From e012a3628baaf5c3786d41b18e78b42ac5dfbcf7 Mon Sep 17 00:00:00 2001
From: "renovate[bot]" <29139614+renovate[bot]@users.noreply.github.com>
Date: Fri, 31 May 2024 09:29:14 +0200
Subject: [PATCH] Renovate: Update module github.com/beevik/ntp to v1.4.3
 (#104)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
---
 go.mod                                        |  2 +-
 go.sum                                        |  4 +--
 vendor/github.com/beevik/ntp/RELEASE_NOTES.md |  8 +++++
 vendor/github.com/beevik/ntp/ntp.go           | 36 +++++++++----------
 vendor/modules.txt                            |  2 +-
 5 files changed, 30 insertions(+), 22 deletions(-)

diff --git a/go.mod b/go.mod
index 6d9a852..f482f73 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module github.com/sapcc/ntp_exporter
 go 1.22
 
 require (
-	github.com/beevik/ntp v1.4.2
+	github.com/beevik/ntp v1.4.3
 	github.com/prometheus/client_golang v1.19.1
 	github.com/sapcc/go-api-declarations v1.11.2
 	github.com/sapcc/go-bits v0.0.0-20240530080859-f4579fb3a074
diff --git a/go.sum b/go.sum
index 02dc8ec..f250c90 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,5 @@
-github.com/beevik/ntp v1.4.2 h1:cjYhZqczanf6br/ocViahE75ipj7CmKQAh7fSBaCNK4=
-github.com/beevik/ntp v1.4.2/go.mod h1:zkATLTt8VUZuOfYX2KgOnir4yvtAxWbnUUA24umXFnc=
+github.com/beevik/ntp v1.4.3 h1:PlbTvE5NNy4QHmA4Mg57n7mcFTmr1W1j3gcK7L1lqho=
+github.com/beevik/ntp v1.4.3/go.mod h1:Unr8Zg+2dRn7d8bHFuehIMSvvUYssHMxW3Q5Nx4RW5Q=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
diff --git a/vendor/github.com/beevik/ntp/RELEASE_NOTES.md b/vendor/github.com/beevik/ntp/RELEASE_NOTES.md
index f53ad47..f55458c 100644
--- a/vendor/github.com/beevik/ntp/RELEASE_NOTES.md
+++ b/vendor/github.com/beevik/ntp/RELEASE_NOTES.md
@@ -1,3 +1,11 @@
+Release v1.4.3
+==============
+
+**Fixes**
+
+* Fixed an overflow bug in the clock offset calculation introduced by
+  release v1.4.2.
+
 Release v1.4.2
 ==============
 
diff --git a/vendor/github.com/beevik/ntp/ntp.go b/vendor/github.com/beevik/ntp/ntp.go
index 8306ffa..197e19f 100644
--- a/vendor/github.com/beevik/ntp/ntp.go
+++ b/vendor/github.com/beevik/ntp/ntp.go
@@ -735,32 +735,32 @@ func generateResponse(h *header, recvTime ntpTime, authErr error) *Response {
 //   dst = Destination Timestamp (client receive time)
 
 func rtt(org, rec, xmt, dst ntpTime) time.Duration {
-	// round trip delay time
-	//   rtt = (dst-org) - (xmt-rec)
-	a := dst.Time().Sub(org.Time())
-	b := xmt.Time().Sub(rec.Time())
+	a := int64(dst - org)
+	b := int64(xmt - rec)
 	rtt := a - b
 	if rtt < 0 {
 		rtt = 0
 	}
-	return rtt
+	return ntpTime(rtt).Duration()
 }
 
 func offset(org, rec, xmt, dst ntpTime) time.Duration {
-	// local clock offset
-	//   offset = ((rec-org) + (xmt-dst)) / 2
-	// The inputs are 64-bit unsigned ints. The output is a 63-bit signed int.
-	// Need to handle conversions with care. See:
-	// https://www.eecis.udel.edu/~mills/time.html
-	a := int64(rec) - int64(org)
-	b := int64(xmt) - int64(dst)
-	d := (a + b) / 2
-
-	if d > 0 {
-		return ntpTime(d).Duration()
-	} else {
-		return -ntpTime(-d).Duration()
+	// The inputs are 64-bit unsigned integer timestamps. These timestamps can
+	// "roll over" at the end of an NTP era, which occurs approximately every
+	// 136 years starting from the year 1900. To ensure an accurate offset
+	// calculation when an era boundary is crossed, we need to take care that
+	// the difference between two 64-bit timestamp values is accurately
+	// calculated even when they are in neighboring eras.
+	//
+	// See: https://www.eecis.udel.edu/~mills/y2k.html
+
+	a := int64(rec - org)
+	b := int64(xmt - dst)
+	offset := a + (b-a)/2
+	if offset < 0 {
+		return -ntpTime(-offset).Duration()
 	}
+	return ntpTime(offset).Duration()
 }
 
 func minError(org, rec, xmt, dst ntpTime) time.Duration {
diff --git a/vendor/modules.txt b/vendor/modules.txt
index 1f5d7be..78b2ba8 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -1,4 +1,4 @@
-# github.com/beevik/ntp v1.4.2
+# github.com/beevik/ntp v1.4.3
 ## explicit; go 1.17
 github.com/beevik/ntp
 # github.com/beorn7/perks v1.0.1