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3a18a09030
The SDP offer/answer model requires an answer to an offer before a new SDP
can be processed. This allows our local SDP creation to be deferred until
we know that we need to create an offer or an answer SDP. Once the local
SDP is created it won't change until the SDP negotiation is restarted.
An offer SDP in an initial SIP INVITE can receive more than one answer
SDP. In this case, we need to merge each answer SDP with our original
offer capabilities to get the currently negotiated capabilities. To
satisfy this requirement means that we cannot update our proposed
capabilities until the negotiations are restarted.
Local topology updates from ast_sdp_state_update_local_topology() are
merged together until the next offer SDP is created. These accumulated
updates are then merged with the current negotiated capabilities to create
the new proposed capabilities that the offer SDP is built.
Local topology updates are merged in several passes to attempt to be smart
about how streams from the system are matched with the previously
negotiated stream slots. To allow for T.38 support when merging, type
matching considers audio and image types to be equivalent. First streams
are matched by stream name and type. Then streams are matched by stream
type only. Any remaining unmatched existing streams are declined. Any
new active streams are either backfilled into pre-merge declined slots or
appended onto the end of the merged topology. Any excess new streams
above the maximum supported number of streams are simply discarded.
Remote topology negotiation merges depend if the topology is an offer or
answer. An offer remote topology negotiation dictates the stream slot
ordering and new streams can be added. A remote offer can do anything to
the previously negotiated streams except reduce the number of stream
slots. An answer remote topology negotiation is limited to what our offer
requested. The answer can only decline streams, pick codecs from the
offered list, or indicate the remote's stream hold state.
I had originally kept the RTP instance if the remote offer SDP changed a
stream type between audio and video since they both use RTP. However, I
later removed this support in favor of simply creating a new RTP instance
since the stream's purpose has to be changing anyway. Any RTP packets
from the old stream type might cause mischief for the bridged peer.
* Added ast_sdp_state_restart_negotiations() to restart the SDP
offer/answer negotiations. We will thus know to create a new local SDP
when it is time to create an offer or answer.
* Removed ast_sdp_state_reset(). Save the current topology before
starting T.38. To recover from T.38 simply update the local topology to
the saved topology and restart the SDP negotiations to get the offer SDP
renegotiating the previous configuration.
* Allow initial topology for ast_sdp_state_alloc() to be NULL so an
initial remote offer SDP can dictate the streams we start with. We can
always update the local topology later if it turns out we need to offer
SDP first because the remote chose to defer sending us a SDP.
* Made the ast_sdp_state_alloc() initial topology limit to max_streams,
limit to configured codecs, handle declined streams, and discard
unsupported types.
* Convert struct ast_sdp to ao2 object. Needed to easily save off a
remote SDP to refer to later for various reasons such as generating
declined m= lines in the local SDP.
* Improve converting remote SDP streams to a topology including stream
state. A stream state of AST_STREAM_STATE_REMOVED indicates the stream is
declined/dead.
* Improve merging streams to take into account the stream state.
* Added query for remote hold state.
* Added maximum streams allowed SDP config option.
* Added ability to create new streams as needed. New streams are created
with configured default audio, video, or image codecs depending on stream
type.
* Added global locally_held state along with a per stream local hold
state. Historically, Asterisk only has a global locally held state
because when the we put the remote on hold we do it for all active
streams.
* Added queries for a rejected offer and current SDP negotiation role.
The rejected query allows the using module to know how to respond to a
failed remote SDP set. Should the using module respond with a 488 Not
Acceptable Here or 500 Internal Error to the offer SDP?
* Moved sdp_state_capabilities.connection_address to ast_sdp_state. There
seems no reason to keep it in the sdp_state_capabilities struct since it
was only used by the ast_sdp_state.proposed_capabilities instance.
* Callbacks are now available to allow the using module some customization
of negotiated streams and to complete setting up streams for use. See the
typedef doxygen for each callback for what is allowable and when they are
called.
* Added topology answerer modify callback.
* Added topology pre and post apply callbacks.
* Added topology offerer modify callback.
* Added topology offerer configure callback.
* Had to rework the unit tests because I changed how SDP topologies are
merged. Replaced several unit tests with new negotiation tests.
