Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 693 insertions, 0 deletions

diff --git a/netwerk/sctp/datachannel/DataChannel.h b/netwerk/sctp/datachannel/DataChannel.h
new file mode 100644
index 0000000000..eefa48ad07
--- /dev/null
+++ b/netwerk/sctp/datachannel/DataChannel.h
@@ -0,0 +1,693 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NETWERK_SCTP_DATACHANNEL_DATACHANNEL_H_
+#define NETWERK_SCTP_DATACHANNEL_DATACHANNEL_H_
+
+#ifdef MOZ_WEBRTC_SIGNALING
+#  define SCTP_DTLS_SUPPORTED 1
+#endif
+
+#include <memory>
+#include <string>
+#include <vector>
+#include <errno.h>
+#include "nsISupports.h"
+#include "nsCOMPtr.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/WeakPtr.h"
+#include "nsString.h"
+#include "nsThreadUtils.h"
+#include "nsTArray.h"
+#include "nsDeque.h"
+#include "mozilla/dom/Blob.h"
+#include "mozilla/Mutex.h"
+#include "DataChannelProtocol.h"
+#include "DataChannelListener.h"
+#include "mozilla/net/NeckoTargetHolder.h"
+#include "DataChannelLog.h"
+
+#ifdef SCTP_DTLS_SUPPORTED
+#  include "transport/sigslot.h"
+#  include "transport/transportlayer.h"  // For TransportLayer::State
+#endif
+
+#ifndef EALREADY
+#  define EALREADY WSAEALREADY
+#endif
+
+extern "C" {
+struct socket;
+struct sctp_rcvinfo;
+}
+
+namespace mozilla {
+
+class DataChannelConnection;
+class DataChannel;
+class DataChannelOnMessageAvailable;
+class MediaPacket;
+class MediaTransportHandler;
+namespace dom {
+struct RTCStatsCollection;
+};
+
+// For sending outgoing messages.
+// This class only holds a reference to the data and the info structure but does
+// not copy it.
+class OutgoingMsg {
+ public:
+  OutgoingMsg(struct sctp_sendv_spa& info, const uint8_t* data, size_t length);
+  ~OutgoingMsg() = default;
+  ;
+  void Advance(size_t offset);
+  struct sctp_sendv_spa& GetInfo() {
+    return *mInfo;
+  };
+  size_t GetLength() const { return mLength; };
+  size_t GetLeft() const { return mLength - mPos; };
+  const uint8_t* GetData() { return (const uint8_t*)(mData + mPos); };
+
+ protected:
+  OutgoingMsg()  // Use this for inheritance only
+      : mLength(0), mData(nullptr), mInfo(nullptr), mPos(0){};
+  size_t mLength;
+  const uint8_t* mData;
+  struct sctp_sendv_spa* mInfo;
+  size_t mPos;
+};
+
+// For queuing outgoing messages
+// This class copies data of an outgoing message.
+class BufferedOutgoingMsg : public OutgoingMsg {
+ public:
+  explicit BufferedOutgoingMsg(OutgoingMsg& message);
+  ~BufferedOutgoingMsg();
+};
+
+// for queuing incoming data messages before the Open or
+// external negotiation is indicated to us
+class QueuedDataMessage {
+ public:
+  QueuedDataMessage(uint16_t stream, uint32_t ppid, int flags, const void* data,
+                    uint32_t length)
+      : mStream(stream), mPpid(ppid), mFlags(flags), mLength(length) {
+    mData = static_cast<uint8_t*>(moz_xmalloc((size_t)length));  // infallible
+    memcpy(mData, data, (size_t)length);
+  }
+
+  ~QueuedDataMessage() { free(mData); }
+
+  uint16_t mStream;
+  uint32_t mPpid;
+  int mFlags;
+  uint32_t mLength;
+  uint8_t* mData;
+};
+
+// One per PeerConnection
+class DataChannelConnection final : public net::NeckoTargetHolder
+#ifdef SCTP_DTLS_SUPPORTED
+    ,
+                                    public sigslot::has_slots<>
+#endif
+{
+  friend class DataChannel;
+  friend class DataChannelOnMessageAvailable;
+  friend class DataChannelConnectRunnable;
+
+  virtual ~DataChannelConnection();
+
+ public:
+  enum {
+    PENDING_NONE = 0U,  // No outgoing messages are pending
+    PENDING_DCEP = 1U,  // Outgoing DCEP messages are pending
+    PENDING_DATA = 2U,  // Outgoing data channel messages are pending
+  };
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(DataChannelConnection)
+
+  class DataConnectionListener : public SupportsWeakPtr {
+   public:
+    virtual ~DataConnectionListener() = default;
+
+    // Called when a new DataChannel has been opened by the other side.
