/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2014 Kay Sievers systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see . ***/ #include #include #include #include #include #include #include #include #include #include #include #include #include #include "missing.h" #include "util.h" #include "sparse-endian.h" #include "log.h" #include "socket-util.h" #include "sd-event.h" #include "sd-resolve.h" #include "sd-daemon.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 /* 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; struct Manager { sd_event *event; sd_resolve *resolve; /* peer */ sd_resolve_query *resolve_query; sd_event_source *event_receive; char *server; union sockaddr_union server_addr; socklen_t server_addr_length; 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 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) { 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; /* * 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); len = sendto(m->server_socket, &ntpmsg, sizeof(ntpmsg), MSG_DONTWAIT, &m->server_addr.sa, m->server_addr_length); if (len == sizeof(ntpmsg)) { m->pending = true; log_debug("Sent NTP request to: %s", m->server); } else log_debug("Sending NTP request to %s failed: %m", m->server); /* 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; return manager_arm_timer(m, m->retry_interval); } 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 }; int r; assert(m); m->event_clock_watch = sd_event_source_unref(m->event_clock_watch); m->clock_watch_fd = safe_close(m->clock_watch_fd); m->clock_watch_fd = timerfd_create(CLOCK_REALTIME, TFD_NONBLOCK|TFD_CLOEXEC); if (m->clock_watch_fd < 0) { log_error("Failed to create timerfd: %m"); return -errno; } if (timerfd_settime(m->clock_watch_fd, TFD_TIMER_ABSTIME|TFD_TIMER_CANCEL_ON_SET, &its, NULL) < 0) { log_error("Failed to set up timerfd: %m"); return -errno; } r = sd_event_add_io(m->event, &m->event_clock_watch, m->clock_watch_fd, EPOLLIN, manager_clock_watch, m); if (r < 0) { log_error("Failed to create clock watch event source: %s", strerror(-r)); return r; } return 0; } static int manager_adjust_clock(Manager *m, double offset, int leap_sec) { struct timex tmx = {}; int r; assert(m); /* * For small deltas, tell the kernel to gradually adjust the system * clock to the NTP time, larger deltas are just directly set. * * Clear STA_UNSYNC, it will enable the kernel's 11-minute mode, which * syncs the system time periodically to the hardware clock. */ if (fabs(offset) < NTP_MAX_ADJUST) { tmx.modes = ADJ_STATUS | ADJ_NANO | ADJ_OFFSET | ADJ_TIMECONST | ADJ_MAXERROR | ADJ_ESTERROR; tmx.status = STA_PLL; tmx.offset = offset * NSEC_PER_SEC; tmx.constant = log2i(m->poll_interval_usec / USEC_PER_SEC) - 4; tmx.maxerror = 0; tmx.esterror = 0; log_debug(" adjust (slew): %+.3f sec\n", offset); } else { tmx.modes = ADJ_SETOFFSET | ADJ_NANO; /* ADJ_NANO uses nanoseconds in the microseconds field */ tmx.time.tv_sec = (long)offset; tmx.time.tv_usec = (offset - tmx.time.tv_sec) * NSEC_PER_SEC; /* the kernel expects -0.3s as {-1, 7000.000.000} */ if (tmx.time.tv_usec < 0) { tmx.time.tv_sec -= 1; tmx.time.tv_usec += NSEC_PER_SEC; } m->jumped = true; log_debug(" adjust (jump): %+.3f sec\n", offset); } switch (leap_sec) { case 1: tmx.status |= STA_INS; break; case -1: tmx.status |= STA_DEL; break; } r = clock_adjtime(CLOCK_REALTIME, &tmx); if (r < 0) return r; m->drift_ppm = tmx.freq / 65536; log_debug(" status : %04i %s\n" " time now : %li.