1 files changed, 412 insertions, 150 deletions

diff --git a/dom/media/webrtc/jsapi/PeerConnectionImpl.cpp b/dom/media/webrtc/jsapi/PeerConnectionImpl.cpp
index 985100153a..9afa7e5dd2 100644
--- a/dom/media/webrtc/jsapi/PeerConnectionImpl.cpp
+++ b/dom/media/webrtc/jsapi/PeerConnectionImpl.cpp
@@ -85,6 +85,7 @@
 #include "mozilla/dom/RTCCertificate.h"
 #include "mozilla/dom/RTCSctpTransportBinding.h"  // RTCSctpTransportState
 #include "mozilla/dom/RTCDtlsTransportBinding.h"  // RTCDtlsTransportState
+#include "mozilla/dom/RTCIceTransportBinding.h"   // RTCIceTransportState
 #include "mozilla/dom/RTCRtpReceiverBinding.h"
 #include "mozilla/dom/RTCRtpSenderBinding.h"
 #include "mozilla/dom/RTCStatsReportBinding.h"
@@ -249,19 +250,41 @@ void PeerConnectionAutoTimer::UnregisterConnection(bool aContainedAV) {
 
 bool PeerConnectionAutoTimer::IsStopped() { return mRefCnt == 0; }
 
+// There is not presently an implementation of these for nsTHashMap :(
+inline void ImplCycleCollectionUnlink(
+    PeerConnectionImpl::RTCDtlsTransportMap& aMap) {
+  for (auto& tableEntry : aMap) {
+    ImplCycleCollectionUnlink(*tableEntry.GetModifiableData());
+  }
+  aMap.Clear();
+}
+
+inline void ImplCycleCollectionTraverse(
+    nsCycleCollectionTraversalCallback& aCallback,
+    PeerConnectionImpl::RTCDtlsTransportMap& aMap, const char* aName,
+    uint32_t aFlags = 0) {
+  for (auto& tableEntry : aMap) {
+    ImplCycleCollectionTraverse(aCallback, *tableEntry.GetModifiableData(),
+                                aName, aFlags);
+  }
+}
+
 NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(PeerConnectionImpl)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(PeerConnectionImpl)
   tmp->Close();
   tmp->BreakCycles();
-  NS_IMPL_CYCLE_COLLECTION_UNLINK(mPCObserver, mWindow, mCertificate,
-                                  mSTSThread, mReceiveStreams, mOperations,
-                                  mSctpTransport, mKungFuDeathGrip)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(
+      mPCObserver, mWindow, mCertificate, mSTSThread, mReceiveStreams,
+      mOperations, mTransportIdToRTCDtlsTransport, mSctpTransport,
+      mLastStableSctpTransport, mLastStableSctpDtlsTransport, mKungFuDeathGrip)
   NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(PeerConnectionImpl)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(
       mPCObserver, mWindow, mCertificate, mSTSThread, mReceiveStreams,
-      mOperations, mTransceivers, mSctpTransport, mKungFuDeathGrip)
+      mOperations, mTransceivers, mTransportIdToRTCDtlsTransport,
+      mSctpTransport, mLastStableSctpTransport, mLastStableSctpDtlsTransport,
+      mKungFuDeathGrip)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTING_ADDREF(PeerConnectionImpl)
@@ -849,6 +872,7 @@ nsresult PeerConnectionImpl::GetDatachannelParameters(
 
   if (!datachannelTransceiver ||
       !datachannelTransceiver->mTransport.mComponents ||
+      !datachannelTransceiver->mTransport.mDtls ||
       !datachannelTransceiver->mSendTrack.GetNegotiatedDetails()) {
     return NS_ERROR_FAILURE;
   }
@@ -1061,7 +1085,7 @@ bool PeerConnectionImpl::CreatedSender(const dom::RTCRtpSender& aSender) const {
   return aSender.IsMyPc(this);
 }
 
-nsresult PeerConnectionImpl::InitializeDataChannel() {
+nsresult PeerConnectionImpl::MaybeInitializeDataChannel() {
   PC_AUTO_ENTER_API_CALL(false);
   CSFLogDebug(LOGTAG, "%s", __FUNCTION__);
 
@@ -1440,6 +1464,16 @@ void PeerConnectionImpl::UpdateNegotiationNeeded() {
       }));
 }
 
