Merge "SDP: Rework SDP offer/answer model and update capabilities merges."

include/asterisk/sdp.h

@@ -253,16 +253,6 @@ void ast_sdp_s_free(struct ast_sdp_s_line *s_line);
  */
 void ast_sdp_t_free(struct ast_sdp_t_line *t_line);
 
-/*!
- * \brief Free an SDP
- * Frees the sdp and all resources it contains
- *
- * \param sdp The sdp to free
- *
- * \since 15
- */
-void ast_sdp_free(struct ast_sdp *sdp);
-
 /*!
  * \brief Allocate an SDP Attribute
  *
@@ -544,7 +534,7 @@ int ast_sdp_m_add_format(struct ast_sdp_m_line *m_line, const struct ast_sdp_opt
 	int rtp_code, int asterisk_format, const struct ast_format *format, int code);
 
 /*!
- * \brief Create an SDP
+ * \brief Create an SDP ao2 object
  *
  * \param o_line Origin
  * \param c_line Connection

include/asterisk/sdp_options.h

@@ -20,6 +20,7 @@
 #define _ASTERISK_SDP_OPTIONS_H
 
 #include "asterisk/udptl.h"
+#include "asterisk/format_cap.h"
 
 struct ast_sdp_options;
 
@@ -79,6 +80,149 @@ enum ast_sdp_options_encryption {
 	AST_SDP_ENCRYPTION_DTLS,
 };
 
+/*!
+ * \brief Callback when processing an offer SDP for our answer SDP.
+ * \since 15.0.0
+ *
+ * \details
+ * This callback is called after merging our last negotiated topology
+ * with the remote's offer topology and before we have sent our answer
+ * SDP.  At this point you can alter new_topology streams.  You can
+ * decline, remove formats, or rename streams.  Changing anything else
+ * on the streams is likely to not end well.
+ *
+ * * To decline a stream simply set the stream state to
+ *   AST_STREAM_STATE_REMOVED.  You could implement a maximum number
+ *   of active streams of a given type policy.
+ *
+ * * To remove formats use the format API to remove any formats from a
+ *   stream.  The streams have the current joint negotiated formats.
+ *   Most likely you would want to remove all but the first format.
+ *
+ * * To rename a stream you need to clone the stream and give it a
+ *   new name and then set it in new_topology using
+ *   ast_stream_topology_set_stream().
+ *
+ * \note Removing all formats is an error.  You should decline the
+ * stream instead.
+ *
+ * \param context User supplied context data pointer for the SDP
+ * state.
+ * \param old_topology Active negotiated topology.  NULL if this is
+ * the first SDP negotiation.  The old topology is available so you
+ * can tell if any streams are new or changing type.
+ * \param new_topology New negotiated topology that we intend to
+ * generate the answer SDP.
+ *
+ * \return Nothing
+ */
+typedef void (*ast_sdp_answerer_modify_cb)(void *context,
+	const struct ast_stream_topology *old_topology,
+	struct ast_stream_topology *new_topology);
+
+/*!
+ * \internal
+ * \brief Callback when generating a topology for our SDP offer.
+ * \since 15.0.0
+ *
+ * \details
+ * This callback is called after merging any topology updates from the
+ * system by ast_sdp_state_update_local_topology() and before we have
+ * sent our offer SDP.  At this point you can alter new_topology
+ * streams.  You can decline, add/remove/update formats, or rename
+ * streams.  Changing anything else on the streams is likely to not
+ * end well.
+ *
+ * * To decline a stream simply set the stream state to
+ *   AST_STREAM_STATE_REMOVED.  You could implement a maximum number
+ *   of active streams of a given type policy.
+ *
+ * * To update formats use the format API to change formats of the
+ *   streams.  The streams have the current proposed formats.  You
+ *   could do whatever you want for formats but you should stay within
+ *   the configured formats for the stream type's endpoint.  However,
+ *   you should use ast_sdp_state_update_local_topology() instead of
+ *   this backdoor method.
+ *
+ * * To rename a stream you need to clone the stream and give it a
+ *   new name and then set it in new_topology using
+ *   ast_stream_topology_set_stream().
+ *
+ * \note Removing all formats is an error.  You should decline the
+ * stream instead.
+ *
+ * \note Declined new streams that are in slots higher than present in
+ * old_topology are removed so the SDP can be smaller.  The remote has
+ * never seen those slots so we shouldn't bother keeping them.
+ *
+ * \param context User supplied context data pointer for the SDP
+ * state.
+ * \param old_topology Active negotiated topology.  NULL if this is
+ * the first SDP negotiation.  The old topology is available so you
+ * can tell if any streams are new or changing type.
+ * \param new_topology Merged topology that we intend to generate the
+ * offer SDP.
+ *
+ * \return Nothing
+ */
+typedef void (*ast_sdp_offerer_modify_cb)(void *context,
+	const struct ast_stream_topology *old_topology,
+	struct ast_stream_topology *new_topology);
+
+/*!
+ * \brief Callback when generating an offer SDP to configure extra stream data.
+ * \since 15.0.0
+ *
+ * \details
+ * This callback is called after any ast_sdp_offerer_modify_cb
+ * callback and before we have sent our offer SDP.  The callback can
+ * call several SDP API calls to configure the proposed capabilities
+ * of streams before we create the SDP offer.  For example, the
+ * callback could configure a stream specific connection address, T.38
+ * parameters, RTP instance, or UDPTL instance parameters.
+ *
+ * \param context User supplied context data pointer for the SDP
+ * state.
+ * \param topology Topology ready to configure extra stream options.
+ *
+ * \return Nothing
+ */
+typedef void (*ast_sdp_offerer_config_cb)(void *context, const struct ast_stream_topology *topology);
+
+/*!
+ * \brief Callback before applying a topology.
+ * \since 15.0.0
+ *
+ * \details
+ * This callback is called before the topology is applied so the
+ * using module can do what is necessary before the topology becomes
+ * active.
+ *
+ * \param context User supplied context data pointer for the SDP
+ * state.
+ * \param topology Topology ready to be applied.
+ *
+ * \return Nothing
+ */
+typedef void (*ast_sdp_preapply_cb)(void *context, const struct ast_stream_topology *topology);
+
+/*!
+ * \brief Callback after applying a topology.
+ * \since 15.0.0
+ *
+ * \details
+ * This callback is called after the topology is applied so the
+ * using module can do what is necessary after the topology becomes
+ * active.
+ *
+ * \param context User supplied context data pointer for the SDP
+ * state.
+ * \param topology Topology already applied.
+ *
+ * \return Nothing
+ */
+typedef void (*ast_sdp_postapply_cb)(void *context, const struct ast_stream_topology *topology);
+
 /*!
  * \since 15.0.0
  * \brief Allocate a new SDP options structure.
@@ -204,6 +348,24 @@ void ast_sdp_options_set_rtp_engine(struct ast_sdp_options *options,
  */
 const char *ast_sdp_options_get_rtp_engine(const struct ast_sdp_options *options);
 