Change-Id: If07fe6d79fbdce33968a9401d41d908385043a06
704 lines
16 KiB
C
704 lines
16 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2017, Digium, Inc.
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*
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* Mark Michelson <mmichelson@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/* NOTE: It is unlikely that you need to include this file. You probably will only need
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* this if you are an SDP translator, or if you are an inner part of the SDP API
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*/
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#ifndef _SDP_PRIV_H
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#define _SDP_PRIV_H
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#include "asterisk/vector.h"
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#include "asterisk/format.h"
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#include "asterisk/sdp_state.h"
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#include "asterisk/stream.h"
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/*!
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* \brief Structure representing an SDP Attribute
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*/
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struct ast_sdp_a_line {
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/*! Attribute name */
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char *name;
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/*! Attribute value. For attributes that have no value, this will be an empty string */
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char *value;
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};
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/*!
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* \brief A collection of SDP Attributes
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*/
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AST_VECTOR(ast_sdp_a_lines, struct ast_sdp_a_line *);
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/*!
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* \brief Structure representing an SDP Connection
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*/
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struct ast_sdp_c_line {
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/* IP family string (e.g. IP4 or IP6) */
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char *address_type;
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/* Connection address. Can be an IP address or FQDN */
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char *address;
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};
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/*!
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* \brief Structre representing SDP Media Payloads
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*/
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struct ast_sdp_payload {
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/* Media format description */
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char *fmt;
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};
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/*!
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* \brief A collection of SDP Media Payloads
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*/
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AST_VECTOR(ast_sdp_payloads, struct ast_sdp_payload *);
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/*!
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* \brief Structure representing an SDP Media Stream
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*
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* This contains both the m line, as well as its
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* constituent a lines.
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*/
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struct ast_sdp_m_line {
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/*! Media type (e.g. "audio" or "video") */
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char *type;
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/*! RTP profile string (e.g. "RTP/AVP") */
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char *proto;
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/*! Port number in m line */
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uint16_t port;
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/*! Number of ports specified in m line */
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uint16_t port_count;
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/*! RTP payloads */
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struct ast_sdp_payloads *payloads;
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/*! Connection information for this media stream */
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struct ast_sdp_c_line *c_line;
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/*! The attributes for this media stream */
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struct ast_sdp_a_lines *a_lines;
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};
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/*!
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* \brief A collection of SDP Media Streams
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*/
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AST_VECTOR(ast_sdp_m_lines, struct ast_sdp_m_line *);
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/*!
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* \brief Structure representing an SDP Origin
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*/
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struct ast_sdp_o_line {
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/*! Origin user name */
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char *username;
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/*! Origin id */
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uint64_t session_id;
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/*! Origin version */
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uint64_t session_version;
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/*! Origin IP address type (e.g. "IP4" or "IP6") */
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char *address_type;
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/*! Origin address. Can be an IP address or FQDN */
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char *address;
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};
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/*!
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* \brief Structure representing an SDP Session Name
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*/
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struct ast_sdp_s_line {
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/* Session Name */
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char *session_name;
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};
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/*!
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* \brief Structure representing SDP Timing
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*/
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struct ast_sdp_t_line {
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/*! Session start time */
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uint64_t start_time;
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/*! Session end time */
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uint64_t stop_time;
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};
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/*!
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* \brief An SDP
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*/
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struct ast_sdp {
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/*! SDP Origin line */
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struct ast_sdp_o_line *o_line;
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/*! SDP Session name */
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struct ast_sdp_s_line *s_line;
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/*! SDP top-level connection information */
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struct ast_sdp_c_line *c_line;
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/*! SDP timing information */
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struct ast_sdp_t_line *t_line;
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/*! SDP top-level attributes */
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struct ast_sdp_a_lines *a_lines;
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/*! SDP media streams */
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struct ast_sdp_m_lines *m_lines;
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};
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/*!
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* \brief A structure representing an SDP rtpmap attribute
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*/
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struct ast_sdp_rtpmap {
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/*! The RTP payload number for the rtpmap */
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int payload;
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/*! The Name of the codec */
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char *encoding_name;
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/*! The clock rate of the codec */
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int clock_rate;
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/*! Optional encoding parameters */
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char *encoding_parameters;
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/*! Area where strings are stored */
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char buf[0];
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};
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/*!
