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 2cffd6cad877d6aafeaf8d71dcf9675704f12296..6c3ba760c719840e1c4a486cd92e59fb02e394fd 100644 (file)
--- 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;