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ntp: add support for processing of transmitted packets

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Add new functions for processing of packets after they are actually
sent by the kernel or HW in order to get a more accurate transmit
timestamp. Rename old functions for processing of received packets and
their parameters to make the naming more consistent.
This commit is contained in:
Miroslav Lichvar
2016-10-07 14:08:07 +02:00
parent a8c6bea2d5
commit 8f6a1b5318
7 changed files with 150 additions and 42 deletions
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107
ntp_core.c
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@@ -227,6 +227,9 @@ static ARR_Instance broadcasts;
/* Maximum allowed time for server to process client packet */
#define MAX_SERVER_INTERVAL 4.0
/* Maximum acceptable delay in transmission for timestamp correction */
#define MAX_TX_DELAY 1.0
/* Minimum and maximum allowed poll interval */
#define MIN_POLL 0
#define MAX_POLL 24
@@ -944,7 +947,7 @@ transmit_packet(NTP_Mode my_mode, /* The mode this machine wants to be */
UTI_TimespecToNtp64(&local_transmit, &message.transmit_ts, &ts_fuzz);
}
ret = NIO_SendPacket(&message, where_to, from, length);
ret = NIO_SendPacket(&message, where_to, from, length, local_tx != NULL);
if (local_tx) {
*local_tx = local_transmit;
@@ -1189,7 +1192,8 @@ check_packet_auth(NTP_Packet *pkt, int length,
/* ================================================== */
static int
receive_packet(NTP_Packet *message, struct timespec *now, double now_err, NCR_Instance inst, NTP_Local_Address *local_addr, int length)
receive_packet(NTP_Packet *message, struct timespec *rx_ts, double rx_ts_err,
NCR_Instance inst, NTP_Local_Address *local_addr, int length)
{
int pkt_leap;
uint32_t pkt_refid, pkt_key_id;
@@ -1315,7 +1319,7 @@ receive_packet(NTP_Packet *message, struct timespec *now, double now_err, NCR_In
symmetric associations using authentication */
if (test5) {
inst->remote_orig = message->transmit_ts;
inst->local_rx = *now;
inst->local_rx = *rx_ts;
}
/* This protects against replay of the last packet we sent */
@@ -1331,7 +1335,7 @@ receive_packet(NTP_Packet *message, struct timespec *now, double now_err, NCR_In
UTI_AverageDiffTimespecs(&remote_receive, &remote_transmit,
&remote_average, &remote_interval);
UTI_AverageDiffTimespecs(&inst->local_tx, now,
UTI_AverageDiffTimespecs(&inst->local_tx, rx_ts,
&local_average, &local_interval);
/* In our case, we work out 'delay' as the worst case delay,
@@ -1362,7 +1366,7 @@ receive_packet(NTP_Packet *message, struct timespec *now, double now_err, NCR_In
skew = (source_freq_hi - source_freq_lo) / 2.0;
/* and then calculate peer dispersion */
dispersion = precision + now_err + skew * fabs(local_interval);
dispersion = precision + rx_ts_err + skew * fabs(local_interval);
/* Additional tests required to pass before accumulating the sample */
@@ -1392,7 +1396,7 @@ receive_packet(NTP_Packet *message, struct timespec *now, double now_err, NCR_In
pkt_refid != UTI_IPToRefid(&local_addr->ip_addr);
} else {
offset = delay = dispersion = 0.0;
sample_time = *now;
sample_time = *rx_ts;
testA = testB = testC = testD = 0;
}
@@ -1534,8 +1538,8 @@ receive_packet(NTP_Packet *message, struct timespec *now, double now_err, NCR_In
| Bcast Client 6 | DSCRD | DSCRD | DSCRD | DSCRD | PROC |
+------------------+-------+-------+-------+-------+-------+
Association mode 0 is implemented in NCR_ProcessUnknown(), other modes
in NCR_ProcessKnown().
Association mode 0 is implemented in NCR_ProcessRxUnknown(), other modes
in NCR_ProcessRxKnown().
Broadcast, manycast and ephemeral symmetric passive associations are not
supported yet.