+    virtual void NotifyDataChannel(already_AddRefed<DataChannel> channel) = 0;
+  };
+
+  // Create a new DataChannel Connection
+  // Must be called on Main thread
+  static Maybe<RefPtr<DataChannelConnection>> Create(
+      DataConnectionListener* aListener, nsISerialEventTarget* aTarget,
+      MediaTransportHandler* aHandler, const uint16_t aLocalPort,
+      const uint16_t aNumStreams, const Maybe<uint64_t>& aMaxMessageSize);
+
+  void Destroy();  // So we can spawn refs tied to runnables in shutdown
+  // Finish Destroy on STS to avoid SCTP race condition with ABORT from far end
+  void DestroyOnSTS(struct socket* aMasterSocket, struct socket* aSocket);
+  void DestroyOnSTSFinal();
+
+  void SetMaxMessageSize(bool aMaxMessageSizeSet, uint64_t aMaxMessageSize);
+  uint64_t GetMaxMessageSize();
+
+  void AppendStatsToReport(const UniquePtr<dom::RTCStatsCollection>& aReport,
+                           const DOMHighResTimeStamp aTimestamp) const;
+#ifdef ALLOW_DIRECT_SCTP_LISTEN_CONNECT
+  // These block; they require something to decide on listener/connector
+  // (though you can do simultaneous Connect()).  Do not call these from
+  // the main thread!
+  bool Listen(unsigned short port);
+  bool Connect(const char* addr, unsigned short port);
+#endif
+
+#ifdef SCTP_DTLS_SUPPORTED
+  bool ConnectToTransport(const std::string& aTransportId, const bool aClient,
+                          const uint16_t aLocalPort,
+                          const uint16_t aRemotePort);
+  void TransportStateChange(const std::string& aTransportId,
+                            TransportLayer::State aState);
+  void CompleteConnect();
+  void SetSignals(const std::string& aTransportId);
+#endif
+
+  typedef enum {
+    RELIABLE = 0,
+    PARTIAL_RELIABLE_REXMIT = 1,
+    PARTIAL_RELIABLE_TIMED = 2
+  } Type;
+
+  [[nodiscard]] already_AddRefed<DataChannel> Open(
+      const nsACString& label, const nsACString& protocol, Type type,
+      bool inOrder, uint32_t prValue, DataChannelListener* aListener,
+      nsISupports* aContext, bool aExternalNegotiated, uint16_t aStream);
+
+  void Stop();
+  void Close(DataChannel* aChannel);
+  void CloseLocked(DataChannel* aChannel) MOZ_REQUIRES(mLock);
+  void CloseAll();
+
+  // Returns a POSIX error code.
+  int SendMsg(uint16_t stream, const nsACString& aMsg) {
+    return SendDataMsgCommon(stream, aMsg, false);
+  }
+
+  // Returns a POSIX error code.
+  int SendBinaryMsg(uint16_t stream, const nsACString& aMsg) {
+    return SendDataMsgCommon(stream, aMsg, true);
+  }
+
+  // Returns a POSIX error code.
