83 lines
3.3 KiB
Diff
83 lines
3.3 KiB
Diff
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From 60bfbd03ff57e6096b13c292ff33fd5570508a05 Mon Sep 17 00:00:00 2001
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From: Miroslav Lichvar <mlichvar@redhat.com>
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Date: Wed, 27 Aug 2014 16:47:20 +0200
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Subject: [PATCH 05/12] timesyncd: check root distance
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NTPv4 servers don't reply with unsynchronized status when they lost
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synchronization, they only keep increasing the root dispersion and it's
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up to the client to decide at which point they no longer consider it
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synchronized.
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Ignore replies with root distance over 5 seconds.
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(cherry picked from commit 3af0442c52090f34ae7a1c8e6b6587c540c06896)
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---
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src/timesync/timesyncd-manager.c | 16 ++++++++++++++++
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1 file changed, 16 insertions(+)
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diff --git a/src/timesync/timesyncd-manager.c b/src/timesync/timesyncd-manager.c
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index 2b0580c..9b8b7d3 100644
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--- a/src/timesync/timesyncd-manager.c
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+++ b/src/timesync/timesyncd-manager.c
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@@ -89,6 +89,9 @@
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#define NTP_FIELD_MODE(f) ((f) & 7)
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#define NTP_FIELD(l, v, m) (((l) << 6) | ((v) << 3) | (m))
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+/* Maximum acceptable root distance in seconds. */
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+#define NTP_MAX_ROOT_DISTANCE 5.0
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+
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/*
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* "NTP timestamps are represented as a 64-bit unsigned fixed-point number,
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* in seconds relative to 0h on 1 January 1900."
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@@ -128,6 +131,10 @@ struct ntp_msg {
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static int manager_arm_timer(Manager *m, usec_t next);
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static int manager_clock_watch_setup(Manager *m);
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+static double ntp_ts_short_to_d(const struct ntp_ts_short *ts) {
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+ return be16toh(ts->sec) + (be16toh(ts->frac) / 65536.0);
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+}
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+
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static double ntp_ts_to_d(const struct ntp_ts *ts) {
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return be32toh(ts->sec) + ((double)be32toh(ts->frac) / UINT_MAX);
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}
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@@ -500,6 +507,7 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
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ssize_t len;
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double origin, receive, trans, dest;
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double delay, offset;
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+ double root_distance;
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bool spike;
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int leap_sec;
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int r;
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@@ -585,6 +593,12 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
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return manager_connect(m);
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}
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+ root_distance = ntp_ts_short_to_d(&ntpmsg.root_delay) / 2 + ntp_ts_short_to_d(&ntpmsg.root_dispersion);
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+ if (root_distance > NTP_MAX_ROOT_DISTANCE) {
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+ log_debug("Server has too large root distance. Disconnecting.");
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+ return manager_connect(m);
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+ }
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+
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/* valid packet */
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m->pending = false;
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m->retry_interval = 0;
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@@ -626,6 +640,7 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
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" mode : %u\n"
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" stratum : %u\n"
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" precision : %.6f sec (%d)\n"
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+ " root distance: %.6f sec\n"
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" reference : %.4s\n"
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" origin : %.3f\n"
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" receive : %.3f\n"
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@@ -641,6 +656,7 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
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NTP_FIELD_MODE(ntpmsg.field),
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ntpmsg.stratum,
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exp2(ntpmsg.precision), ntpmsg.precision,
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+ root_distance,
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ntpmsg.stratum == 1 ? ntpmsg.refid : "n/a",
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origin - OFFSET_1900_1970,
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receive - OFFSET_1900_1970,
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--
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2.1.0
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