Source/WebCore/Modules/mediastream/libwebrtc/LibWebRTCPeerConnectionBackend.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2017 Apple Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "config.h"
 #include "LibWebRTCPeerConnectionBackend.h"

 #if USE(LIBWEBRTC)

 #include "Document.h"
 #include "IceCandidate.h"
 #include "JSRTCStatsReport.h"
 #include "LibWebRTCDataChannelHandler.h"
 #include "LibWebRTCMediaEndpoint.h"
 #include "MediaEndpointConfiguration.h"
 #include "Page.h"
 #include "RTCIceCandidate.h"
 #include "RTCPeerConnection.h"
 #include "RTCRtpReceiver.h"
 #include "RTCSessionDescription.h"
 #include "RealtimeIncomingAudioSource.h"
 #include "RealtimeIncomingVideoSource.h"

 namespace WebCore {

 static std::unique_ptr<PeerConnectionBackend> createLibWebRTCPeerConnectionBackend(RTCPeerConnection& peerConnection)
 {
     if (!LibWebRTCProvider::webRTCAvailable())
         return nullptr;
     return std::make_unique<LibWebRTCPeerConnectionBackend>(peerConnection);
 }

 CreatePeerConnectionBackend PeerConnectionBackend::create = createLibWebRTCPeerConnectionBackend;

 static inline LibWebRTCProvider& libWebRTCProvider(RTCPeerConnection& peerConnection)
 {
     ASSERT(peerConnection.scriptExecutionContext()->isDocument());
     auto* page = static_cast<Document*>(peerConnection.scriptExecutionContext())->page();
     return page->libWebRTCProvider();
 }

 LibWebRTCPeerConnectionBackend::LibWebRTCPeerConnectionBackend(RTCPeerConnection& peerConnection)
     : PeerConnectionBackend(peerConnection)
     , m_endpoint(LibWebRTCMediaEndpoint::create(*this, libWebRTCProvider(peerConnection)))
 {
 }

 LibWebRTCPeerConnectionBackend::~LibWebRTCPeerConnectionBackend()
 {
 }

 static webrtc::PeerConnectionInterface::RTCConfiguration configurationFromMediaEndpointConfiguration(MediaEndpointConfiguration&& configuration)
 {
     webrtc::PeerConnectionInterface::RTCConfiguration rtcConfiguration;

     if (configuration.iceTransportPolicy == RTCIceTransportPolicy::Relay)
         rtcConfiguration.type = webrtc::PeerConnectionInterface::kRelay;

     // FIXME: Support PeerConnectionStates::BundlePolicy::MaxBundle.
     // LibWebRTC does not like it and will fail to set any configuration field otherwise.
     // See https://bugs.webkit.org/show_bug.cgi?id=169389.

     if (configuration.bundlePolicy == RTCBundlePolicy::MaxCompat)
         rtcConfiguration.bundle_policy = webrtc::PeerConnectionInterface::kBundlePolicyMaxCompat;

     for (auto& server : configuration.iceServers) {
         webrtc::PeerConnectionInterface::IceServer iceServer;
         iceServer.username = server.username.utf8().data();
         iceServer.password = server.credential.utf8().data();
         for (auto& url : server.urls)
             iceServer.urls.push_back({ url.string().utf8().data() });
         rtcConfiguration.servers.push_back(WTFMove(iceServer));
     }

     return rtcConfiguration;
 }

 void LibWebRTCPeerConnectionBackend::setConfiguration(MediaEndpointConfiguration&& configuration)
 {
     m_endpoint->backend().SetConfiguration(configurationFromMediaEndpointConfiguration(WTFMove(configuration)));
 }

 void LibWebRTCPeerConnectionBackend::getStats(MediaStreamTrack* track, Ref<DeferredPromise>&& promise)
 {
     if (m_endpoint->isStopped())
         return;

     auto& statsPromise = promise.get();
     m_statsPromises.add(&statsPromise, WTFMove(promise));
     m_endpoint->getStats(track, statsPromise);
 }

 void LibWebRTCPeerConnectionBackend::getStatsSucceeded(const DeferredPromise& promise, Ref<RTCStatsReport>&& report)
 {
     auto statsPromise = m_statsPromises.take(&promise);
     ASSERT(statsPromise);
     statsPromise.value()->resolve<IDLInterface<RTCStatsReport>>(WTFMove(report));
 }