+  int SendBlob(uint16_t stream, nsIInputStream* aBlob);
+
+  // Called on data reception from the SCTP library
+  // must(?) be public so my c->c++ trampoline can call it
+  // May be called with (STS thread) or without the lock
+  int ReceiveCallback(struct socket* sock, void* data, size_t datalen,
+                      struct sctp_rcvinfo rcv, int flags);
+
+  // Find out state
+  enum { CONNECTING = 0U, OPEN = 1U, CLOSING = 2U, CLOSED = 3U };
+
+  Mutex mLock;
+
+  void ReadBlob(already_AddRefed<DataChannelConnection> aThis, uint16_t aStream,
+                nsIInputStream* aBlob);
+
+  bool SendDeferredMessages() MOZ_REQUIRES(mLock);
+
+#ifdef SCTP_DTLS_SUPPORTED
+  int SctpDtlsOutput(void* addr, void* buffer, size_t length, uint8_t tos,
+                     uint8_t set_df);
+#endif
+
+  bool InShutdown() const {
+#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
+    return mShutdown;
+#else
+    return false;
+#endif
+  }
+
+ protected:
+  // Avoid cycles with PeerConnectionImpl
+  // Use from main thread only as WeakPtr is not threadsafe
+  WeakPtr<DataConnectionListener> mListener;
+
+ private:
+  DataChannelConnection(DataConnectionListener* aListener,
+                        nsISerialEventTarget* aTarget,
+                        MediaTransportHandler* aHandler);
+
+  bool Init(const uint16_t aLocalPort, const uint16_t aNumStreams,
+            const Maybe<uint64_t>& aMaxMessageSize);
+
+  // Caller must hold mLock
+  uint16_t GetReadyState() const MOZ_REQUIRES(mLock) {
+    mLock.AssertCurrentThreadOwns();
+
+    return mState;
+  }
+
+  // Caller must hold mLock
+  void SetReadyState(const uint16_t aState) MOZ_REQUIRES(mLock);
+
+#ifdef SCTP_DTLS_SUPPORTED
+  static void DTLSConnectThread(void* data);
+  void SendPacket(std::unique_ptr<MediaPacket>&& packet);
+  void SctpDtlsInput(const std::string& aTransportId,
+                     const MediaPacket& packet);
+#endif
+  DataChannel* FindChannelByStream(uint16_t stream) MOZ_REQUIRES(mLock);
+  uint16_t FindFreeStream() MOZ_REQUIRES(mLock);
+  bool RequestMoreStreams(int32_t aNeeded = 16) MOZ_REQUIRES(mLock);
+  uint32_t UpdateCurrentStreamIndex() MOZ_REQUIRES(mLock);
+  uint32_t GetCurrentStreamIndex() MOZ_REQUIRES(mLock);
+  int SendControlMessage(const uint8_t* data, uint32_t len, uint16_t stream)
+      MOZ_REQUIRES(mLock);
+  int SendOpenAckMessage(uint16_t stream) MOZ_REQUIRES(mLock);
+  int SendOpenRequestMessage(const nsACString& label,
+                             const nsACString& protocol, uint16_t stream,
+                             bool unordered, uint16_t prPolicy,
+                             uint32_t prValue) MOZ_REQUIRES(mLock);
+  bool SendBufferedMessages(nsTArray<UniquePtr<BufferedOutgoingMsg>>& buffer,
+                            size_t* aWritten);
+  int SendMsgInternal(OutgoingMsg& msg, size_t* aWritten);
+  int SendMsgInternalOrBuffer(nsTArray<UniquePtr<BufferedOutgoingMsg>>& buffer,
+                              OutgoingMsg& msg, bool& buffered,
+                              size_t* aWritten) MOZ_REQUIRES(mLock);
+  int SendDataMsgInternalOrBuffer(DataChannel& channel, const uint8_t* data,
+                                  size_t len, uint32_t ppid)
+      MOZ_REQUIRES(mLock);
+  int SendDataMsg(DataChannel& channel, const uint8_t* data, size_t len,
+                  uint32_t ppidPartial, uint32_t ppidFinal) MOZ_REQUIRES(mLock);
+  int SendDataMsgCommon(uint16_t stream, const nsACString& aMsg, bool isBinary);
+
+  void DeliverQueuedData(uint16_t stream) MOZ_REQUIRES(mLock);
+
+  already_AddRefed<DataChannel> OpenFinish(
+      already_AddRefed<DataChannel>&& aChannel) MOZ_REQUIRES(mLock);
+
+  void ProcessQueuedOpens() MOZ_REQUIRES(mLock);
+  void ClearResets() MOZ_REQUIRES(mLock);
