static int sntp_receive_response(sd_event_source *source, int fd, uint32_t revents, void *userdata) {
SNTPContext *sntp = userdata;
unsigned char buf[sizeof(struct ntp_msg)];
struct iovec iov = {
.iov_base = buf,
.iov_len = sizeof(buf),
};
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(struct timeval))];
} control;
struct sockaddr_in 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;
struct ntp_msg *ntpmsg;
double origin, receive, trans, dest;
double delay, offset;
bool spike;
int leap_sec;
int r;
if (revents & (EPOLLHUP|EPOLLERR)) {
log_debug("Server connection returned error. Closing.");
sntp_server_disconnect(sntp);
return -ENOTCONN;
}
len = recvmsg(fd, &msghdr, MSG_DONTWAIT);
if (len < 0) {
log_debug("Error receiving message. Disconnecting.");
return -EINVAL;
}
if (iov.iov_len < sizeof(struct ntp_msg)) {
log_debug("Invalid response from server. Disconnecting.");
return -EINVAL;
}
if (sntp->server_addr.sin_addr.s_addr != server_addr.sin_addr.s_addr) {
log_debug("Response from unknown server. Disconnecting.");
return -EINVAL;
}
recv_time = NULL;
for (cmsg = CMSG_FIRSTHDR(&msghdr); cmsg; cmsg = CMSG_NXTHDR(&msghdr, cmsg)) {
if (cmsg->cmsg_level != SOL_SOCKET)
continue;
switch (cmsg->cmsg_type) {
case SCM_TIMESTAMP:
recv_time = (struct timeval *) CMSG_DATA(cmsg);
break;
}
}
if (!recv_time) {
log_debug("Invalid packet timestamp. Disconnecting.");
return -EINVAL;
}
ntpmsg = iov.iov_base;
if (!sntp->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) != sntp->trans_time.tv_sec + OFFSET_1900_1970 ||
be32toh(ntpmsg->origin_time.frac) != sntp->trans_time.tv_nsec) {
log_debug("Invalid reply; not our transmit time. Ignoring.");
return 0;
}
if (NTP_FIELD_LEAP(ntpmsg->field) == NTP_LEAP_NOTINSYNC) {
log_debug("Server is not synchronized. Disconnecting.");
return -EINVAL;
}
if (NTP_FIELD_VERSION(ntpmsg->field) != 4) {
log_debug("Response NTPv%d. Disconnecting.", NTP_FIELD_VERSION(ntpmsg->field));
return -EINVAL;
}
if (NTP_FIELD_MODE(ntpmsg->field) != NTP_MODE_SERVER) {
log_debug("Unsupported mode %d. Disconnecting.", NTP_FIELD_MODE(ntpmsg->field));
return -EINVAL;
}
/* valid packet */
sntp->pending = false;
sntp->retry_interval = 0;
/* announce leap seconds */
if (NTP_FIELD_LEAP(ntpmsg->field) & NTP_LEAP_PLUSSEC)
leap_sec = 1;
else if (NTP_FIELD_LEAP(ntpmsg->field) & NTP_LEAP_MINUSSEC)
leap_sec = -1;
else
leap_sec = 0;
/*
* "Timestamp Name ID When Generated
* ------------------------------------------------------------
* Originate Timestamp T1 time request sent by client
* Receive Timestamp T2 time request received by server
* Transmit Timestamp T3 time reply sent by server
* Destination Timestamp T4 time reply received by client
*
* The round-trip delay, d, and system clock offset, t, are defined as:
* d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2"
*/
clock_gettime(CLOCK_MONOTONIC, &now_ts);
origin = tv_to_d(recv_time) - (ts_to_d(&now_ts) - ts_to_d(&sntp->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 = sntp_sample_spike_detection(sntp, offset, delay);
sntp_adjust_poll(sntp, offset, spike);
log_debug("NTP response:\n"
" leap : %u\n"
" version : %u\n"
" mode : %u\n"
" stratum : %u\n"
" precision : %f sec (%d)\n"
