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-rw-r--r--src/systemd-timesyncd/.gitignore2
-rw-r--r--src/systemd-timesyncd/systemd-timesyncd.service.in33
-rw-r--r--src/systemd-timesyncd/systemd-timesyncd.service.xml108
-rw-r--r--src/systemd-timesyncd/systemd-timesyncd.sysusers8
-rw-r--r--src/systemd-timesyncd/timesyncd-conf.c106
-rw-r--r--src/systemd-timesyncd/timesyncd-conf.h31
-rw-r--r--src/systemd-timesyncd/timesyncd-gperf.gperf19
-rw-r--r--src/systemd-timesyncd/timesyncd-manager.c1156
-rw-r--r--src/systemd-timesyncd/timesyncd-manager.h104
-rw-r--r--src/systemd-timesyncd/timesyncd-server.c150
-rw-r--r--src/systemd-timesyncd/timesyncd-server.h65
-rw-r--r--src/systemd-timesyncd/timesyncd.c164
-rw-r--r--src/systemd-timesyncd/timesyncd.conf.in16
-rw-r--r--src/systemd-timesyncd/timesyncd.conf.xml112
14 files changed, 2074 insertions, 0 deletions
diff --git a/src/systemd-timesyncd/.gitignore b/src/systemd-timesyncd/.gitignore
new file mode 100644
index 0000000000..35f4d76f79
--- /dev/null
+++ b/src/systemd-timesyncd/.gitignore
@@ -0,0 +1,2 @@
+/timesyncd.conf
+/timesyncd-gperf.c
diff --git a/src/systemd-timesyncd/systemd-timesyncd.service.in b/src/systemd-timesyncd/systemd-timesyncd.service.in
new file mode 100644
index 0000000000..a856dad709
--- /dev/null
+++ b/src/systemd-timesyncd/systemd-timesyncd.service.in
@@ -0,0 +1,33 @@
+# This file is part of systemd.
+#
+# 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.
+
+[Unit]
+Description=Network Time Synchronization
+Documentation=man:systemd-timesyncd.service(8)
+ConditionCapability=CAP_SYS_TIME
+ConditionVirtualization=!container
+DefaultDependencies=no
+RequiresMountsFor=/var/lib/systemd/clock
+After=systemd-remount-fs.service systemd-tmpfiles-setup.service systemd-sysusers.service
+Before=time-sync.target sysinit.target shutdown.target
+Conflicts=shutdown.target
+Wants=time-sync.target
+
+[Service]
+Type=notify
+Restart=always
+RestartSec=0
+ExecStart=@rootlibexecdir@/systemd-timesyncd
+CapabilityBoundingSet=CAP_SYS_TIME CAP_SETUID CAP_SETGID CAP_SETPCAP CAP_CHOWN CAP_DAC_OVERRIDE CAP_FOWNER
+PrivateTmp=yes
+PrivateDevices=yes
+ProtectSystem=full
+ProtectHome=yes
+WatchdogSec=3min
+
+[Install]
+WantedBy=sysinit.target
diff --git a/src/systemd-timesyncd/systemd-timesyncd.service.xml b/src/systemd-timesyncd/systemd-timesyncd.service.xml
new file mode 100644
index 0000000000..6ec384313b
--- /dev/null
+++ b/src/systemd-timesyncd/systemd-timesyncd.service.xml
@@ -0,0 +1,108 @@
+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+ 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 <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="systemd-timesyncd.service" conditional='ENABLE_TIMESYNCD'>
+
+ <refentryinfo>
+ <title>systemd-timesyncd.service</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>Developer</contrib>
+ <firstname>Kay</firstname>
+ <surname>Sievers</surname>
+ <email>kay@vrfy.org</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>systemd-timesyncd.service</refentrytitle>
+ <manvolnum>8</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>systemd-timesyncd.service</refname>
+ <refname>systemd-timesyncd</refname>
+ <refpurpose>Network Time Synchronization</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename>systemd-timesyncd.service</filename></para>
+ <para><filename>/usr/lib/systemd/systemd-timesyncd</filename></para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><filename>systemd-timesyncd</filename> is a system service
+ that may be used to synchronize the local system clock with a
+ remote Network Time Protocol server. It also saves the local time
+ to disk every time the clock has been synchronized and uses this
+ to possibly advance the system realtime clock on subsequent
+ reboots to ensure it monotonically advances even if the system
+ lacks a battery-buffered RTC chip.</para>
+
+ <para>The NTP servers contacted are determined from the global
+ settings in
+ <citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ the per-link static settings in <filename>.network</filename>
+ files, and the per-link dynamic settings received over DHCP. See
+ <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for more details.</para>
+
+ <para><citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+ <command>set-ntp</command> command may be used to enable and
+ start, or disable and stop this service.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Files</title>
+
+ <variablelist>
+ <varlistentry>
+ <term><filename>/var/lib/systemd/clock</filename></term>
+
+ <listitem>
+ <para>This file contains the timestamp of the last successful
+ synchronization.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>timesyncd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>timedatectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>localtime</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>hwclock</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>
diff --git a/src/systemd-timesyncd/systemd-timesyncd.sysusers b/src/systemd-timesyncd/systemd-timesyncd.sysusers
new file mode 100644
index 0000000000..4d7af7b3ae
--- /dev/null
+++ b/src/systemd-timesyncd/systemd-timesyncd.sysusers
@@ -0,0 +1,8 @@
+# This file is part of systemd.
