#include <arpa/inet.h>
#include <netinet/in.h>
#include <netinet/ip.h>
+#include <sys/timerfd.h>
#include <sys/timex.h>
#include <sys/socket.h>
+#include "missing.h"
#include "util.h"
#include "sparse-endian.h"
#include "log.h"
#include "sd-event.h"
#include "timedate-sntp.h"
+#define TIME_T_MAX (time_t)((1UL << ((sizeof(time_t) << 3) - 1)) - 1)
+
#ifndef ADJ_SETOFFSET
#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_POLL_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
} _packed_;
struct SNTPContext {
- sd_event_source *event_receive;
- sd_event_source *event_timer;
+ void (*report)(usec_t poll, double offset, double delay, double jitter, bool spike);
+ /* peer */
+ sd_event_source *event_receive;
char *server;
struct sockaddr_in server_addr;
int server_socket;
uint64_t packet_count;
+ /* last sent packet */
struct timespec trans_time_mon;
struct timespec trans_time;
+ usec_t retry_interval;
bool pending;
- usec_t poll_interval;
+ /* poll timer */
+ sd_event_source *event_timer;
+ usec_t poll_interval_usec;
+ bool poll_resync;
+ /* history data */
struct {
double offset;
double delay;
} samples[8];
unsigned int samples_idx;
double samples_jitter;
+
+ /* last change */
+ bool jumped;
+
+ /* watch for time changes */
+ sd_event_source *event_clock_watch;
+ int clock_watch_fd;
};
-static int sntp_arm_timer(SNTPContext *sntp);
+static int sntp_arm_timer(SNTPContext *sntp, usec_t next);
+static int sntp_clock_watch_setup(SNTPContext *sntp);
static double ntp_ts_to_d(const struct ntp_ts *ts) {
return be32toh(ts->sec) + ((double)be32toh(ts->frac) / UINT_MAX);
* 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);
addr.sin_port = htobe16(123);
addr.sin_addr.s_addr = inet_addr(sntp->server);
len = sendto(sntp->server_socket, &ntpmsg, sizeof(ntpmsg), MSG_DONTWAIT, &addr, sizeof(addr));
- if (len < 0) {
+ if (len == sizeof(ntpmsg)) {
+ sntp->pending = true;
+ log_debug("Sent NTP request to: %s", sntp->server);
+ } else
log_debug("Sending NTP request to %s failed: %m", sntp->server);
- return -errno;
- }
- sntp->pending = true;
-
- /* re-arm timer for next poll interval, in case the packet never arrives back */
- r = sntp_arm_timer(sntp);
+ /* re-arm timer with incresing timeout, in case the packets never arrive back */
+ if (sntp->retry_interval > 0) {
+ if (sntp->retry_interval < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
+ sntp->retry_interval *= 2;
+ } else
+ sntp->retry_interval = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
+ r = sntp_arm_timer(sntp, sntp->retry_interval);
if (r < 0)
return r;
- log_debug("Sent NTP request to: %s", sntp->server);
return 0;
}
return 0;
}
-static int sntp_arm_timer(SNTPContext *sntp) {
+static int sntp_arm_timer(SNTPContext *sntp, usec_t next) {
sd_event *e;
int r;
assert(sntp);
assert(sntp->event_receive);
- if (sntp->poll_interval <= 0) {
+ if (next == 0) {
sntp->event_timer = sd_event_source_unref(sntp->event_timer);
return 0;
}
if (sntp->event_timer) {
- r = sd_event_source_set_time(sntp->event_timer, now(CLOCK_MONOTONIC) + sntp->poll_interval);
+ r = sd_event_source_set_time(sntp->event_timer, now(CLOCK_MONOTONIC) + next);