" reference : %.4s\n"
" origin : %f\n"
" receive : %f\n"
" transmit : %f\n"
" dest : %f\n"
" offset : %+f sec\n"
" delay : %+f sec\n"
" packet count : %"PRIu64"\n"
" jitter : %f%s\n"
" poll interval: %llu\n",
NTP_FIELD_LEAP(ntpmsg->field),
NTP_FIELD_VERSION(ntpmsg->field),
NTP_FIELD_MODE(ntpmsg->field),
ntpmsg->stratum,
exp2(ntpmsg->precision), ntpmsg->precision,
ntpmsg->stratum == 1 ? ntpmsg->refid : "n/a",
origin - OFFSET_1900_1970,
receive - OFFSET_1900_1970,
trans - OFFSET_1900_1970,
dest - OFFSET_1900_1970,
offset, delay,
sntp->packet_count,
sntp->samples_jitter, spike ? " spike" : "",
sntp->poll_interval_usec / USEC_PER_SEC);
if (sntp->report)
sntp->report(sntp->poll_interval_usec, offset, delay, sntp->samples_jitter, spike);
if (!spike) {
r = sntp_adjust_clock(sntp, offset, leap_sec);
if (r < 0)
log_error("Failed to call clock_adjtime(): %m");
}
r = sntp_arm_timer(sntp, sntp->poll_interval_usec);
if (r < 0)
return r;
return 0;
}
int sntp_server_connect(SNTPContext *sntp, const char *server) {
_cleanup_free_ char *s = NULL;
assert(sntp);
assert(server);
assert(sntp->server_socket >= 0);
s = strdup(server);
if (!s)
return -ENOMEM;
free(sntp->server);
sntp->server = s;
s = NULL;
zero(sntp->server_addr);
sntp->server_addr.sin_family = AF_INET;
sntp->server_addr.sin_addr.s_addr = inet_addr(server);
sntp->poll_interval_usec = 2 * NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
return sntp_send_request(sntp);
}
void sntp_server_disconnect(SNTPContext *sntp) {
if (!sntp->server)
return;
sntp->event_timer = sd_event_source_unref(sntp->event_timer);
sntp->event_clock_watch = sd_event_source_unref(sntp->event_clock_watch);
if (sntp->clock_watch_fd > 0)
close(sntp->clock_watch_fd);
sntp->clock_watch_fd = -1;
sntp->event_receive = sd_event_source_unref(sntp->event_receive);
if (sntp->server_socket > 0)
close(sntp->server_socket);
sntp->server_socket = -1;
zero(sntp->server_addr);
free(sntp->server);
sntp->server = NULL;
}
static int sntp_listen_setup(SNTPContext *sntp, sd_event *e) {
_cleanup_close_ int fd = -1;
struct sockaddr_in addr;
const int on = 1;
const int tos = IPTOS_LOWDELAY;
int r;
fd = socket(PF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
if (fd < 0)
return -errno;
zero(addr);
addr.sin_family = AF_INET;
r = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
if (r < 0)
return -errno;
r = setsockopt(fd, SOL_SOCKET, SO_TIMESTAMP, &on, sizeof(on));
if (r < 0)
return -errno;
r = setsockopt(fd, IPPROTO_IP, IP_TOS, &tos, sizeof(tos));
if (r < 0)
return -errno;
r = sd_event_add_io(e, &sntp->event_receive, fd, EPOLLIN, sntp_receive_response, sntp);
if (r < 0)
return r;
sntp->server_socket = fd;
fd = -1;
return 0;
}
static int manager_receive_response(sd_event_source *source, int fd, uint32_t revents, void *userdata) {
Manager *m = userdata;
struct ntp_msg ntpmsg;
struct iovec iov = {
.iov_base = &ntpmsg,
.iov_len = sizeof(ntpmsg),
};
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(struct timeval))];
} control;
union sockaddr_union server_addr;
struct msghdr msghdr = {
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = &control,
.msg_controllen = sizeof(control),
.msg_name = &server_addr,