+#
+# 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.
+
+u systemd-timesync - "systemd Time Synchronization"
diff --git a/src/systemd-timesyncd/timesyncd-conf.c b/src/systemd-timesyncd/timesyncd-conf.c
new file mode 100644
index 0000000000..20c64a3354
--- /dev/null
+++ b/src/systemd-timesyncd/timesyncd-conf.c
@@ -0,0 +1,106 @@
+/***
+ 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 "alloc-util.h"
+#include "def.h"
+#include "extract-word.h"
+#include "string-util.h"
+#include "timesyncd-conf.h"
+#include "timesyncd-manager.h"
+#include "timesyncd-server.h"
+
+int manager_parse_server_string(Manager *m, ServerType type, const char *string) {
+ ServerName *first;
+ int r;
+
+ assert(m);
+ assert(string);
+
+ first = type == SERVER_FALLBACK ? m->fallback_servers : m->system_servers;
+
+ for (;;) {
+ _cleanup_free_ char *word = NULL;
+ bool found = false;
+ ServerName *n;
+
+ r = extract_first_word(&string, &word, NULL, 0);
+ if (r < 0)
+ return log_error_errno(r, "Failed to parse timesyncd server syntax \"%s\": %m", string);
+ if (r == 0)
+ break;
+
+ /* Filter out duplicates */
+ LIST_FOREACH(names, n, first)
+ if (streq_ptr(n->string, word)) {
+ found = true;
+ break;
+ }
+
+ if (found)
+ continue;
+
+ r = server_name_new(m, NULL, type, word);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+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;
+ int r;
+
+ assert(filename);
+ assert(lvalue);
+ assert(rvalue);
+
+ if (isempty(rvalue))
+ manager_flush_server_names(m, ltype);
+ else {
+ r = manager_parse_server_string(m, ltype, rvalue);
+ if (r < 0) {
+ log_syntax(unit, LOG_ERR, filename, line, r, "Failed to parse NTP server string '%s'. Ignoring.", rvalue);
+ return 0;
+ }
+ }
+
+ return 0;
+}
+
+int manager_parse_config_file(Manager *m) {
+ assert(m);
+
+ return config_parse_many(PKGSYSCONFDIR "/timesyncd.conf",
+ CONF_PATHS_NULSTR("systemd/timesyncd.conf.d"),
+ "Time\0",
+ config_item_perf_lookup, timesyncd_gperf_lookup,
+ false, m);
+}
diff --git a/src/systemd-timesyncd/timesyncd-conf.h b/src/systemd-timesyncd/timesyncd-conf.h
new file mode 100644
index 0000000000..cba0724b1b
--- /dev/null
+++ b/src/systemd-timesyncd/timesyncd-conf.h
@@ -0,0 +1,31 @@
+#pragma once
+
+/***
+ 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 "conf-parser.h"
+#include "timesyncd-manager.h"
+
+const struct ConfigPerfItem* timesyncd_gperf_lookup(const char *key, unsigned length);
+
+int manager_parse_server_string(Manager *m, ServerType type, const char *string);
+
+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);
+
+int manager_parse_config_file(Manager *m);
diff --git a/src/systemd-timesyncd/timesyncd-gperf.gperf b/src/systemd-timesyncd/timesyncd-gperf.gperf
new file mode 100644
index 0000000000..29a2cfeef6
--- /dev/null
+++ b/src/systemd-timesyncd/timesyncd-gperf.gperf
@@ -0,0 +1,19 @@
+%{
+#include <stddef.h>
+#include "conf-parser.h"
+#include "timesyncd-conf.h"
+%}
+struct ConfigPerfItem;
+%null_strings
+%language=ANSI-C
+%define slot-name section_and_lvalue
+%define hash-function-name timesyncdd_gperf_hash
+%define lookup-function-name timesyncd_gperf_lookup
+%readonly-tables
+%omit-struct-type
+%struct-type
+%includes
+%%
+Time.NTP, config_parse_servers, SERVER_SYSTEM, 0
+Time.Servers, config_parse_servers, SERVER_SYSTEM, 0
+Time.FallbackNTP, config_parse_servers, SERVER_FALLBACK, 0
diff --git a/src/systemd-timesyncd/timesyncd-manager.c b/src/systemd-timesyncd/timesyncd-manager.c
new file mode 100644
index 0000000000..6a4b52af69
--- /dev/null
+++ b/src/systemd-timesyncd/timesyncd-manager.c
@@ -0,0 +1,1156 @@
+/***
+ 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 <errno.h>
+#include <math.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <resolv.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/timerfd.h>
+#include <sys/timex.h>
+#include <sys/types.h>
+#include <time.h>
+
+#include <systemd/sd-daemon.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "list.h"
+#include "log.h"
+#include "missing.h"
+#include "network-util.h"
+#include "ratelimit.h"
+#include "socket-util.h"
+#include "sparse-endian.h"
+#include "string-util.h"
+#include "strv.h"
+#include "time-util.h"
+#include "timesyncd-conf.h"
+#include "timesyncd-manager.h"
+#include "util.h"
+
+#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))
+
+/* Maximum acceptable root distance in seconds. */
+#define NTP_MAX_ROOT_DISTANCE 5.0
+
+/* Maximum number of missed replies before selecting another source. */
+#define NTP_MAX_MISSED_REPLIES 2
+
+/*
+ * "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 UINT64_C(2208988800)