%03lli\n" " constant : %li\n" " offset : %+.3f sec\n" " freq offset : %+li (%i ppm)\n", tmx.status, tmx.status & STA_UNSYNC ? "" : "sync", tmx.time.tv_sec, tmx.time.tv_usec / NSEC_PER_MSEC, tmx.constant, (double)tmx.offset / NSEC_PER_SEC, tmx.freq, m->drift_ppm); return 0; } static bool manager_sample_spike_detection(Manager *m, double offset, double delay) { unsigned int i, idx_cur, idx_new, idx_min; double jitter; double j; assert(m); m->packet_count++; /* ignore initial sample */ if (m->packet_count == 1) return false; /* store the current data in our samples array */ idx_cur = m->samples_idx; idx_new = (idx_cur + 1) % ELEMENTSOF(m->samples); m->samples_idx = idx_new; m->samples[idx_new].offset = offset; m->samples[idx_new].delay = delay; /* calculate new jitter value from the RMS differences relative to the lowest delay sample */ jitter = m->samples_jitter; for (idx_min = idx_cur, i = 0; i < ELEMENTSOF(m->samples); i++) if (m->samples[i].delay > 0 && m->samples[i].delay < m->samples[idx_min].delay) idx_min = i; j = 0; for (i = 0; i < ELEMENTSOF(m->samples); i++) j += square(m->samples[i].offset - m->samples[idx_min].offset); m->samples_jitter = sqrt(j / (ELEMENTSOF(m->samples) - 1)); /* ignore samples when resyncing */ if (m->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 (m->packet_count < 4) return false; /* do not accept anything worse than the maximum possible error of the best sample */ if (fabs(offset) > m->samples[idx_min].delay) return true; /* compare the difference between the current offset to the previous offset and jitter */ return fabs(offset - m->samples[idx_cur].offset) > 3 * jitter; } static void manager_adjust_poll(Manager *m, double offset, bool spike) { assert(m); if (m->poll_resync) { m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC; m->poll_resync = false; return; } /* set to minimal poll interval */ if (!spike && fabs(offset) > NTP_ACCURACY_SEC) { m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC; return; } /* increase polling interval */ if (fabs(offset) < NTP_ACCURACY_SEC * 0.25) { if (m->poll_interval_usec < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC) m->poll_interval_usec *= 2; return; } /* decrease polling interval */ if (spike || fabs(offset) > NTP_ACCURACY_SEC * 0.75) { if (m->poll_interval_usec > NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC) m->poll_interval_usec /= 2; return; } } static bool sockaddr_equal(union sockaddr_union *a, union sockaddr_union *b) { assert(a); assert(b); if (a->sa.sa_family != b->sa.sa_family) return false; if (a->sa.sa_family == AF_INET) return a->in.sin_addr.s_addr == b->in.sin_addr.s_addr; if (a->sa.sa_family == AF_INET6) return memcmp(&a->in6.sin6_addr, &b->in6.sin6_addr, sizeof(a->in6.sin6_addr)) == 0; return false; } static int manager_receive_response(sd_event_source *source, int fd, uint32_t revents, void *userdata) { Manager *m = userdata; struct ntp_msg ntpmsg; struct iovec iov = { .iov_base = &ntpmsg, .iov_len = sizeof(ntpmsg), }; union { struct cmsghdr cmsghdr; uint8_t buf[CMSG_SPACE(sizeof(struct timeval))]; } control; union sockaddr_union server_addr; struct msghdr msghdr = { .msg_iov = &iov, .msg_iovlen = 1, .msg_control = &control, .msg_controllen = sizeof(control), .msg_name = &server_addr, .msg_namelen = sizeof(server_addr), }; struct cmsghdr *cmsg; struct timespec now_ts; struct timeval *recv_time; ssize_t len; 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."); return -ENOTCONN; } len = recvmsg(fd, &msghdr, MSG_DONTWAIT); if (len < 0) { if (errno == EAGAIN) return 0; log_debug("Error receiving message. Disconnecting."); return -errno; } if (iov.iov_len < sizeof(struct ntp_msg)) { log_debug("Invalid response from server. Disconnecting."); return -EINVAL; } if (!sockaddr_equal(&server_addr, &m->server_addr)) { log_debug("Response from unknown