+  void SendOutgoingStreamReset() MOZ_REQUIRES(mLock);
+  void ResetOutgoingStream(uint16_t stream) MOZ_REQUIRES(mLock);
+  void HandleOpenRequestMessage(
+      const struct rtcweb_datachannel_open_request* req, uint32_t length,
+      uint16_t stream) MOZ_REQUIRES(mLock);
+  void HandleOpenAckMessage(const struct rtcweb_datachannel_ack* ack,
+                            uint32_t length, uint16_t stream);
+  void HandleUnknownMessage(uint32_t ppid, uint32_t length, uint16_t stream)
+      MOZ_REQUIRES(mLock);
+  uint8_t BufferMessage(nsACString& recvBuffer, const void* data,
+                        uint32_t length, uint32_t ppid, int flags);
+  void HandleDataMessage(const void* buffer, size_t length, uint32_t ppid,
+                         uint16_t stream, int flags) MOZ_REQUIRES(mLock);
+  void HandleDCEPMessage(const void* buffer, size_t length, uint32_t ppid,
+                         uint16_t stream, int flags) MOZ_REQUIRES(mLock);
+  void HandleMessage(const void* buffer, size_t length, uint32_t ppid,
+                     uint16_t stream, int flags) MOZ_REQUIRES(mLock);
+  void HandleAssociationChangeEvent(const struct sctp_assoc_change* sac)
+      MOZ_REQUIRES(mLock);
+  void HandlePeerAddressChangeEvent(const struct sctp_paddr_change* spc)
+      MOZ_REQUIRES(mLock);
+  void HandleRemoteErrorEvent(const struct sctp_remote_error* sre)
+      MOZ_REQUIRES(mLock);
+  void HandleShutdownEvent(const struct sctp_shutdown_event* sse)
+      MOZ_REQUIRES(mLock);
+  void HandleAdaptationIndication(const struct sctp_adaptation_event* sai)
+      MOZ_REQUIRES(mLock);
+  void HandlePartialDeliveryEvent(const struct sctp_pdapi_event* spde)
+      MOZ_REQUIRES(mLock);
+  void HandleSendFailedEvent(const struct sctp_send_failed_event* ssfe)
+      MOZ_REQUIRES(mLock);
+  void HandleStreamResetEvent(const struct sctp_stream_reset_event* strrst)
+      MOZ_REQUIRES(mLock);
+  void HandleStreamChangeEvent(const struct sctp_stream_change_event* strchg)
+      MOZ_REQUIRES(mLock);
+  void HandleNotification(const union sctp_notification* notif, size_t n)
+      MOZ_REQUIRES(mLock);
+
+#ifdef SCTP_DTLS_SUPPORTED
+  bool IsSTSThread() const {
+    bool on = false;
+    if (mSTS) {
+      mSTS->IsOnCurrentThread(&on);
+    }
+    return on;
+  }
+#endif
+
+  class Channels {
+   public:
+    Channels() : mMutex("DataChannelConnection::Channels::mMutex") {}
+    void Insert(const RefPtr<DataChannel>& aChannel);
+    bool Remove(const RefPtr<DataChannel>& aChannel);
+    RefPtr<DataChannel> Get(uint16_t aId) const;
+    typedef AutoTArray<RefPtr<DataChannel>, 16> ChannelArray;
+    ChannelArray GetAll() const {
+      MutexAutoLock lock(mMutex);
+      return mChannels.Clone();
+    }
+    RefPtr<DataChannel> GetNextChannel(uint16_t aCurrentId) const;
+
+   private:
+    struct IdComparator {
+      bool Equals(const RefPtr<DataChannel>& aChannel, uint16_t aId) const;
+      bool LessThan(const RefPtr<DataChannel>& aChannel, uint16_t aId) const;
+      bool Equals(const RefPtr<DataChannel>& a1,
+                  const RefPtr<DataChannel>& a2) const;
+      bool LessThan(const RefPtr<DataChannel>& a1,
+                    const RefPtr<DataChannel>& a2) const;
+    };
+    mutable Mutex mMutex;
+    ChannelArray mChannels MOZ_GUARDED_BY(mMutex);
+  };
+
+  bool mSendInterleaved MOZ_GUARDED_BY(mLock) = false;
+  // MainThread only
+  bool mMaxMessageSizeSet = false;
+  // mMaxMessageSize is only set on MainThread, but read off-main-thread
+  uint64_t mMaxMessageSize MOZ_GUARDED_BY(mLock) = 0;
+  // Main thread only
+  Maybe<bool> mAllocateEven;
+  // Data:
+  // NOTE: while this container will auto-expand, increases in the number of
+  // channels available from the stack must be negotiated!