+
+#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 int manager_arm_timer(Manager *m, usec_t next);
+static int manager_clock_watch_setup(Manager *m);
+static int manager_listen_setup(Manager *m);
+static void manager_listen_stop(Manager *m);
+
+static double ntp_ts_short_to_d(const struct ntp_ts_short *ts) {
+ return be16toh(ts->sec) + (be16toh(ts->frac) / 65536.0);
+}
+
+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 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);
+
+ r = manager_listen_setup(m);
+ if (r < 0)
+ return log_warning_errno(r, "Failed to setup connection socket: %m");
+
+ /*
+ * 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_boottime_or_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_errno(errno, "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)
+ return log_error_errno(r, "Failed to rearm timer: %m");
+
+ m->missed_replies++;
+ if (m->missed_replies > NTP_MAX_MISSED_REPLIES) {
+ r = sd_event_add_time(
+ m->event,
+ &m->event_timeout,
+ clock_boottime_or_monotonic(),
+ now(clock_boottime_or_monotonic()) + TIMEOUT_USEC, 0,
+ manager_timeout, m);
+ if (r < 0)
+ return log_error_errno(r, "Failed to arm timeout timer: %m");
+ }
+
+ 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);
+
+ 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_boottime_or_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_boottime_or_monotonic(),
+ now(clock_boottime_or_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_debug("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)
+ return log_error_errno(errno, "Failed to create timerfd: %m");
+
+ if (timerfd_settime(m->clock_watch_fd, TFD_TIMER_ABSTIME|TFD_TIMER_CANCEL_ON_SET, &its, NULL) < 0)
+ return log_error_errno(errno, "Failed to set up timerfd: %m");
+
+ r = sd_event_add_io(m->event, &m->event_clock_watch, m->clock_watch_fd, EPOLLIN, manager_clock_watch, m);
+ if (r < 0)
+ return log_error_errno(r, "Failed to create clock watch event source: %m");
+
+ 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.
+ */
+ 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", offset);
+ } else {
+ tmx.modes = ADJ_STATUS | ADJ_NANO | ADJ_SETOFFSET;
+
+ /* 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", offset);
+ }
+
+ /*
+ * An unset STA_UNSYNC will enable the kernel's 11-minute mode,
+ * which syncs the system time periodically to the RTC.
+ *
+ * In case the RTC runs in local time, never touch the RTC,
+ * we have no way to properly handle daylight saving changes and
+ * mobile devices moving between time zones.
+ */
+ if (m->rtc_local_time)
+ tmx.status |= STA_UNSYNC;
+
+ 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 -errno;
+
+ /* If touch fails, there isn't much we can do. Maybe it'll work next time. */
+ (void) 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 ? "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 += pow(m->samples[i].offset - m->samples[idx_min].offset, 2);
+ 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 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 *recv_time;
+ ssize_t len;
+ double origin, receive, trans, dest;
+ double delay, offset;
+ double root_distance;
+ 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);
+ }
+
+ /* Too short or too long packet? */
+ if (iov.iov_len < sizeof(struct ntp_msg) || (msghdr.msg_flags & MSG_TRUNC)) {
+ 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;
+ CMSG_FOREACH(cmsg, &msghdr) {
+ if (cmsg->cmsg_level != SOL_SOCKET)
+ continue;
+
+ switch (cmsg->cmsg_type) {
+ case SCM_TIMESTAMPNS:
+ recv_time = (struct timespec *) CMSG_DATA(cmsg);
+ break;
+ }
+ }
+ if (!recv_time) {
+ log_error("Invalid packet timestamp.");
+ return -EINVAL;
+ }
+
+ if (!m->pending) {
+ log_debug("Unexpected reply. Ignoring.");
+ return 0;
+ }
+
+ m->missed_replies = 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 ||
+ ntpmsg.stratum == 0 || ntpmsg.stratum >= 16) {
+ 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);
+ }
+
+ root_distance = ntp_ts_short_to_d(&ntpmsg.root_delay) / 2 + ntp_ts_short_to_d(&ntpmsg.root_dispersion);
+ if (root_distance > NTP_MAX_ROOT_DISTANCE) {
+ log_debug("Server has too large root distance. Disconnecting.");
+ return manager_connect(m);
+ }
+
+ /* valid packet */
+ m->pending = false;
+ m->retry_interval = 0;
+
+ /* Stop listening */
+ manager_listen_stop(m);
+
+ /* 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"
+ */
+ origin = ts_to_d(&m->trans_time) + OFFSET_1900_1970;
+ receive = ntp_ts_to_d(&ntpmsg.recv_time);
+ trans = ntp_ts_to_d(&ntpmsg.trans_time);
