#define NTP_FIELD_MODE(f) ((f) & 7)
#define NTP_FIELD(l, v, m) (((l) << 6) | ((v) << 3) | (m))
+/* Maximum acceptable root distance in seconds. */
+#define NTP_MAX_ROOT_DISTANCE 5.0
+
+/* Maximum number of missed replies before selecting another source. */
+#define NTP_MAX_MISSED_REPLIES 2
+
/*
* "NTP timestamps are represented as a 64-bit unsigned fixed-point number,
* in seconds relative to 0h on 1 January 1900."
static int manager_arm_timer(Manager *m, usec_t next);
static int manager_clock_watch_setup(Manager *m);
+static double ntp_ts_short_to_d(const struct ntp_ts_short *ts) {
+ return be16toh(ts->sec) + (be16toh(ts->frac) / 65536.0);
+}
+
static double ntp_ts_to_d(const struct ntp_ts *ts) {
return be32toh(ts->sec) + ((double)be32toh(ts->frac) / UINT_MAX);
}
return ts->tv_sec + (1.0e-9 * ts->tv_nsec);
}
-static double tv_to_d(const struct timeval *tv) {
- return tv->tv_sec + (1.0e-6 * tv->tv_usec);
-}
-
static double square(double d) {
return d * d;
}
return manager_connect(m);
}
- /* re-arm timer with increasing timeout, in case the packets never arrive back */
- if (m->retry_interval > 0) {
- if (m->retry_interval < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
- m->retry_interval *= 2;
- } else
- m->retry_interval = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
-
- r = manager_arm_timer(m, m->retry_interval);
- if (r < 0) {
- log_error("Failed to rearm timer: %s", strerror(-r));
- return r;
- }
-
- r = sd_event_add_time(
- m->event,
- &m->event_timeout,
- clock_boottime_or_monotonic(),
- now(clock_boottime_or_monotonic()) + TIMEOUT_USEC, 0,
- manager_timeout, m);
- if (r < 0) {
- log_error("Failed to arm timeout timer: %s", strerror(-r));
- return r;
+ m->missed_replies++;
+ if (m->missed_replies > NTP_MAX_MISSED_REPLIES) {
+ r = sd_event_add_time(
+ m->event,
+ &m->event_timeout,
+ clock_boottime_or_monotonic(),
+ now(clock_boottime_or_monotonic()) + TIMEOUT_USEC, 0,
+ manager_timeout, m);
+ if (r < 0) {
+ log_error("Failed to arm timeout timer: %s", strerror(-r));
+ return r;
+ }
}
return 0;
.msg_namelen = sizeof(server_addr),
};
struct cmsghdr *cmsg;
- struct timespec now_ts;
- struct timeval *recv_time;
+ struct timespec *recv_time;
ssize_t len;
double origin, receive, trans, dest;
double delay, offset;
+ double root_distance;
bool spike;
int leap_sec;
int r;
continue;
switch (cmsg->cmsg_type) {
- case SCM_TIMESTAMP:
- recv_time = (struct timeval *) CMSG_DATA(cmsg);
+ case SCM_TIMESTAMPNS:
+ recv_time = (struct timespec *) CMSG_DATA(cmsg);
break;
}
}
return 0;
}
+ m->missed_replies = 0;
+
/* check our "time cookie" (we just stored nanoseconds in the fraction field) */
if (be32toh(ntpmsg.origin_time.sec) != m->trans_time.tv_sec + OFFSET_1900_1970 ||
be32toh(ntpmsg.origin_time.frac) != m->trans_time.tv_nsec) {
return manager_connect(m);
}
+ root_distance = ntp_ts_short_to_d(&ntpmsg.root_delay) / 2 + ntp_ts_short_to_d(&ntpmsg.root_dispersion);
+ if (root_distance > NTP_MAX_ROOT_DISTANCE) {
+ log_debug("Server has too large root distance. Disconnecting.");
+ return manager_connect(m);
+ }
+
/* valid packet */
m->pending = false;
- m->retry_interval = 0;
/* announce leap seconds */
if (NTP_FIELD_LEAP(ntpmsg.field) & NTP_LEAP_PLUSSEC)
