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FS-11201 Filter out erroneous RTT values #fix 

Erroneous DLSR in received RTCP report could
cause RTT to be negative (RTT = A - DLSR - LSR).
Add check for this and prevent corruption
of statistics and estimations (estimator code used
bad RTT values).
This commit is contained in:
Piotr Gregor 2018-06-21 16:48:51 +01:00 committed by Muteesa Fred
parent 70f21b8287
commit e66de38ba2
1 changed files with 45 additions and 17 deletions
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62
src/switch_rtp.c
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@ -6502,6 +6502,7 @@ static switch_status_t process_rtcp_report(switch_rtp_t *rtp_session, rtcp_msg_t
uint32_t lsr;
uint32_t packet_ssrc;
double rtt_now = 0;
uint8_t rtt_valid = 0;
int rtt_increase = 0, packet_loss_increase=0;
//if (msg->header.type == _RTCP_PT_SR && rtp_session->ice.ice_user) {
@ -6511,7 +6512,7 @@ static switch_status_t process_rtcp_report(switch_rtp_t *rtp_session, rtcp_msg_t
now = switch_micro_time_now(); /* number of microseconds since 00:00:00 january 1, 1970 UTC */
sec = (uint32_t)(now/1000000); /* converted to second (NTP most significant bits) */
ntp_sec = sec+NTP_TIME_OFFSET; /* 32bits most significant */
ntp_usec = (uint32_t)(now - (sec*1000000)); /* micro seconds */
ntp_usec = (uint32_t)(now - (((switch_time_t) sec) * 1000000)); /* micro seconds */
lsr_now = (uint32_t)(ntp_usec*0.065536) | (ntp_sec&0x0000ffff)<<16; // 0.065536 is used for convertion from useconds
if (msg->header.type == _RTCP_PT_SR) { /* Sender report */
@ -6589,23 +6590,47 @@ static switch_status_t process_rtcp_report(switch_rtp_t *rtp_session, rtcp_msg_t
rtp_session->rtcp_frame.reports[i].jitter = ntohl(report->jitter);
rtp_session->rtcp_frame.reports[i].lsr = ntohl(report->lsr);
rtp_session->rtcp_frame.reports[i].dlsr = ntohl(report->dlsr);
if (rtp_session->rtcp_frame.reports[i].lsr && !rtp_session->flags[SWITCH_RTP_FLAG_RTCP_PASSTHRU]) {
switch_time_exp_gmt(&now_hr,now);
/* Calculating RTT = A - DLSR - LSR */
rtt_now = (double)(lsr_now - rtp_session->rtcp_frame.reports[i].dlsr - rtp_session->rtcp_frame.reports[i].lsr)/65536;
switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(rtp_session->session), SWITCH_LOG_DEBUG3,
"Receiving an RTCP packet\n[%04d-%02d-%02d %02d:%02d:%02d.%d] SSRC[0x%x]\n"
"RTT[%f] = A[%u] - DLSR[%u] - LSR[%u]\n",
1900 + now_hr.tm_year, now_hr.tm_mday, now_hr.tm_mon, now_hr.tm_hour, now_hr.tm_min, now_hr.tm_sec, now_hr.tm_usec,
rtp_session->rtcp_frame.reports[i].ssrc, rtt_now,
lsr_now, rtp_session->rtcp_frame.reports[i].dlsr, rtp_session->rtcp_frame.reports[i].lsr);
if (!rtp_session->rtcp_frame.reports[i].rtt_avg) {
rtp_session->rtcp_frame.reports[i].rtt_avg = rtt_now;
/* Only account RTT if it didn't overflow. */
if (lsr_now > rtp_session->rtcp_frame.reports[i].dlsr + rtp_session->rtcp_frame.reports[i].lsr) {
rtt_valid = 1;
switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(rtp_session->session), SWITCH_LOG_DEBUG3,
"Receiving an RTCP packet\n[%04d-%02d-%02d %02d:%02d:%02d.%d] SSRC[0x%x]\n"
"RTT[%f] = A[%u] - DLSR[%u] - LSR[%u]\n",
1900 + now_hr.tm_year, now_hr.tm_mday, now_hr.tm_mon, now_hr.tm_hour, now_hr.tm_min, now_hr.tm_sec, now_hr.tm_usec,
rtp_session->rtcp_frame.reports[i].ssrc, rtt_now,
lsr_now, rtp_session->rtcp_frame.reports[i].dlsr, rtp_session->rtcp_frame.reports[i].lsr);
