NTPv4 servers don't reply with unsynchronized status when they lost
synchronization, they only keep increasing the root dispersion and it's
up to the client to decide at which point they no longer consider it
synchronized.
Ignore replies with root distance over 5 seconds.
#define NTP_FIELD_MODE(f) ((f) & 7)
#define NTP_FIELD(l, v, m) (((l) << 6) | ((v) << 3) | (m))
#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
+
/*
* "NTP timestamps are represented as a 64-bit unsigned fixed-point number,
* in seconds relative to 0h on 1 January 1900."
/*
* "NTP timestamps are represented as a 64-bit unsigned fixed-point number,
* in seconds relative to 0h on 1 January 1900."
static int manager_arm_timer(Manager *m, usec_t next);
static int manager_clock_watch_setup(Manager *m);
static int manager_arm_timer(Manager *m, usec_t next);
static int manager_clock_watch_setup(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 ntp_ts_to_d(const struct ntp_ts *ts) {
return be32toh(ts->sec) + ((double)be32toh(ts->frac) / UINT_MAX);
}
ssize_t len;
double origin, receive, trans, dest;
double delay, offset;
ssize_t len;
double origin, receive, trans, dest;
double delay, offset;
bool spike;
int leap_sec;
int r;
bool spike;
int leap_sec;
int r;
return manager_connect(m);
}
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;
/* valid packet */
m->pending = false;
m->retry_interval = 0;
" mode : %u\n"
" stratum : %u\n"
" precision : %.6f sec (%d)\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"
" reference : %.4s\n"
" origin : %.3f\n"
" receive : %.3f\n"
NTP_FIELD_MODE(ntpmsg.field),
ntpmsg.stratum,
exp2(ntpmsg.precision), ntpmsg.precision,
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,
ntpmsg.stratum == 1 ? ntpmsg.refid : "n/a",
origin - OFFSET_1900_1970,
receive - OFFSET_1900_1970,