+void ast_sdp_options_set_state_context(struct ast_sdp_options *options, void *state_context);
+void *ast_sdp_options_get_state_context(const struct ast_sdp_options *options);
+
+void ast_sdp_options_set_answerer_modify_cb(struct ast_sdp_options *options, ast_sdp_answerer_modify_cb answerer_modify_cb);
+ast_sdp_answerer_modify_cb ast_sdp_options_get_answerer_modify_cb(const struct ast_sdp_options *options);
+
+void ast_sdp_options_set_offerer_modify_cb(struct ast_sdp_options *options, ast_sdp_offerer_modify_cb offerer_modify_cb);
+ast_sdp_offerer_modify_cb ast_sdp_options_get_offerer_modify_cb(const struct ast_sdp_options *options);
+
+void ast_sdp_options_set_offerer_config_cb(struct ast_sdp_options *options, ast_sdp_offerer_config_cb offerer_config_cb);
+ast_sdp_offerer_config_cb ast_sdp_options_get_offerer_config_cb(const struct ast_sdp_options *options);
+
+void ast_sdp_options_set_preapply_cb(struct ast_sdp_options *options, ast_sdp_preapply_cb preapply_cb);
+ast_sdp_preapply_cb ast_sdp_options_get_preapply_cb(const struct ast_sdp_options *options);
+
+void ast_sdp_options_set_postapply_cb(struct ast_sdp_options *options, ast_sdp_postapply_cb postapply_cb);
+ast_sdp_postapply_cb ast_sdp_options_get_postapply_cb(const struct ast_sdp_options *options);
+
 /*!
  * \since 15.0.0
  * \brief Set SDP Options rtp_symmetric
@@ -503,6 +665,26 @@ void ast_sdp_options_set_udptl_far_max_datagram(struct ast_sdp_options *options,
  */
 unsigned int ast_sdp_options_get_udptl_far_max_datagram(const struct ast_sdp_options *options);
 
+/*!
+ * \since 15.0.0
+ * \brief Set SDP Options max_streams
+ *
+ * \param options SDP Options
+ * \param max_streams
+ */
+void ast_sdp_options_set_max_streams(struct ast_sdp_options *options,
+	unsigned int max_streams);
+
+/*!
+ * \since 15.0.0
+ * \brief Get SDP Options max_streams
+ *
+ * \param options SDP Options
+ *
+ * \returns max_streams
+ */
+unsigned int ast_sdp_options_get_max_streams(const struct ast_sdp_options *options);
+
 /*!
  * \since 15.0.0
  * \brief Enable setting SSRC level attributes on SDPs
@@ -547,4 +729,46 @@ void ast_sdp_options_set_sched_type(struct ast_sdp_options *options,
 struct ast_sched_context *ast_sdp_options_get_sched_type(const struct ast_sdp_options *options,
 	enum ast_media_type type);
 
