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Fix peer polling with shorter remote poll

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If the remote peer uses a polling interval shorter than the local
minimum, the local peer will be unable to send any packets as the
timeout will be updated on every received valid packet and will never
expire.

Modify the delay calculation to aim at poll interval away since the last
transmit.

Also, share the delay calculation code with transmit_timeout().
This commit is contained in:
Miroslav Lichvar 2013-06-04 12:39:17 +02:00
parent cf700a0084
commit 78ae4ebfaa
1 changed files with 18 additions and 14 deletions
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32
ntp_core.c
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@ -330,6 +330,7 @@ NCR_GetInstance(NTP_Remote_Address *remote_addr, NTP_Source_Type type, SourcePar
result->auto_offline = params->auto_offline;
result->local_poll = params->minpoll;
result->remote_poll = 0;
/* Create a source instance for this NTP source */
result->source = SRC_CreateNewInstance(UTI_IPToRefid(&remote_addr->ip_addr), SRC_NTP, params->sel_option, &result->remote_addr.ip_addr);
@ -438,7 +439,7 @@ get_poll_adj(NCR_Instance inst, double error_in_estimate, double peer_distance)
/* ================================================== */
static double
get_transmit_delay(NCR_Instance inst)
get_transmit_delay(NCR_Instance inst, int on_tx, double last_tx)
{
int poll_to_use;
double delay_time;
@ -475,7 +476,7 @@ get_transmit_delay(NCR_Instance inst)
case MODE_ACTIVE:
/* Symmetric active association - aim at some randomised time approx
half the poll interval away, to interleave 50-50 with the peer */
the poll interval away since the last transmit */
/* Use shorter of the local and remote poll interval, but not shorter
than the allowed minimum */
@ -485,7 +486,12 @@ get_transmit_delay(NCR_Instance inst)
if (poll_to_use < inst->minpoll)
poll_to_use = inst->minpoll;
delay_time = (double) (1UL<<poll_to_use) / 2.0;
delay_time = (double) (1UL<<poll_to_use);
if (last_tx > 0.0)
delay_time -= last_tx;
if (delay_time < 0.0)
delay_time = 0.0;
break;
default:
@ -496,7 +502,9 @@ get_transmit_delay(NCR_Instance inst)
case MD_BURST_WAS_ONLINE:
case MD_BURST_WAS_OFFLINE:
delay_time = BURST_INTERVAL;
/* With burst, the timeout for new transmit after valid reply is shorter
than the timeout without reply */
delay_time = on_tx ? BURST_TIMEOUT : BURST_INTERVAL;
break;
default:
assert(0);
@ -635,7 +643,7 @@ static void
transmit_timeout(void *arg)
{
NCR_Instance inst = (NCR_Instance) arg;
double timeout_delay=0.0;
double timeout_delay;
int do_auth;
inst->timer_running = 0;
@ -719,21 +727,17 @@ transmit_timeout(void *arg)
&inst->local_rx, &inst->local_tx, &inst->local_ntp_tx,
&inst->remote_addr);
/* Restart timer for this message */
switch (inst->opmode) {
case MD_ONLINE:
timeout_delay = (double)(1 << inst->local_poll);
break;
case MD_OFFLINE:
assert(0);
return;
case MD_BURST_WAS_ONLINE:
case MD_BURST_WAS_OFFLINE:
--inst->burst_total_samples_to_go;
timeout_delay = BURST_TIMEOUT;
break;
default:
break;
}
/* Restart timer for this message */
timeout_delay = get_transmit_delay(inst, 1, 0.0);
inst->timer_running = 1;
inst->timeout_id = SCH_AddTimeoutInClass(timeout_delay, SAMPLING_SEPARATION,
SAMPLING_RANDOMNESS,
@ -1171,7 +1175,7 @@ receive_packet(NTP_Packet *message, struct timeval *now, double now_err, NCR_Ins
/* And now, requeue the timer. */
if (requeue_transmit && inst->opmode != MD_OFFLINE) {
delay_time = get_transmit_delay(inst);
delay_time = get_transmit_delay(inst, 0, local_interval);
if (kod_rate) {
/* Back off for a while */