if (r < 0)
return r;
}
e = sd_event_source_get_event(sntp->event_receive);
- r = sd_event_add_monotonic(e, &sntp->event_timer, now(CLOCK_MONOTONIC) + sntp->poll_interval, 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;
return 0;
}
+static int sntp_clock_watch(sd_event_source *source, int fd, uint32_t revents, void *userdata) {
+ SNTPContext *sntp = userdata;
+
+ assert(sntp);
+ assert(sntp->event_receive);
+
+ /* rearm timer */
+ sntp_clock_watch_setup(sntp);
+
+ /* skip our own jumps */
+ if (sntp->jumped) {
+ sntp->jumped = false;
+ return 0;
+ }
+
+ /* resync */
+ log_info("System time changed. Resyncing.");
+ sntp->poll_resync = true;
+ sntp_send_request(sntp);
+
+ return 0;
+}
+
+/* wake up when the system time changes underneath us */
+static int sntp_clock_watch_setup(SNTPContext *sntp) {
+ struct itimerspec its = { .it_value.tv_sec = TIME_T_MAX };
+ _cleanup_close_ int fd = -1;
+ sd_event *e;
+ sd_event_source *source;
+ int r;
+
+ assert(sntp);
+ assert(sntp->event_receive);
+
+ fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK|TFD_CLOEXEC);
+ if (fd < 0) {
+ log_error("Failed to create timerfd: %m");
+ return -errno;
+ }
+
+ if (timerfd_settime(fd, TFD_TIMER_ABSTIME|TFD_TIMER_CANCEL_ON_SET, &its, NULL) < 0) {
+ log_error("Failed to set up timerfd: %m");
+ return -errno;
+ }
+
+ e = sd_event_source_get_event(sntp->event_receive);
+ r = sd_event_add_io(e, &source, fd, EPOLLIN, sntp_clock_watch, sntp);
+ if (r < 0) {
+ log_error("Failed to create clock watch event source: %s", strerror(-r));
+ return r;
+ }
+
+ sd_event_source_unref(sntp->event_clock_watch);
+ sntp->event_clock_watch = source;
+
+ if (sntp->clock_watch_fd >= 0)
+ close(sntp->clock_watch_fd);
+ sntp->clock_watch_fd = fd;
+ fd = -1;
+
+ return 0;
+}
+
static int sntp_adjust_clock(SNTPContext *sntp, double offset, int leap_sec) {
struct timex tmx = {};
int r;
* syncs the system time periodically to the hardware clock.
*/
if (offset < NTP_MAX_ADJUST && offset > -NTP_MAX_ADJUST) {
- int constant;
-
- constant = log2i(sntp->poll_interval / USEC_PER_SEC) - 5;
-
- tmx.modes |= ADJ_STATUS | ADJ_OFFSET | ADJ_TIMECONST;
+ tmx.modes |= ADJ_STATUS | ADJ_OFFSET | ADJ_TIMECONST | ADJ_MAXERROR | ADJ_ESTERROR;
tmx.status = STA_PLL;
tmx.offset = offset * 1000 * 1000;
- tmx.constant = constant;
-
+ tmx.constant = log2i(sntp->poll_interval_usec / USEC_PER_SEC) - 6;
+ tmx.maxerror = 0;
+ tmx.esterror = 0;
log_debug(" adjust (slew): %+f sec\n", (double)tmx.offset / USEC_PER_SEC);
} else {
tmx.modes = ADJ_SETOFFSET;
d_to_tv(offset, &tmx.time);
+
+ sntp->jumped = true;
log_debug(" adjust (jump): %+f sec\n", tv_to_d(&tmx.time));
}
static bool sntp_sample_spike_detection(SNTPContext *sntp, double offset, double delay) {
unsigned int i, idx_cur, idx_new, idx_min;
double jitter;
- bool spike;
+ 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;
sntp->samples[idx_new].offset = offset;
sntp->samples[idx_new].delay = delay;
- sntp->packet_count++;
-
- /*
- * Spike detection; compare the difference between the
- * current offset to the previous offset and jitter.