 void LibWebRTCPeerConnectionBackend::getStatsFailed(const DeferredPromise& promise, Exception&& exception)
 {
     auto statsPromise = m_statsPromises.take(&promise);
     ASSERT(statsPromise);
     statsPromise.value()->reject(WTFMove(exception));
 }

 void LibWebRTCPeerConnectionBackend::doSetLocalDescription(RTCSessionDescription& description)
 {
     m_endpoint->doSetLocalDescription(description);
     if (!m_isLocalDescriptionSet) {
         if (m_isRemoteDescriptionSet) {
             while (m_pendingCandidates.size())
                 m_endpoint->addIceCandidate(*m_pendingCandidates.takeLast().release());
         }
         m_isLocalDescriptionSet = true;
     }
 }

 void LibWebRTCPeerConnectionBackend::doSetRemoteDescription(RTCSessionDescription& description)
 {
     m_endpoint->doSetRemoteDescription(description);
     if (!m_isRemoteDescriptionSet) {
         if (m_isLocalDescriptionSet) {
             while (m_pendingCandidates.size())
                 m_endpoint->addIceCandidate(*m_pendingCandidates.takeLast().release());
         }
         m_isRemoteDescriptionSet = true;
     }
 }

 void LibWebRTCPeerConnectionBackend::doCreateOffer(RTCOfferOptions&&)
 {
     m_endpoint->doCreateOffer();
 }

 void LibWebRTCPeerConnectionBackend::doCreateAnswer(RTCAnswerOptions&&)
 {
     if (!m_isRemoteDescriptionSet) {
         createAnswerFailed(Exception { INVALID_STATE_ERR, "No remote description set" });
         return;
     }
     m_endpoint->doCreateAnswer();
 }

 void LibWebRTCPeerConnectionBackend::doStop()
 {
     for (auto& source : m_audioSources)
         source->stop();
     for (auto& source : m_videoSources)
         source->stop();

     m_endpoint->stop();

     m_remoteStreams.clear();
     m_pendingReceivers.clear();
 }

 void LibWebRTCPeerConnectionBackend::doAddIceCandidate(RTCIceCandidate& candidate)
 {
     webrtc::SdpParseError error;
     int sdpMLineIndex = candidate.sdpMLineIndex() ? candidate.sdpMLineIndex().value() : 0;
     std::unique_ptr<webrtc::IceCandidateInterface> rtcCandidate(webrtc::CreateIceCandidate(candidate.sdpMid().utf8().data(), sdpMLineIndex, candidate.candidate().utf8().data(), &error));

     if (!rtcCandidate) {
         String message(error.description.data(), error.description.size());
         addIceCandidateFailed(Exception { OperationError, WTFMove(message) });
         return;
     }

     // libwebrtc does not like that ice candidates are set before the description.
     if (!m_isLocalDescriptionSet || !m_isRemoteDescriptionSet)
         m_pendingCandidates.append(WTFMove(rtcCandidate));
     else if (!m_endpoint->addIceCandidate(*rtcCandidate.get())) {
         ASSERT_NOT_REACHED();
         addIceCandidateFailed(Exception { OperationError, ASCIILiteral("Failed to apply the received candidate") });
         return;
     }
     addIceCandidateSucceeded();
 }

 void LibWebRTCPeerConnectionBackend::addAudioSource(Ref<RealtimeOutgoingAudioSource>&& source)
 {
     m_audioSources.append(WTFMove(source));
 }

 void LibWebRTCPeerConnectionBackend::addVideoSource(Ref<RealtimeOutgoingVideoSource>&& source)
 {
     m_videoSources.append(WTFMove(source));
 }

 static inline Ref<RTCRtpReceiver> createReceiverForSource(ScriptExecutionContext& context, Ref<RealtimeMediaSource>&& source)
 {
     auto remoteTrackPrivate = MediaStreamTrackPrivate::create(WTFMove(source));
     auto remoteTrack = MediaStreamTrack::create(context, WTFMove(remoteTrackPrivate));

     return RTCRtpReceiver::create(WTFMove(remoteTrack));
 }

 static inline Ref<RealtimeMediaSource> createEmptySource(const String& trackKind, String&& trackId)
 {
     // FIXME: trackKind should be an enumeration
     if (trackKind == "audio")
         return RealtimeIncomingAudioSource::create(nullptr, WTFMove(trackId));
     ASSERT(trackKind == "video");
     return RealtimeIncomingVideoSource::create(nullptr, WTFMove(trackId));
 }

