From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Wed, 1 Dec 2021 08:11:09 +0000 (+0100)
Subject: ntp: check for zero timestamp in initial TX timeout
X-Git-Tag: 4.2-pre1~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6a79771898e518cf98242d56084f1db26ecca73e;p=thirdparty%2Fchrony.git

ntp: check for zero timestamp in initial TX timeout

Calculate the delay since the previous transmission only if the
TX timestamp is actually set. This removes an unnecessary delay when
starting at the Unix epoch in 1970 (e.g. in a test).
---

diff --git a/ntp_core.c b/ntp_core.c
index 2cffd6ca..6c3ba760 100644
--- a/ntp_core.c
+++ b/ntp_core.c
@@ -493,11 +493,16 @@ start_initial_timeout(NCR_Instance inst)
   /* In case the offline period was too short, adjust the delay to keep
      the interval between packets at least as long as the current polling
      interval */
-  SCH_GetLastEventTime(&now, NULL, NULL);
-  last_tx = UTI_DiffTimespecsToDouble(&now, &inst->local_tx.ts);
-  if (last_tx < 0.0)
-    last_tx = 0.0;
-  delay = get_transmit_delay(inst, 0, 0.0) - last_tx;
+  if (!UTI_IsZeroTimespec(&inst->local_tx.ts)) {
+    SCH_GetLastEventTime(&now, NULL, NULL);
+    last_tx = UTI_DiffTimespecsToDouble(&now, &inst->local_tx.ts);
+    if (last_tx < 0.0)
+      last_tx = 0.0;
+    delay = get_transmit_delay(inst, 0, 0.0) - last_tx;
+  } else {
+    delay = 0.0;
+  }
+
   if (delay < INITIAL_DELAY)
     delay = INITIAL_DELAY;