Add m-esr52 at 52.6.0

6 files changed, 3429 insertions, 0 deletions

diff --git a/netwerk/sctp/datachannel/DataChannel.cpp b/netwerk/sctp/datachannel/DataChannel.cpp
new file mode 100644
index 000000000..bf7790f51
--- /dev/null
+++ b/netwerk/sctp/datachannel/DataChannel.cpp
@@ -0,0 +1,2661 @@
+/* -*- 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/. */
+
+#include <algorithm>
+#include <stdio.h>
+#include <stdlib.h>
+#if !defined(__Userspace_os_Windows)
+#include <arpa/inet.h>
+#endif
+// usrsctp.h expects to have errno definitions prior to its inclusion.
+#include <errno.h>
+
+#define SCTP_DEBUG 1
+#define SCTP_STDINT_INCLUDE <stdint.h>
+
+#ifdef _MSC_VER
+// Disable "warning C4200: nonstandard extension used : zero-sized array in
+//          struct/union"
+// ...which the third-party file usrsctp.h runs afoul of.
+#pragma warning(push)
+#pragma warning(disable:4200)
+#endif
+
+#include "usrsctp.h"
+
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+
+#include "DataChannelLog.h"
+
+#include "nsServiceManagerUtils.h"
+#include "nsIObserverService.h"
+#include "nsIObserver.h"
+#include "mozilla/Services.h"
+#include "mozilla/Sprintf.h"
+#include "nsProxyRelease.h"
+#include "nsThread.h"
+#include "nsThreadUtils.h"
+#include "nsAutoPtr.h"
+#include "nsNetUtil.h"
+#include "nsNetCID.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/Unused.h"
+#ifdef MOZ_PEERCONNECTION
+#include "mtransport/runnable_utils.h"
+#endif
+
+#define DATACHANNEL_LOG(args) LOG(args)
+#include "DataChannel.h"
+#include "DataChannelProtocol.h"
+
+// Let us turn on and off important assertions in non-debug builds
+#ifdef DEBUG
+#define ASSERT_WEBRTC(x) MOZ_ASSERT((x))
+#elif defined(MOZ_WEBRTC_ASSERT_ALWAYS)
+#define ASSERT_WEBRTC(x) do { if (!(x)) { MOZ_CRASH(); } } while (0)
+#endif
+
+static bool sctp_initialized;
+
+namespace mozilla {
+
+LazyLogModule gDataChannelLog("DataChannel");
+static LazyLogModule gSCTPLog("SCTP");
+
+class DataChannelShutdown : public nsIObserver
+{
+public:
+  // This needs to be tied to some form object that is guaranteed to be
+  // around (singleton likely) unless we want to shutdown sctp whenever
+  // we're not using it (and in which case we'd keep a refcnt'd object
+  // ref'd by each DataChannelConnection to release the SCTP usrlib via
+  // sctp_finish). Right now, the single instance of this class is
+  // owned by the observer service.
+
+  NS_DECL_ISUPPORTS
+
+  DataChannelShutdown() {}
+
+  void Init()
+    {
+      nsCOMPtr<nsIObserverService> observerService =
+        mozilla::services::GetObserverService();
+      if (!observerService)
+        return;
+
+      nsresult rv = observerService->AddObserver(this,
+                                                 "xpcom-will-shutdown",
+                                                 false);
+      MOZ_ASSERT(rv == NS_OK);
+      (void) rv;
+    }
+
+private:
+  // The only instance of DataChannelShutdown is owned by the observer
+  // service, so there is no need to call RemoveObserver here.
+  virtual ~DataChannelShutdown() = default;
+
+public:
+  NS_IMETHOD Observe(nsISupports* aSubject, const char* aTopic,
+                     const char16_t* aData) override {
+    if (strcmp(aTopic, "xpcom-will-shutdown") == 0) {
+      LOG(("Shutting down SCTP"));
+      if (sctp_initialized) {
+        usrsctp_finish();
+        sctp_initialized = false;
+      }
+      nsCOMPtr<nsIObserverService> observerService =
+        mozilla::services::GetObserverService();
+      if (!observerService)
+        return NS_ERROR_FAILURE;
+
+      nsresult rv = observerService->RemoveObserver(this,
+                                                    "xpcom-will-shutdown");
+      MOZ_ASSERT(rv == NS_OK);
+      (void) rv;
+    }
+    return NS_OK;
+  }
+};
+
+NS_IMPL_ISUPPORTS(DataChannelShutdown, nsIObserver);
+
+BufferedMsg::BufferedMsg(struct sctp_sendv_spa &spa, const char *data,
+                         size_t length) : mLength(length)
+{
+  mSpa = new sctp_sendv_spa;
+  *mSpa = spa;
+  auto *tmp = new char[length]; // infallible malloc!
+  memcpy(tmp, data, length);
+  mData = tmp;
+}
+
+BufferedMsg::~BufferedMsg()
+{
+  delete mSpa;
+  delete mData;
+}
+
+static int
+receive_cb(struct socket* sock, union sctp_sockstore addr,
+           void *data, size_t datalen,
+           struct sctp_rcvinfo rcv, int flags, void *ulp_info)
+{
+  DataChannelConnection *connection = static_cast<DataChannelConnection*>(ulp_info);
+  return connection->ReceiveCallback(sock, data, datalen, rcv, flags);
+}
+
+static
+DataChannelConnection *
+GetConnectionFromSocket(struct socket* sock)
+{
+  struct sockaddr *addrs = nullptr;
+  int naddrs = usrsctp_getladdrs(sock, 0, &addrs);
+  if (naddrs <= 0 || addrs[0].sa_family != AF_CONN) {
+    return nullptr;
+  }
+  // usrsctp_getladdrs() returns the addresses bound to this socket, which
+  // contains the SctpDataMediaChannel* as sconn_addr.  Read the pointer,
+  // then free the list of addresses once we have the pointer.  We only open
+  // AF_CONN sockets, and they should all have the sconn_addr set to the
+  // pointer that created them, so [0] is as good as any other.
+  struct sockaddr_conn *sconn = reinterpret_cast<struct sockaddr_conn *>(&addrs[0]);
+  DataChannelConnection *connection =
+    reinterpret_cast<DataChannelConnection *>(sconn->sconn_addr);
+  usrsctp_freeladdrs(addrs);
+
+  return connection;
+}
+
+// called when the buffer empties to the threshold value
+static int
+threshold_event(struct socket* sock, uint32_t sb_free)
+{
+  DataChannelConnection *connection = GetConnectionFromSocket(sock);
+  if (connection) {
+    LOG(("SendDeferred()"));
+    connection->SendDeferredMessages();
+  } else {
+    LOG(("Can't find connection for socket %p", sock));
+  }
+  return 0;
+}
+
+static void
+debug_printf(const char *format, ...)
+{
+  va_list ap;
+  char buffer[1024];
+
+  if (MOZ_LOG_TEST(gSCTPLog, LogLevel::Debug)) {
+    va_start(ap, format);
+#ifdef _WIN32
+    if (vsnprintf_s(buffer, sizeof(buffer), _TRUNCATE, format, ap) > 0) {
+#else
+    if (VsprintfLiteral(buffer, format, ap) > 0) {
+#endif
+      PR_LogPrint("%s", buffer);
+    }
+    va_end(ap);
+  }
+}
+
+DataChannelConnection::DataChannelConnection(DataConnectionListener *listener) :
+   mLock("netwerk::sctp::DataChannelConnection")
+{
+  mState = CLOSED;
+  mSocket = nullptr;
+  mMasterSocket = nullptr;
+  mListener = listener;
+  mLocalPort = 0;
+  mRemotePort = 0;
+  LOG(("Constructor DataChannelConnection=%p, listener=%p", this, mListener.get()));
+  mInternalIOThread = nullptr;
+}
+
+DataChannelConnection::~DataChannelConnection()
+{
+  LOG(("Deleting DataChannelConnection %p", (void *) this));
+  // This may die on the MainThread, or on the STS thread
+  ASSERT_WEBRTC(mState == CLOSED);
+  MOZ_ASSERT(!mMasterSocket);
+  MOZ_ASSERT(mPending.GetSize() == 0);
+
+  // Already disconnected from sigslot/mTransportFlow
+  // TransportFlows must be released from the STS thread
+  if (!IsSTSThread()) {
+    ASSERT_WEBRTC(NS_IsMainThread());
+    if (mTransportFlow) {
+      ASSERT_WEBRTC(mSTS);
+      NS_ProxyRelease(mSTS, mTransportFlow.forget());
+    }
+
+    if (mInternalIOThread) {
+      // Avoid spinning the event thread from here (which if we're mainthread
+      // is in the event loop already)
+      NS_DispatchToMainThread(WrapRunnable(nsCOMPtr<nsIThread>(mInternalIOThread),
+                                           &nsIThread::Shutdown),
+                              NS_DISPATCH_NORMAL);
+    }
+  } else {
+    // on STS, safe to call shutdown
+    if (mInternalIOThread) {
+      mInternalIOThread->Shutdown();
+    }
+  }
+}
+
+void
+DataChannelConnection::Destroy()
+{
+  // Though it's probably ok to do this and close the sockets;
+  // if we really want it to do true clean shutdowns it can
+  // create a dependant Internal object that would remain around
+  // until the network shut down the association or timed out.
+  LOG(("Destroying DataChannelConnection %p", (void *) this));
+  ASSERT_WEBRTC(NS_IsMainThread());
+  CloseAll();
+
+  MutexAutoLock lock(mLock);
+  // If we had a pending reset, we aren't waiting for it - clear the list so
+  // we can deregister this DataChannelConnection without leaking.
+  ClearResets();
+
+  MOZ_ASSERT(mSTS);
+  ASSERT_WEBRTC(NS_IsMainThread());
+  // Must do this in Destroy() since we may then delete this object.
+  // Do this before dispatching to create a consistent ordering of calls to
+  // the SCTP stack.