+RefPtr<dom::RTCRtpTransceiver> PeerConnectionImpl::GetTransceiver(
+    const std::string& aTransceiverId) {
+  for (const auto& transceiver : mTransceivers) {
+    if (transceiver->GetJsepTransceiverId() == aTransceiverId) {
+      return transceiver;
+    }
+  }
+  return nullptr;
+}
+
 void PeerConnectionImpl::NotifyDataChannel(
     already_AddRefed<DataChannel> aChannel) {
   PC_AUTO_ENTER_API_CALL_NO_CHECK();
@@ -1637,7 +1671,6 @@ JsepSdpType ToJsepSdpType(dom::RTCSdpType aType) {
       return kJsepSdpAnswer;
     case dom::RTCSdpType::Rollback:
       return kJsepSdpRollback;
-    case dom::RTCSdpType::EndGuard_:;
   }
 
   MOZ_CRASH("Nonexistent dom::RTCSdpType");
@@ -1989,10 +2022,14 @@ nsresult PeerConnectionImpl::OnAlpnNegotiated(bool aPrivacyRequested) {
 
 void PeerConnectionImpl::OnDtlsStateChange(const std::string& aTransportId,
                                            TransportLayer::State aState) {
-  auto it = mTransportIdToRTCDtlsTransport.find(aTransportId);
-  if (it != mTransportIdToRTCDtlsTransport.end()) {
-    it->second->UpdateState(aState);
+  nsCString key(aTransportId.data(), aTransportId.size());
+  RefPtr<RTCDtlsTransport> dtlsTransport =
+      mTransportIdToRTCDtlsTransport.Get(key);
+  if (!dtlsTransport) {
+    return;
   }
+
+  dtlsTransport->UpdateState(aState);
   // Whenever the state of an RTCDtlsTransport changes or when the [[IsClosed]]
   // slot turns true, the user agent MUST update the connection state by
   // queueing a task that runs the following steps:
@@ -2024,9 +2061,9 @@ RTCPeerConnectionState PeerConnectionImpl::GetNewConnectionState() const {
   // Would use a bitset, but that requires lots of static_cast<size_t>
   // Oh well.
   std::set<RTCDtlsTransportState> statesFound;
-  for (const auto& [id, dtlsTransport] : mTransportIdToRTCDtlsTransport) {
-    Unused << id;
-    statesFound.insert(dtlsTransport->State());
+  std::set<RefPtr<RTCDtlsTransport>> transports(GetActiveTransports());
+  for (const auto& transport : transports) {
+    statesFound.insert(transport->State());
   }
 
   // failed 	The previous state doesn't apply, and either
@@ -2075,9 +2112,9 @@ RTCPeerConnectionState PeerConnectionImpl::GetNewConnectionState() const {
 bool PeerConnectionImpl::UpdateConnectionState() {
   auto newState = GetNewConnectionState();
   if (newState != mConnectionState) {
-    CSFLogDebug(LOGTAG, "%s: %d -> %d (%p)", __FUNCTION__,
-                static_cast<int>(mConnectionState), static_cast<int>(newState),
-                this);
+    CSFLogInfo(LOGTAG, "%s: %d -> %d (%p)", __FUNCTION__,
+               static_cast<int>(mConnectionState), static_cast<int>(newState),
+               this);
     mConnectionState = newState;
     if (mConnectionState != RTCPeerConnectionState::Closed) {
       return true;
@@ -2569,7 +2606,7 @@ PeerConnectionImpl::Close() {
     transceiver->Close();
   }
 
-  mTransportIdToRTCDtlsTransport.clear();
+  mTransportIdToRTCDtlsTransport.Clear();
 
   mQueuedIceCtxOperations.clear();
 
@@ -2964,18 +3001,25 @@ void PeerConnectionImpl::DoSetDescriptionSuccessPostProcessing(
           InvalidateLastReturnedParameters();
         }
 
+        if (aSdpType == dom::RTCSdpType::Offer &&
+            mSignalingState == RTCSignalingState::Stable) {
+          // If description is of type "offer" and
+          // connection.[[SignalingState]] is "stable" then for each
+          // transceiver in connection's set of transceivers, run the following
+          // steps:
+          SaveStateForRollback();
+        }
+
         // Section 4.4.1.5 Set the RTCSessionDescription:
         if (aSdpType == dom::RTCSdpType::Rollback) {
           // - step 4.5.10, type is rollback
-          RollbackRTCDtlsTransports();
+          RestoreStateForRollback();
         } else if (!(aRemote && aSdpType == dom::RTCSdpType::Offer)) {
           // - step 4.5.9 type is not rollback
           // - step 4.5.9.1 when remote is false
           // - step 4.5.9.2.13 when remote is true, type answer or pranswer
           // More simply: not rollback, and not for remote offers.
-          bool markAsStable = aSdpType == dom::RTCSdpType::Offer &&
-                              mSignalingState == RTCSignalingState::Stable;
-          UpdateRTCDtlsTransports(markAsStable);
+          UpdateRTCDtlsTransports();
         }
 
