK
-				// (ErrAuthFailed). With modern NTP servers, it leads to an I/O
+				// With old NTP servers, failed authentication leads to
+				// Crypto-NAK. With modern NTP servers, it leads to an I/O
 				// timeout error.
 				if err != ErrAuthFailed && !strings.Contains(err.Error(), "timeout") {
 					t.Errorf("case %d: expected error [%v], got error [%v]\n", i, c.ExpectedErr, err)

ntp.go

@@ -25,26 +25,22 @@ import (
 )
 
 var (
-	ErrAuthFailed                = errors.New("authentication failed")
-	ErrAuthNAK                   = errors.New("authentication NAK received")
-	ErrExtensionsNotSupported    = errors.New("NTPV3 does not support extension fields")
-	ErrInvalidAuthKey            = errors.New("invalid authentication key")
-	ErrInvalidDispersion         = errors.New("invalid dispersion in response")
-	ErrInvalidDraftID            = errors.New("invalid draft ID value in response")
-	ErrInvalidExtensionField     = errors.New("invalid extension field in response")
-	ErrInvalidLeapSecond         = errors.New("invalid leap second in response")
-	ErrInvalidMode               = errors.New("invalid mode in response")
-	ErrInvalidProtocolVersion    = errors.New("invalid protocol version requested")
-	ErrInvalidReferenceRequest   = errors.New("invalid reference ID request")
-	ErrInvalidStratum            = errors.New("invalid stratum in response")
-	ErrInvalidTime               = errors.New("invalid time reported")
-	ErrInvalidTransmitTime       = errors.New("invalid transmit time in response")
-	ErrKissOfDeath               = errors.New("kiss of death received")
-	ErrServerClockFreshness      = errors.New("server clock not fresh")
-	ErrServerNotSynchronized     = errors.New("NTPv5 server not synchronized")
-	ErrServerResponseMismatch    = errors.New("server response didn't match request")
-	ErrServerTickedBackwards     = errors.New("server clock ticked backwards")
-	ErrUnexpectedCorrectionField = errors.New("unexpected correction extension field in response")
+	ErrAuthFailed             = errors.New("authentication MAC verification failed")
+	ErrAuthNAK                = errors.New("authentication NAK received")
+	ErrExtensionsNotSupported = errors.New("NTPV3 does not support extension fields")
+	ErrInvalidAuthKey         = errors.New("invalid authentication key")
+	ErrInvalidDispersion      = errors.New("invalid dispersion in response")
+	ErrInvalidLeapSecond      = errors.New("invalid leap second in response")
+	ErrInvalidMode            = errors.New("invalid mode in response")
+	ErrInvalidProtocolVersion = errors.New("invalid protocol version requested")
+	ErrInvalidStratum         = errors.New("invalid stratum in response")
+	ErrInvalidTime            = errors.New("invalid time reported")
+	ErrInvalidTransmitTime    = errors.New("invalid transmit time in response")
+	ErrKissOfDeath            = errors.New("kiss of death received")
+	ErrServerClockFreshness   = errors.New("server clock not fresh")
+	ErrServerNotSynchronized  = errors.New("NTPv5 server not synchronized")
+	ErrServerResponseMismatch = errors.New("server response didn't match request")
+	ErrServerTickedBackwards  = errors.New("server clock ticked backwards")
 )
 
 // Internal constants
@@ -147,6 +143,10 @@ type QueryOptions struct {
 	// NTPv5.
 	AdditionalTimescales []Timescale
 
+	// ServerCookie contains the server cookie returned by a prior server
+	// response when operating in interleaved mode. Used only in NTPv5.
+	ServerCookie uint64
+
 	// Auth contains the options used to configure symmetric key
 	// authentication. See RFC 5905 for further details. For NTPv3 and NTPv4,
 	// this results in a MAC or digest being appended to the end of the NTP
@@ -155,22 +155,23 @@ type QueryOptions struct {
 	// authentication.
 	Auth AuthOptions
 
-	// Extensions may be added in order to (a) modify NTP queries before they
-	// are transmitted and (b) process NTP responses after they arrive. When
-	// building an NTP request, extensions are processed in the order listed.
-	// When processing a server response, extensions are processed in reverse
-	// order.
+	// Extensions may be provided in order to (a) modify NTP queries before
+	// they are transmitted and (b) process NTP responses after they arrive.
+	// When building an NTP request, these extensions are processed in the
+	// order listed. When processing a server response, they are processed in
+	// reverse order. An example of an extension is one that implements
+	// Network Time Security (NTS). See: https://github.com/beevik/nts.
 	Extensions []Extension
 
 	// GetSystemTime is a callback used to override the default method of
 	// obtaining the local system time during time synchronization. If not
 	// specified, time.Now is used.
 	GetSystemTime func() time.Time
 
