app_confbridge: Use the SDP 'label' attribute to correlate users

Previously, the msid "label" attribute was used to correlate
participant info but because streams could be reused, the msid
wasn't being updated correctly when someone left the bridge and
another joined.

Now, instead of looking for the msid attribute on a channel's streams,
app_confbridge sets an "SDP:LABEL" attribute on the stream which
res_pjsip_sdp_rtp looks for.  If it finds it, it adds a "label"
attribute to the current sdp.

Change-Id: I6cbaa87fb59a2e0688d956e72d2d09e4ac20d5a5

diff --git a/apps/confbridge/confbridge_manager.c b/apps/confbridge/confbridge_manager.c
index a1015300983c36a57c9af25f34cb88db594b00b7..51112ba7854bde2895d7ed5c18c8d540389e1180 100644 (file)
--- a/apps/confbridge/confbridge_manager.c
+++ b/apps/confbridge/confbridge_manager.c
@@ -388,34 +388,18 @@ static struct ast_stream *get_stream(struct ast_stream_topology *topology,
        return NULL;
 }
 
-static struct ast_json *get_media_labels(struct confbridge_conference *conference,
+static void set_media_labels(struct confbridge_conference *conference,
        struct ast_channel *src_chan, struct ast_channel *dest_chan, enum label_direction dir)
 {
        struct ast_stream_topology *topology;
        struct ast_stream *stream;
-       const char *curr_a_label;
-       const char *a_label = NULL;
-       const char *v_label = NULL;
-       struct ast_json *labels = ast_json_array_create();
+       struct ast_channel *chan = dir == LABEL_DIRECTION_SRC ? dest_chan : src_chan;
 
-       if (!labels) {
-               return NULL;
-       }
-
-       topology = ast_channel_get_stream_topology(dir == LABEL_DIRECTION_SRC ? src_chan : dest_chan);
-       stream = get_stream(topology, AST_MEDIA_TYPE_AUDIO);
-       curr_a_label = stream ? ast_stream_get_metadata(stream, "MSID:LABEL") : NULL;
-       a_label = curr_a_label ?: conference->bridge->uniqueid;
-       ast_json_array_append(labels, ast_json_string_create(a_label));
-
-       topology = ast_channel_get_stream_topology(dir == LABEL_DIRECTION_SRC ? dest_chan : src_chan);
+       topology = ast_channel_get_stream_topology(chan);
        stream = get_stream(topology, AST_MEDIA_TYPE_VIDEO);
-       v_label = stream ? ast_stream_get_metadata(stream, "MSID:LABEL") : NULL;
-       if (v_label) {
-               ast_json_array_append(labels, ast_json_string_create(v_label));
+       if (stream) {
+               ast_stream_set_metadata(stream, "SDP:LABEL", ast_channel_uniqueid(chan));
        }
-
-       return ast_json_pack("{s: o }", "media_source_track_labels", labels);
 }
 
 static void send_message(const char *msg_name, char *conf_name, struct ast_json *json_object,
@@ -505,7 +489,6 @@ static void send_event_to_participants(struct confbridge_conference *conference,
        ao2_lock(conference);
        AST_LIST_TRAVERSE(&conference->active_list, user, list) {
                struct ast_json *json_object;
-               struct ast_json* source_json_labels = NULL;
 
                /*
                 * If the msg type is join, we need to capture all targets channel info so we can
@@ -514,7 +497,6 @@ static void send_event_to_participants(struct confbridge_conference *conference,
                if (source_send_events && stasis_message_type(msg) == confbridge_join_type()) {
                        struct ast_channel_snapshot *target_snapshot;
                        struct ast_json *target_json_channel;
-                       struct ast_json *target_json_labels;
 
                        target_snapshot = ast_channel_snapshot_get_latest(ast_channel_uniqueid(user->chan));
                        if (!target_snapshot) {
@@ -523,17 +505,15 @@ static void send_event_to_participants(struct confbridge_conference *conference,
                                continue;
                        }
 