+ dest = ts_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"
+ " root distance: %.6f sec\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,
+ root_distance,
+ 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_errno(r, "Failed to call clock_adjtime(): %m");
+ }
+
+ log_debug("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)" : "");
+
+ if (!m->good) {
+ _cleanup_free_ char *pretty = NULL;
+
+ m->good = true;
+
+ server_address_pretty(m->current_server_address, &pretty);
+ log_info("Synchronized to time server %s (%s).", strna(pretty), m->current_server_name->string);
+ sd_notifyf(false, "STATUS=Synchronized to time server %s (%s).", strna(pretty), m->current_server_name->string);
+ }
+
+ r = manager_arm_timer(m, m->poll_interval_usec);
+ if (r < 0)
+ return log_error_errno(r, "Failed to rearm timer: %m");
+
+ 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);
+
+ if (m->server_socket >= 0)
+ return 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_TIMESTAMPNS, &on, sizeof(on));
+ if (r < 0)
+ return -errno;
+
+ (void) 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 void manager_listen_stop(Manager *m) {
+ assert(m);
+
+ m->event_receive = sd_event_source_unref(m->event_receive);
+ m->server_socket = safe_close(m->server_socket);
+}
+
+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->good = false;
+ m->missed_replies = NTP_MAX_MISSED_REPLIES;
+ if (m->poll_interval_usec == 0)
+ m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
+
+ server_address_pretty(m->current_server_address, &pretty);
+ log_debug("Connecting to time server %s (%s).", strna(pretty), m->current_server_name->string);
+ sd_notifyf(false, "STATUS=Connecting to time server %s (%s).", strna(pretty), m->current_server_name->string);
+
+ r = manager_clock_watch_setup(m);
+ if (r < 0)
+ return r;
+
+ return manager_send_request(m);
+}
+
+void manager_set_server_name(Manager *m, ServerName *n) {
+ assert(m);
+
+ if (m->current_server_name == n)
+ return;
+
+ m->current_server_name = n;
+ m->current_server_address = NULL;
+
+ manager_disconnect(m);
+
+ if (n)
+ log_debug("Selected server %s.", n->string);
+}
+
+void manager_set_server_address(Manager *m, ServerAddress *a) {
+ assert(m);
+
+ if (m->current_server_address == a)
+ return;
+
+ m->current_server_address = a;
+ /* If a is NULL, we are just clearing the address, without
+ * changing the name. Keep the existing name in that case. */
+ if (a)
+ m->current_server_name = a->name;
+
+ manager_disconnect(m);
+
+ if (a) {
+ _cleanup_free_ char *pretty = NULL;
+ server_address_pretty(a, &pretty);
+ log_debug("Selected address %s of server %s.", strna(pretty), a->name->string);
+ }
+}
+
+static int manager_resolve_handler(sd_resolve_query *q, int ret, const struct addrinfo *ai, void *userdata) {
+ Manager *m = userdata;
+ int r;
+
+ 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);
+ }
+
+ for (; ai; ai = ai->ai_next) {
+ _cleanup_free_ char *pretty = NULL;
+ ServerAddress *a;
+
+ assert(ai->ai_addr);
+ assert(ai->ai_addrlen >= offsetof(struct sockaddr, sa_data));
+
+ 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;
+ }
+
+ r = server_address_new(m->current_server_name, &a, (const union sockaddr_union*) ai->ai_addr, ai->ai_addrlen);
+ if (r < 0)
+ return log_error_errno(r, "Failed to add server address: %m");
+
+ server_address_pretty(a, &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);
+ }
+
+ manager_set_server_address(m, m->current_server_name->addresses);
+
+ return manager_begin(m);
+}
+
+static int manager_retry_connect(sd_event_source *source, usec_t usec, void *userdata) {
+ Manager *m = userdata;
+
+ assert(m);
+
+ return manager_connect(m);
+}
+
+int manager_connect(Manager *m) {
+ 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_boottime_or_monotonic(), now(clock_boottime_or_monotonic()) + RETRY_USEC, 0, manager_retry_connect, m);
+ if (r < 0)
+ return log_error_errno(r, "Failed to create retry timer: %m");
+
+ 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)
+ manager_set_server_address(m, m->current_server_address->addresses_next);
+ else {
+ struct addrinfo hints = {
+ .ai_flags = AI_NUMERICSERV|AI_ADDRCONFIG,
+ .ai_socktype = SOCK_DGRAM,
+ };
+
+ /* Hmm, we are through all addresses, let's look for the next host instead */
+ if (m->current_server_name && m->current_server_name->names_next)
+ manager_set_server_name(m, m->current_server_name->names_next);
+ else {
+ ServerName *f;
+ bool restart = true;
+
+ /* Our current server name list is exhausted,
+ * let's find the next one to iterate. First
+ * we try the system list, then the link list.
