From: otto <otto@openbsd.org>
Date: Wed, 15 Nov 2023 15:52:09 +0000 (+0000)
Subject: Correct denominators when converting NTP fixed point values to double
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=c338e3e2ad38b099fa13a573170a235f9ed893ce;p=openbsd

Correct denominators when converting NTP fixed point values to double
and vice-versa; ok tb@
---

diff --git a/usr.sbin/ntpd/ntp.h b/usr.sbin/ntpd/ntp.h
index fd35bf93791..20d67f31d3d 100644
--- a/usr.sbin/ntpd/ntp.h
+++ b/usr.sbin/ntpd/ntp.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntp.h,v 1.14 2020/01/30 15:55:41 otto Exp $ */
+/*	$OpenBSD: ntp.h,v 1.15 2023/11/15 15:52:09 otto Exp $ */
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
@@ -43,11 +43,13 @@ struct l_fixedpt {
 	u_int32_t int_partl;
 	u_int32_t fractionl;
 };
+#define L_DENOMINATOR	(UINT32_MAX + 1ULL)
 
 struct s_fixedpt {
 	u_int16_t int_parts;
 	u_int16_t fractions;
 };
+#define S_DENOMINATOR	(UINT16_MAX + 1)
 
 /* RFC Section 4
  *
diff --git a/usr.sbin/ntpd/util.c b/usr.sbin/ntpd/util.c
index be113ba856b..d490601b04d 100644
--- a/usr.sbin/ntpd/util.c
+++ b/usr.sbin/ntpd/util.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: util.c,v 1.25 2020/01/30 15:55:41 otto Exp $ */
+/*	$OpenBSD: util.c,v 1.26 2023/11/15 15:52:09 otto Exp $ */
 
 /*
  * Copyright (c) 2004 Alexander Guy <alexander.guy@andern.org>
@@ -96,7 +96,7 @@ lfp_to_d(struct l_fixedpt lfp)
 	if (lfp.int_partl <= INT32_MAX)
 		base++; 
 	ret = base * SECS_IN_ERA;
-	ret += (double)(lfp.int_partl) + ((double)lfp.fractionl / UINT_MAX);
+	ret += (double)(lfp.int_partl) + ((double)lfp.fractionl / L_DENOMINATOR);
 
 	return (ret);
 }
@@ -109,7 +109,7 @@ d_to_lfp(double d)
 	while (d > SECS_IN_ERA)
 		d -= SECS_IN_ERA;
 	lfp.int_partl = htonl((u_int32_t)d);
-	lfp.fractionl = htonl((u_int32_t)((d - (u_int32_t)d) * UINT_MAX));
+	lfp.fractionl = htonl((u_int32_t)((d - (u_int32_t)d) * L_DENOMINATOR));
 
 	return (lfp);
 }
@@ -122,7 +122,7 @@ sfp_to_d(struct s_fixedpt sfp)
 	sfp.int_parts = ntohs(sfp.int_parts);
 	sfp.fractions = ntohs(sfp.fractions);
 
-	ret = (double)(sfp.int_parts) + ((double)sfp.fractions / USHRT_MAX);
+	ret = (double)(sfp.int_parts) + ((double)sfp.fractions / S_DENOMINATOR);
 
 	return (ret);
 }
@@ -133,7 +133,7 @@ d_to_sfp(double d)
 	struct s_fixedpt	sfp;
 
 	sfp.int_parts = htons((u_int16_t)d);
-	sfp.fractions = htons((u_int16_t)((d - (u_int16_t)d) * USHRT_MAX));
+	sfp.fractions = htons((u_int16_t)((d - (u_int16_t)d) * S_DENOMINATOR));
 
 	return (sfp);
 }