bridge: Fix stream topology/participant locking and video misrouting.

This change fixes a few locking issues and some video misrouting.

1. When accessing the stream topology of a channel the channel lock
must be held to guarantee the topology remains valid.

2. When a channel was joined to a bridge the bridge specific
implementation for stream mapping was not invoked, causing video
to be misrouted for a brief period of time.

ASTERISK-27182

Change-Id: I5d2f779248b84d41c5bb3896bf22ba324b336b03

3 files changed, 51 insertions, 22 deletions

diff --git a/bridges/bridge_softmix.c b/bridges/bridge_softmix.c
index c5428a854..b35994895 100644
--- a/bridges/bridge_softmix.c
+++ b/bridges/bridge_softmix.c
@@ -577,13 +577,18 @@ static void sfu_topologies_on_join(struct ast_bridge_channel *joiner, struct ast
 	struct ast_stream_topology *joiner_video = NULL;
 	struct ast_stream_topology *existing_video = NULL;
 	struct ast_bridge_channel *participant;
+	int res;
 
 	joiner_video = ast_stream_topology_alloc();
 	if (!joiner_video) {
 		return;
 	}
 
-	if (append_source_streams(joiner_video, ast_channel_name(joiner->chan), ast_channel_get_stream_topology(joiner->chan))) {
+	ast_channel_lock(joiner->chan);
+	res = append_source_streams(joiner_video, ast_channel_name(joiner->chan), ast_channel_get_stream_topology(joiner->chan));
+	ast_channel_unlock(joiner->chan);
+
+	if (res) {
 		goto cleanup;
 	}
 
@@ -596,13 +601,18 @@ static void sfu_topologies_on_join(struct ast_bridge_channel *joiner, struct ast
 		if (participant == joiner) {
 			continue;
 		}
-		if (append_source_streams(existing_video, ast_channel_name(participant->chan),
-				ast_channel_get_stream_topology(participant->chan))) {
+		ast_channel_lock(participant->chan);
+		res = append_source_streams(existing_video, ast_channel_name(participant->chan),
+				ast_channel_get_stream_topology(participant->chan));
+		ast_channel_unlock(participant->chan);
+		if (res) {
 			goto cleanup;
 		}
 	}
 
+	ast_channel_lock(joiner->chan);
 	joiner_topology = ast_stream_topology_clone(ast_channel_get_stream_topology(joiner->chan));
+	ast_channel_unlock(joiner->chan);
 	if (!joiner_topology) {
 		goto cleanup;
 	}
@@ -617,7 +627,9 @@ static void sfu_topologies_on_join(struct ast_bridge_channel *joiner, struct ast
 		if (participant == joiner) {
 			continue;
 		}
+		ast_channel_lock(participant->chan);
 		participant_topology = ast_stream_topology_clone(ast_channel_get_stream_topology(participant->chan));
+		ast_channel_unlock(participant->chan);
 		if (!participant_topology) {
 			goto cleanup;
 		}
@@ -753,12 +765,16 @@ static int sfu_topologies_on_leave(struct ast_bridge_channel *leaver, struct ast
 			continue;
 		}
 
+		ast_channel_lock(participant->chan);
 		remove_destination_streams(participant_topology, ast_channel_name(leaver->chan), ast_channel_get_stream_topology(participant->chan));
+		ast_channel_unlock(participant->chan);
 		ast_channel_request_stream_topology_change(participant->chan, participant_topology, NULL);
 		ast_stream_topology_free(participant_topology);
 	}
 
+	ast_channel_lock(leaver->chan);
 	remove_destination_streams(leaver_topology, "", ast_channel_get_stream_topology(leaver->chan));
+	ast_channel_unlock(leaver->chan);
 	ast_channel_request_stream_topology_change(leaver->chan, leaver_topology, NULL);
 	ast_stream_topology_free(leaver_topology);
 
@@ -1657,6 +1673,7 @@ static void map_source_to_destinations(const char *source_stream_name, const cha
 		}
 
 		ast_bridge_channel_lock(participant);
+		ast_channel_lock(participant->chan);
 		topology = ast_channel_get_stream_topology(participant->chan);
 
 		for (i = 0; i < ast_stream_topology_get_count(topology); ++i) {
@@ -1668,6 +1685,7 @@ static void map_source_to_destinations(const char *source_stream_name, const cha
 				break;
 			}
 		}
+		ast_channel_unlock(participant->chan);
 		ast_bridge_channel_unlock(participant);
 	}
 }
@@ -1702,16 +1720,9 @@ static void softmix_bridge_stream_topology_changed(struct ast_bridge *bridge, st
 