+ * After having processed the link list we
+ * jump back to the system list. However, if
+ * both lists are empty, we change to the
+ * fallback list. */
+ if (!m->current_server_name || m->current_server_name->type == SERVER_LINK) {
+ f = m->system_servers;
+ if (!f)
+ f = m->link_servers;
+ } else {
+ f = m->link_servers;
+ if (!f)
+ f = m->system_servers;
+ else
+ restart = false;
+ }
+
+ if (!f)
+ f = m->fallback_servers;
+
+ if (!f) {
+ manager_set_server_name(m, NULL);
+ log_debug("No server found.");
+ return 0;
+ }
+
+ if (restart && !m->exhausted_servers && m->poll_interval_usec) {
+ log_debug("Waiting after exhausting servers.");
+ r = sd_event_add_time(m->event, &m->event_retry, clock_boottime_or_monotonic(), now(clock_boottime_or_monotonic()) + m->poll_interval_usec, 0, manager_retry_connect, m);
+ if (r < 0)
+ return log_error_errno(r, "Failed to create retry timer: %m");
+
+ m->exhausted_servers = true;
+
+ /* Increase the polling interval */
+ if (m->poll_interval_usec < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
+ m->poll_interval_usec *= 2;
+
+ return 0;
+ }
+
+ m->exhausted_servers = false;
+
+ manager_set_server_name(m, f);
+ }
+
+ /* Tell the resolver to reread /etc/resolv.conf, in
+ * case it changed. */
+ res_init();
+
+ /* Flush out any previously resolved addresses */
+ server_name_flush_addresses(m->current_server_name);
+
+ log_debug("Resolving %s...", m->current_server_name->string);
+
+ r = sd_resolve_getaddrinfo(m->resolve, &m->resolve_query, m->current_server_name->string, "123", &hints, manager_resolve_handler, m);
+ if (r < 0)
+ return log_error_errno(r, "Failed to create resolver: %m");
+
+ return 1;
+ }
+
+ r = manager_begin(m);
+ if (r < 0)
+ return r;
+
+ return 1;
+}
+
+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);
+
+ manager_listen_stop(m);
+
+ 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.");
+}
+
+void manager_flush_server_names(Manager *m, ServerType t) {
+ assert(m);
+
+ if (t == SERVER_SYSTEM)
+ while (m->system_servers)
+ server_name_free(m->system_servers);
+
+ if (t == SERVER_LINK)
+ while (m->link_servers)
+ server_name_free(m->link_servers);
+
+ if (t == SERVER_FALLBACK)
+ while (m->fallback_servers)
+ server_name_free(m->fallback_servers);
+}
+
+void manager_free(Manager *m) {
+ if (!m)
+ return;
+
+ manager_disconnect(m);
+ manager_flush_server_names(m, SERVER_SYSTEM);
+ manager_flush_server_names(m, SERVER_LINK);
+ manager_flush_server_names(m, SERVER_FALLBACK);
+
+ 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);
+}
+
+static int manager_network_read_link_servers(Manager *m) {
+ _cleanup_strv_free_ char **ntp = NULL;
+ ServerName *n, *nx;
+ char **i;
+ int r;
+
+ assert(m);
+
+ r = sd_network_get_ntp(&ntp);
+ if (r < 0)
+ goto clear;
+
+ LIST_FOREACH(names, n, m->link_servers)
+ n->marked = true;
+
+ STRV_FOREACH(i, ntp) {
+ bool found = false;
+
+ LIST_FOREACH(names, n, m->link_servers)
+ if (streq(n->string, *i)) {
+ n->marked = false;
+ found = true;
+ break;
+ }
+
+ if (!found) {
+ r = server_name_new(m, NULL, SERVER_LINK, *i);
+ if (r < 0)
+ goto clear;
+ }
+ }
+
+ LIST_FOREACH_SAFE(names, n, nx, m->link_servers)
+ if (n->marked)
+ server_name_free(n);
+
+ return 0;
+
+clear:
+ manager_flush_server_names(m, SERVER_LINK);
+ return r;
+}
+
+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);
+
+ sd_network_monitor_flush(m->network_monitor);
+
+ manager_network_read_link_servers(m);
+
+ /* check if the machine is online */
+ online = network_is_online();
+
+ /* check if the client is currently connected */
+ connected = m->server_socket >= 0 || m->resolve_query || m->exhausted_servers;
+
+ 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);
+ else
+ r = manager_connect(m);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+static int manager_network_monitor_listen(Manager *m) {
+ int r, fd, events;
+
+ assert(m);
+
+ r = sd_network_monitor_new(&m->network_monitor, NULL);
+ if (r < 0)
+ return r;
+
+ fd = sd_network_monitor_get_fd(m->network_monitor);
+ if (fd < 0)
+ return fd;
+
+ events = sd_network_monitor_get_events(m->network_monitor);
+ if (events < 0)
+ return events;
+
+ r = sd_event_add_io(m->event, &m->network_event_source, fd, events, manager_network_event_handler, m);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+int manager_new(Manager **ret) {