+/*!
+ * \brief Set all allowed stream types to create new streams.
+ * \since 15.0.0
+ *
+ * \param options SDP Options
+ * \param cap Format capabilities to set all allowed stream types at once.
+ *            Could be NULL to disable creating any new streams.
+ *
+ * \return Nothing
+ */
+void ast_sdp_options_set_format_caps(struct ast_sdp_options *options,
+	struct ast_format_cap *cap);
+
+/*!
+ * \brief Set the SDP options format cap used to create new streams of the type.
+ * \since 15.0.0
+ *
+ * \param options SDP Options
+ * \param type Media type the format cap represents.
+ * \param cap Format capabilities to use for the specified media type.
+ *            Could be NULL to disable creating new streams of type.
+ *
+ * \return Nothing
+ */
+void ast_sdp_options_set_format_cap_type(struct ast_sdp_options *options,
+	enum ast_media_type type, struct ast_format_cap *cap);
+
+/*!
+ * \brief Get the SDP options format cap used to create new streams of the type.
+ * \since 15.0.0
+ *
+ * \param options SDP Options
+ * \param type Media type the format cap represents.
+ *
+ * \retval NULL if stream not allowed to be created.
+ * \retval cap to use in negotiating the new stream.
+ *
+ * \note The returned cap does not have its own ao2 ref.
+ */
+struct ast_format_cap *ast_sdp_options_get_format_cap_type(const struct ast_sdp_options *options,
+	enum ast_media_type type);
+
 #endif /* _ASTERISK_SDP_OPTIONS_H */

include/asterisk/sdp_state.h

@@ -30,12 +30,22 @@ struct ast_control_t38_parameters;
 /*!
  * \brief Allocate a new SDP state
  *
+ * \details
  * SDP state keeps tabs on everything SDP-related for a media session.
  * Most SDP operations will require the state to be provided.
  * Ownership of the SDP options is taken on by the SDP state.
  * A good strategy is to call this during session creation.
+ *
+ * \param topology Initial stream topology to offer.
+ *                NULL if we are going to be the answerer.  We can always
+ *                update the local topology later if it turns out we need
+ *                to be the offerer.
+ * \param options SDP options for the duration of the session.
+ *
+ * \retval SDP state struct
+ * \retval NULL on failure
  */
-struct ast_sdp_state *ast_sdp_state_alloc(struct ast_stream_topology *streams,
+struct ast_sdp_state *ast_sdp_state_alloc(struct ast_stream_topology *topology,
 	struct ast_sdp_options *options);
 
 /*!
@@ -86,6 +96,8 @@ int ast_sdp_state_get_stream_connection_address(const struct ast_sdp_state *sdp_
  *
  * If this is called prior to receiving a remote SDP, then this will just mirror
  * the local configured endpoint capabilities.
+ *
+ * \note Cannot return NULL.  It is a BUG if it does.
  */
 const struct ast_stream_topology *ast_sdp_state_get_joint_topology(
 	const struct ast_sdp_state *sdp_state);
@@ -93,6 +105,7 @@ const struct ast_stream_topology *ast_sdp_state_get_joint_topology(
 /*!
  * \brief Get the local topology
  *
+ * \note Cannot return NULL.  It is a BUG if it does.
  */
 const struct ast_stream_topology *ast_sdp_state_get_local_topology(
 	const struct ast_sdp_state *sdp_state);
@@ -114,9 +127,10 @@ const struct ast_sdp_options *ast_sdp_state_get_options(
  * \retval NULL Failure
  *
  * \note
- * This function will allocate a new SDP with RTP instances if it has not already
- * been allocated.
- *
+ * This function will return the last local SDP created if one were
+ * previously requested for the current negotiation.  Otherwise it
+ * creates our SDP offer/answer depending on what role we are playing
+ * in the current negotiation.
  */
 const struct ast_sdp *ast_sdp_state_get_local_sdp(struct ast_sdp_state *sdp_state);
 
@@ -152,6 +166,7 @@ const void *ast_sdp_state_get_local_sdp_impl(struct ast_sdp_state *sdp_state);
  *
  * \retval 0 Success
  * \retval non-0 Failure
+ *         Use ast_sdp_state_is_offer_rejected() to see if the SDP offer was rejected.
  *
  * \since 15
  */
@@ -165,39 +180,72 @@ int ast_sdp_state_set_remote_sdp(struct ast_sdp_state *sdp_state, const struct a
  *
  * \retval 0 Success
  * \retval non-0 Failure
+ *         Use ast_sdp_state_is_offer_rejected() to see if the SDP offer was rejected.
  *
  * \since 15
  */
 int ast_sdp_state_set_remote_sdp_from_impl(struct ast_sdp_state *sdp_state, const void *remote);
 