         // Did we just apply a local description?
@@ -2992,11 +3036,6 @@ void PeerConnectionImpl::DoSetDescriptionSuccessPostProcessing(
         }
 
         if (mJsepSession->GetState() == kJsepStateStable) {
-          if (aSdpType != dom::RTCSdpType::Rollback) {
-            // We need this initted for UpdateTransports
-            InitializeDataChannel();
-          }
-
           // If we're rolling back a local offer, we might need to remove some
           // transports, and stomp some MediaPipeline setup, but nothing further
           // needs to be done.
@@ -3071,6 +3110,10 @@ void PeerConnectionImpl::DoSetDescriptionSuccessPostProcessing(
         // Spec does not actually tell us to do this, but that is probably a
         // spec bug.
         // https://github.com/w3c/webrtc-pc/issues/2817
+        bool gatheringStateChanged = UpdateIceGatheringState();
+
+        bool iceConnectionStateChanged = UpdateIceConnectionState();
+
         bool connectionStateChanged = UpdateConnectionState();
 
         // This only gets populated for remote descriptions
@@ -3104,6 +3147,16 @@ void PeerConnectionImpl::DoSetDescriptionSuccessPostProcessing(
           pcObserver->OnStateChange(PCObserverStateType::SignalingState, jrv);
         }
 
+        if (gatheringStateChanged) {
+          pcObserver->OnStateChange(PCObserverStateType::IceGatheringState,
+                                    jrv);
+        }
+
+        if (iceConnectionStateChanged) {
+          pcObserver->OnStateChange(PCObserverStateType::IceConnectionState,
+                                    jrv);
+        }
+
         if (connectionStateChanged) {
           pcObserver->OnStateChange(PCObserverStateType::ConnectionState, jrv);
         }
@@ -3290,61 +3343,162 @@ void PeerConnectionImpl::SendLocalIceCandidateToContent(
 }
 
 void PeerConnectionImpl::IceConnectionStateChange(
-    dom::RTCIceConnectionState domState) {
+    const std::string& aTransportId, dom::RTCIceTransportState domState) {
+  // If connection.[[IsClosed]] is true, abort these steps.
   PC_AUTO_ENTER_API_CALL_VOID_RETURN(false);
 
-  CSFLogDebug(LOGTAG, "%s: %d -> %d", __FUNCTION__,
-              static_cast<int>(mIceConnectionState),
-              static_cast<int>(domState));
+  CSFLogDebug(LOGTAG, "IceConnectionStateChange: %s %d (%p)",
+              aTransportId.c_str(), static_cast<int>(domState), this);
 
-  if (domState == mIceConnectionState) {
-    // no work to be done since the states are the same.
-    // this can happen during ICE rollback situations.
+  // Let transport be the RTCIceTransport whose state is changing.
+  nsCString key(aTransportId.data(), aTransportId.size());
+  RefPtr<RTCDtlsTransport> dtlsTransport =
+      mTransportIdToRTCDtlsTransport.Get(key);
+  if (!dtlsTransport) {
     return;
   }
+  RefPtr<RTCIceTransport> transport = dtlsTransport->IceTransport();
 
-  mIceConnectionState = domState;
+  if (domState == RTCIceTransportState::Closed) {
+    mTransportIdToRTCDtlsTransport.Remove(key);
+  }
 