+ _cleanup_(manager_freep) 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 = manager_parse_server_string(m, SERVER_FALLBACK, NTP_SERVERS);
+ if (r < 0)
+ return r;
+
+ r = sd_event_default(&m->event);
+ if (r < 0)
+ return r;
+
+ sd_event_add_signal(m->event, NULL, SIGTERM, NULL, NULL);
+ sd_event_add_signal(m->event, NULL, SIGINT, NULL, NULL);
+
+ sd_event_set_watchdog(m->event, true);
+
+ 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;
+
+ r = manager_network_monitor_listen(m);
+ if (r < 0)
+ return r;
+
+ manager_network_read_link_servers(m);
+
+ *ret = m;
+ m = NULL;
+
+ return 0;
+}
diff --git a/src/systemd-timesyncd/timesyncd-manager.h b/src/systemd-timesyncd/timesyncd-manager.h
new file mode 100644
index 0000000000..fd25647725
--- /dev/null
+++ b/src/systemd-timesyncd/timesyncd-manager.h
@@ -0,0 +1,104 @@
+#pragma once
+
+/***
+ 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 <systemd/sd-event.h>
+#include <systemd/sd-network.h>
+#include <systemd/sd-resolve.h>
+
+#include "list.h"
+#include "ratelimit.h"
+
+typedef struct Manager Manager;
+
+#include "timesyncd-server.h"
+
+struct Manager {
+ sd_event *event;
+ sd_resolve *resolve;
+
+ LIST_HEAD(ServerName, system_servers);
+ LIST_HEAD(ServerName, link_servers);
+ LIST_HEAD(ServerName, fallback_servers);
+
+ RateLimit ratelimit;
+ bool exhausted_servers;
+
+ /* network */
+ sd_event_source *network_event_source;
+ sd_network_monitor *network_monitor;
+
+ /* peer */
+ sd_resolve_query *resolve_query;
+ sd_event_source *event_receive;
+ ServerName *current_server_name;
+ ServerAddress *current_server_address;
+ int server_socket;
+ int missed_replies;
+ uint64_t packet_count;
+ sd_event_source *event_timeout;
+ bool good;
+
+ /* 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;
+ bool sync;
+ int drift_ppm;
+
+ /* watch for time changes */
+ sd_event_source *event_clock_watch;
+ int clock_watch_fd;
+
+ /* Retry connections */
+ sd_event_source *event_retry;
+
+ /* RTC runs in local time, leave it alone */
+ bool rtc_local_time;
+};
+
+int manager_new(Manager **ret);
+void manager_free(Manager *m);
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(Manager*, manager_free);
+
+void manager_set_server_name(Manager *m, ServerName *n);
+void manager_set_server_address(Manager *m, ServerAddress *a);
+void manager_flush_server_names(Manager *m, ServerType t);
+
+int manager_connect(Manager *m);
+void manager_disconnect(Manager *m);
diff --git a/src/systemd-timesyncd/timesyncd-server.c b/src/systemd-timesyncd/timesyncd-server.c
new file mode 100644
index 0000000000..6bda86fe6e
--- /dev/null
+++ b/src/systemd-timesyncd/timesyncd-server.c
@@ -0,0 +1,150 @@
+/***
+ 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 "alloc-util.h"
+#include "timesyncd-server.h"
+
+int server_address_new(
+ ServerName *n,
+ ServerAddress **ret,
+ const union sockaddr_union *sockaddr,
+ socklen_t socklen) {
+
+ ServerAddress *a, *tail;
+
+ assert(n);
+ assert(sockaddr);
+ assert(socklen >= offsetof(struct sockaddr, sa_data));
+ assert(socklen <= sizeof(union sockaddr_union));
+
+ a = new0(ServerAddress, 1);
+ if (!a)
+ return -ENOMEM;
+
+ memcpy(&a->sockaddr, sockaddr, socklen);
+ a->socklen = socklen;
+
+ LIST_FIND_TAIL(addresses, n->addresses, tail);
+ LIST_INSERT_AFTER(addresses, n->addresses, tail, a);
+ a->name = n;
+
+ if (ret)
+ *ret = a;
+
+ return 0;
+}
+
+ServerAddress* server_address_free(ServerAddress *a) {
+ if (!a)
+ return NULL;
+
+ if (a->name) {
+ LIST_REMOVE(addresses, a->name->addresses, a);
+
+ if (a->name->manager && a->name->manager->current_server_address == a)
+ manager_set_server_address(a->name->manager, NULL);
+ }
+
+ free(a);
+ return NULL;
+}
+
+int server_name_new(
+ Manager *m,
+ ServerName **ret,
+ ServerType type,
+ const char *string) {
+
+ ServerName *n, *tail;
+
+ assert(m);
+ assert(string);
+
+ n = new0(ServerName, 1);
+ if (!n)
+ return -ENOMEM;
+
+ n->type = type;
+ n->string = strdup(string);
+ if (!n->string) {
+ free(n);
+ return -ENOMEM;
+ }
+
+ if (type == SERVER_SYSTEM) {
+ LIST_FIND_TAIL(names, m->system_servers, tail);
+ LIST_INSERT_AFTER(names, m->system_servers, tail, n);
+ } else if (type == SERVER_LINK) {
+ LIST_FIND_TAIL(names, m->link_servers, tail);
+ LIST_INSERT_AFTER(names, m->link_servers, tail, n);
+ } else if (type == SERVER_FALLBACK) {
+ LIST_FIND_TAIL(names, m->fallback_servers, tail);