 /*!
- * \brief Reset the SDP state and stream capabilities as if the SDP state had just been allocated.
+ * \brief Was the set remote offer rejected.
+ * \since 15.0.0
  *
  * \param sdp_state
- * \param remote The implementation's representation of an SDP.
  *
- * \retval 0 Success
+ * \retval 0 if not rejected.
+ * \retval non-zero if rejected.
+ */
+int ast_sdp_state_is_offer_rejected(struct ast_sdp_state *sdp_state);
+
+/*!
+ * \brief Are we the SDP offerer.
+ * \since 15.0.0
  *
- * \note
- * This is most useful for when a channel driver is sending a session refresh message
- * and needs to re-advertise its initial capabilities instead of the previously-negotiated
- * joint capabilities.
+ * \param sdp_state
  *
- * \since 15
+ * \retval 0 if we are not the offerer.
+ * \retval non-zero we are the offerer.
  */
-int ast_sdp_state_reset(struct ast_sdp_state *sdp_state);
+int ast_sdp_state_is_offerer(struct ast_sdp_state *sdp_state);
+
+/*!
+ * \brief Are we the SDP answerer.
+ * \since 15.0.0
+ *
+ * \param sdp_state
+ *
+ * \retval 0 if we are not the answerer.
+ * \retval non-zero we are the answerer.
+ */
+int ast_sdp_state_is_answerer(struct ast_sdp_state *sdp_state);
+
+/*!
+ * \brief Restart the SDP offer/answer negotiations.
+ *
+ * \param sdp_state
+ *
+ * \retval 0 Success
+ * \retval non-0 Failure
+ */
+int ast_sdp_state_restart_negotiations(struct ast_sdp_state *sdp_state);
 
 /*!
  * \brief Update the local stream topology on the SDP state.
  *
+ * \details
+ * Basically we are saving off any topology updates until we create the
+ * next SDP offer.  Repeated updates merge with the previous updated
+ * topology.
+ *
  * \param sdp_state
- * \param streams The new stream topology.
+ * \param topology The new stream topology.
  *
  * \retval 0 Success
+ * \retval non-0 Failure
  *
  * \since 15
  */
-int ast_sdp_state_update_local_topology(struct ast_sdp_state *sdp_state, struct ast_stream_topology *streams);
+int ast_sdp_state_update_local_topology(struct ast_sdp_state *sdp_state, struct ast_stream_topology *topology);
 
 /*!
  * \brief Set the local address (IP address) to use for connection addresses
@@ -231,7 +279,26 @@ int ast_sdp_state_set_connection_address(struct ast_sdp_state *sdp_state, int st
 
 /*!
  * \since 15.0.0
- * \brief Set a stream to be held or unheld
+ * \brief Set the global locally held state.
+ *
+ * \param sdp_state
+ * \param locally_held
+ */
+void ast_sdp_state_set_global_locally_held(struct ast_sdp_state *sdp_state, unsigned int locally_held);
+
+/*!
+ * \since 15.0.0
+ * \brief Get the global locally held state.
+ *
+ * \param sdp_state
+ *
+ * \returns locally_held
+ */
+unsigned int ast_sdp_state_get_global_locally_held(const struct ast_sdp_state *sdp_state);
+
+/*!
+ * \since 15.0.0
+ * \brief Set a stream to be held or unheld locally
  *
  * \param sdp_state
  * \param stream_index The stream to set the held value for
@@ -242,25 +309,37 @@ void ast_sdp_state_set_locally_held(struct ast_sdp_state *sdp_state,
 
 /*!
  * \since 15.0.0
- * \brief Set the UDPTL session parameters
+ * \brief Get whether a stream is locally held or not
  *
  * \param sdp_state
- * \param stream_index The stream to set the UDPTL session parameters for
- * \param params
+ * \param stream_index The stream to get the held state for
+ *
+ * \returns locally_held
  */
-void ast_sdp_state_set_t38_parameters(struct ast_sdp_state *sdp_state,
-	int stream_index, struct ast_control_t38_parameters *params);
+unsigned int ast_sdp_state_get_locally_held(const struct ast_sdp_state *sdp_state,
+	int stream_index);
 
 /*!
  * \since 15.0.0
- * \brief Get whether a stream is held or not
+ * \brief Get whether a stream is remotely held or not
  *
  * \param sdp_state
  * \param stream_index The stream to get the held state for
  *
- * \returns locally_held
+ * \returns remotely_held
  */
-unsigned int ast_sdp_state_get_locally_held(const struct ast_sdp_state *sdp_state,
+unsigned int ast_sdp_state_get_remotely_held(const struct ast_sdp_state *sdp_state,
 	int stream_index);
 