 Ref<RTCRtpReceiver> LibWebRTCPeerConnectionBackend::createReceiver(const String&, const String& trackKind, const String& trackId)
 {
     auto receiver = createReceiverForSource(*m_peerConnection.scriptExecutionContext(), createEmptySource(trackKind, String(trackId)));
     m_pendingReceivers.append(receiver.copyRef());
     return receiver;
 }

 LibWebRTCPeerConnectionBackend::VideoReceiver LibWebRTCPeerConnectionBackend::videoReceiver(String&& trackId)
 {
     // FIXME: Add to Vector a utility routine for that take-or-create pattern.
     // FIXME: We should be selecting the receiver based on track id.
     for (size_t cptr = 0; cptr < m_pendingReceivers.size(); ++cptr) {
         if (m_pendingReceivers[cptr]->track()->source().type() == RealtimeMediaSource::Type::Video) {
             Ref<RTCRtpReceiver> receiver = m_pendingReceivers[cptr].copyRef();
             m_pendingReceivers.remove(cptr);
             Ref<RealtimeIncomingVideoSource> source = static_cast<RealtimeIncomingVideoSource&>(receiver->track()->source());
             return { WTFMove(receiver), WTFMove(source) };
         }
     }
     auto source = RealtimeIncomingVideoSource::create(nullptr, WTFMove(trackId));
     auto receiver = createReceiverForSource(*m_peerConnection.scriptExecutionContext(), source.copyRef());
     return { WTFMove(receiver), WTFMove(source) };
 }

 LibWebRTCPeerConnectionBackend::AudioReceiver LibWebRTCPeerConnectionBackend::audioReceiver(String&& trackId)
 {
     // FIXME: Add to Vector a utility routine for that take-or-create pattern.
     // FIXME: We should be selecting the receiver based on track id.
     for (size_t cptr = 0; cptr < m_pendingReceivers.size(); ++cptr) {
         if (m_pendingReceivers[cptr]->track()->source().type() == RealtimeMediaSource::Type::Audio) {
             Ref<RTCRtpReceiver> receiver = m_pendingReceivers[cptr].copyRef();
             m_pendingReceivers.remove(cptr);
             Ref<RealtimeIncomingAudioSource> source = static_cast<RealtimeIncomingAudioSource&>(receiver->track()->source());
             return { WTFMove(receiver), WTFMove(source) };
         }
     }
     auto source = RealtimeIncomingAudioSource::create(nullptr, WTFMove(trackId));
     auto receiver = createReceiverForSource(*m_peerConnection.scriptExecutionContext(), source.copyRef());
     return { WTFMove(receiver), WTFMove(source) };
 }

 std::unique_ptr<RTCDataChannelHandler> LibWebRTCPeerConnectionBackend::createDataChannelHandler(const String& label, const RTCDataChannelInit& options)
 {
     return m_endpoint->createDataChannel(label, options);
 }

 RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::currentLocalDescription() const
 {
     return m_endpoint->currentLocalDescription();
 }

 RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::currentRemoteDescription() const
 {
     return m_endpoint->currentRemoteDescription();
 }

 RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::pendingLocalDescription() const
 {
     return m_endpoint->pendingLocalDescription();
 }

 RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::pendingRemoteDescription() const
 {
     return m_endpoint->pendingRemoteDescription();
 }

 RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::localDescription() const
 {
     return m_endpoint->localDescription();
 }

 RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::remoteDescription() const
 {
     return m_endpoint->remoteDescription();
 }

 void LibWebRTCPeerConnectionBackend::notifyAddedTrack(RTCRtpSender& sender)
 {
     ASSERT(sender.track());
     m_endpoint->addTrack(*sender.track(), sender.mediaStreamIds());
 }

 void LibWebRTCPeerConnectionBackend::removeRemoteStream(MediaStream* mediaStream)
 {
     m_remoteStreams.removeFirstMatching([mediaStream](const auto& item) {
         return item.get() == mediaStream;
     });
 }

 void LibWebRTCPeerConnectionBackend::addRemoteStream(Ref<MediaStream>&& mediaStream)
 {
     m_remoteStreams.append(WTFMove(mediaStream));
 }