+ LIST_INSERT_AFTER(names, m->fallback_servers, tail, n);
+ } else
+ assert_not_reached("Unknown server type");
+
+ n->manager = m;
+
+ if (type != SERVER_FALLBACK &&
+ m->current_server_name &&
+ m->current_server_name->type == SERVER_FALLBACK)
+ manager_set_server_name(m, NULL);
+
+ log_debug("Added new server %s.", string);
+
+ if (ret)
+ *ret = n;
+
+ return 0;
+}
+
+ServerName *server_name_free(ServerName *n) {
+ if (!n)
+ return NULL;
+
+ server_name_flush_addresses(n);
+
+ if (n->manager) {
+ if (n->type == SERVER_SYSTEM)
+ LIST_REMOVE(names, n->manager->system_servers, n);
+ else if (n->type == SERVER_LINK)
+ LIST_REMOVE(names, n->manager->link_servers, n);
+ else if (n->type == SERVER_FALLBACK)
+ LIST_REMOVE(names, n->manager->fallback_servers, n);
+ else
+ assert_not_reached("Unknown server type");
+
+ if (n->manager->current_server_name == n)
+ manager_set_server_name(n->manager, NULL);
+ }
+
+ log_debug("Removed server %s.", n->string);
+
+ free(n->string);
+ free(n);
+
+ return NULL;
+}
+
+void server_name_flush_addresses(ServerName *n) {
+ assert(n);
+
+ while (n->addresses)
+ server_address_free(n->addresses);
+}
diff --git a/src/systemd-timesyncd/timesyncd-server.h b/src/systemd-timesyncd/timesyncd-server.h
new file mode 100644
index 0000000000..8a19e41d67
--- /dev/null
+++ b/src/systemd-timesyncd/timesyncd-server.h
@@ -0,0 +1,65 @@
+#pragma once
+
+/***
+ 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 "list.h"
+#include "socket-util.h"
+
+typedef struct ServerAddress ServerAddress;
+typedef struct ServerName ServerName;
+
+typedef enum ServerType {
+ SERVER_SYSTEM,
+ SERVER_FALLBACK,
+ SERVER_LINK,
+} ServerType;
+
+#include "timesyncd-manager.h"
+
+struct ServerAddress {
+ ServerName *name;
+
+ union sockaddr_union sockaddr;
+ socklen_t socklen;
+
+ LIST_FIELDS(ServerAddress, addresses);
+};
+
+struct ServerName {
+ Manager *manager;
+
+ ServerType type;
+ char *string;
+
+ bool marked:1;
+
+ LIST_HEAD(ServerAddress, addresses);
+ LIST_FIELDS(ServerName, names);
+};
+
+int server_address_new(ServerName *n, ServerAddress **ret, const union sockaddr_union *sockaddr, socklen_t socklen);
+ServerAddress* server_address_free(ServerAddress *a);
+static inline int server_address_pretty(ServerAddress *a, char **pretty) {
+ return sockaddr_pretty(&a->sockaddr.sa, a->socklen, true, true, pretty);
+}
+
+int server_name_new(Manager *m, ServerName **ret, ServerType type,const char *string);
+ServerName *server_name_free(ServerName *n);
+void server_name_flush_addresses(ServerName *n);
diff --git a/src/systemd-timesyncd/timesyncd.c b/src/systemd-timesyncd/timesyncd.c
new file mode 100644
index 0000000000..9e538a82f2
--- /dev/null
+++ b/src/systemd-timesyncd/timesyncd.c
@@ -0,0 +1,164 @@
+/***
+ 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 <systemd/sd-daemon.h>
+#include <systemd/sd-event.h>
+
+#include "capability-util.h"
+#include "clock-util.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "network-util.h"
+#include "signal-util.h"
+#include "timesyncd-conf.h"
+#include "timesyncd-manager.h"
+#include "user-util.h"
+
+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 */
+ (void) fchmod(fd, 0644);
+ (void) fchown(fd, uid, gid);
+
+ } else
+ /* create stamp file with the compiled-in date */
+ (void) 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_errno(errno, "Failed to restore system clock: %m");
+ }
+
+ return 0;
+}
+
+int main(int argc, char *argv[]) {
+ _cleanup_(manager_freep) Manager *m = NULL;
+ const char *user = "systemd-timesync";
+ uid_t uid;
+ gid_t gid;
+ int r;
+
+ log_set_target(LOG_TARGET_AUTO);
+ log_set_facility(LOG_CRON);
+ log_parse_environment();
+ log_open();
+
+ umask(0022);
+
+ if (argc != 1) {
+ log_error("This program does not take arguments.");
+ r = -EINVAL;
+ goto finish;
+ }
+
+ r = get_user_creds(&user, &uid, &gid, NULL, NULL);
+ if (r < 0) {
+ log_error_errno(r, "Cannot resolve user name %s: %m", user);
+ goto finish;
+ }
+
+ r = load_clock_timestamp(uid, gid);
+ if (r < 0)
+ goto finish;
+
+ r = drop_privileges(uid, gid, (1ULL << CAP_SYS_TIME));
+ if (r < 0)
+ goto finish;
+
+ assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, -1) >= 0);
+
+ r = manager_new(&m);
+ if (r < 0) {
+ log_error_errno(r, "Failed to allocate manager: %m");
+ goto finish;
+ }
+
+ if (clock_is_localtime(NULL) > 0) {
+ log_info("The system is configured to read the RTC time in the local time zone. "
