10 Commits (dac5e3a0df5d76967ef581984e79e0d5543c6a89)

Author	SHA1	Message	Date
Richard Mudgett	3a18a09030	SDP: Rework SDP offer/answer model and update capabilities merges. ... 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	8 years ago
Richard Mudgett	e563a1920e	SDP: Add get/set option calls for RTP sched context per type. ... Change-Id: I82dc75c63c48904e9e5a49e2205dcc06e88487e4	8 years ago
Richard Mudgett	16785c0908	SDP: Add interface_address to specify our address to use. ... When we optionally set the interface_address we are forcing the media to go out a specific interface address. This allows us to optionally have the media go out the interface that SIP signalling came in on or if we are configured to have the media always go out a specific address. Change-Id: I160d9fac322a075bd2557b430632544178196189	9 years ago
Richard Mudgett	cd272da7a8	SDP: Replace SDP telephone_event option with dtmf option ... The telephone_event option was used as a flag and a bit mapped value in different places when it is a boolean. It is also inadequate to configure the DTMF operation of the RTP instance created for the stream. Change-Id: Ib1addeaf0ce86f07039f2f979cab29405dc5239b	9 years ago
Mark Michelson	d6535c0080	SDP API: Add SSRC-level attributes ... RFC 5576 defines how SSRC-level attributes may be added to SDP media descriptions. In general, this is useful for grouping related SSRCes, indicating SSRC-level format attributes, and resolving collisions in RTP SSRC values. These attributes are used widely by browsers during WebRTC communications, including attributes defined by documents outside of RFC 5576. This commit introduces the addition of SSRC-level attributes into SDPs generated by Asterisk. Since Asterisk does not tend to use multiple SSRCs on a media stream, the initial support is minimal. Asterisk includes an SSRC-level CNAME attribute if configured to do so. This at least gives browsers (and possibly others) the ability to resolve SSRC collisions at offer-answer time. In order to facilitate this, the RTP engine API has been enhanced to be able to retrieve the SSRC and CNAME on a given RTP instance. res_rtp_asterisk currently does not provide meaningful CNAME values in its RTCP SDES items, and therefore it currently will always return an empty string as the CNAME value. A task in the near future will result in res_rtp_asterisk generating more meaningful CNAMEs. Change-Id: I29e7f23e7db77524f82a3b6e8531b1195ff57789	9 years ago
Joshua Colp	19a79ae12c	sdp: Add support for T.38 ... This change adds a T.38 format which can be used in a stream topology to specify that a UDPTL stream needs to be created. The SDP API has been changed to understand T.38 and create the UDPTL session, add the attributes, and parse the attributes. This change does not change the boundary of the T.38 state machine. It is still up to the channel driver to implement and act on it (such as queueing control frames or reacting to them). ASTERISK-26949 Change-Id: If28956762ccb8ead562ac6c03d162d3d6014f2c7	9 years ago
Mark Michelson	32b3e36c68	SDP: Ensure SDPs "merge" properly. ... The gist of this work ensures that when a remote SDP is received, it is merged properly with the local capabilities. The remote SDP is converted into a stream topology. That topology is then merged with the current local topology on the SDP state. That new merged topology is then used to create an SDP. Finally, adjustments are made to RTP instances based on knowledge gained from the remote SDP. There are also a battery of tests in this commit that ensure that some basic SDP merges work as expected. While this may not sound like a big change, it has the property that it caused lots of ancillary changes. * The remote SDP is no longer stored on the SDP state. Biggest reason: there's no need for it. The remote SDP is used at the time it is being set and nowhere else. * Some new SDP APIs were added in order to find attributes and convert generic SDP attributes into rtpmap structures. * Writing tests made me realize that retrieving a value from an SDP options structure, the SDP options needs to be made const. * The SDP state machine was essentially gutted by a previous commit. Initially, I attempted to reinstate it, but I found that as it had been defined, it was not all that useful. What was more useful was knowing the role we play in SDP negotiation, so the SDP state machine has been transformed into an indicator of role. * Rather than storing separate local and joint stream state capabilities, it makes more sense to keep track of current stream state and update it as things change. Change-Id: I5938c2be3c6f0a003aa88a39a59e0880f8b2df3d	9 years ago
Joshua Colp	f3290d6b66	sdp: Add support for setting connection address and clean up state. ... This change cleans up state management for media streams by moving RTP instances into their own session structure and adding additional details that are not relevant to the core (such as connection address). These can live either in the local capabilities or joint capabilities. The ability to set explicit connection address information for the purposes of direct media and NAT has also been added at the global and stream specific level. ASTERISK-26900 Change-Id: If7e5307239a9534420732de11c451a2705b6b681	9 years ago
George Joseph	8470c2bdea	RFC sdp: Initial SDP creation ... * Added additional fields to ast_sdp_options. * Re-organized ast_sdp. * Updated field names to correspond to RFC4566 terminology. * Created allocs/frees for SDP children. * Created getters/setters for SDP children where appropriate. * Added ast_sdp_create_from_state. * Refactored res_sdp_translator_pjmedia for changes. Change-Id: Iefbd877af7f5a4d3c74deead1bff8802661b0d48	9 years ago
Mark Michelson	8af6342555	Add initial SDP options. ... This is step one of adding an SDP API: defining some configurable settings for SDPs. This is based on options that are currently supported in Asterisk. Change-Id: I1ede91aafed403b12a9ccdfb91a88389baa7e5d7	9 years ago