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Systemd/src/timesync/timesyncd.c

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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2014 Kay Sievers, Lennart Poettering
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 <http://www.gnu.org/licenses/>.
***/
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <math.h>
#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 <resolv.h>
#include <sys/prctl.h>
#include <sys/types.h>
#include <grp.h>
#include "missing.h"
#include "util.h"
#include "sparse-endian.h"
#include "log.h"
#include "socket-util.h"
#include "list.h"
#include "ratelimit.h"
#include "strv.h"
#include "conf-parser.h"
#include "sd-event.h"
#include "sd-resolve.h"
#include "sd-daemon.h"
#include "sd-network.h"
#include "event-util.h"
#include "network-util.h"
#include "clock-util.h"
#include "capability.h"
#include "mkdir.h"
#include "timesyncd.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
#define RETRY_USEC (30*USEC_PER_SEC)
#define RATELIMIT_INTERVAL_USEC (10*USEC_PER_SEC)
#define RATELIMIT_BURST 10
#define TIMEOUT_USEC (10*USEC_PER_SEC)
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_;
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 load_clock_timestamp(uid_t uid, gid_t gid) {
_cleanup_close_ int fd = -1;
usec_t min = TIME_EPOCH * USEC_PER_SEC;
usec_t ct;
int r;
/* Let's try to make sure that the clock is always
* monotonically increasing, by saving the clock whenever we
* have a new NTP time, or when we shut down, and restoring it
* when we start again. This is particularly helpful on
* systems lacking a battery backed RTC. We also will adjust
* the time to at least the build time of systemd. */
fd = open("/var/lib/systemd/clock", O_RDWR|O_CLOEXEC, 0644);
if (fd >= 0) {
struct stat st;
usec_t stamp;
/* check if the recorded time is later than the compiled-in one */
r = fstat(fd, &st);
if (r >= 0) {
stamp = timespec_load(&st.st_mtim);
if (stamp > min)
min = stamp;
}
/* Try to fix the access mode, so that we can still
touch the file after dropping priviliges */
fchmod(fd, 0644);
fchown(fd, uid, gid);
} else
/* create stamp file with the compiled-in date */
touch_file("/var/lib/systemd/clock", true, min, uid, gid, 0644);
ct = now(CLOCK_REALTIME);
if (ct < min) {
struct timespec ts;
char date[FORMAT_TIMESTAMP_MAX];
log_info("System clock time unset or jumped backwards, restoring from recorded timestamp: %s",
format_timestamp(date, sizeof(date), min));
if (clock_settime(CLOCK_REALTIME, timespec_store(&ts, min)) < 0)
log_error("Failed to restore system clock: %m");
}
return 0;
}
static int manager_timeout(sd_event_source *source, usec_t usec, void *userdata) {
_cleanup_free_ char *pretty = NULL;
Manager *m = userdata;
assert(m);
assert(m->current_server_name);
assert(m->current_server_address);
server_address_pretty(m->current_server_address, &pretty);
log_info("Timed out waiting for reply from %s (%s).", strna(pretty), m->current_server_name->string);
return manager_connect(m);
}
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);
m->event_timeout = sd_event_source_unref(m->event_timeout);
/*
* 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);
server_address_pretty(m->current_server_address, &pretty);
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).", strna(pretty), m->current_server_name->string);
} else {
log_debug("Sending NTP request to %s (%s) failed: %m", strna(pretty), m->current_server_name->string);
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_MONOTONIC,
now(CLOCK_MONOTONIC) + TIMEOUT_USEC, 0,
manager_timeout, m);
if (r < 0) {
log_error("Failed to arm timeout 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
};
int r;
assert(m);
m->event_clock_watch = sd_event_source_unref(m->event_clock_watch);
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;
touch("/var/lib/systemd/clock");
m->drift_ppm = tmx.freq / 65536;
log_debug(" status : %04i %s\n"
