On Tue, Apr 20, 2021 at 07:59:51PM +0200, Alexander Bluhm wrote:
> I got a positive test report from Paul de Weerd.
>
> Anyone to ok it?
OK claudio@
> On Thu, Mar 18, 2021 at 01:06:49PM +0100, Alexander Bluhm wrote:
> > Hi,
> >
> > While hunting a bug in ntpd offset handling, I found some things
> > that could be improved.
> >
> > Call the index of the offset loops "shift" consistently.
> > Merge the two offset loops in client_update() into one.
> > Assign the best value instead of memcpy.
> > Use the same mechanism everywhere to avoid an invalid best value.
> >
> > ok?
> >
> > bluhm
> >
> > Index: client.c
> > ===================================================================
> > RCS file: /cvs/src/usr.sbin/ntpd/client.c,v
> > retrieving revision 1.115
> > diff -u -p -r1.115 client.c
> > --- client.c 18 Mar 2021 11:06:41 -0000 1.115
> > +++ client.c 18 Mar 2021 11:20:49 -0000
> > @@ -473,7 +473,7 @@ client_dispatch(struct ntp_peer *p, u_in
> > int
> > client_update(struct ntp_peer *p)
> > {
> > - int i, best = 0, good = 0;
> > + int shift, best = -1, good = 0;
> >
> > /*
> > * clock filter
> > @@ -482,27 +482,22 @@ client_update(struct ntp_peer *p)
> > * invalidate it and all older ones
> > */
> >
> > - for (i = 0; good == 0 && i < OFFSET_ARRAY_SIZE; i++)
> > - if (p->reply[i].good) {
> > + for (shift = 0; shift < OFFSET_ARRAY_SIZE; shift++)
> > + if (p->reply[shift].good) {
> > good++;
> > - best = i;
> > + if (best == -1 ||
> > + p->reply[shift].delay < p->reply[best].delay)
> > + best = shift;
> > }
> >
> > - for (; i < OFFSET_ARRAY_SIZE; i++)
> > - if (p->reply[i].good) {
> > - good++;
> > - if (p->reply[i].delay < p->reply[best].delay)
> > - best = i;
> > - }
> > -
> > - if (good < 8)
> > + if (best == -1 || good < 8)
> > return (-1);
> >
> > - memcpy(&p->update, &p->reply[best], sizeof(p->update));
> > + p->update = p->reply[best];
> > if (priv_adjtime() == 0) {
> > - for (i = 0; i < OFFSET_ARRAY_SIZE; i++)
> > - if (p->reply[i].rcvd <= p->reply[best].rcvd)
> > - p->reply[i].good = 0;
> > + for (shift = 0; shift < OFFSET_ARRAY_SIZE; shift++)
> > + if (p->reply[shift].rcvd <= p->reply[best].rcvd)
> > + p->reply[shift].good = 0;
> > }
> > return (0);
> > }
> > Index: control.c
> > ===================================================================
> > RCS file: /cvs/src/usr.sbin/ntpd/control.c,v
> > retrieving revision 1.18
> > diff -u -p -r1.18 control.c
> > --- control.c 12 Feb 2020 19:14:56 -0000 1.18
> > +++ control.c 18 Mar 2021 11:20:53 -0000
> > @@ -341,7 +341,7 @@ build_show_peer(struct ctl_show_peer *cp
> > const char *a = "not resolved";
> > const char *pool = "", *addr_head_name = "";
> > const char *auth = "";
> > - u_int8_t shift, best, validdelaycnt, jittercnt;
> > + int shift, best = -1, validdelaycnt = 0, jittercnt = 0;
> > time_t now;
> >
> > now = getmonotime();
> > @@ -360,14 +360,14 @@ build_show_peer(struct ctl_show_peer *cp
> > snprintf(cp->peer_desc, sizeof(cp->peer_desc),
> > "%s %s%s%s", a, pool, addr_head_name, auth);
> >
> > - validdelaycnt = best = 0;
> > cp->offset = cp->delay = 0.0;
> > for (shift = 0; shift < OFFSET_ARRAY_SIZE; shift++) {
> > if (p->reply[shift].delay > 0.0) {
> > cp->offset += p->reply[shift].offset;
> > cp->delay += p->reply[shift].delay;
> >
> > - if (p->reply[shift].delay < p->reply[best].delay)
> > + if (best == -1 ||
> > + p->reply[shift].delay < p->reply[best].delay)
> > best = shift;
> >
> > validdelaycnt++;
> > @@ -379,18 +379,19 @@ build_show_peer(struct ctl_show_peer *cp
> > cp->delay /= validdelaycnt;
> > }
> >
> > - jittercnt = 0;
> > cp->jitter = 0.0;
> > - for (shift = 0; shift < OFFSET_ARRAY_SIZE; shift++) {
> > - if (p->reply[shift].delay > 0.0 && shift != best) {
> > - cp->jitter += square(p->reply[shift].delay -
> > - p->reply[best].delay);
> > - jittercnt++;
> > + if (best != -1) {
> > + for (shift = 0; shift < OFFSET_ARRAY_SIZE; shift++) {
> > + if (p->reply[shift].delay > 0.0 && shift != best) {
> > + cp->jitter += square(p->reply[shift].delay -
> > + p->reply[best].delay);
> > + jittercnt++;
> > + }
> > }
> > + if (jittercnt > 1)
> > + cp->jitter /= jittercnt;
> > + cp->jitter = sqrt(cp->jitter);
> > }
> > - if (jittercnt > 1)
> > - cp->jitter /= jittercnt;
> > - cp->jitter = sqrt(cp->jitter);
> >
> > if (p->shift == 0)
> > shift = OFFSET_ARRAY_SIZE - 1;
>
--
:wq Claudio