if (!rtp_session->rtcp_frame.reports[i].rtt_avg) {
rtp_session->rtcp_frame.reports[i].rtt_avg = rtt_now;
} else {
rtp_session->rtcp_frame.reports[i].rtt_avg = (double)((rtp_session->rtcp_frame.reports[i].rtt_avg * .7) + (rtt_now * .3 ));
}
} else {
rtp_session->rtcp_frame.reports[i].rtt_avg = (double)((rtp_session->rtcp_frame.reports[i].rtt_avg * .7) + (rtt_now * .3 ));
#ifdef DEBUG_RTCP
switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(rtp_session->session), SWITCH_LOG_WARNING,
"Receiving RTCP packet\n[%04d-%02d-%02d %02d:%02d:%02d.%d] SSRC[0x%x]\n"
"Ignoring erroneous RTT[%f] = A[%u] - DLSR[%u] - LSR[%u]\n",
1900 + now_hr.tm_year, now_hr.tm_mday, now_hr.tm_mon, now_hr.tm_hour, now_hr.tm_min, now_hr.tm_sec, now_hr.tm_usec,
rtp_session->rtcp_frame.reports[i].ssrc, rtt_now,
lsr_now, rtp_session->rtcp_frame.reports[i].dlsr, rtp_session->rtcp_frame.reports[i].lsr);
#endif
}
rtt_valid = 0;
rtt_now = 0;
switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(rtp_session->session), SWITCH_LOG_DEBUG3, "RTT average %f\n",
rtp_session->rtcp_frame.reports[i].rtt_avg);
rtp_session->rtcp_frame.reports[i].rtt_avg);
}
if (rtp_session->flags[SWITCH_RTP_FLAG_ADJ_BITRATE_CAP] && rtp_session->flags[SWITCH_RTP_FLAG_ESTIMATORS] && !rtp_session->flags[SWITCH_RTP_FLAG_VIDEO]) {
@ -6615,14 +6640,17 @@ static switch_status_t process_rtcp_report(switch_rtp_t *rtp_session, rtcp_msg_t
switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(rtp_session->session), SWITCH_LOG_DEBUG3, "Current packet loss: [%d %%] Current RTT: [%f ms]\n", percent_fraction, rtt_now);
#endif
switch_kalman_estimate(rtp_session->estimators[EST_RTT], rtt_now, EST_RTT);
if (rtt_valid) {
if (switch_kalman_cusum_detect_change(rtp_session->detectors[EST_RTT], rtt_now, rtp_session->estimators[EST_RTT]->val_estimate_last)) {
/* sudden change in the mean value of RTT */
switch_kalman_estimate(rtp_session->estimators[EST_RTT], rtt_now, EST_RTT);
if (switch_kalman_cusum_detect_change(rtp_session->detectors[EST_RTT], rtt_now, rtp_session->estimators[EST_RTT]->val_estimate_last)) {
/* sudden change in the mean value of RTT */
#ifdef DEBUG_ESTIMATORS_
switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(rtp_session->session), SWITCH_LOG_DEBUG3,"Sudden change in the mean value of RTT !\n");
switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(rtp_session->session), SWITCH_LOG_DEBUG3,"Sudden change in the mean value of RTT !\n");
#endif
rtt_increase = 1;
rtt_increase = 1;
}
}
switch_kalman_estimate(rtp_session->estimators[EST_LOSS], percent_fraction, EST_LOSS);
@ -6666,7 +6694,7 @@ static switch_status_t process_rtcp_report(switch_rtp_t *rtp_session, rtcp_msg_t
(void *)&rtp_session->rtcp_frame.reports[i].loss_avg,
SCCT_NONE, NULL, NULL, NULL);
} else if (!rtt_increase && rtp_session->estimators[EST_LOSS]->val_estimate_last >= rtp_session->rtcp_frame.reports[i].loss_avg ) {
} else if (rtt_valid && !rtt_increase && rtp_session->estimators[EST_LOSS]->val_estimate_last >= rtp_session->rtcp_frame.reports[i].loss_avg ) {
/* lossy because of congestion (queues full somewhere -> some packets are dropped , but RTT is good ), packet loss with many small gaps */
#ifdef DEBUG_ESTIMATORS_
switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(rtp_session->session), SWITCH_LOG_DEBUG3, "packet loss, but RTT is not bad\n");