+  if (mUsingDtls) {
+    usrsctp_deregister_address(static_cast<void *>(this));
+    LOG(("Deregistered %p from the SCTP stack.", static_cast<void *>(this)));
+  }
+
+  // Finish Destroy on STS thread to avoid bug 876167 - once that's fixed,
+  // the usrsctp_close() calls can move back here (and just proxy the
+  // disconnect_all())
+  RUN_ON_THREAD(mSTS, WrapRunnable(RefPtr<DataChannelConnection>(this),
+                                   &DataChannelConnection::DestroyOnSTS,
+                                   mSocket, mMasterSocket),
+                NS_DISPATCH_NORMAL);
+
+  // These will be released on STS
+  mSocket = nullptr;
+  mMasterSocket = nullptr; // also a flag that we've Destroyed this connection
+
+  // We can't get any more new callbacks from the SCTP library
+  // All existing callbacks have refs to DataChannelConnection
+
+  // nsDOMDataChannel objects have refs to DataChannels that have refs to us
+}
+
+void DataChannelConnection::DestroyOnSTS(struct socket *aMasterSocket,
+                                         struct socket *aSocket)
+{
+  if (aSocket && aSocket != aMasterSocket)
+    usrsctp_close(aSocket);
+  if (aMasterSocket)
+    usrsctp_close(aMasterSocket);
+
+  disconnect_all();
+}
+
+bool
+DataChannelConnection::Init(unsigned short aPort, uint16_t aNumStreams, bool aUsingDtls)
+{
+  struct sctp_initmsg initmsg;
+  struct sctp_udpencaps encaps;
+  struct sctp_assoc_value av;
+  struct sctp_event event;
+  socklen_t len;
+
+  uint16_t event_types[] = {SCTP_ASSOC_CHANGE,
+                            SCTP_PEER_ADDR_CHANGE,
+                            SCTP_REMOTE_ERROR,
+                            SCTP_SHUTDOWN_EVENT,
+                            SCTP_ADAPTATION_INDICATION,
+                            SCTP_SEND_FAILED_EVENT,
+                            SCTP_STREAM_RESET_EVENT,
+                            SCTP_STREAM_CHANGE_EVENT};
+  {
+    ASSERT_WEBRTC(NS_IsMainThread());
+
+    // MutexAutoLock lock(mLock); Not needed since we're on mainthread always
+    if (!sctp_initialized) {
+      if (aUsingDtls) {
+        LOG(("sctp_init(DTLS)"));
+#ifdef MOZ_PEERCONNECTION
+        usrsctp_init(0,
+                     DataChannelConnection::SctpDtlsOutput,
+                     debug_printf
+                    );
+#else
+        NS_ASSERTION(!aUsingDtls, "Trying to use SCTP/DTLS without mtransport");
+#endif
+      } else {
+        LOG(("sctp_init(%u)", aPort));
+        usrsctp_init(aPort,
+                     nullptr,
+                     debug_printf
+                    );
+      }
+
+      // Set logging to SCTP:LogLevel::Debug to get SCTP debugs
+      if (MOZ_LOG_TEST(gSCTPLog, LogLevel::Debug)) {
+        usrsctp_sysctl_set_sctp_debug_on(SCTP_DEBUG_ALL);
+      }
+
+      usrsctp_sysctl_set_sctp_blackhole(2);
+      // ECN is currently not supported by the Firefox code
+      usrsctp_sysctl_set_sctp_ecn_enable(0);
+      sctp_initialized = true;
+
+      RefPtr<DataChannelShutdown> shutdown = new DataChannelShutdown();
+      shutdown->Init();
+    }
+  }
+
+  // XXX FIX! make this a global we get once
+  // Find the STS thread
+  nsresult rv;
+  mSTS = do_GetService(NS_SOCKETTRANSPORTSERVICE_CONTRACTID, &rv);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+  // Open sctp with a callback
+  if ((mMasterSocket = usrsctp_socket(
+         aUsingDtls ? AF_CONN : AF_INET,
+         SOCK_STREAM, IPPROTO_SCTP, receive_cb, threshold_event,
+         usrsctp_sysctl_get_sctp_sendspace() / 2, this)) == nullptr) {
+    return false;
+  }
+
+  // Make non-blocking for bind/connect.  SCTP over UDP defaults to non-blocking
+  // in associations for normal IO
+  if (usrsctp_set_non_blocking(mMasterSocket, 1) < 0) {
+    LOG(("Couldn't set non_blocking on SCTP socket"));
+    // We can't handle connect() safely if it will block, not that this will
+    // even happen.
+    goto error_cleanup;
+  }
+
+  // Make sure when we close the socket, make sure it doesn't call us back again!
+  // This would cause it try to use an invalid DataChannelConnection pointer
+  struct linger l;
+  l.l_onoff = 1;
+  l.l_linger = 0;
+  if (usrsctp_setsockopt(mMasterSocket, SOL_SOCKET, SO_LINGER,
+                         (const void *)&l, (socklen_t)sizeof(struct linger)) < 0) {
+    LOG(("Couldn't set SO_LINGER on SCTP socket"));
+    // unsafe to allow it to continue if this fails
+    goto error_cleanup;
+  }
+
+  // XXX Consider disabling this when we add proper SDP negotiation.
+  // We may want to leave enabled for supporting 'cloning' of SDP offers, which
+  // implies re-use of the same pseudo-port number, or forcing a renegotiation.
+  {
+    uint32_t on = 1;
+    if (usrsctp_setsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_REUSE_PORT,
+                           (const void *)&on, (socklen_t)sizeof(on)) < 0) {
+      LOG(("Couldn't set SCTP_REUSE_PORT on SCTP socket"));
+    }
+    if (usrsctp_setsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_NODELAY,
+                           (const void *)&on, (socklen_t)sizeof(on)) < 0) {
+      LOG(("Couldn't set SCTP_NODELAY on SCTP socket"));
+    }
+  }
+
+  if (!aUsingDtls) {
+    memset(&encaps, 0, sizeof(encaps));
+    encaps.sue_address.ss_family = AF_INET;
+    encaps.sue_port = htons(aPort);
+    if (usrsctp_setsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_REMOTE_UDP_ENCAPS_PORT,
+                           (const void*)&encaps,
+                           (socklen_t)sizeof(struct sctp_udpencaps)) < 0) {
+      LOG(("*** failed encaps errno %d", errno));
+      goto error_cleanup;
+    }
+    LOG(("SCTP encapsulation local port %d", aPort));
+  }
+
+  av.assoc_id = SCTP_ALL_ASSOC;
+  av.assoc_value = SCTP_ENABLE_RESET_STREAM_REQ | SCTP_ENABLE_CHANGE_ASSOC_REQ;
+  if (usrsctp_setsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_ENABLE_STREAM_RESET, &av,
+                         (socklen_t)sizeof(struct sctp_assoc_value)) < 0) {
+    LOG(("*** failed enable stream reset errno %d", errno));
+    goto error_cleanup;
+  }
+
+  /* Enable the events of interest. */
+  memset(&event, 0, sizeof(event));
+  event.se_assoc_id = SCTP_ALL_ASSOC;
+  event.se_on = 1;
+  for (unsigned short event_type : event_types) {
+    event.se_type = event_type;
+    if (usrsctp_setsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_EVENT, &event, sizeof(event)) < 0) {
+      LOG(("*** failed setsockopt SCTP_EVENT errno %d", errno));
+      goto error_cleanup;
+    }
+  }
+
+  // Update number of streams
+  mStreams.AppendElements(aNumStreams);
+  for (uint32_t i = 0; i < aNumStreams; ++i) {
+    mStreams[i] = nullptr;
+  }
+  memset(&initmsg, 0, sizeof(initmsg));
+  len = sizeof(initmsg);
+  if (usrsctp_getsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_INITMSG, &initmsg, &len) < 0) {
+    LOG(("*** failed getsockopt SCTP_INITMSG"));
+    goto error_cleanup;
+  }
+  LOG(("Setting number of SCTP streams to %u, was %u/%u", aNumStreams,
+       initmsg.sinit_num_ostreams, initmsg.sinit_max_instreams));
+  initmsg.sinit_num_ostreams  = aNumStreams;
+  initmsg.sinit_max_instreams = MAX_NUM_STREAMS;
+  if (usrsctp_setsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_INITMSG, &initmsg,
+                         (socklen_t)sizeof(initmsg)) < 0) {
+    LOG(("*** failed setsockopt SCTP_INITMSG, errno %d", errno));
+    goto error_cleanup;
+  }
+
+  mSocket = nullptr;
+  if (aUsingDtls) {
+    mUsingDtls = true;
+    usrsctp_register_address(static_cast<void *>(this));
+    LOG(("Registered %p within the SCTP stack.", static_cast<void *>(this)));
+  } else {
+    mUsingDtls = false;
+  }
+  return true;
+
+error_cleanup:
+  usrsctp_close(mMasterSocket);
+  mMasterSocket = nullptr;
+  mUsingDtls = false;
+  return false;
+}
+
+#ifdef MOZ_PEERCONNECTION
+void
+DataChannelConnection::SetEvenOdd()
+{
+  ASSERT_WEBRTC(IsSTSThread());
+
+  TransportLayerDtls *dtls = static_cast<TransportLayerDtls *>(
+      mTransportFlow->GetLayer(TransportLayerDtls::ID()));
+  MOZ_ASSERT(dtls);  // DTLS is mandatory
+  mAllocateEven = (dtls->role() == TransportLayerDtls::CLIENT);
+}
+
+bool
+DataChannelConnection::ConnectViaTransportFlow(TransportFlow *aFlow, uint16_t localport, uint16_t remoteport)
+{
+  LOG(("Connect DTLS local %u, remote %u", localport, remoteport));
+
+  NS_PRECONDITION(mMasterSocket, "SCTP wasn't initialized before ConnectViaTransportFlow!");
+  NS_ENSURE_TRUE(aFlow, false);
+
+  mTransportFlow = aFlow;
+  mLocalPort = localport;
+  mRemotePort = remoteport;
+  mState = CONNECTING;
+
+  RUN_ON_THREAD(mSTS, WrapRunnable(RefPtr<DataChannelConnection>(this),
+                                   &DataChannelConnection::SetSignals),
+                NS_DISPATCH_NORMAL);
+  return true;
+}
+
+void
+DataChannelConnection::SetSignals()
+{
+  ASSERT_WEBRTC(IsSTSThread());
+  ASSERT_WEBRTC(mTransportFlow);
+  LOG(("Setting transport signals, state: %d", mTransportFlow->state()));
+  mTransportFlow->SignalPacketReceived.connect(this, &DataChannelConnection::SctpDtlsInput);
+  // SignalStateChange() doesn't call you with the initial state
+  mTransportFlow->SignalStateChange.connect(this, &DataChannelConnection::CompleteConnect);
+  CompleteConnect(mTransportFlow, mTransportFlow->state());
+}
+
+void
+DataChannelConnection::CompleteConnect(TransportFlow *flow, TransportLayer::State state)
+{
+  LOG(("Data transport state: %d", state));
+  MutexAutoLock lock(mLock);
+  ASSERT_WEBRTC(IsSTSThread());
+  // We should abort connection on TS_ERROR.