- */
- spike = sntp->packet_count > 2 && fabs(offset - sntp->samples[idx_cur].offset) > sntp->samples_jitter * 3;
-
/* 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;
- for (jitter = 0, i = 0; i < ELEMENTSOF(sntp->samples); i++)
- jitter += square(sntp->samples[i].offset - sntp->samples[idx_min].offset);
- sntp->samples_jitter = sqrt(jitter / (ELEMENTSOF(sntp->samples) - 1));
+ j = 0;
+ for (i = 0; i < ELEMENTSOF(sntp->samples); i++)
+ j += square(sntp->samples[i].offset - sntp->samples[idx_min].offset);
+ sntp->samples_jitter = sqrt(j / (ELEMENTSOF(sntp->samples) - 1));
- return spike;
-}
+ /* ignore samples when resyncing */
+ if (sntp->poll_resync)
+ return false;
+
+ /* always accept offset if we are farther off than the round-trip delay */
+ if (fabs(offset) > delay)
+ return false;
+
+ /* we need a few samples before looking at them */
+ if (sntp->packet_count < 4)
+ return false;
-static void snmp_adjust_poll(SNTPContext *sntp, double offset, bool spike) {
- double delta;
+ /* do not accept anything worse than the maximum possible error of the best sample */
+ if (fabs(offset) > sntp->samples[idx_min].delay)
+ return true;
- if (spike) {
- if (sntp->poll_interval > NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC)
- sntp->poll_interval /= 2;
+ /* compare the difference between the current offset to the previous offset and jitter */
+ return fabs(offset - sntp->samples[idx_cur].offset) > 3 * jitter;
+}
+
+static void sntp_adjust_poll(SNTPContext *sntp, double offset, bool spike) {
+ if (sntp->poll_resync) {
+ sntp->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
+ sntp->poll_resync = false;
return;
}
- delta = fabs(offset);
-
/* set to minimal poll interval */
- if (delta > NTP_POLL_ACCURACY_SEC) {
- sntp->poll_interval = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
+ if (!spike && fabs(offset) > NTP_ACCURACY_SEC) {
+ sntp->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
return;
}
/* increase polling interval */
- if (delta < NTP_POLL_ACCURACY_SEC * 0.25) {
- if (sntp->poll_interval < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
- sntp->poll_interval *= 2;
+ if (fabs(offset) < NTP_ACCURACY_SEC * 0.25) {
+ if (sntp->poll_interval_usec < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
+ sntp->poll_interval_usec *= 2;
return;
}
/* decrease polling interval */
- if (delta > NTP_POLL_ACCURACY_SEC * 0.75) {
- if (sntp->poll_interval > NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC)
- sntp->poll_interval /= 2;
+ if (spike || fabs(offset) > NTP_ACCURACY_SEC * 0.75) {
+ if (sntp->poll_interval_usec > NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC)
+ sntp->poll_interval_usec /= 2;
return;
}
}
.msg_namelen = sizeof(server_addr),
};
struct cmsghdr *cmsg;
- struct timespec now;
+ struct timespec now_ts;
struct timeval *recv_time;
ssize_t len;
struct ntp_msg *ntpmsg;
- double origin, recv, trans, dest;
+ double origin, receive, trans, dest;
double delay, offset;
bool spike;
int leap_sec;
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;
}
- sntp->pending = false;
/* 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;
}
+ /* valid packet */
+ sntp->pending = false;
+ sntp->retry_interval = 0;
+
/* announce leap seconds */
if (NTP_FIELD_LEAP(ntpmsg->field) & NTP_LEAP_PLUSSEC)
leap_sec = 1;
* 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);
- origin = tv_to_d(recv_time) - (ts_to_d(&now) - ts_to_d(&sntp->trans_time_mon)) + OFFSET_1900_1970;
- recv = ntp_ts_to_d(&ntpmsg->recv_time);
+ clock_gettime(CLOCK_MONOTONIC, &now_ts);