+ "This mode can not be fully supported. All system time to RTC updates are disabled.");
+ m->rtc_local_time = true;
+ }
+
+ r = manager_parse_config_file(m);
+ if (r < 0)
+ log_warning_errno(r, "Failed to parse configuration file: %m");
+
+ log_debug("systemd-timesyncd running as pid " PID_FMT, getpid());
+ sd_notify(false,
+ "READY=1\n"
+ "STATUS=Daemon is running");
+
+ if (network_is_online()) {
+ r = manager_connect(m);
+ if (r < 0)
+ goto finish;
+ }
+
+ r = sd_event_loop(m->event);
+ if (r < 0) {
+ log_error_errno(r, "Failed to run event loop: %m");
+ goto finish;
+ }
+
+ /* if we got an authoritative time, store it in the file system */
+ if (m->sync)
+ (void) touch("/var/lib/systemd/clock");
+
+ sd_event_get_exit_code(m->event, &r);
+
+finish:
+ sd_notify(false,
+ "STOPPING=1\n"
+ "STATUS=Shutting down...");
+
+ return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}
diff --git a/src/systemd-timesyncd/timesyncd.conf.in b/src/systemd-timesyncd/timesyncd.conf.in
new file mode 100644
index 0000000000..b6a2ada273
--- /dev/null
+++ b/src/systemd-timesyncd/timesyncd.conf.in
@@ -0,0 +1,16 @@
+# This file is part of systemd.
+#
+# 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.
+#
+# Entries in this file show the compile time defaults.
+# You can change settings by editing this file.
+# Defaults can be restored by simply deleting this file.
+#
+# See timesyncd.conf(5) for details.
+
+[Time]
+#NTP=
+#FallbackNTP=@NTP_SERVERS@
diff --git a/src/systemd-timesyncd/timesyncd.conf.xml b/src/systemd-timesyncd/timesyncd.conf.xml
new file mode 100644
index 0000000000..8c86fd0074
--- /dev/null
+++ b/src/systemd-timesyncd/timesyncd.conf.xml
@@ -0,0 +1,112 @@
+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+ This file is part of systemd.
+
+ Copyright 2014 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/>.
+-->
+
+<refentry id="timesyncd.conf" conditional='ENABLE_TIMESYNCD'
+ xmlns:xi="http://www.w3.org/2001/XInclude">
+ <refentryinfo>
+ <title>timesyncd.conf</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>Developer</contrib>
+ <firstname>Lennart</firstname>
+ <surname>Poettering</surname>
+ <email>lennart@poettering.net</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>timesyncd.conf</refentrytitle>
+ <manvolnum>5</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>timesyncd.conf</refname>
+ <refname>timesyncd.conf.d</refname>
+ <refpurpose>Network Time Synchronization configuration files</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename>/etc/systemd/timesyncd.conf</filename></para>
+ <para><filename>/etc/systemd/timesyncd.conf.d/*.conf</filename></para>
+ <para><filename>/run/systemd/timesyncd.conf.d/*.conf</filename></para>
+ <para><filename>/usr/lib/systemd/timesyncd.conf.d/*.conf</filename></para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>These configuration files control NTP network time
+ synchronization.</para>
+
+ </refsect1>
+
+ <xi:include href="standard-conf.xml" xpointer="main-conf" />
+
+ <refsect1>
+ <title>Options</title>
+
+ <para>The following settings are configured in the <literal>[Time]</literal> section:</para>
+
+ <variablelist class='network-directives'>
+
+ <varlistentry>
+ <term><varname>NTP=</varname></term>
+ <listitem><para>A space-separated list of NTP server host
+ names or IP addresses. During runtime this list is combined
+ with any per-interface NTP servers acquired from
+ <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
+ systemd-timesyncd will contact all configured system or
+ per-interface servers in turn until one is found that
+ responds. This setting defaults to an empty
+ list.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>FallbackNTP=</varname></term>
+ <listitem><para>A space-separated list of NTP server host
+ names or IP addresses to be used as the fallback NTP servers.
+ Any per-interface NTP servers obtained from
+ <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ take precedence over this setting, as do any servers set via
+ <varname>NTP=</varname> above. This setting is hence only used
+ if no other NTP server information is known. If this option is
+ not given, a compiled-in list of NTP servers is used
+ instead.</para></listitem>
+ </varlistentry>
+
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>
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