" time now : %li.%03llu\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, (unsigned long long) (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;
assert(source);
assert(m);
if (revents & (EPOLLHUP|EPOLLERR)) {
log_warning("Server connection returned error.");
return manager_connect(m);
}
len = recvmsg(fd, &msghdr, MSG_DONTWAIT);
if (len < 0) {
if (errno == EAGAIN)
return 0;
log_warning("Error receiving message. Disconnecting.");
return manager_connect(m);
}
if (iov.iov_len < sizeof(struct ntp_msg)) {
log_warning("Invalid response from server. Disconnecting.");
return manager_connect(m);
}
if (!m->current_server_name ||
!m->current_server_address ||
!sockaddr_equal(&server_addr, &m->current_server_address->sockaddr)) {
log_debug("Response from unknown server.");
return 0;
}
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_error("Invalid packet timestamp.");
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;
}
m->event_timeout = sd_event_source_unref(m->event_timeout);
if (be32toh(ntpmsg.recv_time.sec) < TIME_EPOCH + OFFSET_1900_1970 ||
be32toh(ntpmsg.trans_time.sec) < TIME_EPOCH + OFFSET_1900_1970) {
log_debug("Invalid reply, returned times before epoch. Ignoring.");
return manager_connect(m);
}
if (NTP_FIELD_LEAP(ntpmsg.field) == NTP_LEAP_NOTINSYNC) {
log_debug("Server is not synchronized. Disconnecting.");
return manager_connect(m);
}
if (!IN_SET(NTP_FIELD_VERSION(ntpmsg.field), 3, 4)) {
log_debug("Response NTPv%d. Disconnecting.", NTP_FIELD_VERSION(ntpmsg.field));
return manager_connect(m);
}
if (NTP_FIELD_MODE(ntpmsg.field) != NTP_MODE_SERVER) {
log_debug("Unsupported mode %d. Disconnecting.", NTP_FIELD_MODE(ntpmsg.field));
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)
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: " USEC_FMT "\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) {
m->sync = true;
r = manager_adjust_clock(m, offset, leap_sec);
if (r < 0)
log_error("Failed to call clock_adjtime(): %m");
}
log_info("interval/delta/delay/jitter/drift " USEC_FMT "s/%+.3fs/%.3fs/%.3fs/%+ippm%s",
m->poll_interval_usec / USEC_PER_SEC, offset, delay, m->samples_jitter, m->drift_ppm,
spike ? " (ignored)" : "");
r = manager_arm_timer(m, m->poll_interval_usec);
if (r < 0) {
log_error("Failed to rearm timer: %s", strerror(-r));
return r;
}
return 0;
}
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);
assert(m->current_server_address);
addr.sa.sa_family = m->current_server_address->sockaddr.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->current_server_address->socklen);
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_begin(Manager *m) {
_cleanup_free_ char *pretty = NULL;
int r;
assert(m);
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;
server_address_pretty(m->current_server_address, &pretty);
log_info("Using NTP server %s (%s).", strna(pretty), m->current_server_name->string);
sd_notifyf(false, "STATUS=Using Time Server %s (%s).", strna(pretty), m->current_server_name->string);
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)
return r;
return manager_send_request(m);
}
static void server_name_flush_addresses(ServerName *n) {
ServerAddress *a;
assert(n);
while ((a = n->addresses)) {
LIST_REMOVE(addresses, n->addresses, a);
free(a);
}
}
static void manager_flush_names(Manager *m) {
ServerName *n;
assert(m);
while ((n = m->servers)) {
LIST_REMOVE(names, m->servers, n);
free(n->string);
server_name_flush_addresses(n);
free(n);
}
}
static int manager_resolve_handler(sd_resolve_query *q, int ret, const struct addrinfo *ai, void *userdata) {
Manager *m = userdata;
ServerAddress *a, *last = NULL;
assert(q);
assert(m);
assert(m->current_server_name);
m->resolve_query = sd_resolve_query_unref(m->resolve_query);
if (ret != 0) {
log_debug("Failed to resolve %s: %s", m->current_server_name->string, gai_strerror(ret));
/* Try next host */
return manager_connect(m);
}
server_name_flush_addresses(m->current_server_name);
for (; ai; ai = ai->ai_next) {
_cleanup_free_ char *pretty = NULL;
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("Unsuitable address protocol for %s", m->current_server_name->string);