* The round-trip delay, d, and system clock offset, t, are defined as:
* d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2"
*/
- assert_se(clock_gettime(clock_boottime_or_monotonic(), &now_ts) >= 0);
- origin = tv_to_d(recv_time) - (ts_to_d(&now_ts) - ts_to_d(&m->trans_time_mon)) + OFFSET_1900_1970;
+ origin = ts_to_d(&m->trans_time) + OFFSET_1900_1970;
receive = ntp_ts_to_d(&ntpmsg.recv_time);
trans = ntp_ts_to_d(&ntpmsg.trans_time);
- dest = tv_to_d(recv_time) + OFFSET_1900_1970;
+ dest = ts_to_d(recv_time) + OFFSET_1900_1970;
offset = ((receive - origin) + (trans - dest)) / 2;
delay = (dest - origin) - (trans - receive);
" mode : %u\n"
" stratum : %u\n"
" precision : %.6f sec (%d)\n"
+ " root distance: %.6f sec\n"
" reference : %.4s\n"
" origin : %.3f\n"
" receive : %.3f\n"
NTP_FIELD_MODE(ntpmsg.field),
ntpmsg.stratum,
exp2(ntpmsg.precision), ntpmsg.precision,
+ root_distance,
ntpmsg.stratum == 1 ? ntpmsg.refid : "n/a",
origin - OFFSET_1900_1970,
receive - OFFSET_1900_1970,
if (r < 0)
return -errno;
- r = setsockopt(m->server_socket, SOL_SOCKET, SO_TIMESTAMP, &on, sizeof(on));
+ r = setsockopt(m->server_socket, SOL_SOCKET, SO_TIMESTAMPNS, &on, sizeof(on));
if (r < 0)
return -errno;
assert_return(m->current_server_name, -EHOSTUNREACH);
assert_return(m->current_server_address, -EHOSTUNREACH);
- m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
+ m->missed_replies = NTP_MAX_MISSED_REPLIES;
+ if (m->poll_interval_usec == 0)
+ m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
server_address_pretty(m->current_server_address, &pretty);
log_info("Using NTP server %s (%s).", strna(pretty), m->current_server_name->string);
if (m->current_server_address == a)
return;
- m->current_server_name = a ? a->name : NULL;
m->current_server_address = a;
+ /* If a is NULL, we are just clearing the address, without
+ * changing the name. Keep the existing name in that case. */
+ if (a)
+ m->current_server_name = a->name;
manager_disconnect(m);
manager_set_server_name(m, m->current_server_name->names_next);
else {
ServerName *f;
+ bool restart = true;
/* Our current server name list is exhausted,
* let's find the next one to iterate. First
f = m->link_servers;
if (!f)
f = m->system_servers;
+ else
+ restart = false;
}
if (!f)
return 0;
}
+ if (restart && !m->exhausted_servers && m->poll_interval_usec) {
+ log_debug("Waiting after exhausting servers.");
+ r = sd_event_add_time(m->event, &m->event_retry, clock_boottime_or_monotonic(), now(clock_boottime_or_monotonic()) + m->poll_interval_usec, 0, manager_retry_connect, m);
+ if (r < 0) {
+ log_error("Failed to create retry timer: %s", strerror(-r));
+ return r;
+ }
+
+ m->exhausted_servers = true;
+
+ /* Increase the polling interval */
+ if (m->poll_interval_usec < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
+ m->poll_interval_usec *= 2;
+
+ return 0;
+ }
+
+ m->exhausted_servers = false;
+
manager_set_server_name(m, f);
}
online = network_is_online();
/* check if the client is currently connected */
- connected = m->server_socket >= 0 || m->resolve_query;
+ connected = m->server_socket >= 0 || m->resolve_query || m->exhausted_servers;
if (connected && !online) {
log_info("No network connectivity, watching for changes.");