From: Juergen Perlinger <perlinger@ntp.org>
Date: Tue, 5 Sep 2017 06:40:47 +0000 (+0200)
Subject: [Bug 3394] Leap second deletion does not work on ntpd clients
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3e26058dc2d21c8b350034511e620e82c7793819;p=thirdparty%2Fntp.git

[Bug 3394] Leap second deletion does not work on ntpd clients

bk: 59ae46efO1gOU5GtefrvwlPSz1esBQ
---

diff --git a/ChangeLog b/ChangeLog
index a1a1cfae4..c2b39a9c3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+---
+* [Bug 3394] Leap second deletion does not work on ntpd clients
+  - fixed handling of dynamic deletion w/o leap file <perlinger@ntp.org>
+  
 ---
 (4.2.8p10-win-beta1) 2017/03/21 Released by Harlan Stenn <stenn@ntp.org>
 (4.2.8p10)
diff --git a/ntpd/ntp_leapsec.c b/ntpd/ntp_leapsec.c
index 7a652f5cf..95a067367 100644
--- a/ntpd/ntp_leapsec.c
+++ b/ntpd/ntp_leapsec.c
@@ -743,14 +743,24 @@ add_range(
 	const leap_info_t * pi)
 {
 	/* If the table is full, make room by throwing out the oldest
-	 * entry. But remember the accumulated leap seconds! Likewise,
-	 * assume a positive leap insertion if this is the first entry
-	 * in the table. This is not necessarily the best of all ideas,
-	 * but it helps a great deal if a system does not have a leap
-	 * table and gets updated from an upstream server.
+	 * entry. But remember the accumulated leap seconds!
+	 *
+	 * Setting the first entry is a bit tricky, too: Simply assuming
+	 * it is an insertion is wrong if the first entry is a dynamic
+	 * leap second removal. So we decide on the sign -- if the first
+	 * entry has a negative offset, we assume that it is a leap
+	 * second removal. In both cases the table base offset is set
+	 * accordingly to reflect the decision.
+	 *
+	 * In practice starting with a removal can only happen if the
+	 * first entry is a dynamic request without having a leap file
+	 * for the history proper.
 	 */
 	if (pt->head.size == 0) {
-		pt->head.base_tai = pi->taiof - 1;
+		if (pi->taiof >= 0)
+			pt->head.base_tai = pi->taiof - 1;
+		else
+			pt->head.base_tai = pi->taiof + 1;
 	} else if (pt->head.size >= MAX_HIST) {
 		pt->head.size     = MAX_HIST - 1;
 		pt->head.base_tai = pt->info[pt->head.size].taiof;