.msg_namelen = sizeof(server_addr),
};
struct cmsghdr *cmsg;
struct timespec now_ts;
struct timeval *recv_time;
ssize_t len;
double origin, receive, trans, dest;
double delay, offset;
bool spike;
int leap_sec;
int r;
assert(source);
assert(m);
if (revents & (EPOLLHUP|EPOLLERR)) {
log_warning("Server connection returned error.");
return manager_connect(m);
}
len = recvmsg(fd, &msghdr, MSG_DONTWAIT);
if (len < 0) {
if (errno == EAGAIN)
return 0;
log_warning("Error receiving message. Disconnecting.");
return manager_connect(m);
}
if (iov.iov_len < sizeof(struct ntp_msg)) {
log_warning("Invalid response from server. Disconnecting.");
return manager_connect(m);
}
if (!m->current_server_name ||
!m->current_server_address ||
!sockaddr_equal(&server_addr, &m->current_server_address->sockaddr)) {
log_debug("Response from unknown server.");
return 0;
}
recv_time = NULL;
for (cmsg = CMSG_FIRSTHDR(&msghdr); cmsg; cmsg = CMSG_NXTHDR(&msghdr, cmsg)) {
if (cmsg->cmsg_level != SOL_SOCKET)
continue;
switch (cmsg->cmsg_type) {
case SCM_TIMESTAMP:
recv_time = (struct timeval *) CMSG_DATA(cmsg);
break;
}
}
if (!recv_time) {
log_error("Invalid packet timestamp.");
return -EINVAL;
}
if (!m->pending) {
log_debug("Unexpected reply. Ignoring.");
return 0;
}
/* check our "time cookie" (we just stored nanoseconds in the fraction field) */
if (be32toh(ntpmsg.origin_time.sec) != m->trans_time.tv_sec + OFFSET_1900_1970 ||
be32toh(ntpmsg.origin_time.frac) != m->trans_time.tv_nsec) {
log_debug("Invalid reply; not our transmit time. Ignoring.");
return 0;
}
m->event_timeout = sd_event_source_unref(m->event_timeout);
if (be32toh(ntpmsg.recv_time.sec) < TIME_EPOCH + OFFSET_1900_1970 ||
be32toh(ntpmsg.trans_time.sec) < TIME_EPOCH + OFFSET_1900_1970) {
log_debug("Invalid reply, returned times before epoch. Ignoring.");
return manager_connect(m);
}
if (NTP_FIELD_LEAP(ntpmsg.field) == NTP_LEAP_NOTINSYNC) {
log_debug("Server is not synchronized. Disconnecting.");
return manager_connect(m);
}
if (!IN_SET(NTP_FIELD_VERSION(ntpmsg.field), 3, 4)) {
log_debug("Response NTPv%d. Disconnecting.", NTP_FIELD_VERSION(ntpmsg.field));
return manager_connect(m);
}
if (NTP_FIELD_MODE(ntpmsg.field) != NTP_MODE_SERVER) {
log_debug("Unsupported mode %d. Disconnecting.", NTP_FIELD_MODE(ntpmsg.field));
return manager_connect(m);
}
/* valid packet */
m->pending = false;
m->retry_interval = 0;
/* announce leap seconds */
if (NTP_FIELD_LEAP(ntpmsg.field) & NTP_LEAP_PLUSSEC)
leap_sec = 1;
else if (NTP_FIELD_LEAP(ntpmsg.field) & NTP_LEAP_MINUSSEC)
leap_sec = -1;
else
leap_sec = 0;
/*
* "Timestamp Name ID When Generated
* ------------------------------------------------------------
* Originate Timestamp T1 time request sent by client
* Receive Timestamp T2 time request received by server
* Transmit Timestamp T3 time reply sent by server
* Destination Timestamp T4 time reply received by client
*
* The round-trip delay, d, and system clock offset, t, are defined as:
* d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2"
*/
assert_se(clock_gettime(clock_boottime_or_monotonic(), &now_ts) >= 0);
origin = tv_to_d(recv_time) - (ts_to_d(&now_ts) - ts_to_d(&m->trans_time_mon)) + OFFSET_1900_1970;