-  // Would be nice if we had a means of converting one of these dom enums
-  // to a string that wasn't almost as much text as this switch statement...
-  switch (mIceConnectionState) {
-    case RTCIceConnectionState::New:
-      STAMP_TIMECARD(mTimeCard, "Ice state: new");
-      break;
-    case RTCIceConnectionState::Checking:
-      // For telemetry
-      mIceStartTime = TimeStamp::Now();
-      STAMP_TIMECARD(mTimeCard, "Ice state: checking");
-      break;
-    case RTCIceConnectionState::Connected:
-      STAMP_TIMECARD(mTimeCard, "Ice state: connected");
-      StartCallTelem();
-      break;
-    case RTCIceConnectionState::Completed:
-      STAMP_TIMECARD(mTimeCard, "Ice state: completed");
-      break;
-    case RTCIceConnectionState::Failed:
-      STAMP_TIMECARD(mTimeCard, "Ice state: failed");
-      break;
-    case RTCIceConnectionState::Disconnected:
-      STAMP_TIMECARD(mTimeCard, "Ice state: disconnected");
-      break;
-    case RTCIceConnectionState::Closed:
-      STAMP_TIMECARD(mTimeCard, "Ice state: closed");
-      break;
-    default:
-      MOZ_ASSERT_UNREACHABLE("Unexpected mIceConnectionState!");
+  // Let selectedCandidatePairChanged be false.
+  // TODO(bug 1307994)
+
+  // Let transportIceConnectionStateChanged be false.
+  bool transportIceConnectionStateChanged = false;
+
+  // Let connectionIceConnectionStateChanged be false.
+  bool connectionIceConnectionStateChanged = false;
+
+  // Let connectionStateChanged be false.
+  bool connectionStateChanged = false;
+
+  if (transport->State() == domState) {
+    return;
+  }
+
+  // If transport's RTCIceTransportState was changed, run the following steps:
+
+  // Set transport.[[IceTransportState]] to the new indicated
+  // RTCIceTransportState.
+  transport->SetState(domState);
+
+  // Set transportIceConnectionStateChanged to true.
+  transportIceConnectionStateChanged = true;
+
+  // Set connection.[[IceConnectionState]] to the value of deriving a new state
+  // value as described by the RTCIceConnectionState enum.
+  if (UpdateIceConnectionState()) {
+    // If connection.[[IceConnectionState]] changed in the previous step, set
+    // connectionIceConnectionStateChanged to true.
+    connectionIceConnectionStateChanged = true;
+  }
+
+  // Set connection.[[ConnectionState]] to the value of deriving a new state
+  // value as described by the RTCPeerConnectionState enum.
+  if (UpdateConnectionState()) {
+    // If connection.[[ConnectionState]] changed in the previous step, set
+    // connectionStateChanged to true.
+    connectionStateChanged = true;
+  }
+
+  // If selectedCandidatePairChanged is true, fire an event named
+  // selectedcandidatepairchange at transport.
+  // TODO(bug 1307994)
+
+  // If transportIceConnectionStateChanged is true, fire an event named
+  // statechange at transport.
+  if (transportIceConnectionStateChanged) {
+    transport->FireStateChangeEvent();
   }
 
-  bool connectionStateChanged = UpdateConnectionState();
   WrappableJSErrorResult rv;
   RefPtr<PeerConnectionObserver> pcObserver(mPCObserver);
-  pcObserver->OnStateChange(PCObserverStateType::IceConnectionState, rv);
+
+  // If connectionIceConnectionStateChanged is true, fire an event named
+  // iceconnectionstatechange at connection.
+  if (connectionIceConnectionStateChanged) {
+    pcObserver->OnStateChange(PCObserverStateType::IceConnectionState, rv);
+  }
+
+  // If connectionStateChanged is true, fire an event named
+  // connectionstatechange at connection.
   if (connectionStateChanged) {
     pcObserver->OnStateChange(PCObserverStateType::ConnectionState, rv);
   }
 }
 