+  // Note however that the association will also fail (perhaps with a delay) and
+  // notify us in that way
+  if (state != TransportLayer::TS_OPEN || !mMasterSocket)
+    return;
+
+  struct sockaddr_conn addr;
+  memset(&addr, 0, sizeof(addr));
+  addr.sconn_family = AF_CONN;
+#if defined(__Userspace_os_Darwin)
+  addr.sconn_len = sizeof(addr);
+#endif
+  addr.sconn_port = htons(mLocalPort);
+  addr.sconn_addr = static_cast<void *>(this);
+
+  LOG(("Calling usrsctp_bind"));
+  int r = usrsctp_bind(mMasterSocket, reinterpret_cast<struct sockaddr *>(&addr),
+                       sizeof(addr));
+  if (r < 0) {
+    LOG(("usrsctp_bind failed: %d", r));
+  } else {
+    // This is the remote addr
+    addr.sconn_port = htons(mRemotePort);
+    LOG(("Calling usrsctp_connect"));
+    r = usrsctp_connect(mMasterSocket, reinterpret_cast<struct sockaddr *>(&addr),
+                        sizeof(addr));
+    if (r >= 0 || errno == EINPROGRESS) {
+      struct sctp_paddrparams paddrparams;
+      socklen_t opt_len;
+
+      memset(&paddrparams, 0, sizeof(struct sctp_paddrparams));
+      memcpy(&paddrparams.spp_address, &addr, sizeof(struct sockaddr_conn));
+      opt_len = (socklen_t)sizeof(struct sctp_paddrparams);
+      r = usrsctp_getsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_PEER_ADDR_PARAMS,
+                             &paddrparams, &opt_len);
+      if (r < 0) {
+        LOG(("usrsctp_getsockopt failed: %d", r));
+      } else {
+        // draft-ietf-rtcweb-data-channel-13 section 5: max initial MTU IPV4 1200, IPV6 1280
+        paddrparams.spp_pathmtu = 1200; // safe for either
+        paddrparams.spp_flags &= ~SPP_PMTUD_ENABLE;
+        paddrparams.spp_flags |= SPP_PMTUD_DISABLE;
+        opt_len = (socklen_t)sizeof(struct sctp_paddrparams);
+        r = usrsctp_setsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_PEER_ADDR_PARAMS,
+                               &paddrparams, opt_len);
+        if (r < 0) {
+          LOG(("usrsctp_getsockopt failed: %d", r));
+        } else {
+          LOG(("usrsctp: PMTUD disabled, MTU set to %u", paddrparams.spp_pathmtu));
+        }
+      }
+    }
+    if (r < 0) {
+      if (errno == EINPROGRESS) {
+        // non-blocking
+        return;
+      } else {
+        LOG(("usrsctp_connect failed: %d", errno));
+        mState = CLOSED;
+      }
+    } else {
+      // We set Even/Odd and fire ON_CONNECTION via SCTP_COMM_UP when we get that
+      // This also avoids issues with calling TransportFlow stuff on Mainthread
+      return;
+    }
+  }
+  // Note: currently this doesn't actually notify the application
+  NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                                      DataChannelOnMessageAvailable::ON_CONNECTION,
+                                      this)));
+  return;
+}
+
+// Process any pending Opens
+void
+DataChannelConnection::ProcessQueuedOpens()
+{
+  // The nsDeque holds channels with an AddRef applied.  Another reference
+  // (may) be held by the DOMDataChannel, unless it's been GC'd.  No other
+  // references should exist.
+
+  // Can't copy nsDeque's.  Move into temp array since any that fail will
+  // go back to mPending
+  nsDeque temp;
+  DataChannel *temp_channel; // really already_AddRefed<>
+  while (nullptr != (temp_channel = static_cast<DataChannel *>(mPending.PopFront()))) {
+    temp.Push(static_cast<void *>(temp_channel));
+  }
+
+  RefPtr<DataChannel> channel;
+  // All these entries have an AddRef(); make that explicit now via the dont_AddRef()
+  while (nullptr != (channel = dont_AddRef(static_cast<DataChannel *>(temp.PopFront())))) {
+    if (channel->mFlags & DATA_CHANNEL_FLAGS_FINISH_OPEN) {
+      LOG(("Processing queued open for %p (%u)", channel.get(), channel->mStream));
+      channel->mFlags &= ~DATA_CHANNEL_FLAGS_FINISH_OPEN;
+      // OpenFinish returns a reference itself, so we need to take it can Release it
+      channel = OpenFinish(channel.forget()); // may reset the flag and re-push
+    } else {
+      NS_ASSERTION(false, "How did a DataChannel get queued without the FINISH_OPEN flag?");
+    }
+  }
+
+}
+void
+DataChannelConnection::SctpDtlsInput(TransportFlow *flow,
+                                     const unsigned char *data, size_t len)
+{
+  if (MOZ_LOG_TEST(gSCTPLog, LogLevel::Debug)) {
+    char *buf;
+
+    if ((buf = usrsctp_dumppacket((void *)data, len, SCTP_DUMP_INBOUND)) != nullptr) {
+      PR_LogPrint("%s", buf);
+      usrsctp_freedumpbuffer(buf);
+    }
+  }
+  // Pass the data to SCTP
+  usrsctp_conninput(static_cast<void *>(this), data, len, 0);
+}
+
+int
+DataChannelConnection::SendPacket(unsigned char data[], size_t len, bool release)
+{
+  //LOG(("%p: SCTP/DTLS sent %ld bytes", this, len));
+  int res = mTransportFlow->SendPacket(data, len) < 0 ? 1 : 0;
+  if (release)
+    delete [] data;
+  return res;
+}
+
+/* static */
+int
+DataChannelConnection::SctpDtlsOutput(void *addr, void *buffer, size_t length,
+                                      uint8_t tos, uint8_t set_df)
+{
+  DataChannelConnection *peer = static_cast<DataChannelConnection *>(addr);
+  int res;
+
+  if (MOZ_LOG_TEST(gSCTPLog, LogLevel::Debug)) {
+    char *buf;
+
+    if ((buf = usrsctp_dumppacket(buffer, length, SCTP_DUMP_OUTBOUND)) != nullptr) {
+      PR_LogPrint("%s", buf);
+      usrsctp_freedumpbuffer(buf);
+    }
+  }
+  // We're async proxying even if on the STSThread because this is called
+  // with internal SCTP locks held in some cases (such as in usrsctp_connect()).
+  // SCTP has an option for Apple, on IP connections only, to release at least
+  // one of the locks before calling a packet output routine; with changes to
+  // the underlying SCTP stack this might remove the need to use an async proxy.
+  if ((false /*peer->IsSTSThread()*/)) {
+    res = peer->SendPacket(static_cast<unsigned char *>(buffer), length, false);
+  } else {
+    auto *data = new unsigned char[length];
+    memcpy(data, buffer, length);
+    // Commented out since we have to Dispatch SendPacket to avoid deadlock"
+    // res = -1;
+
+    // XXX It might be worthwhile to add an assertion against the thread
+    // somehow getting into the DataChannel/SCTP code again, as
+    // DISPATCH_SYNC is not fully blocking.  This may be tricky, as it
+    // needs to be a per-thread check, not a global.
+    peer->mSTS->Dispatch(WrapRunnable(
+                           RefPtr<DataChannelConnection>(peer),
+                           &DataChannelConnection::SendPacket, data, length, true),
+                                   NS_DISPATCH_NORMAL);
+    res = 0; // cheat!  Packets can always be dropped later anyways
+  }
+  return res;
+}
+#endif
+
+#ifdef ALLOW_DIRECT_SCTP_LISTEN_CONNECT
+// listen for incoming associations
+// Blocks! - Don't call this from main thread!
+
+#error This code will not work as-is since SetEvenOdd() runs on Mainthread
+
+bool
+DataChannelConnection::Listen(unsigned short port)
+{
+  struct sockaddr_in addr;
+  socklen_t addr_len;
+
+  NS_WARNING_ASSERTION(!NS_IsMainThread(),
+                       "Blocks, do not call from main thread!!!");
+
+  /* Acting as the 'server' */
+  memset((void *)&addr, 0, sizeof(addr));
+#ifdef HAVE_SIN_LEN
+  addr.sin_len = sizeof(struct sockaddr_in);
+#endif
+  addr.sin_family = AF_INET;
+  addr.sin_port = htons(port);
+  addr.sin_addr.s_addr = htonl(INADDR_ANY);
+  LOG(("Waiting for connections on port %u", ntohs(addr.sin_port)));
+  mState = CONNECTING;
+  if (usrsctp_bind(mMasterSocket, reinterpret_cast<struct sockaddr *>(&addr), sizeof(struct sockaddr_in)) < 0) {
+    LOG(("***Failed userspace_bind"));
+    return false;
+  }
+  if (usrsctp_listen(mMasterSocket, 1) < 0) {
+    LOG(("***Failed userspace_listen"));
+    return false;
+  }
+
+  LOG(("Accepting connection"));
+  addr_len = 0;
+  if ((mSocket = usrsctp_accept(mMasterSocket, nullptr, &addr_len)) == nullptr) {
+    LOG(("***Failed accept"));
+    return false;
+  }
+  mState = OPEN;
+
+  struct linger l;
+  l.l_onoff = 1;
+  l.l_linger = 0;
+  if (usrsctp_setsockopt(mSocket, SOL_SOCKET, SO_LINGER,
+                         (const void *)&l, (socklen_t)sizeof(struct linger)) < 0) {
+    LOG(("Couldn't set SO_LINGER on SCTP socket"));
+  }
+
+  SetEvenOdd();
+
+  // Notify Connection open
+  // XXX We need to make sure connection sticks around until the message is delivered
+  LOG(("%s: sending ON_CONNECTION for %p", __FUNCTION__, this));
+  NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                            DataChannelOnMessageAvailable::ON_CONNECTION,
+                            this, (DataChannel *) nullptr)));
+  return true;
+}
+
+// Blocks! - Don't call this from main thread!