receive = ntp_ts_to_d(&ntpmsg.recv_time);
trans = ntp_ts_to_d(&ntpmsg.trans_time);
dest = tv_to_d(recv_time) + OFFSET_1900_1970;
offset = ((receive - origin) + (trans - dest)) / 2;
delay = (dest - origin) - (trans - receive);
spike = manager_sample_spike_detection(m, offset, delay);
manager_adjust_poll(m, offset, spike);
log_debug("NTP response:\n"
" leap : %u\n"
" version : %u\n"
" mode : %u\n"
" stratum : %u\n"
" precision : %.6f sec (%d)\n"
" reference : %.4s\n"
" origin : %.3f\n"
" receive : %.3f\n"
" transmit : %.3f\n"
" dest : %.3f\n"
" offset : %+.3f sec\n"
" delay : %+.3f sec\n"
" packet count : %"PRIu64"\n"
" jitter : %.3f%s\n"
" poll interval: " USEC_FMT "\n",
NTP_FIELD_LEAP(ntpmsg.field),
NTP_FIELD_VERSION(ntpmsg.field),
NTP_FIELD_MODE(ntpmsg.field),
ntpmsg.stratum,
exp2(ntpmsg.precision), ntpmsg.precision,
ntpmsg.stratum == 1 ? ntpmsg.refid : "n/a",
origin - OFFSET_1900_1970,
receive - OFFSET_1900_1970,
trans - OFFSET_1900_1970,
dest - OFFSET_1900_1970,
offset, delay,
m->packet_count,
m->samples_jitter, spike ? " spike" : "",
m->poll_interval_usec / USEC_PER_SEC);
if (!spike) {
m->sync = true;
r = manager_adjust_clock(m, offset, leap_sec);
if (r < 0)
log_error("Failed to call clock_adjtime(): %m");
}
log_info("interval/delta/delay/jitter/drift " USEC_FMT "s/%+.3fs/%.3fs/%.3fs/%+ippm%s",
m->poll_interval_usec / USEC_PER_SEC, offset, delay, m->samples_jitter, m->drift_ppm,
spike ? " (ignored)" : "");
r = manager_arm_timer(m, m->poll_interval_usec);
if (r < 0) {
log_error("Failed to rearm timer: %s", strerror(-r));
return r;
}
return 0;
}
static int manager_listen_setup(Manager *m) {
union sockaddr_union addr = {};
static const int tos = IPTOS_LOWDELAY;
static const int on = 1;
int r;
assert(m);
assert(m->server_socket < 0);
assert(!m->event_receive);
assert(m->current_server_address);
addr.sa.sa_family = m->current_server_address->sockaddr.sa.sa_family;
m->server_socket = socket(addr.sa.sa_family, SOCK_DGRAM | SOCK_CLOEXEC, 0);
if (m->server_socket < 0)
return -errno;
r = bind(m->server_socket, &addr.sa, m->current_server_address->socklen);
if (r < 0)
return -errno;
r = setsockopt(m->server_socket, SOL_SOCKET, SO_TIMESTAMP, &on, sizeof(on));
if (r < 0)
return -errno;
setsockopt(m->server_socket, IPPROTO_IP, IP_TOS, &tos, sizeof(tos));
return sd_event_add_io(m->event, &m->event_receive, m->server_socket, EPOLLIN, manager_receive_response, m);
}
static int manager_begin(Manager *m) {
_cleanup_free_ char *pretty = NULL;
int r;
assert(m);
assert_return(m->current_server_name, -EHOSTUNREACH);
assert_return(m->current_server_address, -EHOSTUNREACH);
m->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
server_address_pretty(m->current_server_address, &pretty);
log_info("Using NTP server %s (%s).", strna(pretty), m->current_server_name->string);
sd_notifyf(false, "STATUS=Using Time Server %s (%s).", strna(pretty), m->current_server_name->string);
r = manager_listen_setup(m);
if (r < 0) {
log_warning("Failed to setup connection socket: %s", strerror(-r));
return r;
}
r = manager_clock_watch_setup(m);
if (r < 0)
return r;
return manager_send_request(m);
}
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);
}