+RTCIceConnectionState PeerConnectionImpl::GetNewIceConnectionState() const {
+  // closed 	The RTCPeerConnection object's [[IsClosed]] slot is true.
+  if (IsClosed()) {
+    return RTCIceConnectionState::Closed;
+  }
+
+  // Would use a bitset, but that requires lots of static_cast<size_t>
+  // Oh well.
+  std::set<RTCIceTransportState> statesFound;
+  std::set<RefPtr<RTCDtlsTransport>> transports(GetActiveTransports());
+  for (const auto& transport : transports) {
+    RefPtr<dom::RTCIceTransport> iceTransport = transport->IceTransport();
+    CSFLogWarn(LOGTAG, "GetNewIceConnectionState: %p %d", iceTransport.get(),
+               static_cast<int>(iceTransport->State()));
+    statesFound.insert(iceTransport->State());
+  }
+
+  // failed 	 None of the previous states apply and any RTCIceTransports are
+  // in the "failed" state.
+  if (statesFound.count(RTCIceTransportState::Failed)) {
+    return RTCIceConnectionState::Failed;
+  }
+
+  // disconnected 	 None of the previous states apply and any
+  // RTCIceTransports are in the "disconnected" state.
+  if (statesFound.count(RTCIceTransportState::Disconnected)) {
+    return RTCIceConnectionState::Disconnected;
+  }
+
+  // new 	 None of the previous states apply and all RTCIceTransports are
+  // in the "new" or "closed" state, or there are no transports.
+  if (!statesFound.count(RTCIceTransportState::Checking) &&
+      !statesFound.count(RTCIceTransportState::Completed) &&
+      !statesFound.count(RTCIceTransportState::Connected)) {
+    return RTCIceConnectionState::New;
+  }
+
+  // checking   None of the previous states apply and any RTCIceTransports are
+  // in the "new" or "checking" state.
+  if (statesFound.count(RTCIceTransportState::New) ||
+      statesFound.count(RTCIceTransportState::Checking)) {
+    return RTCIceConnectionState::Checking;
+  }
+
+  // completed  None of the previous states apply and all RTCIceTransports are
+  // in the "completed" or "closed" state.
+  if (!statesFound.count(RTCIceTransportState::Connected)) {
+    return RTCIceConnectionState::Completed;
+  }
+
+  // connected 	None of the previous states apply.
+  return RTCIceConnectionState::Connected;
+}
+
+bool PeerConnectionImpl::UpdateIceConnectionState() {
+  auto newState = GetNewIceConnectionState();
+  if (newState != mIceConnectionState) {
+    CSFLogInfo(LOGTAG, "%s: %d -> %d (%p)", __FUNCTION__,
+               static_cast<int>(mIceConnectionState),
+               static_cast<int>(newState), this);
+    mIceConnectionState = newState;
+    if (mIceConnectionState != RTCIceConnectionState::Closed) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 void PeerConnectionImpl::OnCandidateFound(const std::string& aTransportId,
                                           const CandidateInfo& aCandidateInfo) {
   if (mStunAddrsRequest && !aCandidateInfo.mMDNSAddress.empty()) {
@@ -3378,18 +3532,82 @@ void PeerConnectionImpl::OnCandidateFound(const std::string& aTransportId,
 }
 
 void PeerConnectionImpl::IceGatheringStateChange(
-    dom::RTCIceGatheringState state) {
+    const std::string& aTransportId, dom::RTCIceGathererState state) {
+  // If connection.[[IsClosed]] is true, abort these steps.
   PC_AUTO_ENTER_API_CALL_VOID_RETURN(false);
 
-  CSFLogDebug(LOGTAG, "%s %d", __FUNCTION__, static_cast<int>(state));
-  if (mIceGatheringState == state) {
+  CSFLogWarn(LOGTAG, "IceGatheringStateChange: %s %d (%p)",
+             aTransportId.c_str(), static_cast<int>(state), this);
+
+  // Let transport be the RTCIceTransport for which candidate gathering
+  // began/finished.
+  nsCString key(aTransportId.data(), aTransportId.size());
+  RefPtr<RTCDtlsTransport> dtlsTransport =
+      mTransportIdToRTCDtlsTransport.Get(key);
+  if (!dtlsTransport) {
+    return;
+  }
+  RefPtr<RTCIceTransport> transport = dtlsTransport->IceTransport();
+
+  if (transport->GatheringState() == state) {
     return;
   }
 
-  mIceGatheringState = state;
+  // Set transport.[[IceGathererState]] to gathering.
+  // or
+  // Set transport.[[IceGathererState]] to complete.
+  transport->SetGatheringState(state);
+
+  // Set connection.[[IceGatheringState]] to the value of deriving a new state
+  // value as described by the RTCIceGatheringState enum.
+  //
+  // Let connectionIceGatheringStateChanged be true if
+  // connection.[[IceGatheringState]] changed in the previous step, otherwise
+  // false.
+  bool gatheringStateChanged = UpdateIceGatheringState();
+
+  // Do not read or modify state beyond this point.
+
+  // Fire an event named gatheringstatechange at transport.
+  transport->FireGatheringStateChangeEvent();
+
+  // If connectionIceGatheringStateChanged is true, fire an event named
+  // icegatheringstatechange at connection.
+  if (gatheringStateChanged) {
+    // NOTE: If we're in the "complete" case, our JS code will fire a null
+    // icecandidate event after firing the icegatheringstatechange event.
+    // Fire an event named icecandidate using the RTCPeerConnectionIceEvent
+    // interface with the candidate attribute set to null at connection.
+    JSErrorResult rv;
+    mPCObserver->OnStateChange(PCObserverStateType::IceGatheringState, rv);
+  }
+}
+
+bool PeerConnectionImpl::UpdateIceGatheringState() {
+  // If connection.[[IsClosed]] is true, abort these steps.
+  if (IsClosed()) {
+    return false;
+  }
+
+  // Let newState be the value of deriving a new state value as
+  // described by the RTCIceGatheringState enum.
+  auto newState = GetNewIceGatheringState();
+
+  // If connection.[[IceGatheringState]] is equal to newState, abort
+  // these steps.
+  if (newState == mIceGatheringState) {
+    return false;
+  }
+
+  CSFLogInfo(LOGTAG, "UpdateIceGatheringState: %d -> %d (%p)",
+             static_cast<int>(mIceGatheringState), static_cast<int>(newState),
+             this);
+  // Set connection.[[IceGatheringState]] to newState.
+  mIceGatheringState = newState;
 
