FS-11561: [core] RTCP: attempt to avoid race cond on calculating DLSR (stats->last_re...

diff --git a/src/switch_rtp.c b/src/switch_rtp.c
index 0609906ad790aef2aae6bf9d35fe33df6fcc36ef..be3724f2184d834c0a1f45747088a0b77504aae6 100644 (file)
--- a/src/switch_rtp.c
+++ b/src/switch_rtp.c
@@ -1800,20 +1800,28 @@ static void rtcp_generate_sender_info(switch_rtp_t *rtp_session, struct switch_r
                        );
 }
 
+static inline uint32_t calc_local_lsr_now() 
+{
+       switch_time_t now;
+       uint32_t ntp_sec, ntp_usec, lsr_now, sec;
+       now = switch_micro_time_now();
+       sec = (uint32_t)(now/1000000);        /* convert to seconds     */
+       ntp_sec = sec+NTP_TIME_OFFSET;  /* convert to NTP seconds */
+       ntp_usec = (uint32_t)(now - ((switch_time_t) sec*1000000)); /* remove seconds to keep only the microseconds */
+
+       lsr_now = (uint32_t)(ntp_usec*0.065536) | (ntp_sec&0x0000ffff)<<16; /* 0.065536 is used for convertion from useconds to fraction of 65536 (x65536/1000000) */
+
+       return lsr_now;
+}
+
 //#define DEBUG_RTCP
 static void rtcp_generate_report_block(switch_rtp_t *rtp_session, struct switch_rtcp_report_block *rtcp_report_block){
 #ifdef DEBUG_RTCP
        switch_core_session_t *session = switch_core_memory_pool_get_data(rtp_session->pool, "__session");
 #endif
        switch_rtcp_numbers_t * stats=&rtp_session->stats.rtcp;
-       switch_time_t now;
-       uint32_t expected_pkt, dlsr;
+       uint32_t expected_pkt, dlsr = 0;
        int32_t pkt_lost;
-       uint32_t ntp_sec, ntp_usec, lsr_now, sec;
-       now = switch_micro_time_now();
-       sec = (uint32_t)(now/1000000);        /* convert to seconds     */
-       ntp_sec = sec+NTP_TIME_OFFSET;  /* convert to NTP seconds */
-       ntp_usec = (uint32_t)(now - (sec*1000000)); /* remove seconds to keep only the microseconds */
 
        /* Packet loss */
        if (stats->rtcp_rtp_count == 0) {
@@ -1850,12 +1858,12 @@ static void rtcp_generate_report_block(switch_rtp_t *rtp_session, struct switch_
        rtcp_report_block->jitter = htonl((uint32_t)stats->inter_jitter);
 
        /* Delay since Last Sender Report (DLSR) : 32bits, 1/65536 seconds */
-       lsr_now = (uint32_t)(ntp_usec*0.065536) | (ntp_sec&0x0000ffff)<<16; /* 0.065536 is used for convertion from useconds to fraction of 65536 (x65536/1000000) */
-
        if (stats->last_recv_lsr_local) {
-               dlsr = lsr_now - stats->last_recv_lsr_local;
-       } else {
-               dlsr = 0;
+               uint32_t lsr_now = calc_local_lsr_now();
+               /* check lsr_now: what we just read from clock may be in the past (race cond), don't send huge dlsr due to uint wrap around */
+               if (lsr_now > stats->last_recv_lsr_local) {
+                       dlsr = lsr_now - stats->last_recv_lsr_local;
+               }
        }
        rtcp_report_block->lsr = stats->last_recv_lsr_peer;
        rtcp_report_block->dlsr = htonl(dlsr);
@@ -6523,9 +6531,11 @@ static switch_status_t process_rtcp_report(switch_rtp_t *rtp_session, rtcp_msg_t
                struct switch_rtcp_report_block *report;
 
                if (msg->header.type == _RTCP_PT_SR || msg->header.type == _RTCP_PT_RR) {
-                       switch_time_t now;
-                       switch_time_exp_t now_hr;
-                       uint32_t sec, ntp_sec, ntp_usec, lsr_now;
+                       int i;
+#ifdef DEBUG_RTCP
+                       switch_time_t now = switch_micro_time_now();
+#endif 
+                       uint32_t lsr_now;
                        uint32_t lsr;
                        uint32_t packet_ssrc;
                        double rtt_now = 0;
@@ -6536,11 +6546,7 @@ static switch_status_t process_rtcp_report(switch_rtp_t *rtp_session, rtcp_msg_t
                        //      rtp_session->send_rr = 1;
                        //}
 
-                       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 - (((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
+                       lsr_now = calc_local_lsr_now();
 
                        if (msg->header.type == _RTCP_PT_SR) { /* Sender report */
                                struct switch_rtcp_sender_report* sr = (struct switch_rtcp_sender_report*)msg->body;
@@ -6620,30 +6626,31 @@ static switch_status_t process_rtcp_report(switch_rtp_t *rtp_session, rtcp_msg_t
                                
                                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)(((int64_t)lsr_now) - rtp_session->rtcp_frame.reports[i].dlsr - rtp_session->rtcp_frame.reports[i].lsr))/65536;
 
                                        /* 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;
-
+#ifdef DEBUG_RTCP
+                                               switch_time_exp_t now_hr;
+                                               switch_time_exp_gmt(&now_hr,now);
                                                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);
+#endif 
+                                               rtt_valid = 1;
                                                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 {
-
 #ifdef DEBUG_RTCP
+                                               switch_time_exp_t now_hr;
+                                               switch_time_exp_gmt(&now_hr,now);
                                                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",