+  // Accessed from both main and sts, API is threadsafe
+  Channels mChannels;
+  // STS only
+  uint32_t mCurrentStream = 0;
+  nsRefPtrDeque<DataChannel> mPending;
+  // STS and main
+  size_t mNegotiatedIdLimit MOZ_GUARDED_BY(mLock) = 0;
+  uint8_t mPendingType MOZ_GUARDED_BY(mLock) = PENDING_NONE;
+  // holds data that's come in before a channel is open
+  nsTArray<UniquePtr<QueuedDataMessage>> mQueuedData MOZ_GUARDED_BY(mLock);
+  // holds outgoing control messages
+  nsTArray<UniquePtr<BufferedOutgoingMsg>> mBufferedControl
+      MOZ_GUARDED_BY(mLock);
+
+  // Streams pending reset. Accessed from main and STS.
+  AutoTArray<uint16_t, 4> mStreamsResetting MOZ_GUARDED_BY(mLock);
+  // accessed from STS thread
+  struct socket* mMasterSocket = nullptr;
+  // cloned from mMasterSocket on successful Connect on STS thread
+  struct socket* mSocket = nullptr;
+  uint16_t mState MOZ_GUARDED_BY(mLock) = CLOSED;  // Protected with mLock
+
+#ifdef SCTP_DTLS_SUPPORTED
+  std::string mTransportId;
+  RefPtr<MediaTransportHandler> mTransportHandler;
+  nsCOMPtr<nsIEventTarget> mSTS;
+#endif
+  uint16_t mLocalPort = 0;  // Accessed from connect thread
+  uint16_t mRemotePort = 0;
+
+  nsCOMPtr<nsIThread> mInternalIOThread = nullptr;
+  nsCString mRecvBuffer;
+
+  // Workaround to prevent a message from being received on main before the
+  // sender sees the decrease in bufferedAmount.
+  bool mDeferSend = false;
+  std::vector<std::unique_ptr<MediaPacket>> mDeferredSend;
+
+#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
+  bool mShutdown;
+#endif
+  uintptr_t mId = 0;
+};
+
+#define ENSURE_DATACONNECTION \
+  do {                        \
+    MOZ_ASSERT(mConnection);  \
+    if (!mConnection) {       \
+      return;                 \
+    }                         \
+  } while (0)
+
+class DataChannel {
+  friend class DataChannelOnMessageAvailable;
+  friend class DataChannelConnection;
+
+ public:
+  enum { CONNECTING = 0U, OPEN = 1U, CLOSING = 2U, CLOSED = 3U };
+
+  DataChannel(DataChannelConnection* connection, uint16_t stream,
+              uint16_t state, const nsACString& label,
+              const nsACString& protocol, uint16_t policy, uint32_t value,
+              bool ordered, bool negotiated, DataChannelListener* aListener,
+              nsISupports* aContext)
+      : mListener(aListener),
+        mContext(aContext),
+        mConnection(connection),
+        mLabel(label),
+        mProtocol(protocol),
+        mReadyState(state),
+        mStream(stream),
+        mPrPolicy(policy),
+        mPrValue(value),
+        mNegotiated(negotiated),
+        mOrdered(ordered),
+        mFlags(0),
+        mIsRecvBinary(false),
+        mBufferedThreshold(0),  // default from spec
+        mBufferedAmount(0),
+        mMainThreadEventTarget(connection->GetNeckoTarget()),
+        mStatsLock("netwer::sctp::DataChannel::mStatsLock") {
+    NS_ASSERTION(mConnection, "NULL connection");
+  }
+
+ private:
+  ~DataChannel();
+
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(DataChannel)
+
+  // when we disconnect from the connection after stream RESET
+  void StreamClosedLocked();
+
+  // Complete dropping of the link between DataChannel and the connection.
+  // After this, except for a few methods below listed to be safe, you can't
+  // call into DataChannel.