-  // Would be nice if we had a means of converting one of these dom enums
-  // to a string that wasn't almost as much text as this switch statement...
+  // Would be nice if we had a means of converting one of these dom
+  // enums to a string that wasn't almost as much text as this switch
+  // statement...
   switch (mIceGatheringState) {
     case RTCIceGatheringState::New:
       STAMP_TIMECARD(mTimeCard, "Ice gathering state: new");
@@ -3404,8 +3622,42 @@ void PeerConnectionImpl::IceGatheringStateChange(
       MOZ_ASSERT_UNREACHABLE("Unexpected mIceGatheringState!");
   }
 
-  JSErrorResult rv;
-  mPCObserver->OnStateChange(PCObserverStateType::IceGatheringState, rv);
+  return true;
+}
+
+RTCIceGatheringState PeerConnectionImpl::GetNewIceGatheringState() const {
+  // new 	Any of the RTCIceTransports are in the "new" gathering state
+  // and none of the transports are in the "gathering" state, or there are no
+  // transports.
+
+  // NOTE! This derives the RTCIce**Gathering**State from the individual
+  // RTCIce**Gatherer**State of the transports. These are different enums.
+  // But they have exactly the same values, in the same order.
+  // ¯\_(ツ)_/¯
+  bool foundComplete = false;
+  std::set<RefPtr<RTCDtlsTransport>> transports(GetActiveTransports());
+  for (const auto& transport : transports) {
+    RefPtr<dom::RTCIceTransport> iceTransport = transport->IceTransport();
+    switch (iceTransport->GatheringState()) {
+      case RTCIceGathererState::New:
+        break;
+      case RTCIceGathererState::Gathering:
+        // gathering 	Any of the RTCIceTransports are in the "gathering"
+        // state.
+        return RTCIceGatheringState::Gathering;
+      case RTCIceGathererState::Complete:
+        foundComplete = true;
+        break;
+    }
+  }
+
+  if (!foundComplete) {
+    return RTCIceGatheringState::New;
+  }
+
+  // This could change depending on the outcome in
+  // https://github.com/w3c/webrtc-pc/issues/2914
+  return RTCIceGatheringState::Complete;
 }
 
 void PeerConnectionImpl::UpdateDefaultCandidate(
@@ -3878,11 +4130,8 @@ void PeerConnectionImpl::StunAddrsHandler::OnStunAddrsAvailable(
   pcw.impl()->mStunAddrs = addrs.Clone();
   pcw.impl()->mLocalAddrsRequestState = STUN_ADDR_REQUEST_COMPLETE;
   pcw.impl()->FlushIceCtxOperationQueueIfReady();
-  // If parent process returns 0 STUN addresses, change ICE connection
-  // state to failed.
-  if (!pcw.impl()->mStunAddrs.Length()) {
-    pcw.impl()->IceConnectionStateChange(dom::RTCIceConnectionState::Failed);
-  }
+  // If this fails, ICE cannot succeed, but we need to still go through the
+  // motions.
 }
 
 void PeerConnectionImpl::InitLocalAddrs() {
@@ -3952,109 +4201,120 @@ void PeerConnectionImpl::EnsureTransports(const JsepSession& aSession) {
   GatherIfReady();
 }
 