+/*!
+ * \since 15.0.0
+ * \brief Set the UDPTL session parameters
+ *
+ * \param sdp_state
+ * \param stream_index The stream to set the UDPTL session parameters for
+ * \param params
+ */
+void ast_sdp_state_set_t38_parameters(struct ast_sdp_state *sdp_state,
+	int stream_index, struct ast_control_t38_parameters *params);
+
 #endif /* _ASTERISK_SDP_STATE_H */

include/asterisk/stream.h

@@ -227,6 +227,17 @@ void ast_stream_set_state(struct ast_stream *stream, enum ast_stream_state state
  */
 const char *ast_stream_state2str(enum ast_stream_state state);
 
+/*!
+ * \brief Convert a string to a stream state
+ *
+ * \param str The string to convert
+ *
+ * \return The stream state
+ *
+ * \since 15.0.0
+ */
+enum ast_stream_state ast_stream_str2state(const char *str);
+
 /*!
  * \brief Get the opaque stream data
  *

main/sdp.c

@@ -109,11 +109,9 @@ void ast_sdp_t_free(struct ast_sdp_t_line *t_line)
 	ast_free(t_line);
 }
 
-void ast_sdp_free(struct ast_sdp *sdp)
+static void ast_sdp_dtor(void *vdoomed)
 {
-	if (!sdp) {
-		return;
-	}
+	struct ast_sdp *sdp = vdoomed;
 
 	ast_sdp_o_free(sdp->o_line);
 	ast_sdp_s_free(sdp->s_line);
@@ -121,7 +119,6 @@ void ast_sdp_free(struct ast_sdp *sdp)
 	ast_sdp_t_free(sdp->t_line);
 	ast_sdp_a_lines_free(sdp->a_lines);
 	ast_sdp_m_lines_free(sdp->m_lines);
-	ast_free(sdp);
 }
 
 #define COPY_STR_AND_ADVANCE(p, dest, source) \
@@ -314,28 +311,28 @@ struct ast_sdp *ast_sdp_alloc(struct ast_sdp_o_line *o_line,
 {
 	struct ast_sdp *new_sdp;
 
-	new_sdp = ast_calloc(1, sizeof *new_sdp);
+	new_sdp = ao2_alloc_options(sizeof(*new_sdp), ast_sdp_dtor, AO2_ALLOC_OPT_LOCK_NOLOCK);
 	if (!new_sdp) {
 		return NULL;
 	}
 
 	new_sdp->a_lines = ast_calloc(1, sizeof(*new_sdp->a_lines));
 	if (!new_sdp->a_lines) {
-		ast_sdp_free(new_sdp);
+		ao2_ref(new_sdp, -1);
 		return NULL;
 	}
 	if (AST_VECTOR_INIT(new_sdp->a_lines, 20)) {
-		ast_sdp_free(new_sdp);
+		ao2_ref(new_sdp, -1);
 		return NULL;
 	}
 
 	new_sdp->m_lines = ast_calloc(1, sizeof(*new_sdp->m_lines));
 	if (!new_sdp->m_lines) {
-		ast_sdp_free(new_sdp);
+		ao2_ref(new_sdp, -1);
 		return NULL;
 	}
 	if (AST_VECTOR_INIT(new_sdp->m_lines, 20)) {
-		ast_sdp_free(new_sdp);
+		ao2_ref(new_sdp, -1);
 		return NULL;
 	}
 
@@ -741,6 +738,62 @@ static void process_fmtp_lines(const struct ast_sdp_m_line *m_line, int payload,
 	}
 }
 
