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-rw-r--r--src/timesync/timesyncd-manager.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/src/timesync/timesyncd-manager.c b/src/timesync/timesyncd-manager.c
index 2b0580cf01..9b8b7d3eb6 100644
--- a/src/timesync/timesyncd-manager.c
+++ b/src/timesync/timesyncd-manager.c
@@ -89,6 +89,9 @@
#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."
@@ -128,6 +131,10 @@ struct ntp_msg {
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);
}
@@ -500,6 +507,7 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
ssize_t len;
double origin, receive, trans, dest;
double delay, offset;
+ double root_distance;
bool spike;
int leap_sec;
int r;
@@ -585,6 +593,12 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
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;
@@ -626,6 +640,7 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
" 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"
@@ -641,6 +656,7 @@ static int manager_receive_response(sd_event_source *source, int fd, uint32_t re
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,