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chrony/main.c
Miroslav Lichvar 7f45eb7957 ntp: add server time smoothing 
Time smoothing determines an offset that needs to be applied to the
cooked time to make it smooth for external observers. Observed offset
and frequency change slowly and there are no discontinuities. This can
be used on an NTP server to make it easier for the clients to track the
time and keep their clocks close together even when large offset or
frequency corrections are applied to the server's clock (e.g. after
being offline for longer time).

Accumulated offset and frequency are smoothed out in three stages. In
the first stage, the frequency is changed at a constant rate (wander) up
to a maximum, in the second stage the frequency stays at the maximum for
as long as needed and in the third stage the frequency is brought back
to zero.

Time smoothing is configured by the smoothtime directive. It takes two
arguments, maximum frequency offset and maximum wander. It's disabled by
default.
2015-04-07 10:42:26 +02:00

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/*
chronyd/chronyc - Programs for keeping computer clocks accurate.
**********************************************************************
* Copyright (C) Richard P. Curnow 1997-2003
* Copyright (C) John G. Hasler 2009
* Copyright (C) Miroslav Lichvar 2012-2014
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
**********************************************************************
=======================================================================
The main program
*/
#include "config.h"
#include "sysincl.h"
#include "main.h"
#include "sched.h"
#include "local.h"
#include "sys.h"
#include "ntp_io.h"
#include "ntp_sources.h"
#include "ntp_core.h"
#include "sources.h"
#include "sourcestats.h"
#include "reference.h"
#include "logging.h"
#include "conf.h"
#include "cmdmon.h"
#include "keys.h"
#include "manual.h"
#include "rtc.h"
#include "refclock.h"
#include "clientlog.h"
#include "nameserv.h"
#include "smooth.h"
#include "tempcomp.h"
/* ================================================== */
/* Set when the initialisation chain has been completed. Prevents finalisation
* chain being run if a fatal error happened early. */
static int initialised = 0;
static int exit_status = 0;
static int reload = 0;
static REF_Mode ref_mode = REF_ModeNormal;
/* ================================================== */
static void
delete_pidfile(void)
{
const char *pidfile = CNF_GetPidFile();
/* Don't care if this fails, there's not a lot we can do */
unlink(pidfile);
}
/* ================================================== */
void
MAI_CleanupAndExit(void)
{
if (!initialised) exit(exit_status);
if (CNF_GetDumpOnExit()) {
SRC_DumpSources();
}
/* Don't update clock when removing sources */
REF_SetMode(REF_ModeIgnore);
SMT_Finalise();
TMC_Finalise();
MNL_Finalise();
CLG_Finalise();
NSR_Finalise();
NCR_Finalise();
CAM_Finalise();
NIO_Finalise();
SST_Finalise();
KEY_Finalise();
RCL_Finalise();
SRC_Finalise();
REF_Finalise();
RTC_Finalise();
SYS_Finalise();
SCH_Finalise();
LCL_Finalise();
delete_pidfile();
CNF_Finalise();
LOG_Finalise();
HSH_Finalise();
exit(exit_status);
}
/* ================================================== */
static void
signal_cleanup(int x)
{
if (!initialised) exit(0);
SCH_QuitProgram();
}
/* ================================================== */
static void
ntp_source_resolving_end(void)
{
NSR_SetSourceResolvingEndHandler(NULL);
if (reload) {
/* Note, we want reload to come well after the initialisation from
the real time clock - this gives us a fighting chance that the
system-clock scale for the reloaded samples still has a
semblence of validity about it. */
SRC_ReloadSources();
}
RTC_StartMeasurements();
RCL_StartRefclocks();
NSR_StartSources();
NSR_AutoStartSources();
/* Special modes can end only when sources update their reachability.
