-
-#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
-
-/* expected accuracy of time synchronization; used to adjust the poll interval */
-#define NTP_ACCURACY_SEC 0.2
-
-/*
- * "A client MUST NOT under any conditions use a poll interval less
- * than 15 seconds."
- */
-#define NTP_POLL_INTERVAL_MIN_SEC 32
-#define NTP_POLL_INTERVAL_MAX_SEC 2048
-
-/*
- * 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
-#define NTP_MODE_CLIENT 3
-#define NTP_MODE_SERVER 4
-#define NTP_FIELD_LEAP(f) (((f) >> 6) & 3)
-#define NTP_FIELD_VERSION(f) (((f) >> 3) & 7)
-#define NTP_FIELD_MODE(f) ((f) & 7)
-#define NTP_FIELD(l, v, m) (((l) << 6) | ((v) << 3) | (m))
-
-/*
- * "NTP timestamps are represented as a 64-bit unsigned fixed-point number,
- * in seconds relative to 0h on 1 January 1900."
- */
-#define OFFSET_1900_1970 2208988800UL
-
-struct ntp_ts {
- be32_t sec;
- be32_t frac;
-} _packed_;
-
-struct ntp_ts_short {
- be16_t sec;
- be16_t frac;
-} _packed_;
-
-struct ntp_msg {
- uint8_t field;
- uint8_t stratum;
- int8_t poll;
- int8_t precision;
- struct ntp_ts_short root_delay;
- struct ntp_ts_short root_dispersion;
- char refid[4];
- struct ntp_ts reference_time;
- struct ntp_ts origin_time;
- struct ntp_ts recv_time;
- struct ntp_ts trans_time;
-} _packed_;
-
-typedef struct Manager Manager;
-typedef struct ServerAddress ServerAddress;
-typedef struct ServerName ServerName;
-
-struct ServerAddress {
- union sockaddr_union sockaddr;
- socklen_t socklen;
- LIST_FIELDS(ServerAddress, addresses);
-};
-
-struct ServerName {
- char *string;
- LIST_HEAD(ServerAddress, addresses);
- LIST_FIELDS(ServerName, names);
-};
-
-struct Manager {
- sd_event *event;
- sd_resolve *resolve;
-
- LIST_HEAD(ServerName, servers);
-
- /* peer */
- sd_resolve_query *resolve_query;
- sd_event_source *event_receive;
- ServerName *current_server_name;
- ServerAddress *current_server_address;
- 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;
-
- /* 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;
- int drift_ppm;
-
- /* watch for time changes */
- sd_event_source *event_clock_watch;
- int clock_watch_fd;
-
- /* Handle SIGINT/SIGTERM */
- sd_event_source *sigterm, *sigint;
-};
-
-static void manager_free(Manager *m);
-DEFINE_TRIVIAL_CLEANUP_FUNC(Manager*, manager_free);
-#define _cleanup_manager_free_ _cleanup_(manager_freep)
-
-static int manager_arm_timer(Manager *m, usec_t next);
-static int manager_clock_watch_setup(Manager *m);
-static int manager_connect(Manager *m);
-static void manager_disconnect(Manager *m);
-
-static double ntp_ts_to_d(const struct ntp_ts *ts) {
- return be32toh(ts->sec) + ((double)be32toh(ts->frac) / UINT_MAX);
-}
-
-static double ts_to_d(const struct timespec *ts) {
- 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;
-}
-
-static int manager_send_request(Manager *m) {
- _cleanup_free_ char *pretty = NULL;
- struct ntp_msg ntpmsg = {
- /*
- * "The client initializes the NTP message header, sends the request
- * to the server, and strips the time of day from the Transmit
- * Timestamp field of the reply. For this purpose, all the NTP
- * header fields are set to 0, except the Mode, VN, and optional
- * Transmit Timestamp fields."
- */
- .field = NTP_FIELD(0, 4, NTP_MODE_CLIENT),
- };
- ssize_t len;
- int r;
-
- assert(m);
- assert(m->current_server_name);
- assert(m->current_server_address);
-
- /*
- * Set transmit timestamp, remember it; the server will send that back
- * as the origin timestamp and we have an indication that this is the
- * 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.
- */
- assert_se(clock_gettime(CLOCK_MONOTONIC, &m->trans_time_mon) >= 0);
- assert_se(clock_gettime(CLOCK_REALTIME, &m->trans_time) >= 0);
- ntpmsg.trans_time.sec = htobe32(m->trans_time.tv_sec + OFFSET_1900_1970);
- ntpmsg.trans_time.frac = htobe32(m->trans_time.tv_nsec);
-
- r = sockaddr_pretty(&m->current_server_address->sockaddr.sa, m->current_server_address->socklen, true, &pretty);
- if (r < 0) {
- log_error("Failed to format sockaddr: %s", strerror(-r));
- return r;
- }
-
- len = sendto(m->server_socket, &ntpmsg, sizeof(ntpmsg), MSG_DONTWAIT, &m->current_server_address->sockaddr.sa, m->current_server_address->socklen);
- if (len == sizeof(ntpmsg)) {
- m->pending = true;
- log_debug("Sent NTP request to %s (%s)", pretty, m->current_server_name->string);
- } else
- log_debug("Sending NTP request to %s (%s) failed: %m", pretty, m->current_server_name->string);
-
- /* re-arm timer with incresing 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;
- }
-
- return 0;
-}
-
-static int manager_timer(sd_event_source *source, usec_t usec, void *userdata) {
- Manager *m = userdata;
-
- assert(m);
-
- return manager_send_request(m);
-}
-
-static int manager_arm_timer(Manager *m, usec_t next) {
- int r;
-
- assert(m);
- assert(m->event_receive);
-
- if (next == 0) {
- m->event_timer = sd_event_source_unref(m->event_timer);
- return 0;
- }
-
- if (m->event_timer) {
- r = sd_event_source_set_time(m->event_timer, now(CLOCK_MONOTONIC) + next);
- if (r < 0)
- return r;
-
- return sd_event_source_set_enabled(m->event_timer, SD_EVENT_ONESHOT);
- }
-
- return sd_event_add_time(
- m->event,
- &m->event_timer,
- CLOCK_MONOTONIC,
- now(CLOCK_MONOTONIC) + next, 0,
- manager_timer, m);
-}
-
-static int manager_clock_watch(sd_event_source *source, int fd, uint32_t revents, void *userdata) {
- Manager *m = userdata;
-
- assert(m);
-
- /* rearm timer */
- manager_clock_watch_setup(m);
-
- /* skip our own jumps */
- if (m->jumped) {
- m->jumped = false;
- return 0;
- }
-
- /* resync */
- log_info("System time changed. Resyncing.");
- m->poll_resync = true;
- return manager_send_request(m);
-}
-
-/* wake up when the system time changes underneath us */
-static int manager_clock_watch_setup(Manager *m) {
-
- struct itimerspec its = {
- .it_value.tv_sec = TIME_T_MAX
- };
-