diff options
| -rw-r--r-- | networking/ntpd.c | 42 |
1 files changed, 34 insertions, 8 deletions
diff --git a/networking/ntpd.c b/networking/ntpd.c index 0f4319ef2..9ec255814 100644 --- a/networking/ntpd.c +++ b/networking/ntpd.c @@ -95,6 +95,7 @@ #define RETRY_INTERVAL 5 /* on error, retry in N secs */ #define RESPONSE_INTERVAL 15 /* wait for reply up to N secs */ #define INITIAL_SAMPLES 4 /* how many samples do we want for init */ +#define BAD_DELAY_GROWTH 4 /* drop packet if its delay grew by more than this */ /* Clock discipline parameters and constants */ @@ -1616,6 +1617,7 @@ recv_and_process_peer_pkt(peer_t *p) ssize_t size; msg_t msg; double T1, T2, T3, T4; + double dv; unsigned interval; datapoint_t *datapoint; peer_t *q; @@ -1665,9 +1667,8 @@ recv_and_process_peer_pkt(peer_t *p) // TODO: stratum 0 responses may have commands in 32-bit m_refid field: // "DENY", "RSTR" - peer does not like us at all // "RATE" - peer is overloaded, reduce polling freq - interval = poll_interval(0); - bb_error_msg("reply from %s: peer is unsynced, next query in %us", p->p_dotted, interval); - goto set_next_and_ret; + bb_error_msg("reply from %s: peer is unsynced", p->p_dotted); + goto pick_normal_interval; } // /* Verify valid root distance */ @@ -1700,21 +1701,31 @@ recv_and_process_peer_pkt(peer_t *p) T4 = G.cur_time; p->lastpkt_recv_time = T4; - VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time); - p->datapoint_idx = p->reachable_bits ? (p->datapoint_idx + 1) % NUM_DATAPOINTS : 0; - datapoint = &p->filter_datapoint[p->datapoint_idx]; - datapoint->d_recv_time = T4; - datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2; + /* The delay calculation is a special case. In cases where the * server and client clocks are running at different rates and * with very fast networks, the delay can appear negative. In * order to avoid violating the Principle of Least Astonishment, * the delay is clamped not less than the system precision. */ + dv = p->lastpkt_delay; p->lastpkt_delay = (T4 - T1) - (T3 - T2); if (p->lastpkt_delay < G_precision_sec) p->lastpkt_delay = G_precision_sec; + /* + * If this packet's delay is much bigger than the last one, + * it's better to just ignore it than use its much less precise value. + */ + if (p->reachable_bits && p->lastpkt_delay > dv * BAD_DELAY_GROWTH) { + bb_error_msg("reply from %s: delay %f is too high, ignoring", p->p_dotted, p->lastpkt_delay); + goto pick_normal_interval; + } + + p->datapoint_idx = p->reachable_bits ? (p->datapoint_idx + 1) % NUM_DATAPOINTS : 0; + datapoint = &p->filter_datapoint[p->datapoint_idx]; + datapoint->d_recv_time = T4; + datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2; datapoint->d_dispersion = LOG2D(msg.m_precision_exp) + G_precision_sec; if (!p->reachable_bits) { /* 1st datapoint ever - replicate offset in every element */ @@ -1811,6 +1822,7 @@ recv_and_process_peer_pkt(peer_t *p) } /* Decide when to send new query for this peer */ + pick_normal_interval: interval = poll_interval(0); set_next_and_ret: @@ -2195,6 +2207,20 @@ int ntpd_main(int argc UNUSED_PARAM, char **argv) gettime1900d(); /* sets G.cur_time */ } } + + if (G.ntp_peers && G.stratum != MAXSTRAT) { + for (item = G.ntp_peers; item != NULL; item = item->link) { + peer_t *p = (peer_t *) item->data; + if (p->reachable_bits) + goto have_reachable_peer; + } + /* No peer responded for last 8 packets, panic */ + G.polladj_count = 0; + G.poll_exp = MINPOLL; + G.stratum = MAXSTRAT; + run_script("unsync", G.last_update_offset); + have_reachable_peer: ; + } } /* while (!bb_got_signal) */ remove_pidfile(CONFIG_PID_FILE_PATH "/ntpd.pid"); |