Give up immediatelly if there are no active sources. */
if (ref_mode != REF_ModeNormal && !SRC_ActiveSources()) {
REF_SetUnsynchronised();
}
}
/* ================================================== */
static void
post_init_ntp_hook(void *anything)
{
if (ref_mode == REF_ModeInitStepSlew) {
/* Remove the initstepslew sources and set normal mode */
NSR_RemoveAllSources();
ref_mode = REF_ModeNormal;
REF_SetMode(ref_mode);
}
/* Close the pipe to the foreground process so it can exit */
LOG_CloseParentFd();
CNF_AddSources();
CNF_AddBroadcasts();
NSR_SetSourceResolvingEndHandler(ntp_source_resolving_end);
NSR_ResolveSources();
}
/* ================================================== */
static void
reference_mode_end(int result)
{
switch (ref_mode) {
case REF_ModeNormal:
case REF_ModeUpdateOnce:
case REF_ModePrintOnce:
exit_status = !result;
SCH_QuitProgram();
break;
case REF_ModeInitStepSlew:
/* Switch to the normal mode, the delay is used to prevent polling
interval shorter than the burst interval if some configured servers
were used also for initstepslew */
SCH_AddTimeoutByDelay(2.0, post_init_ntp_hook, NULL);
break;
default:
assert(0);
}
}
/* ================================================== */
static void
post_init_rtc_hook(void *anything)
{
if (CNF_GetInitSources() > 0) {
CNF_AddInitSources();
NSR_StartSources();
assert(REF_GetMode() != REF_ModeNormal);
/* Wait for mode end notification */
} else {
(post_init_ntp_hook)(NULL);
}
}
/* ================================================== */
/* Return 1 if the process exists on the system. */
static int
does_process_exist(int pid)
{
int status;
status = getsid(pid);
if (status >= 0) {
return 1;
} else {
return 0;
}
}
/* ================================================== */
static int
maybe_another_chronyd_running(int *other_pid)
{
const char *pidfile = CNF_GetPidFile();
FILE *in;
int pid, count;
*other_pid = 0;
in = fopen(pidfile, "r");
if (!in) return 0;
count = fscanf(in, "%d", &pid);
fclose(in);
if (count != 1) return 0;
*other_pid = pid;
return does_process_exist(pid);
}
/* ================================================== */
static void
write_lockfile(void)
{
const char *pidfile = CNF_GetPidFile();
FILE *out;
out = fopen(pidfile, "w");
if (!out) {
LOG_FATAL(LOGF_Main, "could not open lockfile %s for writing", pidfile);
} else {
fprintf(out, "%d\n", getpid());
fclose(out);
}
}
/* ================================================== */
static void
go_daemon(void)
{
#ifdef WINNT
#else
int pid, fd, pipefd[2];
/* Create pipe which will the daemon use to notify the grandparent
when it's initialised or send an error message */
if (pipe(pipefd)) {
LOG_FATAL(LOGF_Logging, "Could not detach, pipe failed : %s", strerror(errno));
}
/* Does this preserve existing signal handlers? */
pid = fork();
if (pid < 0) {
LOG_FATAL(LOGF_Logging, "Could not detach, fork failed : %s", strerror(errno));
} else if (pid > 0) {
/* In the 'grandparent' */
char message[1024];
int r;
close(pipefd[1]);
r = read(pipefd[0], message, sizeof (message));
if (r) {
if (r > 0) {
/* Print the error message from the child */
fprintf(stderr, "%.1024s\n", message);
}
exit(1);
} else
exit(0);
} else {
close(pipefd[0]);
setsid();
/* Do 2nd fork, as-per recommended practice for launching daemons. */
pid = fork();
if (pid < 0) {
LOG_FATAL(LOGF_Logging, "Could not detach, fork failed : %s", strerror(errno));
} else if (pid > 0) {
exit(0); /* In the 'parent' */
} else {
/* In the child we want to leave running as the daemon */
/* Change current directory to / */
if (chdir("/") < 0) {
LOG_FATAL(LOGF_Logging, "Could not chdir to / : %s", strerror(errno));
}
/* Don't keep stdin/out/err from before. But don't close
the parent pipe yet. */
for (fd=0; fd<1024; fd++) {
if (fd != pipefd[1])
close(fd);
}
LOG_SetParentFd(pipefd[1]);
}
}
#endif
}
/* ================================================== */
int main
(int argc, char **argv)
{
const char *conf_file = DEFAULT_CONF_FILE;
char *user = NULL;
int debug = 0, nofork = 0, address_family = IPADDR_UNSPEC;
int do_init_rtc = 0, restarted = 0;
int other_pid;
int lock_memory = 0, sched_priority = 0;
int system_log = 1;
int config_args = 0;
LOG_Initialise();