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* \brief Free an SDP Attribute
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*
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* \param a_line The attribute to free
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*
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* \since 15
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*/
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void ast_sdp_a_free(struct ast_sdp_a_line *a_line);
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/*!
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* \brief Free an SDP Attribute collection
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*
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* \param a_lines The attribute collection to free
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*
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* \since 15
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*/
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void ast_sdp_a_lines_free(struct ast_sdp_a_lines *a_lines);
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/*!
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* \brief Free SDP Connection Data
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*
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* \param c_line The connection data to free
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*
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* \since 15
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*/
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void ast_sdp_c_free(struct ast_sdp_c_line *c_line);
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/*!
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* \brief Free an SDP Media Description Payload
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*
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* \param payload The payload to free
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*
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* \since 15
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*/
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void ast_sdp_payload_free(struct ast_sdp_payload *payload);
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/*!
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* \brief Free an SDP Media Description Payload collection
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*
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* \param payloads collection to free
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*
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* \since 15
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*/
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void ast_sdp_payloads_free(struct ast_sdp_payloads *payloads);
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/*!
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* \brief Free an SDP Media Description
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* Frees the media description and all resources it contains
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*
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* \param m_line The media description to free
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*
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* \since 15
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*/
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void ast_sdp_m_free(struct ast_sdp_m_line *m_line);
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/*!
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* \brief Free an SDP Media Description collection
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*
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* \param m_lines The collection description to free
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*
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* \since 15
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*/
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void ast_sdp_m_lines_free(struct ast_sdp_m_lines *m_lines);
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/*!
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* \brief Free an SDP Origin
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*
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* \param o_line The origin description to free
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*
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* \since 15
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*/
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void ast_sdp_o_free(struct ast_sdp_o_line *o_line);
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/*!
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* \brief Free an SDP Session
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*
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* \param s_line The session to free
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*
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* \since 15
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*/
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void ast_sdp_s_free(struct ast_sdp_s_line *s_line);
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/*!
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* \brief Free SDP Timing
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*
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* \param t_line The timing description to free
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*
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* \since 15
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*/
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void ast_sdp_t_free(struct ast_sdp_t_line *t_line);
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/*!
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* \brief Allocate an SDP Attribute
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*
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* \param name Attribute Name
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* \param value Attribute Name
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*
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* \retval non-NULL Success
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* \retval NULL Failure
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*
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* \since 15
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*/
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struct ast_sdp_a_line *ast_sdp_a_alloc(const char *name, const char *value);
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/*!
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* \brief Allocate an SDP Connection
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*
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* \param family Family ("IN", etc)
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* \param addr Address
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*
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* \retval non-NULL Success
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* \retval NULL Failure
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*
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* \since 15
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*/
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struct ast_sdp_c_line *ast_sdp_c_alloc(const char *family, const char *addr);
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/*!
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* \brief Allocate an SDP Media Description Payload
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*
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* \param fmt The media format description
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*
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* \retval non-NULL Success
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* \retval NULL Failure
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*
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* \since 15
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*/
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struct ast_sdp_payload *ast_sdp_payload_alloc(const char *fmt);
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/*!
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* \brief Allocate an SDP Media Description
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*
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* \param type ("audio", "video", etc)
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* \param port Starting port
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* \param port_count Port pairs to allocate
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* \param proto ("RTP/AVP", "RTP/SAVP", "udp")
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* \param c_line Connection to add. May be NULL
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*
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* \retval non-NULL Success
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* \retval NULL Failure
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*
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* \since 15
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*/
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struct ast_sdp_m_line *ast_sdp_m_alloc(const char *type, uint16_t port,
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uint16_t port_count, const char *proto, struct ast_sdp_c_line *c_line);
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/*!
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* \brief Allocate an SDP Session
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*
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* \param session_name The session name
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*
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* \retval non-NULL Success
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* \retval NULL Failure
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*
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* \since 15
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*/
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struct ast_sdp_s_line *ast_sdp_s_alloc(const char *session_name);
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/*!
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* \brief Allocate SDP Timing
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*
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* \param start_time (Seconds since 1900)
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* \param end_time (Seconds since 1900)
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*
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* \retval non-NULL Success
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* \retval NULL Failure
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*
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* \since 15
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*/
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struct ast_sdp_t_line *ast_sdp_t_alloc(uint64_t start_time, uint64_t stop_time);
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/*!