+bool
+DataChannelConnection::Connect(const char *addr, unsigned short port)
+{
+  struct sockaddr_in addr4;
+  struct sockaddr_in6 addr6;
+
+  NS_WARNING_ASSERTION(!NS_IsMainThread(),
+                       "Blocks, do not call from main thread!!!");
+
+  /* Acting as the connector */
+  LOG(("Connecting to %s, port %u", addr, port));
+  memset((void *)&addr4, 0, sizeof(struct sockaddr_in));
+  memset((void *)&addr6, 0, sizeof(struct sockaddr_in6));
+#ifdef HAVE_SIN_LEN
+  addr4.sin_len = sizeof(struct sockaddr_in);
+#endif
+#ifdef HAVE_SIN6_LEN
+  addr6.sin6_len = sizeof(struct sockaddr_in6);
+#endif
+  addr4.sin_family = AF_INET;
+  addr6.sin6_family = AF_INET6;
+  addr4.sin_port = htons(port);
+  addr6.sin6_port = htons(port);
+  mState = CONNECTING;
+
+#if !defined(__Userspace_os_Windows)
+  if (inet_pton(AF_INET6, addr, &addr6.sin6_addr) == 1) {
+    if (usrsctp_connect(mMasterSocket, reinterpret_cast<struct sockaddr *>(&addr6), sizeof(struct sockaddr_in6)) < 0) {
+      LOG(("*** Failed userspace_connect"));
+      return false;
+    }
+  } else if (inet_pton(AF_INET, addr, &addr4.sin_addr) == 1) {
+    if (usrsctp_connect(mMasterSocket, reinterpret_cast<struct sockaddr *>(&addr4), sizeof(struct sockaddr_in)) < 0) {
+      LOG(("*** Failed userspace_connect"));
+      return false;
+    }
+  } else {
+    LOG(("*** Illegal destination address."));
+  }
+#else
+  {
+    struct sockaddr_storage ss;
+    int sslen = sizeof(ss);
+
+    if (!WSAStringToAddressA(const_cast<char *>(addr), AF_INET6, nullptr, (struct sockaddr*)&ss, &sslen)) {
+      addr6.sin6_addr = (reinterpret_cast<struct sockaddr_in6 *>(&ss))->sin6_addr;
+      if (usrsctp_connect(mMasterSocket, reinterpret_cast<struct sockaddr *>(&addr6), sizeof(struct sockaddr_in6)) < 0) {
+        LOG(("*** Failed userspace_connect"));
+        return false;
+      }
+    } else if (!WSAStringToAddressA(const_cast<char *>(addr), AF_INET, nullptr, (struct sockaddr*)&ss, &sslen)) {
+      addr4.sin_addr = (reinterpret_cast<struct sockaddr_in *>(&ss))->sin_addr;
+      if (usrsctp_connect(mMasterSocket, reinterpret_cast<struct sockaddr *>(&addr4), sizeof(struct sockaddr_in)) < 0) {
+        LOG(("*** Failed userspace_connect"));
+        return false;
+      }
+    } else {
+      LOG(("*** Illegal destination address."));
+    }
+  }
+#endif
+
+  mSocket = mMasterSocket;
+
+  LOG(("connect() succeeded!  Entering connected mode"));
+  mState = OPEN;
+
+  SetEvenOdd();
+
+  // Notify Connection open
+  // XXX We need to make sure connection sticks around until the message is delivered
+  LOG(("%s: sending ON_CONNECTION for %p", __FUNCTION__, this));
+  NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                            DataChannelOnMessageAvailable::ON_CONNECTION,
+                            this, (DataChannel *) nullptr)));
+  return true;
+}
+#endif
+
+DataChannel *
+DataChannelConnection::FindChannelByStream(uint16_t stream)
+{
+  return mStreams.SafeElementAt(stream);
+}
+
+uint16_t
+DataChannelConnection::FindFreeStream()
+{
+  uint32_t i, j, limit;
+
+  limit = mStreams.Length();
+  if (limit > MAX_NUM_STREAMS)
+    limit = MAX_NUM_STREAMS;
+
+  for (i = (mAllocateEven ? 0 : 1); i < limit; i += 2) {
+    if (!mStreams[i]) {
+      // Verify it's not still in the process of closing
+      for (j = 0; j < mStreamsResetting.Length(); ++j) {
+        if (mStreamsResetting[j] == i) {
+          break;
+        }
+      }
+      if (j == mStreamsResetting.Length())
+        break;
+    }
+  }
+  if (i >= limit) {
+    return INVALID_STREAM;
+  }
+  return i;
+}
+
+bool
+DataChannelConnection::RequestMoreStreams(int32_t aNeeded)
+{
+  struct sctp_status status;
+  struct sctp_add_streams sas;
+  uint32_t outStreamsNeeded;
+  socklen_t len;
+
+  if (aNeeded + mStreams.Length() > MAX_NUM_STREAMS) {
+    aNeeded = MAX_NUM_STREAMS - mStreams.Length();
+  }
+  if (aNeeded <= 0) {
+    return false;
+  }
+
+  len = (socklen_t)sizeof(struct sctp_status);
+  if (usrsctp_getsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_STATUS, &status, &len) < 0) {
+    LOG(("***failed: getsockopt SCTP_STATUS"));
+    return false;
+  }
+  outStreamsNeeded = aNeeded; // number to add
+
+  // Note: if multiple channel opens happen when we don't have enough space,
+  // we'll call RequestMoreStreams() multiple times
+  memset(&sas, 0, sizeof(sas));
+  sas.sas_instrms = 0;
+  sas.sas_outstrms = (uint16_t)outStreamsNeeded; /* XXX error handling */
+  // Doesn't block, we get an event when it succeeds or fails
+  if (usrsctp_setsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_ADD_STREAMS, &sas,
+                         (socklen_t) sizeof(struct sctp_add_streams)) < 0) {
+    if (errno == EALREADY) {
+      LOG(("Already have %u output streams", outStreamsNeeded));
+      return true;
+    }
+
+    LOG(("***failed: setsockopt ADD errno=%d", errno));
+    return false;
+  }
+  LOG(("Requested %u more streams", outStreamsNeeded));
+  // We add to mStreams when we get a SCTP_STREAM_CHANGE_EVENT and the
+  // values are larger than mStreams.Length()
+  return true;
+}
+
+int32_t
+DataChannelConnection::SendControlMessage(void *msg, uint32_t len, uint16_t stream)
+{
+  struct sctp_sndinfo sndinfo;
+
+  // Note: Main-thread IO, but doesn't block
+  memset(&sndinfo, 0, sizeof(struct sctp_sndinfo));
+  sndinfo.snd_sid = stream;
+  sndinfo.snd_ppid = htonl(DATA_CHANNEL_PPID_CONTROL);
+  if (usrsctp_sendv(mSocket, msg, len, nullptr, 0,
+                    &sndinfo, (socklen_t)sizeof(struct sctp_sndinfo),
+                    SCTP_SENDV_SNDINFO, 0) < 0) {
+    //LOG(("***failed: sctp_sendv")); don't log because errno is a return!
+    return (0);
+  }
+  return (1);
+}
+
+int32_t
+DataChannelConnection::SendOpenAckMessage(uint16_t stream)
+{
+  struct rtcweb_datachannel_ack ack;
+
+  memset(&ack, 0, sizeof(struct rtcweb_datachannel_ack));
+  ack.msg_type = DATA_CHANNEL_ACK;
+
+  return SendControlMessage(&ack, sizeof(ack), stream);
+}
+
+int32_t
+DataChannelConnection::SendOpenRequestMessage(const nsACString& label,
+                                              const nsACString& protocol,
+                                              uint16_t stream, bool unordered,
+                                              uint16_t prPolicy, uint32_t prValue)
+{
+  const int label_len = label.Length(); // not including nul
+  const int proto_len = protocol.Length(); // not including nul
+  // careful - request struct include one char for the label
+  const int req_size = sizeof(struct rtcweb_datachannel_open_request) - 1 +
+                        label_len + proto_len;
+  struct rtcweb_datachannel_open_request *req =
+    (struct rtcweb_datachannel_open_request*) moz_xmalloc(req_size);
+
+  memset(req, 0, req_size);
+  req->msg_type = DATA_CHANNEL_OPEN_REQUEST;
+  switch (prPolicy) {
+  case SCTP_PR_SCTP_NONE:
+    req->channel_type = DATA_CHANNEL_RELIABLE;
+    break;
+  case SCTP_PR_SCTP_TTL:
+    req->channel_type = DATA_CHANNEL_PARTIAL_RELIABLE_TIMED;
+    break;
+  case SCTP_PR_SCTP_RTX:
+    req->channel_type = DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT;
+    break;
+  default:
+    // FIX! need to set errno!  Or make all these SendXxxx() funcs return 0 or errno!
+    free(req);
+    return (0);
+  }
+  if (unordered) {
+    // Per the current types, all differ by 0x80 between ordered and unordered
+    req->channel_type |= 0x80; // NOTE: be careful if new types are added in the future
+  }
+
+  req->reliability_param = htonl(prValue);
+  req->priority = htons(0); /* XXX: add support */
+  req->label_length = htons(label_len);
+  req->protocol_length = htons(proto_len);
+  memcpy(&req->label[0], PromiseFlatCString(label).get(), label_len);
+  memcpy(&req->label[label_len], PromiseFlatCString(protocol).get(), proto_len);
+
+  int32_t result = SendControlMessage(req, req_size, stream);
+
+  free(req);
+  return result;
+}
+
+// XXX This should use a separate thread (outbound queue) which should
+// select() to know when to *try* to send data to the socket again.
+// Alternatively, it can use a timeout, but that's guaranteed to be wrong
+// (just not sure in what direction).  We could re-implement NSPR's
+// PR_POLL_WRITE/etc handling... with a lot of work.
+
+// Better yet, use the SCTP stack's notifications on buffer state to avoid
+// filling the SCTP's buffers.
+
+// returns if we're still blocked or not
+bool
+DataChannelConnection::SendDeferredMessages()
+{
+  uint32_t i;
+  RefPtr<DataChannel> channel; // we may null out the refs to this
+  bool still_blocked = false;
+
+  // This may block while something is modifying channels, but should not block for IO
+  MutexAutoLock lock(mLock);
+
+  // XXX For total fairness, on a still_blocked we'd start next time at the
+  // same index.  Sorry, not going to bother for now.
+  for (i = 0; i < mStreams.Length(); ++i) {
+    channel = mStreams[i];
+    if (!channel)
+      continue;
+
+    // Only one of these should be set....