/* Parse command line options */
while (++argv, (--argc)>0) {
if (!strcmp("-f", *argv)) {
++argv, --argc;
conf_file = *argv;
} else if (!strcmp("-P", *argv)) {
++argv, --argc;
if (argc == 0 || sscanf(*argv, "%d", &sched_priority) != 1) {
LOG_FATAL(LOGF_Main, "Bad scheduler priority");
}
} else if (!strcmp("-m", *argv)) {
lock_memory = 1;
} else if (!strcmp("-r", *argv)) {
reload = 1;
} else if (!strcmp("-R", *argv)) {
restarted = 1;
} else if (!strcmp("-u", *argv)) {
++argv, --argc;
if (argc == 0) {
LOG_FATAL(LOGF_Main, "Missing user name");
} else {
user = *argv;
}
} else if (!strcmp("-s", *argv)) {
do_init_rtc = 1;
} else if (!strcmp("-v", *argv) || !strcmp("--version",*argv)) {
/* This write to the terminal is OK, it comes before we turn into a daemon */
printf("chronyd (chrony) version %s (%s)\n", CHRONY_VERSION, CHRONYD_FEATURES);
exit(0);
} else if (!strcmp("-n", *argv)) {
nofork = 1;
} else if (!strcmp("-d", *argv)) {
debug++;
nofork = 1;
system_log = 0;
} else if (!strcmp("-q", *argv)) {
ref_mode = REF_ModeUpdateOnce;
nofork = 1;
system_log = 0;
} else if (!strcmp("-Q", *argv)) {
ref_mode = REF_ModePrintOnce;
nofork = 1;
system_log = 0;
} else if (!strcmp("-4", *argv)) {
address_family = IPADDR_INET4;
} else if (!strcmp("-6", *argv)) {
address_family = IPADDR_INET6;
} else if (*argv[0] == '-') {
LOG_FATAL(LOGF_Main, "Unrecognized command line option [%s]", *argv);
} else {
/* Process remaining arguments and configuration lines */
config_args = argc;
break;
}
}
if (getuid() != 0) {
/* This write to the terminal is OK, it comes before we turn into a daemon */
fprintf(stderr,"Not superuser\n");
exit(1);
}
/* Turn into a daemon */
if (!nofork) {
go_daemon();
}
if (system_log) {
LOG_OpenSystemLog();
}
LOG_SetDebugLevel(debug);
LOG(LOGS_INFO, LOGF_Main, "chronyd version %s starting (%s)",
CHRONY_VERSION, CHRONYD_FEATURES);
DNS_SetAddressFamily(address_family);
CNF_Initialise(restarted);
/* Parse the config file or the remaining command line arguments */
if (!config_args) {
CNF_ReadFile(conf_file);
} else {
do {
CNF_ParseLine(NULL, config_args - argc + 1, *argv);
} while (++argv, --argc);
}
/* Check whether another chronyd may already be running. Do this after
* forking, so that message logging goes to the right place (i.e. syslog), in
* case this chronyd is being run from a boot script. */
if (maybe_another_chronyd_running(&other_pid)) {
LOG_FATAL(LOGF_Main, "Another chronyd may already be running (pid=%d), check lockfile (%s)",
other_pid, CNF_GetPidFile());
}
/* Write our lockfile to prevent other chronyds running. This has *GOT* to
* be done *AFTER* the daemon-creation fork() */
write_lockfile();
LCL_Initialise();
SCH_Initialise();
SYS_Initialise();
RTC_Initialise(do_init_rtc);
SRC_Initialise();
RCL_Initialise();
KEY_Initialise();
/* Command-line switch must have priority */
if (!sched_priority) {
sched_priority = CNF_GetSchedPriority();
}
if (sched_priority) {
SYS_SetScheduler(sched_priority);
}
if (lock_memory || CNF_GetLockMemory()) {
SYS_LockMemory();
}
if (!user) {
user = CNF_GetUser();
}
if (user && strcmp(user, "root")) {
SYS_DropRoot(user);
}
LOG_CreateLogFileDir();
REF_Initialise();
SST_Initialise();
NIO_Initialise(address_family);
CAM_Initialise(address_family);
NCR_Initialise();
NSR_Initialise();
CLG_Initialise();
MNL_Initialise();
TMC_Initialise();
SMT_Initialise();
/* From now on, it is safe to do finalisation on exit */
initialised = 1;
CNF_SetupAccessRestrictions();
if (ref_mode == REF_ModeNormal && CNF_GetInitSources() > 0) {
ref_mode = REF_ModeInitStepSlew;
}
REF_SetModeEndHandler(reference_mode_end);
REF_SetMode(ref_mode);
if (do_init_rtc) {
RTC_TimeInit(post_init_rtc_hook, NULL);
} else {
post_init_rtc_hook(NULL);
}
signal(SIGINT, signal_cleanup);
signal(SIGTERM, signal_cleanup);
#if !defined(WINNT)
signal(SIGQUIT, signal_cleanup);
signal(SIGHUP, signal_cleanup);
#endif /* WINNT */
/* The program normally runs under control of the main loop in
the scheduler. */
SCH_MainLoop();
LOG(LOGS_INFO, LOGF_Main, "chronyd exiting");
MAI_CleanupAndExit();
return 0;
}
/* ================================================== */
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