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* \brief Allocate an SDP Origin
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*
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* \param username User name
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* \param sesison_id Session ID
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* \param sesison_version Session Version
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* \param address_type Address type ("IN4", "IN6", etc)
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* \param address Unicast address
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*
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* \retval non-NULL Success
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* \retval NULL Failure
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*
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* \since 15
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*/
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struct ast_sdp_o_line *ast_sdp_o_alloc(const char *username, uint64_t session_id,
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uint64_t session_version, const char *address_type, const char *address);
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/*!
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* \brief Add an SDP Attribute to an SDP
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*
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* \param sdp SDP
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* \param a_line Attribute
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*
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* \retval 0 Success
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* \retval non-0 Failure
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*
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* \since 15
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*/
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int ast_sdp_add_a(struct ast_sdp *sdp, struct ast_sdp_a_line *a_line);
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/*!
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* \brief Get the count of Attributes on an SDP
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*
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* \param sdp SDP
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*
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* \returns Number of Attributes
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*
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* \since 15
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*/
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int ast_sdp_get_a_count(const struct ast_sdp *sdp);
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/*!
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* \brief Get an Attribute from an SDP
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*
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* \param sdp SDP
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* \param index Attribute index
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*
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* \retval non-NULL Success
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* \retval NULL Failure
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*
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* \since 15
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*/
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struct ast_sdp_a_line *ast_sdp_get_a(const struct ast_sdp *sdp, int index);
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/*!
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* \brief Add a Media Description to an SDP
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*
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* \param sdp SDP
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* \param m_line Media Description
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*
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* \retval 0 Success
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* \retval non-0 Failure
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*
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* \since 15
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*/
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int ast_sdp_add_m(struct ast_sdp *sdp, struct ast_sdp_m_line *m_line);
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/*!
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* \brief Add an RTP Media Description to an SDP
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*
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* \param sdp SDP
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* \param sdp_state SDP state information
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* \param options SDP Options
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* \param stream_index stream
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*
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* \retval 0 Success
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* \retval non-0 Failure
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*
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* \since 15
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*/
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int ast_sdp_add_m_from_rtp_stream(struct ast_sdp *sdp, const struct ast_sdp_state *sdp_state,
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const struct ast_sdp_options *options, int stream_index);
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/*!
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* \brief Get the count of Media Descriptions on an SDP
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*
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* \param sdp SDP
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*
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* \returns The number of Media Descriptions
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*
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* \since 15
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*/
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int ast_sdp_get_m_count(const struct ast_sdp *sdp);
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/*!
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* \brief Get a Media Descriptions from an SDP
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*
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* \param sdp SDP
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* \param index Media Description index
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*
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* \retval non-NULL Success
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* \retval NULL Failure
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*
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* \since 15
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*/
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struct ast_sdp_m_line *ast_sdp_get_m(const struct ast_sdp *sdp, int index);
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/*!
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* \brief Add an SDP Attribute to a Media Description
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*
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* \param m_line Media Description
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* \param a_line Attribute
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*
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* \retval 0 Success
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* \retval non-0 Failure
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*
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* \since 15
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*/
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int ast_sdp_m_add_a(struct ast_sdp_m_line *m_line, struct ast_sdp_a_line *a_line);
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/*!
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* \brief Get the count of Attributes on a Media Description
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*
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* \param m_line Media Description
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*
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* \returns Number of Attributes
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*
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* \since 15
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*/
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int ast_sdp_m_get_a_count(const struct ast_sdp_m_line *m_line);
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/*!
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* \brief Get an Attribute from a Media Description
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*
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* \param m_line Media Description
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* \param index Attribute index
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*
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* \retval non-NULL Success
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* \retval NULL Failure
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*
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* \since 15
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*/
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struct ast_sdp_a_line *ast_sdp_m_get_a(const struct ast_sdp_m_line *m_line, int index);
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/*!