+    if (channel->mFlags & DATA_CHANNEL_FLAGS_SEND_REQ) {
+      if (SendOpenRequestMessage(channel->mLabel, channel->mProtocol,
+                                 channel->mStream,
+                                 channel->mFlags & DATA_CHANNEL_FLAGS_OUT_OF_ORDER_ALLOWED,
+                                 channel->mPrPolicy, channel->mPrValue)) {
+        channel->mFlags &= ~DATA_CHANNEL_FLAGS_SEND_REQ;
+
+        channel->mState = OPEN;
+        channel->mReady = true;
+        LOG(("%s: sending ON_CHANNEL_OPEN for %p", __FUNCTION__, channel.get()));
+        NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                                  DataChannelOnMessageAvailable::ON_CHANNEL_OPEN, this,
+                                  channel)));
+      } else {
+        if (errno == EAGAIN || errno == EWOULDBLOCK) {
+          still_blocked = true;
+        } else {
+          // Close the channel, inform the user
+          mStreams[channel->mStream] = nullptr;
+          channel->mState = CLOSED;
+          // Don't need to reset; we didn't open it
+          NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                                    DataChannelOnMessageAvailable::ON_CHANNEL_CLOSED, this,
+                                    channel)));
+        }
+      }
+    }
+    if (still_blocked)
+      break;
+
+    if (channel->mFlags & DATA_CHANNEL_FLAGS_SEND_ACK) {
+      if (SendOpenAckMessage(channel->mStream)) {
+        channel->mFlags &= ~DATA_CHANNEL_FLAGS_SEND_ACK;
+      } else {
+        if (errno == EAGAIN || errno == EWOULDBLOCK) {
+          still_blocked = true;
+        } else {
+          // Close the channel, inform the user
+          CloseInt(channel);
+          // XXX send error via DataChannelOnMessageAvailable (bug 843625)
+        }
+      }
+    }
+    if (still_blocked)
+      break;
+
+    if (channel->mFlags & DATA_CHANNEL_FLAGS_SEND_DATA) {
+      bool failed_send = false;
+      int32_t result;
+
+      if (channel->mState == CLOSED || channel->mState == CLOSING) {
+        channel->mBufferedData.Clear();
+      }
+
+      uint32_t buffered_amount = channel->GetBufferedAmountLocked();
+      uint32_t threshold = channel->GetBufferedAmountLowThreshold();
+      bool was_over_threshold = buffered_amount >= threshold;
+
+      while (!channel->mBufferedData.IsEmpty() &&
+             !failed_send) {
+        struct sctp_sendv_spa *spa = channel->mBufferedData[0]->mSpa;
+        const char *data           = channel->mBufferedData[0]->mData;
+        size_t len                 = channel->mBufferedData[0]->mLength;
+
+        // SCTP will return EMSGSIZE if the message is bigger than the buffer
+        // size (or EAGAIN if there isn't space)
+        if ((result = usrsctp_sendv(mSocket, data, len,
+                                    nullptr, 0,
+                                    (void *)spa, (socklen_t)sizeof(struct sctp_sendv_spa),
+                                    SCTP_SENDV_SPA,
+                                    0)) < 0) {
+          if (errno == EAGAIN || errno == EWOULDBLOCK) {
+            // leave queued for resend
+            failed_send = true;
+            LOG(("queue full again when resending %d bytes (%d)", len, result));
+          } else {
+            LOG(("error %d re-sending string", errno));
+            failed_send = true;
+          }
+        } else {
+          LOG(("Resent buffer of %d bytes (%d)", len, result));
+          // In theory this could underflow if >4GB was buffered and re
+          // truncated in GetBufferedAmount(), but this won't cause any problems.
+          buffered_amount -= channel->mBufferedData[0]->mLength;
+          channel->mBufferedData.RemoveElementAt(0);
+          // can never fire with default threshold of 0
+          if (was_over_threshold && buffered_amount < threshold) {
+            LOG(("%s: sending BUFFER_LOW_THRESHOLD for %s/%s: %u", __FUNCTION__,
+                 channel->mLabel.get(), channel->mProtocol.get(), channel->mStream));
+            NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                                                DataChannelOnMessageAvailable::BUFFER_LOW_THRESHOLD,
+                                                this, channel)));
+            was_over_threshold = false;
+          }
+          if (buffered_amount == 0) {
+            // buffered-to-not-buffered transition; tell the DOM code in case this makes it
+            // available for GC
+            LOG(("%s: sending NO_LONGER_BUFFERED for %s/%s: %u", __FUNCTION__,
+                 channel->mLabel.get(), channel->mProtocol.get(), channel->mStream));
+            NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                                                DataChannelOnMessageAvailable::NO_LONGER_BUFFERED,
+                                                this, channel)));
+          }
+        }
+      }
+      if (channel->mBufferedData.IsEmpty())
+        channel->mFlags &= ~DATA_CHANNEL_FLAGS_SEND_DATA;
+      else
+        still_blocked = true;
+    }
+    if (still_blocked)
+      break;
+  }
+
+  return still_blocked;
+}
+
+void
+DataChannelConnection::HandleOpenRequestMessage(const struct rtcweb_datachannel_open_request *req,
+                                                size_t length,
+                                                uint16_t stream)
+{
+  RefPtr<DataChannel> channel;
+  uint32_t prValue;
+  uint16_t prPolicy;
+  uint32_t flags;
+
+  mLock.AssertCurrentThreadOwns();
+
+  if (length != (sizeof(*req) - 1) + ntohs(req->label_length) + ntohs(req->protocol_length)) {
+    LOG(("%s: Inconsistent length: %u, should be %u", __FUNCTION__, length,
+         (sizeof(*req) - 1) + ntohs(req->label_length) + ntohs(req->protocol_length)));
+    if (length < (sizeof(*req) - 1) + ntohs(req->label_length) + ntohs(req->protocol_length))
+      return;
+  }
+
+  LOG(("%s: length %u, sizeof(*req) = %u", __FUNCTION__, length, sizeof(*req)));
+
+  switch (req->channel_type) {
+    case DATA_CHANNEL_RELIABLE:
+    case DATA_CHANNEL_RELIABLE_UNORDERED:
+      prPolicy = SCTP_PR_SCTP_NONE;
+      break;
+    case DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT:
+    case DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED:
+      prPolicy = SCTP_PR_SCTP_RTX;
+      break;
+    case DATA_CHANNEL_PARTIAL_RELIABLE_TIMED:
+    case DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED:
+      prPolicy = SCTP_PR_SCTP_TTL;
+      break;
+    default:
+      LOG(("Unknown channel type", req->channel_type));
+      /* XXX error handling */
+      return;
+  }
+  prValue = ntohl(req->reliability_param);
+  flags = (req->channel_type & 0x80) ? DATA_CHANNEL_FLAGS_OUT_OF_ORDER_ALLOWED : 0;
+
+  if ((channel = FindChannelByStream(stream))) {
+    if (!(channel->mFlags & DATA_CHANNEL_FLAGS_EXTERNAL_NEGOTIATED)) {
+      LOG(("ERROR: HandleOpenRequestMessage: channel for stream %u is in state %d instead of CLOSED.",
+           stream, channel->mState));
+     /* XXX: some error handling */
+    } else {
+      LOG(("Open for externally negotiated channel %u", stream));
+      // XXX should also check protocol, maybe label
+      if (prPolicy != channel->mPrPolicy ||
+          prValue != channel->mPrValue ||
+          flags != (channel->mFlags & DATA_CHANNEL_FLAGS_OUT_OF_ORDER_ALLOWED))
+      {
+        LOG(("WARNING: external negotiation mismatch with OpenRequest:"
+             "channel %u, policy %u/%u, value %u/%u, flags %x/%x",
+             stream, prPolicy, channel->mPrPolicy,
+             prValue, channel->mPrValue, flags, channel->mFlags));
+      }
+    }
+    return;
+  }
+  if (stream >= mStreams.Length()) {
+    LOG(("%s: stream %u out of bounds (%u)", __FUNCTION__, stream, mStreams.Length()));
+    return;
+  }
+
+  nsCString label(nsDependentCSubstring(&req->label[0], ntohs(req->label_length)));
+  nsCString protocol(nsDependentCSubstring(&req->label[ntohs(req->label_length)],
+                                           ntohs(req->protocol_length)));
+
+  channel = new DataChannel(this,
+                            stream,
+                            DataChannel::CONNECTING,
+                            label,
+                            protocol,
+                            prPolicy, prValue,
+                            flags,
+                            nullptr, nullptr);
+  mStreams[stream] = channel;
+
+  channel->mState = DataChannel::WAITING_TO_OPEN;
+
+  LOG(("%s: sending ON_CHANNEL_CREATED for %s/%s: %u (state %u)", __FUNCTION__,
+       channel->mLabel.get(), channel->mProtocol.get(), stream, channel->mState));
+  NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                            DataChannelOnMessageAvailable::ON_CHANNEL_CREATED,
+                            this, channel)));
+
+  LOG(("%s: deferring sending ON_CHANNEL_OPEN for %p", __FUNCTION__, channel.get()));
+
+  if (!SendOpenAckMessage(stream)) {
+    // XXX Only on EAGAIN!?  And if not, then close the channel??
+    channel->mFlags |= DATA_CHANNEL_FLAGS_SEND_ACK;
+    // Note: we're locked, so there's no danger of a race with the
+    // buffer-threshold callback
+  }
+
+  // Now process any queued data messages for the channel (which will
+  // themselves likely get queued until we leave WAITING_TO_OPEN, plus any
+  // more that come in before that happens)
+  DeliverQueuedData(stream);
+}
+
+// NOTE: the updated spec from the IETF says we should set in-order until we receive an ACK.
+// That would make this code moot.  Keep it for now for backwards compatibility.
+void
+DataChannelConnection::DeliverQueuedData(uint16_t stream)
+{
+  mLock.AssertCurrentThreadOwns();
+
+  uint32_t i = 0;
+  while (i < mQueuedData.Length()) {
+    // Careful! we may modify the array length from within the loop!
+    if (mQueuedData[i]->mStream == stream) {
+      LOG(("Delivering queued data for stream %u, length %u",
+           stream, (unsigned int) mQueuedData[i]->mLength));
+      // Deliver the queued data
+      HandleDataMessage(mQueuedData[i]->mPpid,
+                        mQueuedData[i]->mData, mQueuedData[i]->mLength,
+                        mQueuedData[i]->mStream);
+      mQueuedData.RemoveElementAt(i);
+      continue; // don't bump index since we removed the element
+    }
+    i++;
+  }
+}
+
+void
+DataChannelConnection::HandleOpenAckMessage(const struct rtcweb_datachannel_ack *ack,
+                                            size_t length, uint16_t stream)
+{
+  DataChannel *channel;
+
+  mLock.AssertCurrentThreadOwns();
+
+  channel = FindChannelByStream(stream);
+  NS_ENSURE_TRUE_VOID(channel);
+
+  LOG(("OpenAck received for stream %u, waiting=%d", stream,
+       (channel->mFlags & DATA_CHANNEL_FLAGS_WAITING_ACK) ? 1 : 0));
+
+  channel->mFlags &= ~DATA_CHANNEL_FLAGS_WAITING_ACK;
+}
+
+void
+DataChannelConnection::HandleUnknownMessage(uint32_t ppid, size_t length, uint16_t stream)
+{
+  /* XXX: Send an error message? */
+  LOG(("unknown DataChannel message received: %u, len %ld on stream %lu", ppid, length, stream));
+  // XXX Log to JS error console if possible
+}
+
+void
+DataChannelConnection::HandleDataMessage(uint32_t ppid,
+                                         const void *data, size_t length,
+                                         uint16_t stream)
+{
+  DataChannel *channel;
+  const char *buffer = (const char *) data;
+
+  mLock.AssertCurrentThreadOwns();
+
+  channel = FindChannelByStream(stream);
+
+  // XXX A closed channel may trip this... check
+  // NOTE: the updated spec from the IETF says we should set in-order until we receive an ACK.
+  // That would make this code moot.  Keep it for now for backwards compatibility.
+  if (!channel) {
+    // In the updated 0-RTT open case, the sender can send data immediately
+    // after Open, and doesn't set the in-order bit (since we don't have a
+    // response or ack).  Also, with external negotiation, data can come in
+    // before we're told about the external negotiation.  We need to buffer
+    // data until either a) Open comes in, if the ordering get messed up,
+    // or b) the app tells us this channel was externally negotiated.  When
+    // these occur, we deliver the data.