+  void ReleaseConnection();
+
+  // Close this DataChannel.  Can be called multiple times.  MUST be called
+  // before destroying the DataChannel (state must be CLOSED or CLOSING).
+  void Close();
+
+  // Set the listener (especially for channels created from the other side)
+  void SetListener(DataChannelListener* aListener, nsISupports* aContext);
+
+  // Helper for send methods that converts POSIX error codes to an ErrorResult.
+  static void SendErrnoToErrorResult(int error, size_t aMessageSize,
+                                     ErrorResult& aRv);
+
+  // Send a string
+  void SendMsg(const nsACString& aMsg, ErrorResult& aRv);
+
+  // Send a binary message (TypedArray)
+  void SendBinaryMsg(const nsACString& aMsg, ErrorResult& aRv);
+
+  // Send a binary blob
+  void SendBinaryBlob(dom::Blob& aBlob, ErrorResult& aRv);
+
+  uint16_t GetType() const { return mPrPolicy; }
+
+  dom::Nullable<uint16_t> GetMaxPacketLifeTime() const;
+
+  dom::Nullable<uint16_t> GetMaxRetransmits() const;
+
+  bool GetNegotiated() const { return mNegotiated; }
+
+  bool GetOrdered() const { return mOrdered; }
+
+  void IncrementBufferedAmount(uint32_t aSize, ErrorResult& aRv);
+  void DecrementBufferedAmount(uint32_t aSize);
+
+  // Amount of data buffered to send
+  uint32_t GetBufferedAmount() const {
+    MOZ_ASSERT(NS_IsMainThread());
+    return mBufferedAmount;
+  }
+
+  // Trigger amount for generating BufferedAmountLow events
+  uint32_t GetBufferedAmountLowThreshold() const;
+  void SetBufferedAmountLowThreshold(uint32_t aThreshold);
+
+  void AnnounceOpen();
+  // TODO(bug 843625): Optionally pass an error here.
+  void AnnounceClosed();
+
+  // Find out state
+  uint16_t GetReadyState() const {
+    MOZ_ASSERT(NS_IsMainThread());
+    return mReadyState;
+  }
+
+  // Set ready state
+  void SetReadyState(const uint16_t aState);
+
+  void GetLabel(nsAString& aLabel) { CopyUTF8toUTF16(mLabel, aLabel); }
+  void GetProtocol(nsAString& aProtocol) {
+    CopyUTF8toUTF16(mProtocol, aProtocol);
+  }
+  uint16_t GetStream() const { return mStream; }
+
+  void SendOrQueue(DataChannelOnMessageAvailable* aMessage);
+
+  struct TrafficCounters {
+    uint32_t mMessagesSent = 0;
+    uint64_t mBytesSent = 0;
+    uint32_t mMessagesReceived = 0;
+    uint64_t mBytesReceived = 0;
+  };
+
+  TrafficCounters GetTrafficCounters() const;
+
+ protected:
+  // These are both mainthread only
+  DataChannelListener* mListener;
+  nsCOMPtr<nsISupports> mContext;
+
+ private:
+  nsresult AddDataToBinaryMsg(const char* data, uint32_t size);
+  bool EnsureValidStream(ErrorResult& aRv);
+  void WithTrafficCounters(const std::function<void(TrafficCounters&)>&);
+
+  RefPtr<DataChannelConnection> mConnection;
+  nsCString mLabel;
+  nsCString mProtocol;
+  // This is mainthread only
+  uint16_t mReadyState;
+  uint16_t mStream;
+  uint16_t mPrPolicy;
+  uint32_t mPrValue;
+  // Accessed on main and STS
+  const bool mNegotiated;
+  const bool mOrdered;
+  uint32_t mFlags;
+  bool mIsRecvBinary;
+  size_t mBufferedThreshold;
+  // Read/written on main only. Decremented via message-passing, because the
+  // spec requires us to queue a task for this.
