From 64e21d6281ad2d4c845854ad59dcc4dad767fa59 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Thu, 5 Sep 2019 17:14:30 +0200
Subject: [PATCH] reference: make local reference timestamp consistent

In the local reference mode, instead of returning the adjusted current
time as the reference time, return the same timestamp updated only once
per about 62.5 seconds.

This will enable chronyd to detect polling of itself even when the local
reference mode is active.
---
 reference.c                    | 25 +++++++++++++++++--------
 test/simulation/115-cmdmontime |  5 ++---
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/reference.c b/reference.c
index cdc6196..b40ae38 100644
--- a/reference.c
+++ b/reference.c
@@ -42,11 +42,15 @@
 /* The minimum allowed skew */
 #define MIN_SKEW 1.0e-12
 
+/* The update interval of the reference in the local reference mode */
+#define LOCAL_REF_UPDATE_INTERVAL 64.0
+
 static int are_we_synchronised;
 static int enable_local_stratum;
 static int local_stratum;
 static int local_orphan;
 static double local_distance;
+static struct timespec local_ref_time;
 static NTP_Leap our_leap_status;
 static int our_leap_sec;
 static int our_tai_offset;
@@ -234,6 +238,7 @@ REF_Initialise(void)
   correction_time_ratio = CNF_GetCorrectionTimeRatio();
 
   enable_local_stratum = CNF_AllowLocalReference(&local_stratum, &local_orphan, &local_distance);
+  UTI_ZeroTimespec(&local_ref_time);
 
   leap_timeout_id = 0;
   leap_in_progress = 0;
@@ -1178,7 +1183,7 @@ REF_GetReferenceParams
  double *root_dispersion
 )
 {
-  double dispersion;
+  double dispersion, delta;
 
   assert(initialised);
 
@@ -1210,13 +1215,17 @@ REF_GetReferenceParams
 
     *stratum = local_stratum;
     *ref_id = NTP_REFID_LOCAL;
-    /* Make the reference time be now less a second - this will
-       scarcely affect the client, but will ensure that the transmit
-       timestamp cannot come before this (which would cause test 7 to
-       fail in the client's read routine) if the local system clock's
-       read routine is broken in any way. */
-    *ref_time = *local_time;
-    --ref_time->tv_sec;
+
+    /* Keep the reference timestamp up to date.  Adjust the timestamp to make
+       sure that the transmit timestamp cannot come before this (which might
+       fail a test of an NTP client). */
+    delta = UTI_DiffTimespecsToDouble(local_time, &local_ref_time);
+    if (delta > LOCAL_REF_UPDATE_INTERVAL || delta < 1.0) {
+      UTI_AddDoubleToTimespec(local_time, -1.0, &local_ref_time);
+      fuzz_ref_time(&local_ref_time);
+    }
+
+    *ref_time = local_ref_time;
 
     /* Not much else we can do for leap second bits - maybe need to
        have a way for the administrator to feed leap bits in */
diff --git a/test/simulation/115-cmdmontime b/test/simulation/115-cmdmontime
index 732decd..ea79b26 100755
--- a/test/simulation/115-cmdmontime
+++ b/test/simulation/115-cmdmontime
@@ -15,11 +15,10 @@ chronyc_start="1.5"
 chronyc_conf="tracking"
 
 for year in `seq 1850 100 2300`; do
-	date="Jan 01 00:00:00 $year"
-	export CLKNETSIM_START_DATE=$(date -d "$date UTC" +'%s')
+	export CLKNETSIM_START_DATE=$(date -d "Jan 01 00:00:05 $year UTC" +'%s')
 	run_test || test_fail
 	check_chronyd_exit || test_fail
-	check_chronyc_output "^.*Ref time \(UTC\).*$date.*$" || test_fail
+	check_chronyc_output "^.*Ref time \(UTC\).*Jan 01 00:00:0. $year.*$" || test_fail
 done
 
 test_pass