patch: add alternative protocols to sdp

- sdp_media_set_alt_protos() and accessor function


Example usage:

	err = sdp_media_set_alt_protos(m->sdp, 4,
				       "RTP/AVP",
       				       "RTP/AVPF",
       				       "RTP/SAVP",
       				       "RTP/SAVPF");

include/re_sdp.h

@@ -87,6 +87,7 @@ struct sdp_media;
 
 int  sdp_media_add(struct sdp_media **mp, struct sdp_session *sess,
 		   const char *name, uint16_t port, const char *proto);
+int  sdp_media_set_alt_protos(struct sdp_media *m, unsigned protoc, ...);
 void sdp_media_set_encode_handler(struct sdp_media *m, sdp_media_enc_h *ench,
 				  void *arg);
 void sdp_media_set_fmt_ignore(struct sdp_media *m, bool fmt_ignore);
@@ -101,6 +102,7 @@ void sdp_media_set_ldir(struct sdp_media *m, enum sdp_dir dir);
 int  sdp_media_set_lattr(struct sdp_media *m, bool replace,
 			 const char *name, const char *value, ...);
 void sdp_media_del_lattr(struct sdp_media *m, const char *name);
+const char *sdp_media_proto(const struct sdp_media *m);
 uint16_t sdp_media_rport(const struct sdp_media *m);
 const struct sa *sdp_media_raddr(const struct sdp_media *m);
 void sdp_media_raddr_rtcp(const struct sdp_media *m, struct sa *raddr);

src/sdp/media.c

@@ -18,6 +18,7 @@
 static void destructor(void *arg)
 {
 	struct sdp_media *m = arg;
+	unsigned i;
 
 	list_flush(&m->lfmtl);
 	list_flush(&m->rfmtl);
@@ -31,6 +32,9 @@ static void destructor(void *arg)
 		return;
 	}
 
+	for (i=0; i<ARRAY_SIZE(m->protov); i++)
+		mem_deref(m->protov[i]);
+
 	list_unlink(&m->le);
 	mem_deref(m->name);
 	mem_deref(m->proto);
@@ -171,18 +175,57 @@ void sdp_media_rreset(struct sdp_media *m)
 }
 
 
+/**
+ * Compare media line protocols
+ *
+ * @param m      SDP Media line
+ * @param proto  Transport protocol
+ * @param update Update media protocol if match is found in alternate set
+ *
+ * @return True if matching, False if not
+ */
+bool sdp_media_proto_cmp(struct sdp_media *m, const struct pl *proto,
+			 bool update)
+{
+	unsigned i;
+
+	if (!m || !proto)
+		return false;
+
+	if (!pl_strcmp(proto, m->proto))
+		return true;
+
+	for (i=0; i<ARRAY_SIZE(m->protov); i++) {
+
+		if (!m->protov[i] || pl_strcmp(proto, m->protov[i]))
+			continue;
+
+		if (update) {
+			mem_deref(m->proto);
+			m->proto = mem_ref(m->protov[i]);
+		}
+
+		return true;
+	}
+
+	return false;
+}
+
+
 /**
  * Find an SDP Media line from name and transport protocol
  *
  * @param sess  SDP Session
  * @param name  Media name
  * @param proto Transport protocol
+ * @param update_proto Update media transport protocol
  *
  * @return Matching media line if found, NULL if not found
  */
 struct sdp_media *sdp_media_find(const struct sdp_session *sess,
 				 const struct pl *name,
-				 const struct pl *proto)
+				 const struct pl *proto,
+				 bool update_proto)
 {
 	struct le *le;
 
@@ -196,7 +239,7 @@ struct sdp_media *sdp_media_find(const struct sdp_session *sess,
 		if (pl_strcmp(name, m->name))
 			continue;
 
-		if (pl_strcmp(proto, m->proto))
+		if (!sdp_media_proto_cmp(m, proto, update_proto))
 			continue;
 
 		return m;
@@ -290,6 +333,44 @@ void sdp_media_align_formats(struct sdp_media *m, bool offer)
 }
 
 
+/**
+ * Set alternative protocols for an SDP Media line
+ *
+ * @param m      SDP Media line
+ * @param protoc Number of alternative protocols
+ *
+ * @return 0 if success, otherwise errorcode
+ */
+int sdp_media_set_alt_protos(struct sdp_media *m, unsigned protoc, ...)
+{
+	const char *proto;
+	int err = 0;
+	unsigned i;
+	va_list ap;
+
+	if (!m)
+		return EINVAL;
+
+	va_start(ap, protoc);
+
+	for (i=0; i<ARRAY_SIZE(m->protov); i++) {
+
+		m->protov[i] = mem_deref(m->protov[i]);
+
+		if (i >= protoc)
+			continue;
+
+		proto = va_arg(ap, const char *);
+		if (proto)
+			err |= str_dup(&m->protov[i], proto);
+	}
+
+	va_end(ap);
+
+	return err;
+}
+
+
 /**
  * Set SDP Media line encode handler
  *
@@ -475,6 +556,12 @@ void sdp_media_del_lattr(struct sdp_media *m, const char *name)
 }
 
 
+const char *sdp_media_proto(const struct sdp_media *m)
+{
+	return m ? m->proto : NULL;
+}
+
+
 /**
  * Get the remote port number of an SDP Media line
  *

src/sdp/msg.c

@@ -181,7 +181,7 @@ static int media_decode(struct sdp_media **mp, struct sdp_session *sess,
 		if (!offer)
 			return EPROTO;
 
-		m = sdp_media_find(sess, &name, &proto);
+		m = sdp_media_find(sess, &name, &proto, true);
 		if (!m) {
 			err = sdp_media_radd(&m, sess, &name, &proto);
 			if (err)
@@ -196,7 +196,7 @@ static int media_decode(struct sdp_media **mp, struct sdp_session *sess,
 		if (pl_strcmp(&name, m->name))
 			return offer ? ENOTSUP : EPROTO;
 
-		if (pl_strcmp(&proto, m->proto))
+		if (!sdp_media_proto_cmp(m, &proto, offer))
 			return ENOTSUP;
 	}
 

src/sdp/sdp.h

@@ -39,6 +39,7 @@ struct sdp_media {
 	int32_t rbwv[SDP_BANDWIDTH_MAX];
 	char *name;
 	char *proto;
+	char *protov[8];
 	sdp_media_enc_h *ench;
 	void *arg;
 	enum sdp_dir ldir;
@@ -57,9 +58,12 @@ void sdp_session_rreset(struct sdp_session *sess);
 int  sdp_media_radd(struct sdp_media **mp, struct sdp_session *sess,
 		    const struct pl *name, const struct pl *proto);
 void sdp_media_rreset(struct sdp_media *m);
+bool sdp_media_proto_cmp(struct sdp_media *m, const struct pl *proto,
+			 bool update);
 struct sdp_media *sdp_media_find(const struct sdp_session *sess,
 				 const struct pl *name,
-				 const struct pl *proto);
+				 const struct pl *proto,
+				 bool update_proto);
 void sdp_media_align_formats(struct sdp_media *m, bool offer);