+
+    // Since this is rare and non-performance, keep a single list of queued
+    // data messages to deliver once the channel opens.
+    LOG(("Queuing data for stream %u, length %u", stream, length));
+    // Copies data
+    mQueuedData.AppendElement(new QueuedDataMessage(stream, ppid, data, length));
+    return;
+  }
+
+  // XXX should this be a simple if, no warnings/debugbreaks?
+  NS_ENSURE_TRUE_VOID(channel->mState != CLOSED);
+
+  {
+    nsAutoCString recvData(buffer, length); // copies (<64) or allocates
+    bool is_binary = true;
+
+    if (ppid == DATA_CHANNEL_PPID_DOMSTRING ||
+        ppid == DATA_CHANNEL_PPID_DOMSTRING_LAST) {
+      is_binary = false;
+    }
+    if (is_binary != channel->mIsRecvBinary && !channel->mRecvBuffer.IsEmpty()) {
+      NS_WARNING("DataChannel message aborted by fragment type change!");
+      channel->mRecvBuffer.Truncate(0);
+    }
+    channel->mIsRecvBinary = is_binary;
+
+    switch (ppid) {
+      case DATA_CHANNEL_PPID_DOMSTRING:
+      case DATA_CHANNEL_PPID_BINARY:
+        channel->mRecvBuffer += recvData;
+        LOG(("DataChannel: Partial %s message of length %lu (total %u) on channel id %u",
+             is_binary ? "binary" : "string", length, channel->mRecvBuffer.Length(),
+             channel->mStream));
+        return; // Not ready to notify application
+
+      case DATA_CHANNEL_PPID_DOMSTRING_LAST:
+        LOG(("DataChannel: String message received of length %lu on channel %u",
+             length, channel->mStream));
+        if (!channel->mRecvBuffer.IsEmpty()) {
+          channel->mRecvBuffer += recvData;
+          LOG(("%s: sending ON_DATA (string fragmented) for %p", __FUNCTION__, channel));
+          channel->SendOrQueue(new DataChannelOnMessageAvailable(
+                                 DataChannelOnMessageAvailable::ON_DATA, this,
+                                 channel, channel->mRecvBuffer, -1));
+          channel->mRecvBuffer.Truncate(0);
+          return;
+        }
+        // else send using recvData normally
+        length = -1; // Flag for DOMString
+
+        // WebSockets checks IsUTF8() here; we can try to deliver it
+        break;
+
+      case DATA_CHANNEL_PPID_BINARY_LAST:
+        LOG(("DataChannel: Received binary message of length %lu on channel id %u",
+             length, channel->mStream));
+        if (!channel->mRecvBuffer.IsEmpty()) {
+          channel->mRecvBuffer += recvData;
+          LOG(("%s: sending ON_DATA (binary fragmented) for %p", __FUNCTION__, channel));
+          channel->SendOrQueue(new DataChannelOnMessageAvailable(
+                                 DataChannelOnMessageAvailable::ON_DATA, this,
+                                 channel, channel->mRecvBuffer,
+                                 channel->mRecvBuffer.Length()));
+          channel->mRecvBuffer.Truncate(0);
+          return;
+        }
+        // else send using recvData normally
+        break;
+
+      default:
+        NS_ERROR("Unknown data PPID");
+        return;
+    }
+    /* Notify onmessage */
+    LOG(("%s: sending ON_DATA for %p", __FUNCTION__, channel));
+    channel->SendOrQueue(new DataChannelOnMessageAvailable(
+                           DataChannelOnMessageAvailable::ON_DATA, this,
+                           channel, recvData, length));
+  }
+}
+
+// Called with mLock locked!
+void
+DataChannelConnection::HandleMessage(const void *buffer, size_t length, uint32_t ppid, uint16_t stream)
+{
+  const struct rtcweb_datachannel_open_request *req;
+  const struct rtcweb_datachannel_ack *ack;
+
+  mLock.AssertCurrentThreadOwns();
+
+  switch (ppid) {
+    case DATA_CHANNEL_PPID_CONTROL:
+      req = static_cast<const struct rtcweb_datachannel_open_request *>(buffer);
+
+      NS_ENSURE_TRUE_VOID(length >= sizeof(*ack)); // smallest message
+      switch (req->msg_type) {
+        case DATA_CHANNEL_OPEN_REQUEST:
+          // structure includes a possibly-unused char label[1] (in a packed structure)
+          NS_ENSURE_TRUE_VOID(length >= sizeof(*req) - 1);
+
+          HandleOpenRequestMessage(req, length, stream);
+          break;
+        case DATA_CHANNEL_ACK:
+          // >= sizeof(*ack) checked above
+
+          ack = static_cast<const struct rtcweb_datachannel_ack *>(buffer);
+          HandleOpenAckMessage(ack, length, stream);
+          break;
+        default:
+          HandleUnknownMessage(ppid, length, stream);
+          break;
+      }
+      break;
+    case DATA_CHANNEL_PPID_DOMSTRING:
+    case DATA_CHANNEL_PPID_DOMSTRING_LAST:
+    case DATA_CHANNEL_PPID_BINARY:
+    case DATA_CHANNEL_PPID_BINARY_LAST:
+      HandleDataMessage(ppid, buffer, length, stream);
+      break;
+    default:
+      LOG(("Message of length %lu, PPID %u on stream %u received.",
+           length, ppid, stream));
+      break;
+  }
+}
+
+void
+DataChannelConnection::HandleAssociationChangeEvent(const struct sctp_assoc_change *sac)
+{
+  uint32_t i, n;
+
+  switch (sac->sac_state) {
+  case SCTP_COMM_UP:
+    LOG(("Association change: SCTP_COMM_UP"));
+    if (mState == CONNECTING) {
+      mSocket = mMasterSocket;
+      mState = OPEN;
+
+      SetEvenOdd();
+
+      NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                                DataChannelOnMessageAvailable::ON_CONNECTION,
+                                this)));
+      LOG(("DTLS connect() succeeded!  Entering connected mode"));
+
+      // Open any streams pending...
+      ProcessQueuedOpens();
+
+    } else if (mState == OPEN) {
+      LOG(("DataConnection Already OPEN"));
+    } else {
+      LOG(("Unexpected state: %d", mState));
+    }
+    break;
+  case SCTP_COMM_LOST:
+    LOG(("Association change: SCTP_COMM_LOST"));
+    // This association is toast, so also close all the channels -- from mainthread!
+    NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                              DataChannelOnMessageAvailable::ON_DISCONNECTED,
+                              this)));
+    break;
+  case SCTP_RESTART:
+    LOG(("Association change: SCTP_RESTART"));
+    break;
+  case SCTP_SHUTDOWN_COMP:
+    LOG(("Association change: SCTP_SHUTDOWN_COMP"));
+    NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                              DataChannelOnMessageAvailable::ON_DISCONNECTED,
+                              this)));
+    break;
+  case SCTP_CANT_STR_ASSOC:
+    LOG(("Association change: SCTP_CANT_STR_ASSOC"));
+    break;
+  default:
+    LOG(("Association change: UNKNOWN"));
+    break;
+  }
+  LOG(("Association change: streams (in/out) = (%u/%u)",
+       sac->sac_inbound_streams, sac->sac_outbound_streams));
+
+  NS_ENSURE_TRUE_VOID(sac);
+  n = sac->sac_length - sizeof(*sac);
+  if (((sac->sac_state == SCTP_COMM_UP) ||
+        (sac->sac_state == SCTP_RESTART)) && (n > 0)) {
+    for (i = 0; i < n; ++i) {
+      switch (sac->sac_info[i]) {
+      case SCTP_ASSOC_SUPPORTS_PR:
+        LOG(("Supports: PR"));
+        break;
+      case SCTP_ASSOC_SUPPORTS_AUTH:
+        LOG(("Supports: AUTH"));
+        break;
+      case SCTP_ASSOC_SUPPORTS_ASCONF:
+        LOG(("Supports: ASCONF"));
+        break;
+      case SCTP_ASSOC_SUPPORTS_MULTIBUF:
+        LOG(("Supports: MULTIBUF"));
+        break;
+      case SCTP_ASSOC_SUPPORTS_RE_CONFIG:
+        LOG(("Supports: RE-CONFIG"));
+        break;
+      default:
+        LOG(("Supports: UNKNOWN(0x%02x)", sac->sac_info[i]));
+        break;
+      }
+    }
+  } else if (((sac->sac_state == SCTP_COMM_LOST) ||
+              (sac->sac_state == SCTP_CANT_STR_ASSOC)) && (n > 0)) {
+    LOG(("Association: ABORT ="));
+    for (i = 0; i < n; ++i) {
+      LOG((" 0x%02x", sac->sac_info[i]));
+    }
+  }
+  if ((sac->sac_state == SCTP_CANT_STR_ASSOC) ||
+      (sac->sac_state == SCTP_SHUTDOWN_COMP) ||
+      (sac->sac_state == SCTP_COMM_LOST)) {
+    return;
+  }
+}
+
+void
+DataChannelConnection::HandlePeerAddressChangeEvent(const struct sctp_paddr_change *spc)
+{
+  const char *addr = "";
+#if !defined(__Userspace_os_Windows)
+  char addr_buf[INET6_ADDRSTRLEN];
+  struct sockaddr_in *sin;
+  struct sockaddr_in6 *sin6;
+#endif
+
+  switch (spc->spc_aaddr.ss_family) {
+  case AF_INET:
+#if !defined(__Userspace_os_Windows)
+    sin = (struct sockaddr_in *)&spc->spc_aaddr;
+    addr = inet_ntop(AF_INET, &sin->sin_addr, addr_buf, INET6_ADDRSTRLEN);
+#endif
+    break;
+  case AF_INET6:
+#if !defined(__Userspace_os_Windows)
+    sin6 = (struct sockaddr_in6 *)&spc->spc_aaddr;
+    addr = inet_ntop(AF_INET6, &sin6->sin6_addr, addr_buf, INET6_ADDRSTRLEN);
+#endif
+    break;
+  case AF_CONN:
+    addr = "DTLS connection";
+    break;
+  default:
+    break;
+  }
+  LOG(("Peer address %s is now ", addr));
+  switch (spc->spc_state) {
+  case SCTP_ADDR_AVAILABLE:
+    LOG(("SCTP_ADDR_AVAILABLE"));
+    break;
+  case SCTP_ADDR_UNREACHABLE:
+    LOG(("SCTP_ADDR_UNREACHABLE"));
+    break;
+  case SCTP_ADDR_REMOVED:
+    LOG(("SCTP_ADDR_REMOVED"));
+    break;
+  case SCTP_ADDR_ADDED:
+    LOG(("SCTP_ADDR_ADDED"));
+    break;
+  case SCTP_ADDR_MADE_PRIM:
+    LOG(("SCTP_ADDR_MADE_PRIM"));
+    break;
+  case SCTP_ADDR_CONFIRMED:
+    LOG(("SCTP_ADDR_CONFIRMED"));
+    break;
+  default:
+    LOG(("UNKNOWN"));
+    break;
+  }
+  LOG((" (error = 0x%08x).\n", spc->spc_error));
+}
+
+void
+DataChannelConnection::HandleRemoteErrorEvent(const struct sctp_remote_error *sre)
+{
+  size_t i, n;
+
+  n = sre->sre_length - sizeof(struct sctp_remote_error);
+  LOG(("Remote Error (error = 0x%04x): ", sre->sre_error));
+  for (i = 0; i < n; ++i) {
+    LOG((" 0x%02x", sre-> sre_data[i]));
+  }
+}
+
