From 66864fcb23012a86827b56b182395d864be7fcd2 Mon Sep 17 00:00:00 2001
From: Andrew Johnson <anj@aps.anl.gov>
Date: Fri, 22 Oct 2010 17:34:13 -0500
Subject: [PATCH] libCom/osi: More NTP time quality checking.

Reject NTP timespec values before the EPICS epoch.
---
 src/libCom/osi/osiNTPTime.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/libCom/osi/osiNTPTime.c b/src/libCom/osi/osiNTPTime.c
index a5676d402..d085cca31 100644
--- a/src/libCom/osi/osiNTPTime.c
+++ b/src/libCom/osi/osiNTPTime.c
@@ -99,10 +99,12 @@ static void NTPTime_InitOnce(void *pprio)
     /* Try to sync with NTP server */
     if (!osdNTPGet(&timespecNow)) {
         NTPTimePvt.syncTick = osdTickGet();
-        epicsTimeFromTimespec(&NTPTimePvt.syncTime, &timespecNow);
-        NTPTimePvt.clockTick = NTPTimePvt.syncTick;
-        NTPTimePvt.clockTime = NTPTimePvt.syncTime;
-        NTPTimePvt.synchronized = 1;
+        if (timespecNow.tv_sec > POSIX_TIME_AT_EPICS_EPOCH && epicsTimeOK ==
+            epicsTimeFromTimespec(&NTPTimePvt.syncTime, &timespecNow)) {
+            NTPTimePvt.clockTick = NTPTimePvt.syncTick;
+            NTPTimePvt.clockTime = NTPTimePvt.syncTime;
+            NTPTimePvt.synchronized = 1;
+        }
     }
 
     /* Start the sync thread */
@@ -164,9 +166,14 @@ static void NTPTimeSync(void *dummy)
             continue;
         }
 
-        epicsTimeFromTimespec(&timeNow, &timespecNow);
-        ntpDelta = epicsTimeDiffInSeconds(&timeNow, &NTPTimePvt.syncTime);
+        if (timespecNow.tv_sec <= POSIX_TIME_AT_EPICS_EPOCH ||
+            epicsTimeFromTimespec(&timeNow, &timespecNow) == epicsTimeERROR) {
+            errlogPrintf("NTPTimeSync: Bad time received from NTP server\n");
+            NTPTimePvt.synchronized = 0;
+            continue;
+        }
 
+        ntpDelta = epicsTimeDiffInSeconds(&timeNow, &NTPTimePvt.syncTime);
         if (ntpDelta <= 0.0 && NTPTimePvt.synchronized) {
             errlogPrintf("NTPTimeSync: NTP time not increasing, delta = %g\n",
                 ntpDelta);