 } // namespace WebCore

 #endif // USE(LIBWEBRTC)
	/*
	* Copyright (C) 2017 Apple Inc.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
	* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
	* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
	* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
	* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
	* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "config.h"
	#include "LibWebRTCPeerConnectionBackend.h"

	#if USE(LIBWEBRTC)

	#include "Document.h"
	#include "IceCandidate.h"
	#include "JSRTCStatsReport.h"
	#include "LibWebRTCDataChannelHandler.h"
	#include "LibWebRTCMediaEndpoint.h"
	#include "MediaEndpointConfiguration.h"
	#include "Page.h"
	#include "RTCIceCandidate.h"
	#include "RTCPeerConnection.h"
	#include "RTCRtpReceiver.h"
	#include "RTCSessionDescription.h"
	#include "RealtimeIncomingAudioSource.h"
	#include "RealtimeIncomingVideoSource.h"

	namespace WebCore {

	static std::unique_ptr<PeerConnectionBackend> createLibWebRTCPeerConnectionBackend(RTCPeerConnection& peerConnection)
	{
	if (!LibWebRTCProvider::webRTCAvailable())
	return nullptr;
	return std::make_unique<LibWebRTCPeerConnectionBackend>(peerConnection);
	}

	CreatePeerConnectionBackend PeerConnectionBackend::create = createLibWebRTCPeerConnectionBackend;

	static inline LibWebRTCProvider& libWebRTCProvider(RTCPeerConnection& peerConnection)
	{
	ASSERT(peerConnection.scriptExecutionContext()->isDocument());
	auto* page = static_cast<Document*>(peerConnection.scriptExecutionContext())->page();
	return page->libWebRTCProvider();
	}

	LibWebRTCPeerConnectionBackend::LibWebRTCPeerConnectionBackend(RTCPeerConnection& peerConnection)
	: PeerConnectionBackend(peerConnection)
	, m_endpoint(LibWebRTCMediaEndpoint::create(*this, libWebRTCProvider(peerConnection)))
	{
	}

	LibWebRTCPeerConnectionBackend::~LibWebRTCPeerConnectionBackend()
	{
	}

	static webrtc::PeerConnectionInterface::RTCConfiguration configurationFromMediaEndpointConfiguration(MediaEndpointConfiguration&& configuration)
	{
	webrtc::PeerConnectionInterface::RTCConfiguration rtcConfiguration;

	if (configuration.iceTransportPolicy == RTCIceTransportPolicy::Relay)
	rtcConfiguration.type = webrtc::PeerConnectionInterface::kRelay;

	// FIXME: Support PeerConnectionStates::BundlePolicy::MaxBundle.
	// LibWebRTC does not like it and will fail to set any configuration field otherwise.
	// See https://bugs.webkit.org/show_bug.cgi?id=169389.

	if (configuration.bundlePolicy == RTCBundlePolicy::MaxCompat)
	rtcConfiguration.bundle_policy = webrtc::PeerConnectionInterface::kBundlePolicyMaxCompat;

	for (auto& server : configuration.iceServers) {
	webrtc::PeerConnectionInterface::IceServer iceServer;
	iceServer.username = server.username.utf8().data();
	iceServer.password = server.credential.utf8().data();
	for (auto& url : server.urls)
	iceServer.urls.push_back({ url.string().utf8().data() });
	rtcConfiguration.servers.push_back(WTFMove(iceServer));
	}

	return rtcConfiguration;
	}

	void LibWebRTCPeerConnectionBackend::setConfiguration(MediaEndpointConfiguration&& configuration)
	{
	m_endpoint->backend().SetConfiguration(configurationFromMediaEndpointConfiguration(WTFMove(configuration)));
	}

	void LibWebRTCPeerConnectionBackend::getStats(MediaStreamTrack* track, Ref<DeferredPromise>&& promise)
	{
	if (m_endpoint->isStopped())
	return;

	auto& statsPromise = promise.get();
	m_statsPromises.add(&statsPromise, WTFMove(promise));
	m_endpoint->getStats(track, statsPromise);
	}

	void LibWebRTCPeerConnectionBackend::getStatsSucceeded(const DeferredPromise& promise, Ref<RTCStatsReport>&& report)
	{
	auto statsPromise = m_statsPromises.take(&promise);
	ASSERT(statsPromise);
	statsPromise.value()->resolve<IDLInterface<RTCStatsReport>>(WTFMove(report));
	}