-void PeerConnectionImpl::UpdateRTCDtlsTransports(bool aMarkAsStable) {
+void PeerConnectionImpl::UpdateRTCDtlsTransports() {
+  // We use mDataConnection below, make sure it is initted if necessary
+  MaybeInitializeDataChannel();
+
+  // Make sure that the SCTP transport is unset if we do not see a DataChannel.
+  // We'll restore this if we do see a DataChannel.
+  RefPtr<dom::RTCSctpTransport> oldSctp = mSctpTransport.forget();
+
   mJsepSession->ForEachTransceiver(
-      [this, self = RefPtr<PeerConnectionImpl>(this)](
-          const JsepTransceiver& jsepTransceiver) {
+      [this, self = RefPtr<PeerConnectionImpl>(this),
+       oldSctp](const JsepTransceiver& jsepTransceiver) {
         std::string transportId = jsepTransceiver.mTransport.mTransportId;
-        if (transportId.empty()) {
-          return;
+        RefPtr<dom::RTCDtlsTransport> dtlsTransport;
+        if (!transportId.empty()) {
+          nsCString key(transportId.data(), transportId.size());
+          dtlsTransport = mTransportIdToRTCDtlsTransport.GetOrInsertNew(
+              key, GetParentObject());
         }
-        if (!mTransportIdToRTCDtlsTransport.count(transportId)) {
-          mTransportIdToRTCDtlsTransport.emplace(
-              transportId, new RTCDtlsTransport(GetParentObject()));
+
+        if (jsepTransceiver.GetMediaType() == SdpMediaSection::kApplication) {
+          // Spec says we only update the RTCSctpTransport when negotiation
+          // completes. This is probably a spec bug.
+          // https://github.com/w3c/webrtc-pc/issues/2898
+          if (!dtlsTransport || !mDataConnection) {
+            return;
+          }
+
+          // Why on earth does the spec use a floating point for this?
+          double maxMessageSize =
+              static_cast<double>(mDataConnection->GetMaxMessageSize());
+          Nullable<uint16_t> maxChannels;
+
+          if (!oldSctp) {
+            mSctpTransport = new RTCSctpTransport(
+                GetParentObject(), *dtlsTransport, maxMessageSize, maxChannels);
+          } else {
+            // Restore the SCTP transport we had before this function was called
+            oldSctp->SetTransport(*dtlsTransport);
+            oldSctp->SetMaxMessageSize(maxMessageSize);
+            oldSctp->SetMaxChannels(maxChannels);
+            mSctpTransport = oldSctp;
+          }
+        } else {
+          RefPtr<dom::RTCRtpTransceiver> domTransceiver =
+              GetTransceiver(jsepTransceiver.GetUuid());
+          if (domTransceiver) {
+            domTransceiver->SetDtlsTransport(dtlsTransport);
+          }
         }
       });
+}
 
-  for (auto& transceiver : mTransceivers) {
-    std::string transportId = transceiver->GetTransportId();
-    if (transportId.empty()) {
-      continue;
-    }
-    if (mTransportIdToRTCDtlsTransport.count(transportId)) {
-      transceiver->SetDtlsTransport(mTransportIdToRTCDtlsTransport[transportId],
-                                    aMarkAsStable);
-    }
+void PeerConnectionImpl::SaveStateForRollback() {
+  // This could change depending on the outcome in
+  // https://github.com/w3c/webrtc-pc/issues/2899
+  if (mSctpTransport) {
+    // We have to save both of these things, because the DTLS transport could
+    // change without the SCTP transport changing.
+    mLastStableSctpTransport = mSctpTransport;
+    mLastStableSctpDtlsTransport = mSctpTransport->Transport();
+  } else {
+    mLastStableSctpTransport = nullptr;
+    mLastStableSctpDtlsTransport = nullptr;
   }
 
-  // Spec says we only update the RTCSctpTransport when negotiation completes
+  for (auto& transceiver : mTransceivers) {
+    transceiver->SaveStateForRollback();
+  }
 }
 
-void PeerConnectionImpl::RollbackRTCDtlsTransports() {
+void PeerConnectionImpl::RestoreStateForRollback() {
   for (auto& transceiver : mTransceivers) {
     transceiver->RollbackToStableDtlsTransport();
   }
+
+  mSctpTransport = mLastStableSctpTransport;
+  if (mSctpTransport) {
+    mSctpTransport->SetTransport(*mLastStableSctpDtlsTransport);
+  }
 }
 
-void PeerConnectionImpl::RemoveRTCDtlsTransportsExcept(
-    const std::set<std::string>& aTransportIds) {
-  for (auto iter = mTransportIdToRTCDtlsTransport.begin();
-       iter != mTransportIdToRTCDtlsTransport.end();) {
-    if (!aTransportIds.count(iter->first)) {
-      iter = mTransportIdToRTCDtlsTransport.erase(iter);
-    } else {
-      ++iter;
+std::set<RefPtr<dom::RTCDtlsTransport>>
+PeerConnectionImpl::GetActiveTransports() const {
+  std::set<RefPtr<dom::RTCDtlsTransport>> result;
+  for (const auto& transceiver : mTransceivers) {
+    if (transceiver->GetDtlsTransport()) {
+      result.insert(transceiver->GetDtlsTransport());
     }
   }
+
+  if (mSctpTransport && mSctpTransport->Transport()) {
+    result.insert(mSctpTransport->Transport());
+  }
+  return result;
 }
 
