diff options
| -rw-r--r-- | src/timesync/timesyncd-manager.c | 16 |
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, |