continue;
}
a = new0(ServerAddress, 1);
if (!a)
return log_oom();
memcpy(&a->sockaddr, ai->ai_addr, ai->ai_addrlen);
a->socklen = ai->ai_addrlen;
LIST_INSERT_AFTER(addresses, m->current_server_name->addresses, last, a);
last = a;
sockaddr_pretty(&a->sockaddr.sa, a->socklen, true, &pretty);
log_debug("Resolved address %s for %s.", pretty, m->current_server_name->string);
}
if (!m->current_server_name->addresses) {
log_error("Failed to find suitable address for host %s.", m->current_server_name->string);
/* Try next host */
return manager_connect(m);
}
m->current_server_address = m->current_server_name->addresses;
return manager_begin(m);
}
static int manager_retry(sd_event_source *source, usec_t usec, void *userdata) {
Manager *m = userdata;
assert(m);
return manager_connect(m);
}
static int manager_connect(Manager *m) {
struct addrinfo hints = {
.ai_flags = AI_NUMERICSERV|AI_ADDRCONFIG,
.ai_socktype = SOCK_DGRAM,
};
int r;
assert(m);
manager_disconnect(m);
m->event_retry = sd_event_source_unref(m->event_retry);
if (!ratelimit_test(&m->ratelimit)) {
log_debug("Slowing down attempts to contact servers.");
r = sd_event_add_time(m->event, &m->event_retry, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + RETRY_USEC, 0, manager_retry, m);
if (r < 0) {
log_error("Failed to create retry timer: %s", strerror(-r));
return r;
}
return 0;
}
/* If we already are operating on some address, switch to the
* next one. */
if (m->current_server_address && m->current_server_address->addresses_next)
m->current_server_address = m->current_server_address->addresses_next;
else {
/* Hmm, we are through all addresses, let's look for the next host instead */
m->current_server_address = NULL;
if (m->current_server_name && m->current_server_name->names_next)
m->current_server_name = m->current_server_name->names_next;
else {
if (!m->servers) {
m->current_server_name = NULL;
log_debug("No server found.");
return 0;
}
m->current_server_name = m->servers;
}
/* Tell the resolver to reread /etc/resolv.conf, in
* case it changed. */
res_init();
r = sd_resolve_getaddrinfo(m->resolve, &m->resolve_query, m->current_server_name->string, "123", &hints, manager_resolve_handler, m);
if (r < 0) {
log_error("Failed to create resolver: %s", strerror(-r));
return r;
}
return 1;
}
r = manager_begin(m);
if (r < 0)
return r;
return 1;
}
static int manager_add_server(Manager *m, const char *server) {
ServerName *n, *tail;
assert(m);
assert(server);
n = new0(ServerName, 1);
if (!n)
return -ENOMEM;
n->string = strdup(server);
if (!n->string) {
free(n);
return -ENOMEM;
}
LIST_FIND_TAIL(names, m->servers, tail);
LIST_INSERT_AFTER(names, m->servers, tail, n);
return 0;
}
static int manager_add_server_string(Manager *m, const char *string) {
char *w, *state;
size_t l;
int r;
assert(m);
assert(string);
FOREACH_WORD_QUOTED(w, l, string, state) {
char t[l+1];
memcpy(t, w, l);
t[l] = 0;
r = manager_add_server(m, t);
if (r < 0)
log_error("Failed to add server %s to configuration, ignoring: %s", t, strerror(-r));
}
return 0;
}
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);
m->event_clock_watch = sd_event_source_unref(m->event_clock_watch);
m->clock_watch_fd = safe_close(m->clock_watch_fd);
m->event_timeout = sd_event_source_unref(m->event_timeout);
sd_notifyf(false, "STATUS=Idle.");
}
static int manager_new(Manager **ret) {
_cleanup_manager_free_ Manager *m = NULL;
int r;
assert(ret);
m = new0(Manager, 1);
if (!m)
return -ENOMEM;
m->server_socket = m->clock_watch_fd = -1;
RATELIMIT_INIT(m->ratelimit, RATELIMIT_INTERVAL_USEC, RATELIMIT_BURST);
r = sd_event_default(&m->event);
if (r < 0)
return r;
sd_event_set_watchdog(m->event, true);
sd_event_add_signal(m->event, NULL, SIGTERM, NULL, NULL);
sd_event_add_signal(m->event, NULL, 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 r;
*ret = m;
m = NULL;
return 0;
}
static void manager_free(Manager *m) {
if (!m)
return;
manager_disconnect(m);
manager_flush_names(m);
sd_event_source_unref(m->event_retry);
