[Asterisk-code-review] res pjsip session/ sdp rtp: Handling of 'msid' is incorrect (asterisk[master])

[Kevin Harwell]

Kevin Harwell has uploaded this change for review. ( https://gerrit.asterisk.org/6163


Change subject: res_pjsip_session/_sdp_rtp: Handling of 'msid' is incorrect
......................................................................

res_pjsip_session/_sdp_rtp: Handling of 'msid' is incorrect

Currently, the handling of the msid attribute is not quite right. According to
the spec the msid's between the offer/answer are not dependent upon one another.
Meaning the same msid's given in an offer do not have to be returned in the
answer for a given stream. And they probably shouldn't be (copied/reused) since
this can potentially cause some browser side confusion.

This patch generates new msids when both an offer and answer are sent from
Asterisk. However, Asterisk does reuse the original msid it sent out for a
reinvite. Also audio+video streams are paired together by sharing the same
stream id, but a different track id.

ASTERISK-27179 #close

Change-Id: Ifaec06dc7e65ad841633a24ebec8c8a9302d6643
---
M include/asterisk/res_pjsip_session.h
M res/res_pjsip_sdp_rtp.c
M res/res_pjsip_session.c
3 files changed, 32 insertions(+), 30 deletions(-)



  git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/63/6163/1

diff --git a/include/asterisk/res_pjsip_session.h b/include/asterisk/res_pjsip_session.h
index caf10db..5f49c82 100644
--- a/include/asterisk/res_pjsip_session.h
+++ b/include/asterisk/res_pjsip_session.h
@@ -105,8 +105,10 @@
 	int bundle_group;
 	/*! \brief Whether this stream is currently bundled or not */
 	unsigned int bundled;
-	/*! \brief RTP/Media streams association identifier */
-	char *msid;
+	/*! \brief Media stream label */
+	char mslabel[AST_UUID_STR_LEN];
+	/*! \brief Track label */
+	char label[AST_UUID_STR_LEN];
 };
 
 /*!
diff --git a/res/res_pjsip_sdp_rtp.c b/res/res_pjsip_sdp_rtp.c
index f79c4cb..ad1abd2 100644
--- a/res/res_pjsip_sdp_rtp.c
+++ b/res/res_pjsip_sdp_rtp.c
@@ -1025,44 +1025,46 @@
 	}
 }
 
-static void process_msid_attribute(struct ast_sip_session *session,
-	struct ast_sip_session_media *session_media, pjmedia_sdp_media *media)
-{
-	pjmedia_sdp_attr *attr;
-
-	if (!session->endpoint->media.webrtc) {
-		return;
-	}
-
-	attr = pjmedia_sdp_media_find_attr2(media, "msid", NULL);
-	if (attr) {
-		ast_free(session_media->msid);
-		ast_copy_pj_str2(&session_media->msid, &attr->value);
-	}
-}
-
 static void add_msid_to_stream(struct ast_sip_session *session,
-	struct ast_sip_session_media *session_media, pj_pool_t *pool, pjmedia_sdp_media *media)
+	struct ast_sip_session_media *session_media, pj_pool_t *pool, pjmedia_sdp_media *media,
+	struct ast_stream *stream)
 {
 	pj_str_t stmp;
 	pjmedia_sdp_attr *attr;
+	char msid[(AST_UUID_STR_LEN * 2) + 2];
 
 	if (!session->endpoint->media.webrtc) {
 		return;
 	}
 
-	if (ast_strlen_zero(session_media->msid)) {
-		char uuid1[AST_UUID_STR_LEN], uuid2[AST_UUID_STR_LEN];
+	if (ast_strlen_zero(session_media->mslabel)) {
+		if (ast_sip_session_is_pending_stream_default(session, stream)) {
+			int index;
 
-		if (ast_asprintf(&session_media->msid, "{%s} {%s}",
-			ast_uuid_generate_str(uuid1, sizeof(uuid1)),
-			ast_uuid_generate_str(uuid2, sizeof(uuid2))) < 0) {
-			session_media->msid = NULL;
-			return;
+			/* If this is a default stream we group them together under the same stream, but as different tracks */
+			for (index = 0; index < AST_VECTOR_SIZE(&session->pending_media_state->sessions); ++index) {
+				struct ast_sip_session_media *other_session_media = AST_VECTOR_GET(&session->pending_media_state->sessions, index);
+
+				if (session_media == other_session_media) {
+					continue;
+				}
+
+				ast_copy_string(session_media->mslabel, other_session_media->mslabel, sizeof(session_media->mslabel));
+				break;
+			}
+                }
+
+		if (ast_strlen_zero(session_media->mslabel)) {
+			ast_uuid_generate_str(session_media->mslabel, sizeof(session_media->mslabel));
 		}
 	}
 
-	attr = pjmedia_sdp_attr_create(pool, "msid", pj_cstr(&stmp, session_media->msid));
+	if (ast_strlen_zero(session_media->label)) {
+		ast_uuid_generate_str(session_media->label, sizeof(session_media->label));
+	}
+
+	snprintf(msid, sizeof(msid), "%s %s", session_media->mslabel, session_media->label);
+	attr = pjmedia_sdp_attr_create(pool, "msid", pj_cstr(&stmp, msid));
 	pjmedia_sdp_attr_add(&media->attr_count, media->attr, attr);
 }
 
@@ -1127,7 +1129,6 @@
 	}
 
 	process_ssrc_attributes(session, session_media, stream);
-	process_msid_attribute(session, session_media, stream);
 	session_media_transport = ast_sip_session_media_get_transport(session, session_media);
 
 	if (session_media_transport == session_media || !session_media->bundled) {
@@ -1586,7 +1587,7 @@
 	}
 
 	add_ssrc_to_stream(session, session_media, pool, media);
-	add_msid_to_stream(session, session_media, pool, media);
+	add_msid_to_stream(session, session_media, pool, media, stream);
 	add_rtcp_fb_to_stream(session, session_media, pool, media);
 
 	/* Add the media stream to the SDP */
diff --git a/res/res_pjsip_session.c b/res/res_pjsip_session.c
index bb349a4..607f329 100644
--- a/res/res_pjsip_session.c
+++ b/res/res_pjsip_session.c
@@ -395,7 +395,6 @@
 	}
 
 	ast_free(session_media->mid);
-	ast_free(session_media->msid);
 }
 
 struct ast_sip_session_media *ast_sip_session_media_state_add(struct ast_sip_session *session,

-- 
To view, visit https://gerrit.asterisk.org/6163
To unsubscribe, visit https://gerrit.asterisk.org/settings

Gerrit-Project: asterisk
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: Ifaec06dc7e65ad841633a24ebec8c8a9302d6643
Gerrit-Change-Number: 6163
Gerrit-PatchSet: 1
Gerrit-Owner: Kevin Harwell <kharwell at digium.com>
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