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* \brief Add a Payload to a Media Description
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*
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* \param m_line Media Description
|
|
* \param payload Payload
|
|
*
|
|
* \retval 0 Success
|
|
* \retval non-0 Failure
|
|
*
|
|
* \since 15
|
|
*/
|
|
int ast_sdp_m_add_payload(struct ast_sdp_m_line *m_line,
|
|
struct ast_sdp_payload *payload);
|
|
|
|
/*!
|
|
* \brief Get the count of Payloads on a Media Description
|
|
*
|
|
* \param m_line Media Description
|
|
*
|
|
* \returns Number of Attributes
|
|
*
|
|
* \since 15
|
|
*/
|
|
int ast_sdp_m_get_payload_count(const struct ast_sdp_m_line *m_line);
|
|
|
|
/*!
|
|
* \brief Get a Payload from a Media Description
|
|
*
|
|
* \param m_line Media Description
|
|
* \param index Payload index
|
|
*
|
|
* \retval non-NULL Success
|
|
* \retval NULL Failure
|
|
*
|
|
* \since 15
|
|
*/
|
|
struct ast_sdp_payload *ast_sdp_m_get_payload(const struct ast_sdp_m_line *m_line, int index);
|
|
|
|
/*!
|
|
* \brief Add a Format to a Media Description
|
|
*
|
|
* \param m_line Media Description
|
|
* \param options SDP Options
|
|
* \param rtp_code rtp_code from ast_rtp_codecs_payload_code
|
|
* \param asterisk_format True if the value in format is to be used.
|
|
* \param format Format
|
|
* \param code from AST_RTP list
|
|
*
|
|
* \retval 0 Success
|
|
* \retval non-0 Failure
|
|
*
|
|
* \since 15
|
|
*/
|
|
int ast_sdp_m_add_format(struct ast_sdp_m_line *m_line, const struct ast_sdp_options *options,
|
|
int rtp_code, int asterisk_format, const struct ast_format *format, int code);
|
|
|
|
/*!
|
|
* \brief Create an SDP ao2 object
|
|
*
|
|
* \param o_line Origin
|
|
* \param c_line Connection
|
|
* \param s_line Session
|
|
* \param t_line Timing
|
|
*
|
|
* \retval non-NULL Success
|
|
* \retval NULL Failure
|
|
*
|
|
* \since 15
|
|
*/
|
|
struct ast_sdp *ast_sdp_alloc(struct ast_sdp_o_line *o_line,
|
|
struct ast_sdp_c_line *c_line, struct ast_sdp_s_line *s_line,
|
|
struct ast_sdp_t_line *t_line);
|
|
|
|
/*!
|
|
* \brief Find the first attribute match index in the top-level SDP
|
|
*
|
|
* \note This will not search within streams for the given attribute.
|
|
*
|
|
* \param sdp The SDP in which to search
|
|
* \param attr_name The name of the attribute to search for
|
|
* \param payload Optional payload number to search for. If irrelevant, set to -1
|
|
*
|
|
* \retval index of attribute line on success.
|
|
* \retval -1 on failure or not found.
|
|
*
|
|
* \since 15.0.0
|
|
*/
|
|
int ast_sdp_find_a_first(const struct ast_sdp *sdp, const char *attr_name, int payload);
|
|
|
|
/*!
|
|
* \brief Find the next attribute match index in the top-level SDP
|
|
*
|
|
* \note This will not search within streams for the given attribute.
|
|
*
|
|
* \param sdp The SDP in which to search
|
|
* \param last The last matching index found
|
|
* \param attr_name The name of the attribute to search for
|
|
* \param payload Optional payload number to search for. If irrelevant, set to -1
|
|
*
|
|
* \retval index of attribute line on success.
|
|
* \retval -1 on failure or not found.
|
|
*
|
|
* \since 15.0.0
|
|
*/
|
|
int ast_sdp_find_a_next(const struct ast_sdp *sdp, int last, const char *attr_name, int payload);
|
|
|
|
/*!
|
|
* \brief Find an attribute in the top-level SDP
|
|
*
|
|
* \note This will not search within streams for the given attribute.
|
|
*
|
|
* \param sdp The SDP in which to search
|
|
* \param attr_name The name of the attribute to search for
|
|
* \param payload Optional payload number to search for. If irrelevant, set to -1
|
|
*
|
|
* \retval NULL Could not find the given attribute
|
|
* \retval Non-NULL The attribute to find
|
|
*
|
|
* \since 15.0.0
|
|
*/
|
|
struct ast_sdp_a_line *ast_sdp_find_attribute(const struct ast_sdp *sdp,
|
|
const char *attr_name, int payload);
|
|
|
|
/*!