sd_event_source_unref(m->network_event_source);
sd_network_monitor_unref(m->network_monitor);
sd_resolve_unref(m->resolve);
sd_event_unref(m->event);
free(m);
}
int config_parse_servers(
const char *unit,
const char *filename,
unsigned line,
const char *section,
unsigned section_line,
const char *lvalue,
int ltype,
const char *rvalue,
void *data,
void *userdata) {
Manager *m = userdata;
assert(filename);
assert(lvalue);
assert(rvalue);
manager_flush_names(m);
manager_add_server_string(m, rvalue);
return 0;
}
static int manager_parse_config_file(Manager *m) {
static const char fn[] = "/etc/systemd/timesyncd.conf";
_cleanup_fclose_ FILE *f = NULL;
int r;
assert(m);
f = fopen(fn, "re");
if (!f) {
if (errno == ENOENT)
return 0;
log_warning("Failed to open configuration file %s: %m", fn);
return -errno;
}
r = config_parse(NULL, fn, f, "Time\0", config_item_perf_lookup,
timesyncd_gperf_lookup, false, false, m);
if (r < 0)
log_warning("Failed to parse configuration file: %s", strerror(-r));
return r;
}
static bool network_is_online(void) {
_cleanup_free_ char *state = NULL;
int r;
r = sd_network_get_operational_state(&state);
if (r >= 0 && STR_IN_SET(state, "routable", "degraded"))
return true;
return false;
}
static int manager_network_event_handler(sd_event_source *s, int fd, uint32_t revents,
void *userdata) {
Manager *m = userdata;
bool connected, online;
int r;
assert(m);
/* check if the machine is online */
online = network_is_online();
/* check if the client is currently connected */
connected = (m->server_socket != -1);
if (connected && !online) {
log_info("No network connectivity, watching for changes.");
manager_disconnect(m);
} else if (!connected && online) {
log_info("Network configuration changed, trying to establish connection.");
if (m->current_server_address) {
r = manager_begin(m);
if (r < 0)
return r;
} else {
r = manager_connect(m);
if (r < 0)
return r;
}
}
sd_network_monitor_flush(m->network_monitor);
return 0;
}
static int manager_network_monitor_listen(Manager *m) {
_cleanup_event_source_unref_ sd_event_source *event_source = NULL;
_cleanup_network_monitor_unref_ sd_network_monitor *monitor = NULL;
int r, fd, events;
r = sd_network_monitor_new(NULL, &monitor);
if (r < 0)
return r;
fd = sd_network_monitor_get_fd(monitor);
if (fd < 0)
return fd;
events = sd_network_monitor_get_events(monitor);
if (events < 0)
return events;
r = sd_event_add_io(m->event, &event_source, fd, events,
&manager_network_event_handler, m);
if (r < 0)
return r;
m->network_monitor = monitor;
m->network_event_source = event_source;
monitor = NULL;
event_source = NULL;
return 0;
}
int main(int argc, char *argv[]) {
const char *user = "systemd-timesync";
_cleanup_manager_free_ Manager *m = NULL;
uid_t uid;
gid_t gid;
int r;
if (argc > 1) {
log_error("This program does not take arguments.");
return EXIT_FAILURE;
}
log_set_target(LOG_TARGET_AUTO);
log_set_facility(LOG_CRON);
log_parse_environment();
log_open();
umask(0022);
r = get_user_creds(&user, &uid, &gid, NULL, NULL);
if (r < 0) {
log_error("Cannot resolve user name %s: %s", user, strerror(-r));
return r;
}
r = load_clock_timestamp(uid, gid);
if (r < 0)
goto out;
r = drop_privileges(uid, gid, (1ULL << CAP_SYS_TIME));
if (r < 0)
goto out;
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;
}
manager_add_server_string(m, NTP_SERVERS);
manager_parse_config_file(m);
r = manager_network_monitor_listen(m);
if (r < 0) {
log_error("Failed to listen to networkd events: %s", strerror(-r));
goto out;
}
log_debug("systemd-timesyncd running as pid %lu", (unsigned long) getpid());
sd_notify(false, "READY=1");
if (network_is_online()) {
r = manager_connect(m);
if (r < 0)
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);
/* if we got an authoritative time, store it in the file system */
if (m->sync)
touch("/var/lib/systemd/clock");
out:
sd_notify(false, "STATUS=Shutting down...");
return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}
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