+/*!
+ * \internal
+ * \brief Determine the RTP stream direction in the given a lines.
+ * \since 15.0.0
+ *
+ * \param a_lines Attribute lines to search.
+ *
+ * \retval Stream direction on success.
+ * \retval AST_STREAM_STATE_REMOVED on failure.
+ *
+ * \return Nothing
+ */
+static enum ast_stream_state get_a_line_direction(const struct ast_sdp_a_lines *a_lines)
+{
+	if (a_lines) {
+		enum ast_stream_state direction;
+		int idx;
+		const struct ast_sdp_a_line *a_line;
+
+		for (idx = 0; idx < AST_VECTOR_SIZE(a_lines); ++idx) {
+			a_line = AST_VECTOR_GET(a_lines, idx);
+			direction = ast_stream_str2state(a_line->name);
+			if (direction != AST_STREAM_STATE_REMOVED) {
+				return direction;
+			}
+		}
+	}
+
+	return AST_STREAM_STATE_REMOVED;
+}
+
+/*!
+ * \internal
+ * \brief Determine the RTP stream direction.
+ * \since 15.0.0
+ *
+ * \param a_lines The SDP media global attributes
+ * \param m_line The SDP media section to convert
+ *
+ * \return Stream direction
+ */
+static enum ast_stream_state get_stream_direction(const struct ast_sdp_a_lines *a_lines, const struct ast_sdp_m_line *m_line)
+{
+	enum ast_stream_state direction;
+
+	direction = get_a_line_direction(m_line->a_lines);
+	if (direction != AST_STREAM_STATE_REMOVED) {
+		return direction;
+	}
+	direction = get_a_line_direction(a_lines);
+	if (direction != AST_STREAM_STATE_REMOVED) {
+		return direction;
+	}
+	return AST_STREAM_STATE_SENDRECV;
+}
+
 /*
  * Needed so we don't have an external function referenced as data.
  * The dynamic linker doesn't handle that very well.
@@ -758,13 +811,14 @@ static void rtp_codecs_free(struct ast_rtp_codecs *codecs)
  * Given an m-line from an SDP, convert it into an ast_stream structure.
  * This takes formats, as well as clock-rate and fmtp attributes into account.
  *
+ * \param a_lines The SDP media global attributes
  * \param m_line The SDP media section to convert
  * \param g726_non_standard Non-zero if G.726 is non-standard
  *
  * \retval NULL An error occurred
  * \retval non-NULL The converted stream
  */
-static struct ast_stream *get_stream_from_m(const struct ast_sdp_m_line *m_line, int g726_non_standard)
+static struct ast_stream *get_stream_from_m(const struct ast_sdp_a_lines *a_lines, const struct ast_sdp_m_line *m_line, int g726_non_standard)
 {
 	int i;
 	int non_ast_fmts;
@@ -793,6 +847,14 @@ static struct ast_stream *get_stream_from_m(const struct ast_sdp_m_line *m_line,
 			ao2_ref(caps, -1);
 			return NULL;
 		}
+		ast_stream_set_data(stream, AST_STREAM_DATA_RTP_CODECS, codecs,
+			(ast_stream_data_free_fn) rtp_codecs_free);
+
+		if (!m_line->port) {
+			/* Stream is declined.  There may not be any attributes. */
+			ast_stream_set_state(stream, AST_STREAM_STATE_REMOVED);
+			break;
+		}
 
 		options = g726_non_standard ? AST_RTP_OPT_G726_NONSTANDARD : 0;
 		for (i = 0; i < ast_sdp_m_get_payload_count(m_line); ++i) {
@@ -819,10 +881,16 @@ static struct ast_stream *get_stream_from_m(const struct ast_sdp_m_line *m_line,
 		}
 
 		ast_rtp_codecs_payload_formats(codecs, caps, &non_ast_fmts);
-		ast_stream_set_data(stream, AST_STREAM_DATA_RTP_CODECS, codecs,
-			(ast_stream_data_free_fn) rtp_codecs_free);
+
+		ast_stream_set_state(stream, get_stream_direction(a_lines, m_line));
 		break;
 	case AST_MEDIA_TYPE_IMAGE:
+		if (!m_line->port) {
+			/* Stream is declined.  There may not be any attributes. */
+			ast_stream_set_state(stream, AST_STREAM_STATE_REMOVED);
+			break;
+		}
+
 		for (i = 0; i < ast_sdp_m_get_payload_count(m_line); ++i) {
 			struct ast_sdp_payload *payload;
 
@@ -830,12 +898,15 @@ static struct ast_stream *get_stream_from_m(const struct ast_sdp_m_line *m_line,
 			payload = ast_sdp_m_get_payload(m_line, i);
 			if (!strcasecmp(payload->fmt, "t38")) {
 				ast_format_cap_append(caps, ast_format_t38, 0);
+				ast_stream_set_state(stream, AST_STREAM_STATE_SENDRECV);
 			}
 		}
 		break;
 	case AST_MEDIA_TYPE_UNKNOWN:
 	case AST_MEDIA_TYPE_TEXT:
 	case AST_MEDIA_TYPE_END:
+		/* Consider these unsupported streams as declined */
+		ast_stream_set_state(stream, AST_STREAM_STATE_REMOVED);
 		break;
 	}
 
@@ -858,7 +929,7 @@ struct ast_stream_topology *ast_get_topology_from_sdp(const struct ast_sdp *sdp,
 	for (i = 0; i < ast_sdp_get_m_count(sdp); ++i) {
 		struct ast_stream *stream;
 
-		stream = get_stream_from_m(ast_sdp_get_m(sdp, i), g726_non_standard);
+		stream = get_stream_from_m(sdp->a_lines, ast_sdp_get_m(sdp, i), g726_non_standard);
 		if (!stream) {
 			/*
 			 * The topology cannot match the SDP because

main/sdp_options.c

@@ -27,6 +27,7 @@
 #define DEFAULT_ICE AST_SDP_ICE_DISABLED
 #define DEFAULT_IMPL AST_SDP_IMPL_STRING
 #define DEFAULT_ENCRYPTION AST_SDP_ENCRYPTION_DISABLED
+#define DEFAULT_MAX_STREAMS 16	/* Set to match our PJPROJECT PJMEDIA_MAX_SDP_MEDIA. */
 