|
|
* \brief Find the first attribute match index in an SDP stream (m-line)
|
|
*
|
|
* \param m_line The SDP m-line in which to search
|
|
* \param attr_name The name of the attribute to search for
|
|
* \param payload Optional payload number to search for. If irrelevant, set to -1
|
|
*
|
|
* \retval index of attribute line on success.
|
|
* \retval -1 on failure or not found.
|
|
*
|
|
* \since 15.0.0
|
|
*/
|
|
int ast_sdp_m_find_a_first(const struct ast_sdp_m_line *m_line, const char *attr_name,
|
|
int payload);
|
|
|
|
/*!
|
|
* \brief Find the next attribute match index in an SDP stream (m-line)
|
|
*
|
|
* \param m_line The SDP m-line in which to search
|
|
* \param last The last matching index found
|
|
* \param attr_name The name of the attribute to search for
|
|
* \param payload Optional payload number to search for. If irrelevant, set to -1
|
|
*
|
|
* \retval index of attribute line on success.
|
|
* \retval -1 on failure or not found.
|
|
*
|
|
* \since 15.0.0
|
|
*/
|
|
int ast_sdp_m_find_a_next(const struct ast_sdp_m_line *m_line, int last,
|
|
const char *attr_name, int payload);
|
|
|
|
/*!
|
|
* \brief Find an attribute in an SDP stream (m-line)
|
|
*
|
|
* \param m_line The SDP m-line in which to search
|
|
* \param attr_name The name of the attribute to search for
|
|
* \param payload Optional payload number to search for. If irrelevant, set to -1
|
|
*
|
|
* \retval NULL Could not find the given attribute
|
|
* \retval Non-NULL The attribute to find
|
|
*
|
|
* \since 15.0.0
|
|
*/
|
|
struct ast_sdp_a_line *ast_sdp_m_find_attribute(const struct ast_sdp_m_line *m_line,
|
|
const char *attr_name, int payload);
|
|
|
|
/*!
|
|
* \brief Convert an SDP a_line into an rtpmap
|
|
*
|
|
* The returned value is heap-allocated and must be freed with
|
|
* ast_sdp_rtpmap_free()
|
|
*
|
|
* \param a_line The SDP a_line to convert
|
|
*
|
|
* \retval NULL Fail
|
|
* \retval non-NULL Success
|
|
*
|
|
* \since 15.0.0
|
|
*/
|
|
struct ast_sdp_rtpmap *ast_sdp_a_get_rtpmap(const struct ast_sdp_a_line *a_line);
|
|
|
|
|
|
/*!
|
|
* \brief Allocate a new SDP rtpmap
|
|
*
|
|
* \param payload The RTP payload number
|
|
* \param encoding_name The human-readable name for the codec
|
|
* \param clock_rate The rate of the codec, in cycles per second
|
|
* \param encoding_parameters Optional codec-specific parameters (such as number of channels)
|
|
*
|
|
* \retval NULL Fail
|
|
* \retval non-NULL Success
|
|
*
|
|
* \since 15.0.0
|
|
*/
|
|
struct ast_sdp_rtpmap *ast_sdp_rtpmap_alloc(int payload, const char *encoding_name,
|
|
int clock_rate, const char *encoding_parameters);
|
|
|
|
/*!
|
|
* \brief Free an SDP rtpmap
|
|
*
|
|
* \since 15.0.0
|
|
*/
|
|
void ast_sdp_rtpmap_free(struct ast_sdp_rtpmap *rtpmap);
|
|
|
|
/*!
|
|
* \brief Turn an SDP into a stream topology
|
|
*
|
|
* This traverses the m-lines of the SDP and creates a stream topology, with
|
|
* each m-line corresponding to a stream in the created topology.
|
|
*
|
|
* \param sdp The SDP to convert
|
|
* \param g726_non_standard Non-zero if G.726 is non-standard
|
|
*
|
|
* \retval NULL An error occurred when converting
|
|
* \retval non-NULL The generated stream topology
|
|
*
|
|
* \since 15.0.0
|
|
*/
|
|
struct ast_stream_topology *ast_get_topology_from_sdp(const struct ast_sdp *sdp, int g726_non_standard);
|
|
#endif /* _SDP_PRIV_H */
|