#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 "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

#define NTP_ACCURACY_SEC 0.2

#define NTP_POLL_INTERVAL_MIN_SEC 32

#define NTP_POLL_INTERVAL_MAX_SEC 2048

#define NTP_MAX_ADJUST 0.4

#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))

#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 int load_clock(uid_t uid, gid_t gid) {

usec_t nt = TIME_EPOCH * USEC_PER_SEC, ct;

_cleanup_close_ int fd = -1;

/* Let's try to make sure that the clock is always

mkdir_p("/var/lib/systemd", 0755);

/* First, we try to create the clock file if it doesn't exist yet */

fd = open("/var/lib/systemd/clock", O_RDWR|O_CLOEXEC|O_EXCL, 0644);

if (fd < 0) {

fd = open("/var/lib/systemd/clock", O_RDWR|O_CLOEXEC|O_CREAT, 0644);

if (fd < 0) {

log_error("Failed to create /var/lib/systemd/clock: %m");

return -errno;

}

} else {

struct stat st;

usec_t ft;

if (fstat(fd, &st) < 0) {

log_error("fstat() failed: %m");

return -errno;

}

ft = timespec_load(&st.st_mtim);

if (ft > nt)

nt = ft;

}

ct = now(CLOCK_REALTIME);

if (nt > ct) {

struct timespec ts;

log_info("System clock time unset or jumped backwards, restoring.");

if (clock_settime(CLOCK_REALTIME, timespec_store(&ts, nt)) < 0)

log_error("Failed to restore system clock: %m");

}

/* Try to fix the access mode, so that we can still

fchmod(fd, 0644);

fchown(fd, uid, gid);

return 0;

}

static int save_clock(void) {

static const struct timespec ts[2] = {

{ .tv_sec = 0, .tv_nsec = UTIME_NOW },

{ .tv_sec = 0, .tv_nsec = UTIME_NOW },

};

int r;

r = utimensat(-1, "/var/lib/systemd/clock", ts, AT_SYMLINK_NOFOLLOW);

if (r < 0) {

log_warning("Failed to touch /var/lib/systemd/clock: %m");

return -errno;

}

return 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 double tv_to_d(const struct timeval *tv) {

return tv->tv_sec + (1.0e-6 * tv->tv_usec);

}

static double square(double d) {

return d * d;

}

static int manager_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);

sockaddr_pretty(&m->current_server_address->sockaddr.sa, m->current_server_address->socklen, true, &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 = {

/*

.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);

/*

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);

sockaddr_pretty(&m->current_server_address->sockaddr.sa, m->current_server_address->socklen, true, &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);

}

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);

/*

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);

save_clock();

if (r < 0)

return r;

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;

/*

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) {

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;

sockaddr_pretty(&m->current_server_address->sockaddr.sa, m->current_server_address->socklen, true, &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_info("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

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

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;

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;

r = manager_clock_watch_setup(m);

if (r < 0)

return r;

*ret = m;

m = NULL;

return 0;

}

static void manager_free(Manager *m) {

if (!m)

return;

manager_disconnect(m);

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,

(void*) 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. Suspending.");

manager_disconnect(m);

} else if (!connected && online) {

log_info("Network connectivity detected. Resuming.");

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;

}

static int drop_privileges(uid_t uid, gid_t gid) {

static const cap_value_t bits[] = {

CAP_SYS_TIME,

};

_cleanup_cap_free_ cap_t d = NULL;

int r;

/* Unfortunately we cannot leave privilege dropping to PID 1

if (setresgid(gid, gid, gid) < 0) {

log_error("Failed change group ID: %m");

return -errno;

}

if (setgroups(0, NULL) < 0) {

log_error("Failed to drop auxiliary groups list: %m");

return -errno;

}

if (prctl(PR_SET_KEEPCAPS, 1) < 0) {

log_error("Failed to enable keep capabilities flag: %m");

return -errno;

}

r = setresuid(uid, uid, uid);

if (r < 0) {

log_error("Failed change user ID: %m");

return -errno;

}

if (prctl(PR_SET_KEEPCAPS, 0) < 0) {

log_error("Failed to disable keep capabilities flag: %m");

return -errno;

}

r = capability_bounding_set_drop(~(1ULL << CAP_SYS_TIME), true);

if (r < 0) {

log_error("Failed to drop capabilities: %s", strerror(-r));

return r;

}

d = cap_init();

if (!d)

return log_oom();

if (cap_set_flag(d, CAP_EFFECTIVE, ELEMENTSOF(bits), bits, CAP_SET) < 0 ||

cap_set_flag(d, CAP_PERMITTED, ELEMENTSOF(bits), bits, CAP_SET) < 0) {

log_error("Failed to enable capabilities bits: %m");

return -errno;

}

if (cap_set_proc(d) < 0) {

log_error("Failed to increase capabilities: %m");

return -errno;

}

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(uid, gid);

if (r < 0)

goto out;

r = drop_privileges(uid, gid);

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);

save_clock();

out:

sd_notify(false, "STATUS=Shutting down...");

return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;

}