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ntp: close client sockets sooner with unsynchronised sources

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When a valid packet is received from an unsynchronised source (i.e. only
a test of leap, stratum or root distance failed), there is no point in
waiting for another packet or the RX timeout, and the client socket can
be immediately closed.
This commit is contained in:
Miroslav Lichvar 2016-08-03 12:07:43 +02:00
parent c619d555f0
commit cea21adbbb
1 changed files with 29 additions and 36 deletions
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65
ntp_core.c
View file

@ -1232,7 +1232,7 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
/* RFC 5905 packet tests */
int test1, test2, test3, test5, test6, test7;
int valid_packet;
int valid_packet, synced_packet;
/* Additional tests */
int testA, testB, testC, testD;
@ -1254,7 +1254,6 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
double error_in_estimate;
double delay_time, precision;
int requeue_transmit;
/* ==================== */
@ -1305,8 +1304,10 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
defined maximum. */
test7 = pkt_root_delay / 2.0 + pkt_root_dispersion < NTP_MAX_DISPERSION;
/* The packet is considered valid if the tests above passed */
valid_packet = test1 && test2 && test3 && test5 && test6 && test7;
/* The packet is considered valid if the tests 1-5 passed. The timestamps
can be used for synchronisation if the tests 6 and 7 passed too. */
valid_packet = test1 && test2 && test3 && test5;
synced_packet = valid_packet && test6 && test7;
/* Check for Kiss-o'-Death codes */
kod_rate = 0;
@ -1328,7 +1329,7 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
if (test2)
inst->local_ntp_tx.hi = inst->local_ntp_tx.lo = 0;
if (valid_packet) {
if (synced_packet) {
precision = LCL_GetSysPrecisionAsQuantum() +
UTI_Log2ToDouble(message->precision);
@ -1425,25 +1426,13 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
test1, test2, test3, test5, test6, test7, testA, testB, testC, testD,
kod_rate, valid_packet, good_packet);
requeue_transmit = 0;
/* Reduce polling rate if KoD RATE was received */
if (kod_rate) {
/* Stop ongoing burst */
if (inst->opmode == MD_BURST_WAS_OFFLINE || inst->opmode == MD_BURST_WAS_ONLINE) {
inst->burst_good_samples_to_go = 0;
LOG(LOGS_WARN, LOGF_NtpCore, "Received KoD RATE from %s, burst sampling stopped",
UTI_IPToString(&inst->remote_addr.ip_addr));
}
requeue_transmit = 1;
}
if (valid_packet) {
inst->remote_poll = message->poll;
inst->remote_stratum = message->stratum;
inst->tx_count = 0;
SRC_UpdateReachability(inst->source, 1);
if (synced_packet) {
inst->remote_poll = message->poll;
inst->remote_stratum = message->stratum;
inst->tx_count = 0;
SRC_UpdateReachability(inst->source, 1);
}
if (good_packet) {
/* Do this before we accumulate a new sample into the stats registers, obviously */
@ -1483,7 +1472,7 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
default:
break;
}
} else {
} else if (synced_packet) {
/* Slowly increase the polling interval if we can't get good packet */
adjust_poll(inst, 0.1);
}
@ -1495,21 +1484,25 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
/* Update the local address */
inst->local_addr.ip_addr = local_addr->ip_addr;
requeue_transmit = 1;
}
/* And now, requeue the timer */
if (inst->opmode != MD_OFFLINE) {
delay_time = get_transmit_delay(inst, 0, local_interval);
/* And now, requeue the timer. */
if (requeue_transmit && inst->opmode != MD_OFFLINE) {
delay_time = get_transmit_delay(inst, 0, local_interval);
if (kod_rate) {
/* Back off for a while and stop ongoing burst */
delay_time += 4 * (1UL << inst->minpoll);
if (kod_rate) {
/* Back off for a while */
delay_time += (double) (4 * (1UL << inst->minpoll));
if (inst->opmode == MD_BURST_WAS_OFFLINE || inst->opmode == MD_BURST_WAS_ONLINE) {
inst->burst_good_samples_to_go = 0;
LOG(LOGS_WARN, LOGF_NtpCore, "Received KoD RATE from %s, burst sampling stopped",
UTI_IPToString(&inst->remote_addr.ip_addr));
}
}
/* Get rid of old timeout and start a new one */
assert(inst->tx_timeout_id);
restart_timeout(inst, delay_time);
}
/* Get rid of old timeout and start a new one */
assert(inst->tx_timeout_id);
restart_timeout(inst, delay_time);
}
/* Do measurement logging */