Add initial SDP state code.

This establishes the basic allocation/destruction of an SDP state
object, plus some of the simpler getter methods involved. Subsequent
tasks will deal with adding a state machine, creating SDPs from
capabilities and options, and merging SDPs into a joint SDP.

Change-Id: Ie3757ce186f04b65e9d1883f5aace53f24e53709

1 files changed, 58 insertions, 0 deletions

diff --git a/include/asterisk/sdp_state.h b/include/asterisk/sdp_state.h
new file mode 100644
index 000000000..b5e44179e
--- /dev/null
+++ b/include/asterisk/sdp_state.h
@@ -0,0 +1,58 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2017, Digium, Inc.
+ *
+ * Mark Michelson <mmichelson@digium.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+#ifndef _ASTERISK_SDP_STATE_H
+#define _ASTERISK_SDP_STATE_H
+
+struct ast_sdp_state;
+struct ast_sdp_options;
+struct ast_stream_topology;
+
+/*!
+ * \brief Allocate a new SDP state
+ *
+ * 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.
+ */
+struct ast_sdp_state *ast_sdp_state_alloc(struct ast_stream_topology *streams, struct ast_sdp_options *options);
+
+/*!
+ * \brief Free the SDP state.
+ *
+ * A good strategy is to call this during session destruction
+ */
+void ast_sdp_state_free(struct ast_sdp_state *sdp_state);
+
+/*!
+ * \brief Get the associated RTP instance for a particular stream on the SDP state.
+ *
+ * Stream numbers correspond to the streams in the topology of the associated channel
+ */
+struct ast_rtp_instance *ast_sdp_state_get_rtp_instance(struct ast_sdp_state *sdp_state, int stream_index);
+
+/*!
+ * \brief Get the joint negotiated streams based on local and remote capabilities.
+ *
+ * If this is called prior to receiving a remote SDP, then this will just mirror
+ * the local configured endpoint capabilities.
+ */
+struct ast_stream_topology *ast_sdp_state_get_joint_topology(struct ast_sdp_state *sdp_state);
+
+#endif /* _ASTERISK_SDP_STATE_H */