+  size_t mBufferedAmount;
+  nsCString mRecvBuffer;
+  nsTArray<UniquePtr<BufferedOutgoingMsg>>
+      mBufferedData;  // MOZ_GUARDED_BY(mConnection->mLock)
+  nsCOMPtr<nsISerialEventTarget> mMainThreadEventTarget;
+  mutable Mutex mStatsLock;  // protects mTrafficCounters
+  TrafficCounters mTrafficCounters MOZ_GUARDED_BY(mStatsLock);
+};
+
+// used to dispatch notifications of incoming data to the main thread
+// Patterned on CallOnMessageAvailable in WebSockets
+// Also used to proxy other items to MainThread
+class DataChannelOnMessageAvailable : public Runnable {
+ public:
+  enum {
+    ON_CONNECTION,
+    ON_DISCONNECTED,
+    ON_CHANNEL_CREATED,
+    ON_DATA_STRING,
+    ON_DATA_BINARY,
+  }; /* types */
+
+  DataChannelOnMessageAvailable(
+      int32_t aType, DataChannelConnection* aConnection, DataChannel* aChannel,
+      nsCString& aData)  // XXX this causes inefficiency
+      : Runnable("DataChannelOnMessageAvailable"),
+        mType(aType),
+        mChannel(aChannel),
+        mConnection(aConnection),
+        mData(aData) {}
+
+  DataChannelOnMessageAvailable(int32_t aType, DataChannel* aChannel)
+      : Runnable("DataChannelOnMessageAvailable"),
+        mType(aType),
+        mChannel(aChannel) {}
+  // XXX is it safe to leave mData uninitialized?  This should only be
+  // used for notifications that don't use them, but I'd like more
+  // bulletproof compile-time checking.
+
+  DataChannelOnMessageAvailable(int32_t aType,
+                                DataChannelConnection* aConnection,
+                                DataChannel* aChannel)
+      : Runnable("DataChannelOnMessageAvailable"),
+        mType(aType),
+        mChannel(aChannel),
+        mConnection(aConnection) {}
+
+  // for ON_CONNECTION/ON_DISCONNECTED
+  DataChannelOnMessageAvailable(int32_t aType,
+                                DataChannelConnection* aConnection)
+      : Runnable("DataChannelOnMessageAvailable"),
+        mType(aType),
+        mConnection(aConnection) {}
+
+  NS_IMETHOD Run() override {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    // Note: calling the listeners can indirectly cause the listeners to be
+    // made available for GC (by removing event listeners), especially for
+    // OnChannelClosed().  We hold a ref to the Channel and the listener
+    // while calling this.
+    switch (mType) {
+      case ON_DATA_STRING:
+      case ON_DATA_BINARY:
+        if (!mChannel->mListener) {
+          DC_ERROR(("DataChannelOnMessageAvailable (%d) with null Listener!",
+                    mType));
+          return NS_OK;
+        }
+
+        if (mChannel->GetReadyState() == DataChannel::CLOSED ||
+            mChannel->GetReadyState() == DataChannel::CLOSING) {
+          // Closed by JS, probably
+          return NS_OK;
+        }
+
+        if (mType == ON_DATA_STRING) {
+          mChannel->mListener->OnMessageAvailable(mChannel->mContext, mData);
+        } else {
+          mChannel->mListener->OnBinaryMessageAvailable(mChannel->mContext,
+                                                        mData);
+        }
+        break;
+      case ON_DISCONNECTED:
+        // If we've disconnected, make sure we close all the streams - from
+        // mainthread!
+        mConnection->CloseAll();
+        break;
+      case ON_CHANNEL_CREATED:
+        if (!mConnection->mListener) {
+          DC_ERROR(("DataChannelOnMessageAvailable (%d) with null Listener!",
+                    mType));
+          return NS_OK;
+        }
+
+        // important to give it an already_AddRefed pointer!
+        mConnection->mListener->NotifyDataChannel(mChannel.forget());
+        break;
+      case ON_CONNECTION:
+        // TODO: Notify someday? How? What does the spec say about this?
+        break;
+    }
+    return NS_OK;
+  }
+
+ private:
+  ~DataChannelOnMessageAvailable() = default;
+
+  int32_t mType;
+  // XXX should use union
+  RefPtr<DataChannel> mChannel;
+  RefPtr<DataChannelConnection> mConnection;
+  nsCString mData;
+};
+
+}  // namespace mozilla
+
+#endif  // NETWERK_SCTP_DATACHANNEL_DATACHANNEL_H_