-	// ReferenceIDRequest is an optional field used to request NTPv5 reference
-	// ID bloom filter values. The filter values are returned in the Response
-	// struct's ReferenceIDFilterValues field. Used only in NTPv5.
-	ReferenceIDRequest ReferenceIDRequest
+	// RequestReferenceID is a struct used to request reference ID bloom
+	// filter values, which are returned in the ReferenceIDFilterValues field
+	// of the response. Used only in NTPv5.
+	RequestReferenceID ReferenceIDRequest
 
 	// RequestSupportedVersions indicates whether to request which versions of
 	// the NTP protocol are supported by the server in its response. Used only
@@ -199,10 +200,6 @@ type QueryOptions struct {
 	// only in NTPv5.
 	RequestInterleavedMode bool
 
-	// ServerCookie contains the server cookie returned by a prior server
-	// response when operating in interleaved mode. Used only in NTPv5.
-	ServerCookie uint64
-
 	// 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

ntp5.go

@@ -13,11 +13,19 @@ import (
 	"crypto/rand"
 	"crypto/subtle"
 	"encoding/binary"
+	"errors"
 	"math"
 	"net"
 	"time"
 )
 
+var (
+	ErrInvalidDraftID            = errors.New("invalid draft ID value in response")
+	ErrInvalidExtensionField     = errors.New("invalid extension field in response")
+	ErrInvalidReferenceRequest   = errors.New("invalid reference ID request")
+	ErrUnexpectedCorrectionField = errors.New("unexpected correction extension field in response")
+)
+
 // Timescale represents the time reference system used by an NTPv5 server.
 type Timescale uint8
 
@@ -281,6 +289,12 @@ func queryV5(conn net.Conn, opt *QueryOptions) (*Response, error) {
 	if m.getMode() != responseMode {
 		return nil, ErrInvalidMode
 	}
+	if m.TransmitTime == timestamp(0) {
+		return nil, ErrInvalidTransmitTime
+	}
+	if m.ReceiveTime > m.TransmitTime {
+		return nil, ErrServerTickedBackwards
+	}
 	if m.getVersion() != 5 {
 		return nil, ErrInvalidProtocolVersion
 	}
@@ -482,14 +496,14 @@ func buildV5Request(opt *QueryOptions, clientCookie uint64) (*bytes.Buffer, erro
 	// finalized.
 	writeExtDraftID(buf)
 
-	if opt.ReferenceIDRequest.ChunkSize > 0 {
-		request := opt.ReferenceIDRequest
+	if opt.RequestReferenceID.ChunkSize > 0 {
+		request := opt.RequestReferenceID
 		if request.ChunkOffset+request.ChunkSize > 512 ||
 			request.ChunkOffset%4 != 0 ||
 			request.ChunkSize%4 != 0 {
 			return nil, ErrInvalidReferenceRequest
 		}
-		writeExtRefIDRequest(buf, opt.ReferenceIDRequest)
+		writeExtRefIDRequest(buf, opt.RequestReferenceID)
 	}
 
 	if opt.RequestSupportedVersions {

ntp5_test.go

@@ -23,6 +23,7 @@ func logResponseV5(t *testing.T, r *Response) {
 	t.Logf("[%s]     Version: %d", host, r.Version)
 	t.Logf("[%s] ClockOffset: %s", host, r.ClockOffset)
 	t.Logf("[%s]         RTT: %s", host, r.RTT)
+	t.Logf("[%s]  Correction: %s", host, fmtCorrection(r.Correction))
 	t.Logf("[%s]  SystemTime: %s", host, fmtTime(now))
 	t.Logf("[%s]   ~TrueTime: %s", host, fmtTime(now.Add(r.ClockOffset)))
 	t.Logf("[%s]    XmitTime: %s", host, fmtTime(r.Time))
@@ -38,7 +39,6 @@ func logResponseV5(t *testing.T, r *Response) {
 	t.Logf("[%s]   MonoEpoch: %s", host, fmtEpoch(r.MonotonicEpochID))
 	t.Logf("[%s]   Supported: %v", host, r.SupportedVersions)
 	t.Logf("[%s]        Poll: %s", host, r.Poll)
-	t.Logf("[%s]  Correction: %s", host, fmtCorrection(r.Correction))
 	t.Logf("[%s]   Precision: %s", host, r.Precision)
 	t.Logf("[%s]   RootDelay: %s", host, r.RootDelay)
 	t.Logf("[%s]    RootDisp: %s", host, r.RootDispersion)
@@ -133,7 +133,7 @@ func TestOnlineV5Query(t *testing.T) {
 		RequestReferenceTime:     true,
 		RequestMonotonic:         true,
 		RequestInterleavedMode:   true,
-		ReferenceIDRequest: ReferenceIDRequest{
+		RequestReferenceID: ReferenceIDRequest{
 			ChunkOffset: 0,
 			ChunkSize:   uint16(512),
 		},