 #define DEFINE_STRINGFIELD_GETTERS_SETTERS_FOR(field, assert_on_null) \
 void ast_sdp_options_set_##field(struct ast_sdp_options *options, const char *value) \
@@ -60,6 +61,12 @@ DEFINE_STRINGFIELD_GETTERS_SETTERS_FOR(sdpowner, 0);
 DEFINE_STRINGFIELD_GETTERS_SETTERS_FOR(sdpsession, 0);
 DEFINE_STRINGFIELD_GETTERS_SETTERS_FOR(rtp_engine, 0);
 
+DEFINE_GETTERS_SETTERS_FOR(void *, state_context);
+DEFINE_GETTERS_SETTERS_FOR(ast_sdp_answerer_modify_cb, answerer_modify_cb);
+DEFINE_GETTERS_SETTERS_FOR(ast_sdp_offerer_modify_cb, offerer_modify_cb);
+DEFINE_GETTERS_SETTERS_FOR(ast_sdp_offerer_config_cb, offerer_config_cb);
+DEFINE_GETTERS_SETTERS_FOR(ast_sdp_preapply_cb, preapply_cb);
+DEFINE_GETTERS_SETTERS_FOR(ast_sdp_postapply_cb, postapply_cb);
 DEFINE_GETTERS_SETTERS_FOR(unsigned int, rtp_symmetric);
 DEFINE_GETTERS_SETTERS_FOR(unsigned int, udptl_symmetric);
 DEFINE_GETTERS_SETTERS_FOR(enum ast_t38_ec_modes, udptl_error_correction);
@@ -71,6 +78,7 @@ DEFINE_GETTERS_SETTERS_FOR(unsigned int, tos_audio);
 DEFINE_GETTERS_SETTERS_FOR(unsigned int, cos_audio);
 DEFINE_GETTERS_SETTERS_FOR(unsigned int, tos_video);
 DEFINE_GETTERS_SETTERS_FOR(unsigned int, cos_video);
+DEFINE_GETTERS_SETTERS_FOR(unsigned int, max_streams);
 DEFINE_GETTERS_SETTERS_FOR(enum ast_sdp_options_dtmf, dtmf);
 DEFINE_GETTERS_SETTERS_FOR(enum ast_sdp_options_ice, ice);
 DEFINE_GETTERS_SETTERS_FOR(enum ast_sdp_options_impl, impl);
@@ -110,12 +118,87 @@ void ast_sdp_options_set_sched_type(struct ast_sdp_options *options, enum ast_me
 	}
 }
 
+struct ast_format_cap *ast_sdp_options_get_format_cap_type(const struct ast_sdp_options *options,
+	enum ast_media_type type)
+{
+	struct ast_format_cap *cap = NULL;
+
+	switch (type) {
+	case AST_MEDIA_TYPE_AUDIO:
+	case AST_MEDIA_TYPE_VIDEO:
+	case AST_MEDIA_TYPE_IMAGE:
+	case AST_MEDIA_TYPE_TEXT:
+		cap = options->caps[type];
+		break;
+	case AST_MEDIA_TYPE_UNKNOWN:
+	case AST_MEDIA_TYPE_END:
+		break;
+	}
+	return cap;
+}
+
+void ast_sdp_options_set_format_cap_type(struct ast_sdp_options *options,
+	enum ast_media_type type, struct ast_format_cap *cap)
+{
+	switch (type) {
+	case AST_MEDIA_TYPE_AUDIO:
+	case AST_MEDIA_TYPE_VIDEO:
+	case AST_MEDIA_TYPE_IMAGE:
+	case AST_MEDIA_TYPE_TEXT:
+		ao2_cleanup(options->caps[type]);
+		options->caps[type] = NULL;
+		if (cap && !ast_format_cap_empty(cap)) {
+			ao2_ref(cap, +1);
+			options->caps[type] = cap;
+		}
+		break;
+	case AST_MEDIA_TYPE_UNKNOWN:
+	case AST_MEDIA_TYPE_END:
+		break;
+	}
+}
+
+void ast_sdp_options_set_format_caps(struct ast_sdp_options *options,
+	struct ast_format_cap *cap)
+{
+	enum ast_media_type type;
+
+	for (type = AST_MEDIA_TYPE_UNKNOWN; type < AST_MEDIA_TYPE_END; ++type) {
+		ao2_cleanup(options->caps[type]);
+		options->caps[type] = NULL;
+	}
+
+	if (!cap || ast_format_cap_empty(cap)) {
+		return;
+	}
+
+	for (type = AST_MEDIA_TYPE_UNKNOWN + 1; type < AST_MEDIA_TYPE_END; ++type) {
+		struct ast_format_cap *type_cap;
+
+		type_cap = ast_format_cap_alloc(AST_FORMAT_CAP_FLAG_DEFAULT);
+		if (!type_cap) {
+			continue;
+		}
+
+		ast_format_cap_set_framing(type_cap, ast_format_cap_get_framing(cap));
+		if (ast_format_cap_append_from_cap(type_cap, cap, type)
+			|| ast_format_cap_empty(type_cap)) {
+			ao2_ref(type_cap, -1);
+			continue;
+		}
+
+		/* This takes the allocation reference */
+		options->caps[type] = type_cap;
+	}
+}
+
 static void set_defaults(struct ast_sdp_options *options)
 {
 	options->dtmf = DEFAULT_DTMF;
 	options->ice = DEFAULT_ICE;
 	options->impl = DEFAULT_IMPL;
 	options->encryption = DEFAULT_ENCRYPTION;
+	options->max_streams = DEFAULT_MAX_STREAMS;
 }
 