	void LibWebRTCPeerConnectionBackend::getStatsFailed(const DeferredPromise& promise, Exception&& exception)
	{
	auto statsPromise = m_statsPromises.take(&promise);
	ASSERT(statsPromise);
	statsPromise.value()->reject(WTFMove(exception));
	}

	void LibWebRTCPeerConnectionBackend::doSetLocalDescription(RTCSessionDescription& description)
	{
	m_endpoint->doSetLocalDescription(description);
	if (!m_isLocalDescriptionSet) {
	if (m_isRemoteDescriptionSet) {
	while (m_pendingCandidates.size())
	m_endpoint->addIceCandidate(*m_pendingCandidates.takeLast().release());
	}
	m_isLocalDescriptionSet = true;
	}
	}

	void LibWebRTCPeerConnectionBackend::doSetRemoteDescription(RTCSessionDescription& description)
	{
	m_endpoint->doSetRemoteDescription(description);
	if (!m_isRemoteDescriptionSet) {
	if (m_isLocalDescriptionSet) {
	while (m_pendingCandidates.size())
	m_endpoint->addIceCandidate(*m_pendingCandidates.takeLast().release());
	}
	m_isRemoteDescriptionSet = true;
	}
	}

	void LibWebRTCPeerConnectionBackend::doCreateOffer(RTCOfferOptions&&)
	{
	m_endpoint->doCreateOffer();
	}

	void LibWebRTCPeerConnectionBackend::doCreateAnswer(RTCAnswerOptions&&)
	{
	if (!m_isRemoteDescriptionSet) {
	createAnswerFailed(Exception { INVALID_STATE_ERR, "No remote description set" });
	return;
	}
	m_endpoint->doCreateAnswer();
	}

	void LibWebRTCPeerConnectionBackend::doStop()
	{
	for (auto& source : m_audioSources)
	source->stop();
	for (auto& source : m_videoSources)
	source->stop();

	m_endpoint->stop();

	m_remoteStreams.clear();
	m_pendingReceivers.clear();
	}

	void LibWebRTCPeerConnectionBackend::doAddIceCandidate(RTCIceCandidate& candidate)
	{
	webrtc::SdpParseError error;
	int sdpMLineIndex = candidate.sdpMLineIndex() ? candidate.sdpMLineIndex().value() : 0;
	std::unique_ptr<webrtc::IceCandidateInterface> rtcCandidate(webrtc::CreateIceCandidate(candidate.sdpMid().utf8().data(), sdpMLineIndex, candidate.candidate().utf8().data(), &error));

	if (!rtcCandidate) {
	String message(error.description.data(), error.description.size());
	addIceCandidateFailed(Exception { OperationError, WTFMove(message) });
	return;
	}

	// libwebrtc does not like that ice candidates are set before the description.
	if (!m_isLocalDescriptionSet \|\| !m_isRemoteDescriptionSet)
	m_pendingCandidates.append(WTFMove(rtcCandidate));
	else if (!m_endpoint->addIceCandidate(*rtcCandidate.get())) {
	ASSERT_NOT_REACHED();
	addIceCandidateFailed(Exception { OperationError, ASCIILiteral("Failed to apply the received candidate") });
	return;
	}
	addIceCandidateSucceeded();
	}

	void LibWebRTCPeerConnectionBackend::addAudioSource(Ref<RealtimeOutgoingAudioSource>&& source)
	{
	m_audioSources.append(WTFMove(source));
	}

	void LibWebRTCPeerConnectionBackend::addVideoSource(Ref<RealtimeOutgoingVideoSource>&& source)
	{
	m_videoSources.append(WTFMove(source));
	}

	static inline Ref<RTCRtpReceiver> createReceiverForSource(ScriptExecutionContext& context, Ref<RealtimeMediaSource>&& source)
	{
	auto remoteTrackPrivate = MediaStreamTrackPrivate::create(WTFMove(source));
	auto remoteTrack = MediaStreamTrack::create(context, WTFMove(remoteTrackPrivate));

	return RTCRtpReceiver::create(WTFMove(remoteTrack));
	}

	static inline Ref<RealtimeMediaSource> createEmptySource(const String& trackKind, String&& trackId)
	{
	// FIXME: trackKind should be an enumeration
	if (trackKind == "audio")
	return RealtimeIncomingAudioSource::create(nullptr, WTFMove(trackId));
	ASSERT(trackKind == "video");
	return RealtimeIncomingVideoSource::create(nullptr, WTFMove(trackId));
	}

