#define ADJ_SETOFFSET 0x0100 /* add 'time' to current time */
#endif
-/* Maximum delta in seconds which the system clock is gradually adjusted
- * to approach the network time. Deltas larger that this are set by letting
- * the system time jump. The maximum for adjtime is 500ms.
- */
-#define NTP_MAX_ADJUST 0.2
+/* expected accuracy of time synchronization; used to adjust the poll interval */
+#define NTP_ACCURACY_SEC 0.2
/*
- * "Define the required accuracy of the system clock, then calculate the
- * maximum timeout. Use the longest maximum timeout possible given the system
- * constraints to minimize time server aggregate load."
- *
* "A client MUST NOT under any conditions use a poll interval less
* than 15 seconds."
*/
-#define NTP_POLL_INTERVAL_MIN_SEC 16
+#define NTP_POLL_INTERVAL_MIN_SEC 32
#define NTP_POLL_INTERVAL_MAX_SEC 2048
-#define NTP_ACCURACY_SEC 0.1
+/*
+ * Maximum delta in seconds which the system clock is gradually adjusted
+ * (slew) to approach the network time. Deltas larger that this are set by
+ * letting the system time jump. The kernel's limit for adjtime is 0.5s.
+ */
+#define NTP_MAX_ADJUST 0.4
+
+/* NTP protocol, packet header */
#define NTP_LEAP_PLUSSEC 1
#define NTP_LEAP_MINUSSEC 2
#define NTP_LEAP_NOTINSYNC 3
* matching answer to our request.
*
* The actual value does not matter, We do not care about the correct
- * NTP UINT_MAX fraction, we just pass the plain nanosecond value.
+ * NTP UINT_MAX fraction; we just pass the plain nanosecond value.
*/
clock_gettime(CLOCK_MONOTONIC, &sntp->trans_time_mon);
clock_gettime(CLOCK_REALTIME, &sntp->trans_time);
}
e = sd_event_source_get_event(sntp->event_receive);
- r = sd_event_add_monotonic(e, &sntp->event_timer, now(CLOCK_MONOTONIC) + next, 0, sntp_timer, sntp);
+ r = sd_event_add_time(
+ e,
+ &sntp->event_timer,
+ CLOCK_MONOTONIC,
+ now(CLOCK_MONOTONIC) + next, 0,
+ sntp_timer, sntp);
if (r < 0)
return r;
}
/* resync */
- log_info("System time changed, resyncing.");
+ log_info("System time changed. Resyncing.");
sntp->poll_resync = true;
sntp_send_request(sntp);
double jitter;
double j;
+ sntp->packet_count++;
+
+ /* ignore initial sample */
+ if (sntp->packet_count == 1)
+ return false;
+
/* store the current data in our samples array */
idx_cur = sntp->samples_idx;
idx_new = (idx_cur + 1) % ELEMENTSOF(sntp->samples);
sntp->samples[idx_new].offset = offset;
sntp->samples[idx_new].delay = delay;
- sntp->packet_count++;
- jitter = sntp->samples_jitter;
-
/* calculate new jitter value from the RMS differences relative to the lowest delay sample */
+ jitter = sntp->samples_jitter;
for (idx_min = idx_cur, i = 0; i < ELEMENTSOF(sntp->samples); i++)
if (sntp->samples[i].delay > 0 && sntp->samples[i].delay < sntp->samples[idx_min].delay)
idx_min = i;
}
/* set to minimal poll interval */
- if (fabs(offset) > NTP_ACCURACY_SEC) {
+ if (!spike && fabs(offset) > NTP_ACCURACY_SEC) {
sntp->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
return;
}
int r;
if (revents & (EPOLLHUP|EPOLLERR)) {
- log_debug("Server connection returned error, closing.");
+ log_debug("Server connection returned error. Closing.");
sntp_server_disconnect(sntp);
return -ENOTCONN;
}
len = recvmsg(fd, &msghdr, MSG_DONTWAIT);
if (len < 0) {
- log_debug("Error receiving message, disconnecting");
+ log_debug("Error receiving message. Disconnecting.");
return -EINVAL;
}
if (iov.iov_len < sizeof(struct ntp_msg)) {
- log_debug("Invalid response from server, disconnecting");
+ log_debug("Invalid response from server. Disconnecting.");
return -EINVAL;
}
if (sntp->server_addr.sin_addr.s_addr != server_addr.sin_addr.s_addr) {
- log_debug("Response from unknown server, disconnecting");
+ log_debug("Response from unknown server. Disconnecting.");
return -EINVAL;
}
}
}
if (!recv_time) {
- log_debug("Invalid packet timestamp, disconnecting");
+ log_debug("Invalid packet timestamp. Disconnecting.");
return -EINVAL;
}
ntpmsg = iov.iov_base;
if (!sntp->pending) {
- log_debug("Unexpected reply, ignoring");
+ log_debug("Unexpected reply. Ignoring.");
return 0;
}
/* check our "time cookie" (we just stored nanoseconds in the fraction field) */
- if (be32toh(ntpmsg->origin_time.sec) != sntp->trans_time.tv_sec + OFFSET_1900_1970||
+ if (be32toh(ntpmsg->origin_time.sec) != sntp->trans_time.tv_sec + OFFSET_1900_1970 ||
be32toh(ntpmsg->origin_time.frac) != sntp->trans_time.tv_nsec) {
- log_debug("Invalid reply, not our transmit time, ignoring");
+ log_debug("Invalid reply; not our transmit time. Ignoring.");
return 0;
}
if (NTP_FIELD_LEAP(ntpmsg->field) == NTP_LEAP_NOTINSYNC) {
- log_debug("Server is not synchronized, disconnecting");
+ log_debug("Server is not synchronized. Disconnecting.");
return -EINVAL;
}
if (NTP_FIELD_VERSION(ntpmsg->field) != 4) {
- log_debug("Response NTPv%d, disconnecting", NTP_FIELD_VERSION(ntpmsg->field));
+ log_debug("Response NTPv%d. Disconnecting.", NTP_FIELD_VERSION(ntpmsg->field));
return -EINVAL;
}
if (NTP_FIELD_MODE(ntpmsg->field) != NTP_MODE_SERVER) {
- log_debug("Unsupported mode %d, disconnecting", NTP_FIELD_MODE(ntpmsg->field));
+ log_debug("Unsupported mode %d. Disconnecting.", NTP_FIELD_MODE(ntpmsg->field));
return -EINVAL;
}
* Transmit Timestamp T3 time reply sent by server
* Destination Timestamp T4 time reply received by client
*
- * The roundtrip delay d and system clock offset t are defined as:
+ * The round-trip delay, d, and system clock offset, t, are defined as:
* d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2"
*/
clock_gettime(CLOCK_MONOTONIC, &now_ts);
sntp->server_addr.sin_family = AF_INET;
sntp->server_addr.sin_addr.s_addr = inet_addr(server);
- sntp->poll_interval_usec = 2 * NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
+ sntp->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
return sntp_send_request(sntp);
}
~ianmdlvl / elogind.git / blobdiff