TT#121752 fix RTCP RR SSRC substitution when transcoding

Perform reverse SSRC mapping even if output media is not known, and use
the appropriate media side when looking up SSRCs for received RTCP
timestamps.

closes #1298

Change-Id: Ifa5a982163bf7b0510ffc2a92ae25995d1adb888
(cherry picked from commit 93377588ad)

daemon/rtcp.c

@@ -1307,7 +1307,7 @@ static void transcode_rr(struct rtcp_process_ctx *ctx, struct report_block *rr)
 		return;
 	if (ctx->scratch.rr.from != ctx->mp->ssrc_in->parent->h.ssrc)
 		return;
-	if (!ctx->mp->media || !ctx->mp->media_out)
+	if (!ctx->mp->media)
 		return;
 
 	// reverse SSRC mapping
@@ -1315,6 +1315,9 @@ static void transcode_rr(struct rtcp_process_ctx *ctx, struct report_block *rr)
 			SSRC_DIR_OUTPUT, ctx->mp->media->monologue);
 	rr->ssrc = htonl(map_ctx->ssrc_map_out);
 
+	if (!ctx->mp->media_out)
+		return;
+
 	// for reception stats
 	struct ssrc_ctx *input_ctx = get_ssrc_ctx(map_ctx->ssrc_map_out,
 			ctx->mp->media_out->monologue->ssrc_hash,

daemon/ssrc.c

@@ -84,7 +84,7 @@ static void mos_calc(struct ssrc_stats_block *ssb) {
 	ssb->mos = intmos;
 }
 
-static struct ssrc_entry *find_ssrc(uint32_t ssrc, struct ssrc_hash *ht) {
+static void *find_ssrc(uint32_t ssrc, struct ssrc_hash *ht) {
 	rwlock_lock_r(&ht->lock);
 	struct ssrc_entry *ret = g_atomic_pointer_get(&ht->cache);
 	if (!ret || ret->ssrc != ssrc) {
@@ -257,14 +257,25 @@ static long long __calc_rtt(struct call_monologue *ml, uint32_t ssrc, uint32_t n
 
 	if (!ntp_middle_bits || !delay)
 		return 0;
+	if (!ml->active_dialogue)
+		return 0;
 
-	struct ssrc_entry_call *e = get_ssrc(ssrc, ml->ssrc_hash);
+	struct ssrc_entry_call *e = find_ssrc(ssrc, ml->active_dialogue->ssrc_hash);
 	if (G_UNLIKELY(!e))
 		return 0;
 
 	if (pt_p)
 		*pt_p = e->output_ctx.tracker.most[0] == 255 ? -1 : e->output_ctx.tracker.most[0];
 
+	// grab the opposite side SSRC for the time reports
+	uint32_t map_ssrc = e->output_ctx.ssrc_map_out;
+	if (!map_ssrc)
+		map_ssrc = e->h.ssrc;
+	obj_put(&e->h);
+	e = find_ssrc(map_ssrc, ml->ssrc_hash);
+	if (G_UNLIKELY(!e))
+		return 0;
+
 	struct ssrc_time_item *sti;
 	GQueue *q = (((void *) e) + reports_queue_offset);
 	mutex_lock(&e->h.lock);