server. Disconnecting."); return -EINVAL; } recv_time = NULL; for (cmsg = CMSG_FIRSTHDR(&msghdr); cmsg; cmsg = CMSG_NXTHDR(&msghdr, cmsg)) { if (cmsg->cmsg_level != SOL_SOCKET) continue; switch (cmsg->cmsg_type) { case SCM_TIMESTAMP: recv_time = (struct timeval *) CMSG_DATA(cmsg); break; } } if (!recv_time) { log_debug("Invalid packet timestamp. Disconnecting."); return -EINVAL; } if (!m->pending) { 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) != m->trans_time.tv_sec + OFFSET_1900_1970 || be32toh(ntpmsg.origin_time.frac) != m->trans_time.tv_nsec) { 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."); return -EINVAL; } if (NTP_FIELD_VERSION(ntpmsg.field) != 4) { 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)); return -EINVAL; } /* valid packet */ m->pending = false; m->retry_interval = 0; /* announce leap seconds */ if (NTP_FIELD_LEAP(ntpmsg.field) & NTP_LEAP_PLUSSEC) leap_sec = 1; else if (NTP_FIELD_LEAP(ntpmsg.field) & NTP_LEAP_MINUSSEC) leap_sec = -1; else leap_sec = 0; /* * "Timestamp Name ID When Generated * ------------------------------------------------------------ * Originate Timestamp T1 time request sent by client * Receive Timestamp T2 time request received by server * Transmit Timestamp T3 time reply sent by server * Destination Timestamp T4 time reply received by client * * 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_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; 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 = ((receive - origin) + (trans - dest)) / 2; delay = (dest - origin) - (trans - receive); spike = manager_sample_spike_detection(m, offset, delay); manager_adjust_poll(m, offset, spike); log_debug("NTP response:\n" " leap : %u\n" " version : %u\n" " mode : %u\n" " stratum : %u\n" " precision : %.6f sec (%d)\n" " reference : %.4s\n" " origin : %.3f\n" " receive : %.3f\n" " transmit : %.3f\n" " dest : %.3f\n" " offset : %+.3f sec\n" " delay : %+.3f sec\n" " packet count : %"PRIu64"\n" " jitter : %.3f%s\n" " poll interval: %llu\n", NTP_FIELD_LEAP(ntpmsg.field), NTP_FIELD_VERSION(ntpmsg.field), NTP_FIELD_MODE(ntpmsg.field), ntpmsg.stratum, exp2(ntpmsg.precision), ntpmsg.precision, ntpmsg.stratum == 1 ? ntpmsg.refid : "n/a", origin - OFFSET_1900_1970, receive - OFFSET_1900_1970, trans - OFFSET_1900_1970, dest - OFFSET_1900_1970, offset, delay, m->packet_count, m->samples_jitter, spike ? " spike" : "", m->poll_interval_usec / USEC_PER_SEC); if (!spike) { r = manager_adjust_clock(m, offset, leap_sec); if (r < 0) log_error("Failed to call clock_adjtime(): %m"); } log_info("%s: interval/delta/delay/jitter/drift %llus/%+.3fs/%.3fs/%.3fs/%+ippm%s", m->server, m->poll_interval_usec / USEC_PER_SEC, offset, delay, m->samples_jitter, m->drift_ppm, spike ? " (ignored)" : ""); return manager_arm_timer(m, m->poll_interval_usec); } static int manager_listen_setup(Manager *m) { union sockaddr_union addr = {}; static const int tos = IPTOS_LOWDELAY; static const int on = 1; int r; assert(m); assert(m->server_socket < 0); assert(!m->event_receive); addr.sa.sa_family = m->server_addr.sa.sa_family; m->server_socket = socket(addr.sa.sa_family, SOCK_DGRAM | SOCK_CLOEXEC, 0); if (m->server_socket < 0) return -errno; r = bind(m->server_socket, &addr.sa, m->server_addr_length); if (r < 0) return -errno; r = setsockopt(m->server_socket, SOL_SOCKET, SO_TIMESTAMP, &on, sizeof(on)); if (r < 0) return -errno; setsockopt(m->server_socket, IPPROTO_IP, IP_TOS, &tos, sizeof(tos)); return sd_event_add_io(m->event, &m->event_receive, m->server_socket, EPOLLIN, manager_receive_response, m); } static int manager_resolve_handler(sd_resolve_query *q, int ret, const struct addrinfo *ai, void *userdata) { _cleanup_free_ char *pretty = NULL; Manager *m = userdata; int r; assert(q); assert(m); m->resolve_query = sd_resolve_query_unref(m->resolve_query); if (ret != 0) { log_error("Failed to resolve %s: %s", m->server, gai_strerror(ret)); return -EHOSTUNREACH; } assert(ai); assert(ai->ai_addr); assert(ai->ai_addrlen >= offsetof(struct sockaddr, sa_data)); assert(ai->ai_addrlen <= sizeof(union sockaddr_union)); if (!IN_SET(ai->ai_addr->sa_family, AF_INET, AF_INET6)) { log_warning("Failed to find IP address for %s", m->server); return -EHOSTUNREACH; } memcpy(&m->server_addr, ai->ai_addr, ai->ai_addrlen); m->server_addr_length = ai->ai_addrlen; r = sockaddr_pretty(&m->server_addr.sa, m->server_addr_length, true, &pretty); if (r < 0) { log_warning("Failed to decode address of %s: %s", m->server, strerror(-r)); return r; } log_debug("Connecting to NTP server %s.", pretty); sd_notifyf(false, "STATUS=Using Time Server %s", pretty); r = manager_listen_setup(m); if (r < 0) { log_warning("Failed to setup connection socket: %s", strerror(-r)); return r; } r = manager_clock_watch_setup(m); if (r < 0) { log_warning("Failed to setup clock watch: %s", strerror(-r)); return r; } return manager_send_request(m); } static int manager_connect(Manager *m, const char *server) { struct addrinfo hints = { .ai_flags = AI_NUMERICSERV|AI_ADDRCONFIG, .ai_socktype = SOCK_DGRAM, }; assert(m); assert(server); if (m->server) return -EBUSY; m->server = strdup(server); if (!m->server) return -ENOMEM; m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC; return sd_resolve_getaddrinfo(m->resolve, &m->resolve_query, m->server, "123", &hints, manager_resolve_handler, m); } static void manager_disconnect(Manager *m) { assert(m); m->resolve_query = sd_resolve_query_unref(m->resolve_query); m->event_timer = sd_event_source_unref(m->event_timer); m->event_receive = sd_event_source_unref(m->event_receive); m->server_socket = safe_close(m->server_socket); zero(m->server_addr); m->server_addr_length = 0; free(m->server); m->server = NULL; m->event_clock_watch = sd_event_source_unref(m->event_clock_watch); m->clock_watch_fd = safe_close(m->clock_watch_fd); } static int manager_new(Manager **ret) { _cleanup_manager_free_ Manager *m = NULL; int r; m = new0(Manager, 1); if (!m) return -ENOMEM; m->server_socket = m->clock_watch_fd = -1; r = sd_event_default(&m->event); if (r < 0) return r; sd_event_add_signal(m->event, &m->sigterm, SIGTERM, NULL, NULL); sd_event_add_signal(m->event, &m->sigint, SIGINT, NULL, NULL); r = sd_resolve_default(&m->resolve); if (r < 0) return r; r = sd_resolve_attach_event(m->resolve, m->event, 0); if (r < 0) return 0; r = manager_clock_watch_setup(m); if (r < 0) return r; *ret = m; m = NULL; return 0; } static void manager_free(Manager *m) { if (!m) return; manager_disconnect(m); sd_event_source_unref(m->sigint); sd_event_source_unref(m->sigterm); sd_resolve_unref(m->resolve); sd_event_unref(m->event); free(m); } int main(int argc, char *argv[]) { _cleanup_manager_free_ Manager *m = NULL; int r; log_set_target(LOG_TARGET_AUTO); log_parse_environment(); log_open(); assert_se(sigprocmask_many(SIG_BLOCK, SIGTERM, SIGINT, -1) == 0); r = manager_new(&m); if (r < 0) { log_error("Failed to allocate manager: %s", strerror(-r)); goto out; } sd_notify(false, "READY=1"); r = manager_connect(m, "time1.google.com"); if (r < 0) { log_error("Failed to initiate connection: %s", strerror(-r)); goto out; } r = sd_event_loop(m->event); if (r < 0) { log_error("Failed to run event loop: %s", strerror(-r)); goto out; } sd_event_get_exit_code(m->event, &r); out: return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS; }