+ origin = tv_to_d(recv_time) - (ts_to_d(&now_ts) - ts_to_d(&sntp->trans_time_mon)) + 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;
- offset = ((recv - origin) + (trans - dest)) / 2;
- delay = (dest - origin) - (trans - recv);
+ offset = ((receive - origin) + (trans - dest)) / 2;
+ delay = (dest - origin) - (trans - receive);
spike = sntp_sample_spike_detection(sntp, offset, delay);
- snmp_adjust_poll(sntp, offset, spike);
+ sntp_adjust_poll(sntp, offset, spike);
log_debug("NTP response:\n"
" leap : %u\n"
" precision : %f sec (%d)\n"
" reference : %.4s\n"
" origin : %f\n"
- " recv : %f\n"
+ " receive : %f\n"
" transmit : %f\n"
" dest : %f\n"
" offset : %+f sec\n"
" delay : %+f sec\n"
" packet count : %"PRIu64"\n"
- " jitter/spike : %f (%s)\n"
+ " jitter : %f%s\n"
" poll interval: %llu\n",
NTP_FIELD_LEAP(ntpmsg->field),
NTP_FIELD_VERSION(ntpmsg->field),
exp2(ntpmsg->precision), ntpmsg->precision,
ntpmsg->stratum == 1 ? ntpmsg->refid : "n/a",
origin - OFFSET_1900_1970,
- recv - OFFSET_1900_1970,
+ receive - OFFSET_1900_1970,
trans - OFFSET_1900_1970,
dest - OFFSET_1900_1970,
offset, delay,
sntp->packet_count,
- sntp->samples_jitter, spike ? "yes" : "no",
- sntp->poll_interval / USEC_PER_SEC);
+ sntp->samples_jitter, spike ? " spike" : "",
+ sntp->poll_interval_usec / USEC_PER_SEC);
- log_info("%4llu %s %+12f", sntp->poll_interval / USEC_PER_SEC, spike ? "y" : "n", offset);
+ if (sntp->report)
+ sntp->report(sntp->poll_interval_usec, offset, delay, sntp->samples_jitter, spike);
if (!spike) {
r = sntp_adjust_clock(sntp, offset, leap_sec);
log_error("Failed to call clock_adjtime(): %m");
}
- r = sntp_arm_timer(sntp);
+ r = sntp_arm_timer(sntp, sntp->poll_interval_usec);
if (r < 0)
return r;
sntp->server_addr.sin_family = AF_INET;
sntp->server_addr.sin_addr.s_addr = inet_addr(server);
- sntp->poll_interval = 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);
}
return;
sntp->event_timer = sd_event_source_unref(sntp->event_timer);
+
+ sntp->event_clock_watch = sd_event_source_unref(sntp->event_clock_watch);
+ if (sntp->clock_watch_fd > 0)
+ close(sntp->clock_watch_fd);
+ sntp->clock_watch_fd = -1;
+
sntp->event_receive = sd_event_source_unref(sntp->event_receive);
if (sntp->server_socket > 0)
close(sntp->server_socket);
sntp->server_socket = -1;
+
zero(sntp->server_addr);
free(sntp->server);
sntp->server = NULL;
}
-int sntp_new(SNTPContext **sntp, sd_event *e) {
- _cleanup_free_ SNTPContext *c;
+static int sntp_listen_setup(SNTPContext *sntp, sd_event *e) {
_cleanup_close_ int fd = -1;
struct sockaddr_in addr;
const int on = 1;
const int tos = IPTOS_LOWDELAY;
int r;
- c = new0(SNTPContext, 1);
- if (!c)
- return -ENOMEM;
-
fd = socket(PF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
if (fd < 0)
return -errno;
if (r < 0)
return -errno;
- r = sd_event_add_io(e, &c->event_receive, fd, EPOLLIN, sntp_receive_response, c);
+ r = sd_event_add_io(e, &sntp->event_receive, fd, EPOLLIN, sntp_receive_response, sntp);
if (r < 0)
return r;
- c->server_socket = fd;
+ sntp->server_socket = fd;
fd = -1;
+ return 0;
+}
+
+void sntp_report_register(SNTPContext *sntp, void (*report)(usec_t poll_usec, double offset, double delay, double jitter, bool spike)) {
+ sntp->report = report;
+}
+
+int sntp_new(SNTPContext **sntp, sd_event *e) {
+ _cleanup_free_ SNTPContext *c;
+ int r;
+
+ c = new0(SNTPContext, 1);
+ if (!c)
+ return -ENOMEM;
+
+ r = sntp_listen_setup(c, e);
+ if (r < 0)
+ return r;
+
+ r = sntp_clock_watch_setup(c);
+ if (r < 0)
+ return r;
+
*sntp = c;
c = NULL;
~ianmdlvl / elogind.git / blobdiff