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Make receive_packet() more readable

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This commit is contained in:
Miroslav Lichvar 2013-06-03 14:27:09 +02:00
parent 5079f6bbff
commit 030e3b2dab
1 changed files with 95 additions and 102 deletions
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197
ntp_core.c
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@ -389,6 +389,39 @@ adjust_poll(NCR_Instance inst, double adj)
/* ================================================== */
static double
get_poll_adj(NCR_Instance inst, double error_in_estimate, double peer_distance)
{
double poll_adj;
if (error_in_estimate > peer_distance) {
int shift = 0;
unsigned long temp = (int)(error_in_estimate / peer_distance);
do {
shift++;
temp>>=1;
} while (temp);
poll_adj = -shift - inst->poll_score + 0.5;
} else {
int samples = SRC_Samples(inst->source);
/* Adjust polling interval so that the number of sourcestats samples
remains close to the target value */
poll_adj = ((double)samples / inst->poll_target - 1.0) / inst->poll_target;
/* Make interval shortening quicker */
if (samples < inst->poll_target) {
poll_adj *= 2.0;
}
}
return poll_adj;
}
/* ================================================== */
static void
transmit_packet(NTP_Mode my_mode, /* The mode this machine wants to be */
int my_poll, /* The log2 of the local poll interval */
@ -716,7 +749,6 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
int poll_to_use;
double delay_time = 0;
int requeue_transmit = 0;
double poll_adj;
/* ==================== */
@ -935,7 +967,7 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
}
/* Check for Kiss-of-Death */
if (message->stratum > NTP_MAX_STRATUM && !source_is_synchronized) {
if (!test7i && !source_is_synchronized) {
if (!memcmp(&message->reference_id, "RATE", 4))
kod_rate = 1;
}
@ -982,6 +1014,26 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
LOG(LOGS_INFO, LOGF_NtpCore, "kod_rate=%d valid_kod=%d", kod_rate, valid_kod);
#endif
/* Reduce polling rate if KoD RATE was received */
if (kod_rate && valid_kod) {
if (inst->remote_poll > inst->minpoll) {
inst->minpoll = inst->remote_poll;
if (inst->minpoll > inst->maxpoll)
inst->maxpoll = inst->minpoll;
if (inst->minpoll > inst->local_poll)
inst->local_poll = inst->minpoll;
LOG(LOGS_WARN, LOGF_NtpCore, "Received KoD RATE from %s, minpoll set to %d",
UTI_IPToString(&inst->remote_addr.ip_addr), inst->minpoll);
}
/* 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), inst->minpoll);
}
}
if (valid_header && valid_data) {
inst->tx_count = 0;
SRC_UpdateReachability(inst->source, 1);
@ -996,103 +1048,52 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
} else {
SRC_UnsetSelectable(inst->source);
}
}
/* Do this before we accumulate a new sample into the stats registers, obviously */
estimated_offset = SRC_PredictOffset(inst->source, &sample_time);
if (good_data) {
/* Do this before we accumulate a new sample into the stats registers, obviously */
estimated_offset = SRC_PredictOffset(inst->source, &sample_time);
if (valid_header && good_data) {
SRC_AccumulateSample(inst->source,
&sample_time,
theta, delta, epsilon,
root_delay, root_dispersion,
message->stratum, (NTP_Leap) pkt_leap);
SRC_AccumulateSample(inst->source,
&sample_time,
theta, delta, epsilon,
root_delay, root_dispersion,
message->stratum, (NTP_Leap) pkt_leap);
/* Now examine the registers. First though, if the prediction is
not even within +/- the peer distance of the peer, we are clearly
not tracking the peer at all well, so we back off the sampling
rate depending on just how bad the situation is. */
error_in_estimate = fabs(-theta - estimated_offset);
/* Now update the polling interval */
/* Now examine the registers. First though, if the prediction is