-                       target_json_labels = get_media_labels(conference, chan, user->chan, LABEL_DIRECTION_SRC);
-                       target_json_channel = channel_to_json(target_snapshot, extras, target_json_labels);
+                       set_media_labels(conference, chan, user->chan, LABEL_DIRECTION_SRC);
+                       target_json_channel = channel_to_json(target_snapshot, extras, NULL);
                        ao2_ref(target_snapshot, -1);
-                       ast_json_unref(target_json_labels);
 
                        if (!json_channels) {
                                json_channels = ast_json_array_create();
                                if (!json_channels) {
                                        ast_log(LOG_ERROR, "Unable to allocate json array\n");
                                        ast_json_unref(target_json_channel);
-                                       ast_json_unref(target_json_labels);
                                        return;
                                }
                        }
@@ -555,11 +535,9 @@ static void send_event_to_participants(struct confbridge_conference *conference,
                        continue;
                }
 
-               source_json_labels = get_media_labels(conference, chan, user->chan, LABEL_DIRECTION_DEST);
-               ast_json_object_update(extras, source_json_labels);
+               set_media_labels(conference, chan, user->chan, LABEL_DIRECTION_DEST);
 
-               json_object = pack_snapshots(obj->bridge, obj->channel, extras, source_json_labels, msg);
-               ast_json_unref(source_json_labels);
+               json_object = pack_snapshots(obj->bridge, obj->channel, extras, NULL, msg);
 
                if (!json_object) {
                        ast_log(LOG_ERROR, "Unable to convert %s message to json\n", msg_name);

diff --git a/res/res_pjsip_sdp_rtp.c b/res/res_pjsip_sdp_rtp.c
index c9c0f17eca10552c9caf13dd62356189a2a13b98..d435d8ff03ab6a941728271a86a395e7b076e23c 100644 (file)
--- a/res/res_pjsip_sdp_rtp.c
+++ b/res/res_pjsip_sdp_rtp.c
@@ -1100,6 +1100,7 @@ static void add_msid_to_stream(struct ast_sip_session *session,
        pj_str_t stmp;
        pjmedia_sdp_attr *attr;
        char msid[(AST_UUID_STR_LEN * 2) + 2];
+       const char *stream_label = ast_stream_get_metadata(stream, "SDP:LABEL");
 
        if (!session->endpoint->media.webrtc) {
                return;
@@ -1119,19 +1120,7 @@ static void add_msid_to_stream(struct ast_sip_session *session,
        }
 
        if (ast_strlen_zero(session_media->label)) {
-               /*
-                * If this stream has already been assigned a label, use it.
-                * This will ensure that a confbridge participant is known by
-                * the same label by all other participants.
-                */
-               const char *stream_label = ast_stream_get_metadata(stream, "MSID:LABEL");
-
-               if (!ast_strlen_zero(stream_label)) {
-                       ast_copy_string(session_media->label, stream_label, sizeof(session_media->label));
-               } else {
                        ast_uuid_generate_str(session_media->label, sizeof(session_media->label));
-                       ast_stream_set_metadata(stream, "MSID:LABEL", session_media->label);
-               }
        }
 
        snprintf(msid, sizeof(msid), "%s %s", session_media->mslabel, session_media->label);
@@ -1139,6 +1128,14 @@ static void add_msid_to_stream(struct ast_sip_session *session,
                ast_codec_media_type2str(ast_stream_get_type(stream)), msid);
        attr = pjmedia_sdp_attr_create(pool, "msid", pj_cstr(&stmp, msid));
        pjmedia_sdp_attr_add(&media->attr_count, media->attr, attr);
+
+       /* 'label' must come after 'msid' */
+       if (!ast_strlen_zero(stream_label)) {
+               ast_debug(3, "Stream Label: %p %s %s\n", stream,
+                       ast_codec_media_type2str(ast_stream_get_type(stream)), stream_label);
+               attr = pjmedia_sdp_attr_create(pool, "label", pj_cstr(&stmp, stream_label));
+               pjmedia_sdp_attr_add(&media->attr_count, media->attr, attr);
+       }
 }
 
 static void add_rtcp_fb_to_stream(struct ast_sip_session *session,