+void
+DataChannelConnection::HandleShutdownEvent(const struct sctp_shutdown_event *sse)
+{
+  LOG(("Shutdown event."));
+  /* XXX: notify all channels. */
+  // Attempts to actually send anything will fail
+}
+
+void
+DataChannelConnection::HandleAdaptationIndication(const struct sctp_adaptation_event *sai)
+{
+  LOG(("Adaptation indication: %x.", sai-> sai_adaptation_ind));
+}
+
+void
+DataChannelConnection::HandleSendFailedEvent(const struct sctp_send_failed_event *ssfe)
+{
+  size_t i, n;
+
+  if (ssfe->ssfe_flags & SCTP_DATA_UNSENT) {
+    LOG(("Unsent "));
+  }
+   if (ssfe->ssfe_flags & SCTP_DATA_SENT) {
+    LOG(("Sent "));
+  }
+  if (ssfe->ssfe_flags & ~(SCTP_DATA_SENT | SCTP_DATA_UNSENT)) {
+    LOG(("(flags = %x) ", ssfe->ssfe_flags));
+  }
+  LOG(("message with PPID = %u, SID = %d, flags: 0x%04x due to error = 0x%08x",
+       ntohl(ssfe->ssfe_info.snd_ppid), ssfe->ssfe_info.snd_sid,
+       ssfe->ssfe_info.snd_flags, ssfe->ssfe_error));
+  n = ssfe->ssfe_length - sizeof(struct sctp_send_failed_event);
+  for (i = 0; i < n; ++i) {
+    LOG((" 0x%02x", ssfe->ssfe_data[i]));
+  }
+}
+
+void
+DataChannelConnection::ClearResets()
+{
+  // Clear all pending resets
+  if (!mStreamsResetting.IsEmpty()) {
+    LOG(("Clearing resets for %d streams", mStreamsResetting.Length()));
+  }
+
+  for (uint32_t i = 0; i < mStreamsResetting.Length(); ++i) {
+    RefPtr<DataChannel> channel;
+    channel = FindChannelByStream(mStreamsResetting[i]);
+    if (channel) {
+      LOG(("Forgetting channel %u (%p) with pending reset",channel->mStream, channel.get()));
+      mStreams[channel->mStream] = nullptr;
+    }
+  }
+  mStreamsResetting.Clear();
+}
+
+void
+DataChannelConnection::ResetOutgoingStream(uint16_t stream)
+{
+  uint32_t i;
+
+  mLock.AssertCurrentThreadOwns();
+  LOG(("Connection %p: Resetting outgoing stream %u",
+       (void *) this, stream));
+  // Rarely has more than a couple items and only for a short time
+  for (i = 0; i < mStreamsResetting.Length(); ++i) {
+    if (mStreamsResetting[i] == stream) {
+      return;
+    }
+  }
+  mStreamsResetting.AppendElement(stream);
+}
+
+void
+DataChannelConnection::SendOutgoingStreamReset()
+{
+  struct sctp_reset_streams *srs;
+  uint32_t i;
+  size_t len;
+
+  LOG(("Connection %p: Sending outgoing stream reset for %d streams",
+       (void *) this, mStreamsResetting.Length()));
+  mLock.AssertCurrentThreadOwns();
+  if (mStreamsResetting.IsEmpty()) {
+    LOG(("No streams to reset"));
+    return;
+  }
+  len = sizeof(sctp_assoc_t) + (2 + mStreamsResetting.Length()) * sizeof(uint16_t);
+  srs = static_cast<struct sctp_reset_streams *> (moz_xmalloc(len)); // infallible malloc
+  memset(srs, 0, len);
+  srs->srs_flags = SCTP_STREAM_RESET_OUTGOING;
+  srs->srs_number_streams = mStreamsResetting.Length();
+  for (i = 0; i < mStreamsResetting.Length(); ++i) {
+    srs->srs_stream_list[i] = mStreamsResetting[i];
+  }
+  if (usrsctp_setsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_RESET_STREAMS, srs, (socklen_t)len) < 0) {
+    LOG(("***failed: setsockopt RESET, errno %d", errno));
+    // if errno == EALREADY, this is normal - we can't send another reset
+    // with one pending.
+    // When we get an incoming reset (which may be a response to our
+    // outstanding one), see if we have any pending outgoing resets and
+    // send them
+  } else {
+    mStreamsResetting.Clear();
+  }
+  free(srs);
+}
+
+void
+DataChannelConnection::HandleStreamResetEvent(const struct sctp_stream_reset_event *strrst)
+{
+  uint32_t n, i;
+  RefPtr<DataChannel> channel; // since we may null out the ref to the channel
+
+  if (!(strrst->strreset_flags & SCTP_STREAM_RESET_DENIED) &&
+      !(strrst->strreset_flags & SCTP_STREAM_RESET_FAILED)) {
+    n = (strrst->strreset_length - sizeof(struct sctp_stream_reset_event)) / sizeof(uint16_t);
+    for (i = 0; i < n; ++i) {
+      if (strrst->strreset_flags & SCTP_STREAM_RESET_INCOMING_SSN) {
+        channel = FindChannelByStream(strrst->strreset_stream_list[i]);
+        if (channel) {
+          // The other side closed the channel
+          // We could be in three states:
+          // 1. Normal state (input and output streams (OPEN)
+          //    Notify application, send a RESET in response on our
+          //    outbound channel.  Go to CLOSED
+          // 2. We sent our own reset (CLOSING); either they crossed on the
+          //    wire, or this is a response to our Reset.
+          //    Go to CLOSED
+          // 3. We've sent a open but haven't gotten a response yet (CONNECTING)
+          //    I believe this is impossible, as we don't have an input stream yet.
+
+          LOG(("Incoming: Channel %u  closed, state %d",
+               channel->mStream, channel->mState));
+          ASSERT_WEBRTC(channel->mState == DataChannel::OPEN ||
+                        channel->mState == DataChannel::CLOSING ||
+                        channel->mState == DataChannel::CONNECTING ||
+                        channel->mState == DataChannel::WAITING_TO_OPEN);
+          if (channel->mState == DataChannel::OPEN ||
+              channel->mState == DataChannel::WAITING_TO_OPEN) {
+            // Mark the stream for reset (the reset is sent below)
+            ResetOutgoingStream(channel->mStream);
+          }
+          mStreams[channel->mStream] = nullptr;
+
+          LOG(("Disconnected DataChannel %p from connection %p",
+               (void *) channel.get(), (void *) channel->mConnection.get()));
+          // This sends ON_CHANNEL_CLOSED to mainthread
+          channel->StreamClosedLocked();
+        } else {
+          LOG(("Can't find incoming channel %d",i));
+        }
+      }
+    }
+  }
+
+  // Process any pending resets now:
+  if (!mStreamsResetting.IsEmpty()) {
+    LOG(("Sending %d pending resets", mStreamsResetting.Length()));
+    SendOutgoingStreamReset();
+  }
+}
+
+void
+DataChannelConnection::HandleStreamChangeEvent(const struct sctp_stream_change_event *strchg)
+{
+  uint16_t stream;
+  RefPtr<DataChannel> channel;
+
+  if (strchg->strchange_flags == SCTP_STREAM_CHANGE_DENIED) {
+    LOG(("*** Failed increasing number of streams from %u (%u/%u)",
+         mStreams.Length(),
+         strchg->strchange_instrms,
+         strchg->strchange_outstrms));
+    // XXX FIX! notify pending opens of failure
+    return;
+  } else {
+    if (strchg->strchange_instrms > mStreams.Length()) {
+      LOG(("Other side increased streams from %u to %u",
+           mStreams.Length(), strchg->strchange_instrms));
+    }
+    if (strchg->strchange_outstrms > mStreams.Length() ||
+        strchg->strchange_instrms > mStreams.Length()) {
+      uint16_t old_len = mStreams.Length();
+      uint16_t new_len = std::max(strchg->strchange_outstrms,
+                                  strchg->strchange_instrms);
+      LOG(("Increasing number of streams from %u to %u - adding %u (in: %u)",
+           old_len, new_len, new_len - old_len,
+           strchg->strchange_instrms));
+      // make sure both are the same length
+      mStreams.AppendElements(new_len - old_len);
+      LOG(("New length = %d (was %d)", mStreams.Length(), old_len));
+      for (size_t i = old_len; i < mStreams.Length(); ++i) {
+        mStreams[i] = nullptr;
+      }
+      // Re-process any channels waiting for streams.
+      // Linear search, but we don't increase channels often and
+      // the array would only get long in case of an app error normally
+
+      // Make sure we request enough streams if there's a big jump in streams
+      // Could make a more complex API for OpenXxxFinish() and avoid this loop
+      size_t num_needed = mPending.GetSize();
+      LOG(("%d of %d new streams already needed", num_needed,
+           new_len - old_len));
+      num_needed -= (new_len - old_len); // number we added
+      if (num_needed > 0) {
+        if (num_needed < 16)
+          num_needed = 16;
+        LOG(("Not enough new streams, asking for %d more", num_needed));
+        RequestMoreStreams(num_needed);
+      } else if (strchg->strchange_outstrms < strchg->strchange_instrms) {
+        LOG(("Requesting %d output streams to match partner",
+             strchg->strchange_instrms - strchg->strchange_outstrms));
+        RequestMoreStreams(strchg->strchange_instrms - strchg->strchange_outstrms);
+      }
+
+      ProcessQueuedOpens();
+    }
+    // else probably not a change in # of streams
+  }
+
+  for (uint32_t i = 0; i < mStreams.Length(); ++i) {
+    channel = mStreams[i];
+    if (!channel)
+      continue;
+
+    if ((channel->mState == CONNECTING) &&
+        (channel->mStream == INVALID_STREAM)) {
+      if ((strchg->strchange_flags & SCTP_STREAM_CHANGE_DENIED) ||
+          (strchg->strchange_flags & SCTP_STREAM_CHANGE_FAILED)) {
+        /* XXX: Signal to the other end. */
+        channel->mState = CLOSED;
+        NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                                  DataChannelOnMessageAvailable::ON_CHANNEL_CLOSED, this,
+                                  channel)));
+        // maybe fire onError (bug 843625)
+      } else {
+        stream = FindFreeStream();
+        if (stream != INVALID_STREAM) {
+          channel->mStream = stream;
+          mStreams[stream] = channel;
+          channel->mFlags |= DATA_CHANNEL_FLAGS_SEND_REQ;
+          // Note: we're locked, so there's no danger of a race with the
+          // buffer-threshold callback
+        } else {
+          /* We will not find more ... */
+          break;
+        }
+      }
+    }
+  }
+}
+
+// Called with mLock locked!