 	/* First traversal: re-initialize all of the participants' stream maps */
 	AST_LIST_TRAVERSE(&bridge->channels, participant, entry) {
-		int size;
-
 		ast_bridge_channel_lock(participant);
-		size = ast_stream_topology_get_count(ast_channel_get_stream_topology(participant->chan));
-
-		AST_VECTOR_FREE(&participant->stream_map.to_channel);
-		AST_VECTOR_FREE(&participant->stream_map.to_bridge);
-
-		AST_VECTOR_INIT(&participant->stream_map.to_channel, size);
-		AST_VECTOR_INIT(&participant->stream_map.to_bridge, size);
+		AST_VECTOR_RESET(&participant->stream_map.to_channel, AST_VECTOR_ELEM_CLEANUP_NOOP);
+		AST_VECTOR_RESET(&participant->stream_map.to_bridge, AST_VECTOR_ELEM_CLEANUP_NOOP);
 		ast_bridge_channel_unlock(participant);
 	}
 
@@ -1727,6 +1738,8 @@ static void softmix_bridge_stream_topology_changed(struct ast_bridge *bridge, st
 		int i;
 		struct ast_stream_topology *topology;
 
+		ast_channel_lock(participant->chan);
+
 		topology = ast_channel_get_stream_topology(participant->chan);
 
 		for (i = 0; i < ast_stream_topology_get_count(topology); ++i) {
@@ -1766,6 +1779,8 @@ static void softmix_bridge_stream_topology_changed(struct ast_bridge *bridge, st
 			}
 			ast_bridge_channel_unlock(participant);
 		}
+
+		ast_channel_unlock(participant->chan);
 	}
 }
 
diff --git a/main/bridge.c b/main/bridge.c
index a1a1a6f55..b732d5fc5 100644
--- a/main/bridge.c
+++ b/main/bridge.c
@@ -446,7 +446,12 @@ static void bridge_channel_complete_join(struct ast_bridge *bridge, struct ast_b
 	 * media types vector. This way all streams map to the same media type index for
 	 * a given channel.
 	 */
-	ast_bridge_channel_stream_map(bridge_channel);
+	if (bridge_channel->bridge->technology->stream_topology_changed) {
+		bridge_channel->bridge->technology->stream_topology_changed(
+			bridge_channel->bridge, bridge_channel);
+	} else {
+		ast_bridge_channel_stream_map(bridge_channel);
+	}
 }
 
 /*!
diff --git a/main/bridge_channel.c b/main/bridge_channel.c
index 2e943000c..1427fd014 100644
--- a/main/bridge_channel.c
+++ b/main/bridge_channel.c
@@ -2344,16 +2344,23 @@ static void bridge_channel_handle_write(struct ast_bridge_channel *bridge_channe
 	case AST_FRAME_NULL:
 		break;
 	default:
-		if (fr->stream_num > 0 &&
-				(fr->stream_num >= (int)AST_VECTOR_SIZE(&bridge_channel->stream_map.to_channel) ||
-				AST_VECTOR_GET(&bridge_channel->stream_map.to_channel, fr->stream_num) == -1)) {
-			/* Nowhere to write to, so drop it */
-			break;
-		}
+		/* Assume that there is no mapped stream for this */
+		num = -1;
 
-		/* Find what stream number to write to for the channel */
-		num = fr->stream_num < 0 ? -1 :
-			AST_VECTOR_GET(&bridge_channel->stream_map.to_channel, fr->stream_num);
+		if (fr->stream_num > -1) {
+			ast_bridge_channel_lock(bridge_channel);
+			if (fr->stream_num < (int)AST_VECTOR_SIZE(&bridge_channel->stream_map.to_channel)) {
+				num = AST_VECTOR_GET(&bridge_channel->stream_map.to_channel, fr->stream_num);
+			}
+			ast_bridge_channel_unlock(bridge_channel);
+
+			/* If there is no mapped stream after checking the mapping then there is nowhere
+			 * to write this frame to, so drop it.
+			 */
+			if (num == -1) {
+				break;
+			}
+		}
 
 		/* Write the frame to the channel. */
 		bridge_channel->activity = BRIDGE_CHANNEL_THREAD_SIMPLE;
@@ -2983,7 +2990,9 @@ struct ast_bridge_channel *bridge_channel_internal_alloc(struct ast_bridge *brid
 
 void ast_bridge_channel_stream_map(struct ast_bridge_channel *bridge_channel)
 {
+	ast_channel_lock(bridge_channel->chan);
 	ast_stream_topology_map(ast_channel_get_stream_topology(bridge_channel->chan),
 		&bridge_channel->bridge->media_types, &bridge_channel->stream_map.to_bridge,
 		&bridge_channel->stream_map.to_channel);
+	ast_channel_unlock(bridge_channel->chan);
 }