 struct ast_sdp_options *ast_sdp_options_alloc(void)
@@ -138,6 +221,15 @@ struct ast_sdp_options *ast_sdp_options_alloc(void)
 
 void ast_sdp_options_free(struct ast_sdp_options *options)
 {
+	enum ast_media_type type;
+
+	if (!options) {
+		return;
+	}
+
+	for (type = AST_MEDIA_TYPE_UNKNOWN; type < AST_MEDIA_TYPE_END; ++type) {
+		ao2_cleanup(options->caps[type]);
+	}
 	ast_string_field_free_memory(options);
 	ast_free(options);
 }

main/sdp_private.h

@@ -24,7 +24,7 @@
 
 struct ast_sdp_options {
 	AST_DECLARE_STRING_FIELDS(
-		/*! Media address to use in SDP */
+		/*! Media address to advertise in SDP session c= line */
 		AST_STRING_FIELD(media_address);
 		/*! Optional address of the interface media should use. */
 		AST_STRING_FIELD(interface_address);
@@ -37,12 +37,25 @@ struct ast_sdp_options {
 	);
 	/*! Scheduler context for the media stream types (Mainly for RTP) */
 	struct ast_sched_context *sched[AST_MEDIA_TYPE_END];
+	/*! Capabilities to create new streams of the indexed media type. */
+	struct ast_format_cap *caps[AST_MEDIA_TYPE_END];
+	/*! User supplied context data pointer for the SDP state. */
+	void *state_context;
+	/*! Modify negotiated topology before create answer SDP callback. */
+	ast_sdp_answerer_modify_cb answerer_modify_cb;
+	/*! Modify proposed topology before create offer SDP callback. */
+	ast_sdp_offerer_modify_cb offerer_modify_cb;
+	/*! Configure proposed topology extra stream options before create offer SDP callback. */
+	ast_sdp_offerer_config_cb offerer_config_cb;
+	/*! Negotiated topology is about to be applied callback. */
+	ast_sdp_preapply_cb preapply_cb;
+	/*! Negotiated topology was just applied callback. */
+	ast_sdp_postapply_cb postapply_cb;
 	struct {
 		unsigned int rtp_symmetric:1;
 		unsigned int udptl_symmetric:1;
 		unsigned int rtp_ipv6:1;
 		unsigned int g726_non_standard:1;
-		unsigned int locally_held:1;
 		unsigned int rtcp_mux:1;
 		unsigned int ssrc:1;
 	};
@@ -52,6 +65,8 @@ struct ast_sdp_options {
 		unsigned int tos_video;
 		unsigned int cos_video;
 		unsigned int udptl_far_max_datagram;
+		/*! Maximum number of streams to allow. */
+		unsigned int max_streams;
 	};
 	enum ast_sdp_options_dtmf dtmf;
 	enum ast_sdp_options_ice ice;

main/stream.c

@@ -214,6 +214,23 @@ const char *ast_stream_state2str(enum ast_stream_state state)
 	}
 }
 
+enum ast_stream_state ast_stream_str2state(const char *str)
+{
+	if (!strcmp("sendrecv", str)) {
+		return AST_STREAM_STATE_SENDRECV;
+	}
+	if (!strcmp("sendonly", str)) {
+		return AST_STREAM_STATE_SENDONLY;
+	}
+	if (!strcmp("recvonly", str)) {
+		return AST_STREAM_STATE_RECVONLY;
+	}
+	if (!strcmp("inactive", str)) {
+		return AST_STREAM_STATE_INACTIVE;
+	}
+	return AST_STREAM_STATE_REMOVED;
+}
+
 void *ast_stream_get_data(struct ast_stream *stream, enum ast_stream_data_slot slot)
 {
 	ast_assert(stream != NULL);

res/res_sdp_translator_pjmedia.c

@@ -484,7 +484,7 @@ AST_TEST_DEFINE(pjmedia_to_sdp_test)
 	}
 
 cleanup:
-	ast_sdp_free(sdp);
+	ao2_cleanup(sdp);
 	ast_sdp_translator_free(translator);
 	pj_pool_release(pool);
 	return res;
@@ -560,7 +560,7 @@ AST_TEST_DEFINE(sdp_to_pjmedia_test)
 	}
 
 cleanup:
-	ast_sdp_free(sdp);
+	ao2_cleanup(sdp);
 	ast_sdp_translator_free(translator);
 	pj_pool_release(pool);
 	return res;