not even within +/- the peer distance of the peer, we are clearly
not tracking the peer at all well, so we back off the sampling
rate depending on just how bad the situation is. */
error_in_estimate = fabs(-theta - estimated_offset);
if (error_in_estimate > peer_distance) {
int shift = 0;
unsigned long temp = (int)(error_in_estimate / peer_distance);
do {
shift++;
temp>>=1;
} while (temp);
poll_adj = -shift - inst->poll_score + 0.5;
/* Now update the polling interval */
adjust_poll(inst, get_poll_adj(inst, error_in_estimate, peer_distance));
/* If we're in burst mode, check whether the burst is completed and
revert to the previous mode */
switch (inst->opmode) {
case MD_BURST_WAS_ONLINE:
case MD_BURST_WAS_OFFLINE:
--inst->burst_good_samples_to_go;
if (inst->burst_good_samples_to_go <= 0) {
if (inst->opmode == MD_BURST_WAS_ONLINE) {
inst->opmode = MD_ONLINE;
} else {
inst->opmode = MD_OFFLINE;
if (inst->timer_running) {
SCH_RemoveTimeout(inst->timeout_id);
inst->timer_running = 0;
}
}
}
break;
default:
break;
}
} else {
int samples = SRC_Samples(inst->source);
/* Adjust polling interval so that the number of sourcestats samples
remains close to the target value */
poll_adj = ((double)samples / inst->poll_target - 1.0) / inst->poll_target;
/* Use higher gain when decreasing the interval */
if (samples < inst->poll_target) {
poll_adj *= 2.0;
}
/* Slowly increase the polling interval if we can't get good_data */
adjust_poll(inst, 0.1);
}
adjust_poll(inst, poll_adj);
} else if (valid_header && valid_data) {
/* Slowly increase the polling interval if we can't get good_data */
adjust_poll(inst, 0.1);
}
/* Reduce polling rate if KoD RATE was received */
if (kod_rate && valid_kod) {
if (inst->remote_poll > inst->minpoll) {
inst->minpoll = inst->remote_poll;
if (inst->minpoll > inst->maxpoll)
inst->maxpoll = inst->minpoll;
if (inst->minpoll > inst->local_poll)
inst->local_poll = inst->minpoll;
LOG(LOGS_WARN, LOGF_NtpCore, "Received KoD RATE from %s, minpoll set to %d", UTI_IPToString(&inst->remote_addr.ip_addr), inst->minpoll);
}
/* 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), inst->minpoll);
}
}
/* If we're in burst mode, check whether the burst is completed and
revert to the previous mode */
switch (inst->opmode) {
case MD_BURST_WAS_ONLINE:
if (valid_header && good_data) {
--inst->burst_good_samples_to_go;
}
if (inst->burst_good_samples_to_go <= 0) {
inst->opmode = MD_ONLINE;
}
break;
case MD_BURST_WAS_OFFLINE:
if (valid_header && good_data) {
--inst->burst_good_samples_to_go;
}
if (inst->burst_good_samples_to_go <= 0) {
inst->opmode = MD_OFFLINE;
if (inst->timer_running) {
SCH_RemoveTimeout(inst->timeout_id);
}
inst->timer_running = 0;
}
break;
default:
break;
}
/* And now, requeue the timer.
@ -1151,12 +1152,10 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
assert(0);
break;
}
break;
case MD_BURST_WAS_ONLINE:
case MD_BURST_WAS_OFFLINE:
requeue_transmit = 1;
delay_time = BURST_INTERVAL;
break;
@ -1164,7 +1163,6 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
default:
assert(0);
break;
}
if (kod_rate && valid_kod) {
@ -1174,6 +1172,7 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
if (requeue_transmit) {
/* Get rid of old timeout and start a new one */
assert(inst->timer_running);
SCH_RemoveTimeout(inst->timeout_id);
inst->timeout_id = SCH_AddTimeoutInClass(delay_time, SAMPLING_SEPARATION,
SAMPLING_RANDOMNESS,
@ -1196,12 +1195,6 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
theta, delta, epsilon,
pkt_root_delay, pkt_root_dispersion);
}
/* At this point we will have to do something about trimming the
poll interval for the source and requeueing the polling timeout.
Left until the source statistics management has been written */
}
/* ================================================== */