 nsresult PeerConnectionImpl::UpdateTransports(const JsepSession& aSession,
                                               const bool forceIceTcp) {
   std::set<std::string> finalTransports;
-  Maybe<std::string> sctpTransport;
   mJsepSession->ForEachTransceiver(
       [&, this, self = RefPtr<PeerConnectionImpl>(this)](
           const JsepTransceiver& transceiver) {
-        if (transceiver.GetMediaType() == SdpMediaSection::kApplication &&
-            transceiver.HasTransport()) {
-          sctpTransport = Some(transceiver.mTransport.mTransportId);
-        }
-
         if (transceiver.HasOwnTransport()) {
           finalTransports.insert(transceiver.mTransport.mTransportId);
           UpdateTransport(transceiver, forceIceTcp);
         }
       });
 
-  // clean up the unused RTCDtlsTransports
-  RemoveRTCDtlsTransportsExcept(finalTransports);
-
   mTransportHandler->RemoveTransportsExcept(finalTransports);
 
   for (const auto& transceiverImpl : mTransceivers) {
     transceiverImpl->UpdateTransport();
   }
 
-  if (sctpTransport.isSome()) {
-    auto it = mTransportIdToRTCDtlsTransport.find(*sctpTransport);
-    if (it == mTransportIdToRTCDtlsTransport.end()) {
-      // What?
-      MOZ_ASSERT(false);
-      return NS_ERROR_FAILURE;
-    }
-    if (!mDataConnection) {
-      // What?
-      MOZ_ASSERT(false);
-      return NS_ERROR_FAILURE;
-    }
-    RefPtr<RTCDtlsTransport> dtlsTransport = it->second;
-    // Why on earth does the spec use a floating point for this?
-    double maxMessageSize =
-        static_cast<double>(mDataConnection->GetMaxMessageSize());
-    Nullable<uint16_t> maxChannels;
-
-    if (!mSctpTransport) {
-      mSctpTransport = new RTCSctpTransport(GetParentObject(), *dtlsTransport,
-                                            maxMessageSize, maxChannels);
-    } else {
-      mSctpTransport->SetTransport(*dtlsTransport);
-      mSctpTransport->SetMaxMessageSize(maxMessageSize);
-      mSctpTransport->SetMaxChannels(maxChannels);
-    }
-  } else {
-    mSctpTransport = nullptr;
-  }
-
   return NS_OK;
 }
 
@@ -4141,6 +4401,9 @@ nsresult PeerConnectionImpl::UpdateMediaPipelines() {
 
 void PeerConnectionImpl::StartIceChecks(const JsepSession& aSession) {
   MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mJsepSession->GetState() == kJsepStateStable);
+
+  auto transports = GetActiveTransports();
 
   if (!mCanRegisterMDNSHostnamesDirectly) {
     for (auto& pair : mMDNSHostnamesToRegister) {
@@ -4472,32 +4735,31 @@ std::string PeerConnectionImpl::GetTransportIdMatchingSendTrack(
 }
 
 void PeerConnectionImpl::SignalHandler::IceGatheringStateChange_s(
-    dom::RTCIceGatheringState aState) {
+    const std::string& aTransportId, dom::RTCIceGathererState aState) {
   ASSERT_ON_THREAD(mSTSThread);
-
   GetMainThreadSerialEventTarget()->Dispatch(
       NS_NewRunnableFunction(__func__,
-                             [handle = mHandle, aState] {
+                             [handle = mHandle, aTransportId, aState] {
                                PeerConnectionWrapper wrapper(handle);
                                if (wrapper.impl()) {
                                  wrapper.impl()->IceGatheringStateChange(
-                                     aState);
+                                     aTransportId, aState);
                                }
                              }),
       NS_DISPATCH_NORMAL);
 }
 
 void PeerConnectionImpl::SignalHandler::IceConnectionStateChange_s(
-    dom::RTCIceConnectionState aState) {
+    const std::string& aTransportId, dom::RTCIceTransportState aState) {
   ASSERT_ON_THREAD(mSTSThread);
 
   GetMainThreadSerialEventTarget()->Dispatch(
       NS_NewRunnableFunction(__func__,
-                             [handle = mHandle, aState] {
+                             [handle = mHandle, aTransportId, aState] {
                                PeerConnectionWrapper wrapper(handle);
                                if (wrapper.impl()) {
                                  wrapper.impl()->IceConnectionStateChange(
-                                     aState);
+                                     aTransportId, aState);
                                }
                              }),
       NS_DISPATCH_NORMAL);