@@ -1546,10 +1550,10 @@ receive_packet(NTP_Packet *message, struct timespec *now, double now_err, NCR_In
and it relates to a source we have an ongoing protocol exchange with */
int
NCR_ProcessKnown
NCR_ProcessRxKnown
(NTP_Packet *message, /* the received message */
struct timespec *now, /* timestamp at time of receipt */
double now_err,
struct timespec *rx_ts, /* timestamp at time of receipt */
double rx_ts_err,
NCR_Instance inst, /* the instance record for this peer/server */
NTP_Local_Address *local_addr, /* the receiving address */
int length /* the length of the received packet */
@@ -1660,10 +1664,10 @@ NCR_ProcessKnown
return 0;
}
return receive_packet(message, now, now_err, inst, local_addr, length);
return receive_packet(message, rx_ts, rx_ts_err, inst, local_addr, length);
} else if (proc_as_unknown) {
NCR_ProcessUnknown(message, now, now_err, &inst->remote_addr,
local_addr, length);
NCR_ProcessRxUnknown(message, rx_ts, rx_ts_err, &inst->remote_addr,
local_addr, length);
/* It's not a reply to our request, don't return success */
return 0;
} else {
@@ -1678,10 +1682,10 @@ NCR_ProcessKnown
and it relates to a source we don't know (not our server or peer) */
void
NCR_ProcessUnknown
NCR_ProcessRxUnknown
(NTP_Packet *message, /* the received message */
struct timespec *now, /* timestamp at time of receipt */
double now_err, /* assumed error in the timestamp */
struct timespec *rx_ts, /* timestamp at time of receipt */
double rx_ts_err, /* assumed error in the timestamp */
NTP_Remote_Address *remote_addr,
NTP_Local_Address *local_addr,
int length /* the length of the received packet */
@@ -1726,7 +1730,7 @@ NCR_ProcessUnknown
return;
}
log_index = CLG_LogNTPAccess(&remote_addr->ip_addr, now);
log_index = CLG_LogNTPAccess(&remote_addr->ip_addr, rx_ts);
/* Don't reply to all requests if the rate is excessive */
if (log_index >= 0 && CLG_LimitNTPResponseRate(log_index)) {
@@ -1760,12 +1764,77 @@ NCR_ProcessUnknown
- don't save our transmit timestamp as we aren't maintaining state about
this client */
transmit_packet(my_mode, message->poll, NTP_LVM_TO_VERSION(message->lvm),
auth_mode, key_id, &message->transmit_ts, now, NULL, NULL,
auth_mode, key_id, &message->transmit_ts, rx_ts, NULL, NULL,
remote_addr, local_addr);
}
/* ================================================== */
static void
update_tx_timestamp(struct timespec *tx_ts, struct timespec *new_tx_ts,
NTP_int64 *local_ntp_tx, NTP_Packet *message)
{
double delay;
if (UTI_IsZeroTimespec(tx_ts)) {
DEBUG_LOG(LOGF_NtpCore, "Unexpected TX update");
return;
}
/* Check if this is the last packet that was sent */
if (message->transmit_ts.hi != local_ntp_tx->hi ||
message->transmit_ts.lo != local_ntp_tx->lo) {
DEBUG_LOG(LOGF_NtpCore, "TX timestamp mismatch");
return;
}
delay = UTI_DiffTimespecsToDouble(new_tx_ts, tx_ts);
if (delay < 0.0 || delay > MAX_TX_DELAY) {
DEBUG_LOG(LOGF_NtpCore, "Unacceptable TX delay %.9f", delay);
return;
}
*tx_ts = *new_tx_ts;
DEBUG_LOG(LOGF_NtpCore, "Updated TX timestamp delay=%.9f", delay);
}
/* ================================================== */
void
NCR_ProcessTxKnown(NTP_Packet *message, struct timespec *tx_ts, double tx_ts_err,
NCR_Instance inst, NTP_Local_Address *local_addr, int length)
{
NTP_Mode pkt_mode;
if (!check_packet_format(message, length))
return;
pkt_mode = NTP_LVM_TO_MODE(message->lvm);
/* Server and passive mode packets are responses to unknown sources */
if (pkt_mode != MODE_CLIENT && pkt_mode != MODE_ACTIVE) {
NCR_ProcessTxUnknown(message, tx_ts, tx_ts_err, &inst->remote_addr,
local_addr, length);
return;
}
update_tx_timestamp(&inst->local_tx, tx_ts, &inst->local_ntp_tx, message);
}
/* ================================================== */
void
NCR_ProcessTxUnknown(NTP_Packet *message, struct timespec *tx_ts, double tx_ts_err,
NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr, int length)
{
/* Nothing to do yet */
DEBUG_LOG(LOGF_NtpCore, "Process TX unknown");
}
/* ================================================== */
void
NCR_SlewTimes(NCR_Instance inst, struct timespec *when, double dfreq, double doffset)
{