	Ref<RTCRtpReceiver> LibWebRTCPeerConnectionBackend::createReceiver(const String&, const String& trackKind, const String& trackId)
	{
	auto receiver = createReceiverForSource(*m_peerConnection.scriptExecutionContext(), createEmptySource(trackKind, String(trackId)));
	m_pendingReceivers.append(receiver.copyRef());
	return receiver;
	}

	LibWebRTCPeerConnectionBackend::VideoReceiver LibWebRTCPeerConnectionBackend::videoReceiver(String&& trackId)
	{
	// FIXME: Add to Vector a utility routine for that take-or-create pattern.
	// FIXME: We should be selecting the receiver based on track id.
	for (size_t cptr = 0; cptr < m_pendingReceivers.size(); ++cptr) {
	if (m_pendingReceivers[cptr]->track()->source().type() == RealtimeMediaSource::Type::Video) {
	Ref<RTCRtpReceiver> receiver = m_pendingReceivers[cptr].copyRef();
	m_pendingReceivers.remove(cptr);
	Ref<RealtimeIncomingVideoSource> source = static_cast<RealtimeIncomingVideoSource&>(receiver->track()->source());
	return { WTFMove(receiver), WTFMove(source) };
	}
	}
	auto source = RealtimeIncomingVideoSource::create(nullptr, WTFMove(trackId));
	auto receiver = createReceiverForSource(*m_peerConnection.scriptExecutionContext(), source.copyRef());
	return { WTFMove(receiver), WTFMove(source) };
	}

	LibWebRTCPeerConnectionBackend::AudioReceiver LibWebRTCPeerConnectionBackend::audioReceiver(String&& trackId)
	{
	// FIXME: Add to Vector a utility routine for that take-or-create pattern.
	// FIXME: We should be selecting the receiver based on track id.
	for (size_t cptr = 0; cptr < m_pendingReceivers.size(); ++cptr) {
	if (m_pendingReceivers[cptr]->track()->source().type() == RealtimeMediaSource::Type::Audio) {
	Ref<RTCRtpReceiver> receiver = m_pendingReceivers[cptr].copyRef();
	m_pendingReceivers.remove(cptr);
	Ref<RealtimeIncomingAudioSource> source = static_cast<RealtimeIncomingAudioSource&>(receiver->track()->source());
	return { WTFMove(receiver), WTFMove(source) };
	}
	}
	auto source = RealtimeIncomingAudioSource::create(nullptr, WTFMove(trackId));
	auto receiver = createReceiverForSource(*m_peerConnection.scriptExecutionContext(), source.copyRef());
	return { WTFMove(receiver), WTFMove(source) };
	}

	std::unique_ptr<RTCDataChannelHandler> LibWebRTCPeerConnectionBackend::createDataChannelHandler(const String& label, const RTCDataChannelInit& options)
	{
	return m_endpoint->createDataChannel(label, options);
	}

	RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::currentLocalDescription() const
	{
	return m_endpoint->currentLocalDescription();
	}

	RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::currentRemoteDescription() const
	{
	return m_endpoint->currentRemoteDescription();
	}

	RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::pendingLocalDescription() const
	{
	return m_endpoint->pendingLocalDescription();
	}

	RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::pendingRemoteDescription() const
	{
	return m_endpoint->pendingRemoteDescription();
	}

	RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::localDescription() const
	{
	return m_endpoint->localDescription();
	}

	RefPtr<RTCSessionDescription> LibWebRTCPeerConnectionBackend::remoteDescription() const
	{
	return m_endpoint->remoteDescription();
	}

	void LibWebRTCPeerConnectionBackend::notifyAddedTrack(RTCRtpSender& sender)
	{
	ASSERT(sender.track());
	m_endpoint->addTrack(*sender.track(), sender.mediaStreamIds());
	}

	void LibWebRTCPeerConnectionBackend::removeRemoteStream(MediaStream* mediaStream)
	{
	m_remoteStreams.removeFirstMatching([mediaStream](const auto& item) {
	return item.get() == mediaStream;
	});
	}

	void LibWebRTCPeerConnectionBackend::addRemoteStream(Ref<MediaStream>&& mediaStream)
	{
	m_remoteStreams.append(WTFMove(mediaStream));
	}

	} // namespace WebCore

	#endif // USE(LIBWEBRTC)