+void
+DataChannelConnection::HandleNotification(const union sctp_notification *notif, size_t n)
+{
+  mLock.AssertCurrentThreadOwns();
+  if (notif->sn_header.sn_length != (uint32_t)n) {
+    return;
+  }
+  switch (notif->sn_header.sn_type) {
+  case SCTP_ASSOC_CHANGE:
+    HandleAssociationChangeEvent(&(notif->sn_assoc_change));
+    break;
+  case SCTP_PEER_ADDR_CHANGE:
+    HandlePeerAddressChangeEvent(&(notif->sn_paddr_change));
+    break;
+  case SCTP_REMOTE_ERROR:
+    HandleRemoteErrorEvent(&(notif->sn_remote_error));
+    break;
+  case SCTP_SHUTDOWN_EVENT:
+    HandleShutdownEvent(&(notif->sn_shutdown_event));
+    break;
+  case SCTP_ADAPTATION_INDICATION:
+    HandleAdaptationIndication(&(notif->sn_adaptation_event));
+    break;
+  case SCTP_PARTIAL_DELIVERY_EVENT:
+    LOG(("SCTP_PARTIAL_DELIVERY_EVENT"));
+    break;
+  case SCTP_AUTHENTICATION_EVENT:
+    LOG(("SCTP_AUTHENTICATION_EVENT"));
+    break;
+  case SCTP_SENDER_DRY_EVENT:
+    //LOG(("SCTP_SENDER_DRY_EVENT"));
+    break;
+  case SCTP_NOTIFICATIONS_STOPPED_EVENT:
+    LOG(("SCTP_NOTIFICATIONS_STOPPED_EVENT"));
+    break;
+  case SCTP_SEND_FAILED_EVENT:
+    HandleSendFailedEvent(&(notif->sn_send_failed_event));
+    break;
+  case SCTP_STREAM_RESET_EVENT:
+    HandleStreamResetEvent(&(notif->sn_strreset_event));
+    break;
+  case SCTP_ASSOC_RESET_EVENT:
+    LOG(("SCTP_ASSOC_RESET_EVENT"));
+    break;
+  case SCTP_STREAM_CHANGE_EVENT:
+    HandleStreamChangeEvent(&(notif->sn_strchange_event));
+    break;
+  default:
+    LOG(("unknown SCTP event: %u", (uint32_t)notif->sn_header.sn_type));
+    break;
+   }
+ }
+
+int
+DataChannelConnection::ReceiveCallback(struct socket* sock, void *data, size_t datalen,
+                                       struct sctp_rcvinfo rcv, int32_t flags)
+{
+  ASSERT_WEBRTC(!NS_IsMainThread());
+
+  if (!data) {
+    usrsctp_close(sock); // SCTP has finished shutting down
+  } else {
+    MutexAutoLock lock(mLock);
+    if (flags & MSG_NOTIFICATION) {
+      HandleNotification(static_cast<union sctp_notification *>(data), datalen);
+    } else {
+      HandleMessage(data, datalen, ntohl(rcv.rcv_ppid), rcv.rcv_sid);
+    }
+  }
+  // sctp allocates 'data' with malloc(), and expects the receiver to free
+  // it (presumably with free).
+  // XXX future optimization: try to deliver messages without an internal
+  // alloc/copy, and if so delay the free until later.
+  free(data);
+  // usrsctp defines the callback as returning an int, but doesn't use it
+  return 1;
+}
+
+already_AddRefed<DataChannel>
+DataChannelConnection::Open(const nsACString& label, const nsACString& protocol,
+                            Type type, bool inOrder,
+                            uint32_t prValue, DataChannelListener *aListener,
+                            nsISupports *aContext, bool aExternalNegotiated,
+                            uint16_t aStream)
+{
+  // aStream == INVALID_STREAM to have the protocol allocate
+  uint16_t prPolicy = SCTP_PR_SCTP_NONE;
+  uint32_t flags;
+
+  LOG(("DC Open: label %s/%s, type %u, inorder %d, prValue %u, listener %p, context %p, external: %s, stream %u",
+       PromiseFlatCString(label).get(), PromiseFlatCString(protocol).get(),
+       type, inOrder, prValue, aListener, aContext,
+       aExternalNegotiated ? "true" : "false", aStream));
+  switch (type) {
+    case DATA_CHANNEL_RELIABLE:
+      prPolicy = SCTP_PR_SCTP_NONE;
+      break;
+    case DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT:
+      prPolicy = SCTP_PR_SCTP_RTX;
+      break;
+    case DATA_CHANNEL_PARTIAL_RELIABLE_TIMED:
+      prPolicy = SCTP_PR_SCTP_TTL;
+      break;
+  }
+  if ((prPolicy == SCTP_PR_SCTP_NONE) && (prValue != 0)) {
+    return nullptr;
+  }
+
+  // Don't look past currently-negotiated streams
+  if (aStream != INVALID_STREAM && aStream < mStreams.Length() && mStreams[aStream]) {
+    LOG(("ERROR: external negotiation of already-open channel %u", aStream));
+    // XXX How do we indicate this up to the application?  Probably the
+    // caller's job, but we may need to return an error code.
+    return nullptr;
+  }
+
+  flags = !inOrder ? DATA_CHANNEL_FLAGS_OUT_OF_ORDER_ALLOWED : 0;
+  RefPtr<DataChannel> channel(new DataChannel(this,
+                                                aStream,
+                                                DataChannel::CONNECTING,
+                                                label, protocol,
+                                                type, prValue,
+                                                flags,
+                                                aListener, aContext));
+  if (aExternalNegotiated) {
+    channel->mFlags |= DATA_CHANNEL_FLAGS_EXTERNAL_NEGOTIATED;
+  }
+
+  MutexAutoLock lock(mLock); // OpenFinish assumes this
+  return OpenFinish(channel.forget());
+}
+
+// Separate routine so we can also call it to finish up from pending opens
+already_AddRefed<DataChannel>
+DataChannelConnection::OpenFinish(already_AddRefed<DataChannel>&& aChannel)
+{
+  RefPtr<DataChannel> channel(aChannel); // takes the reference passed in
+  // Normally 1 reference if called from ::Open(), or 2 if called from
+  // ProcessQueuedOpens() unless the DOMDataChannel was gc'd
+  uint16_t stream = channel->mStream;
+  bool queue = false;
+
+  mLock.AssertCurrentThreadOwns();
+
+  // Cases we care about:
+  // Pre-negotiated:
+  //    Not Open:
+  //      Doesn't fit:
+  //         -> change initial ask or renegotiate after open
+  //      -> queue open
+  //    Open:
+  //      Doesn't fit:
+  //         -> RequestMoreStreams && queue
+  //      Does fit:
+  //         -> open
+  // Not negotiated:
+  //    Not Open:
+  //      -> queue open
+  //    Open:
+  //      -> Try to get a stream
+  //      Doesn't fit:
+  //         -> RequestMoreStreams && queue
+  //      Does fit:
+  //         -> open
+  // So the Open cases are basically the same
+  // Not Open cases are simply queue for non-negotiated, and
+  // either change the initial ask or possibly renegotiate after open.
+
+  if (mState == OPEN) {
+    if (stream == INVALID_STREAM) {
+      stream = FindFreeStream(); // may be INVALID_STREAM if we need more
+    }
+    if (stream == INVALID_STREAM || stream >= mStreams.Length()) {
+      // RequestMoreStreams() limits to MAX_NUM_STREAMS -- allocate extra streams
+      // to avoid going back immediately for more if the ask to N, N+1, etc
+      int32_t more_needed = (stream == INVALID_STREAM) ? 16 :
+                            (stream-((int32_t)mStreams.Length())) + 16;
+      if (!RequestMoreStreams(more_needed)) {
+        // Something bad happened... we're done
+        goto request_error_cleanup;
+      }
+      queue = true;
+    }
+  } else {
+    // not OPEN
+    if (stream != INVALID_STREAM && stream >= mStreams.Length() &&
+        mState == CLOSED) {
+      // Update number of streams for init message
+      struct sctp_initmsg initmsg;
+      socklen_t len = sizeof(initmsg);
+      int32_t total_needed = stream+16;
+
+      memset(&initmsg, 0, sizeof(initmsg));
+      if (usrsctp_getsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_INITMSG, &initmsg, &len) < 0) {
+        LOG(("*** failed getsockopt SCTP_INITMSG"));
+        goto request_error_cleanup;
+      }
+      LOG(("Setting number of SCTP streams to %u, was %u/%u", total_needed,
+           initmsg.sinit_num_ostreams, initmsg.sinit_max_instreams));
+      initmsg.sinit_num_ostreams  = total_needed;
+      initmsg.sinit_max_instreams = MAX_NUM_STREAMS;
+      if (usrsctp_setsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_INITMSG, &initmsg,
+                             (socklen_t)sizeof(initmsg)) < 0) {
+        LOG(("*** failed setsockopt SCTP_INITMSG, errno %d", errno));
+        goto request_error_cleanup;
+      }
+
+      int32_t old_len = mStreams.Length();
+      mStreams.AppendElements(total_needed - old_len);
+      for (int32_t i = old_len; i < total_needed; ++i) {
+        mStreams[i] = nullptr;
+      }
+    }
+    // else if state is CONNECTING, we'll just re-negotiate when OpenFinish
+    // is called, if needed
+    queue = true;
+  }
+  if (queue) {
+    LOG(("Queuing channel %p (%u) to finish open", channel.get(), stream));
+    // Also serves to mark we told the app
+    channel->mFlags |= DATA_CHANNEL_FLAGS_FINISH_OPEN;
+    // we need a ref for the nsDeQue and one to return
+    DataChannel* rawChannel = channel;
+    rawChannel->AddRef();
+    mPending.Push(rawChannel);
+    return channel.forget();
+  }
+
+  MOZ_ASSERT(stream != INVALID_STREAM);
+  // just allocated (& OPEN), or externally negotiated
+  mStreams[stream] = channel; // holds a reference
+  channel->mStream = stream;
+
+#ifdef TEST_QUEUED_DATA
+  // It's painful to write a test for this...
+  channel->mState = OPEN;
+  channel->mReady = true;
+  SendMsgInternal(channel, "Help me!", 8, DATA_CHANNEL_PPID_DOMSTRING_LAST);
+#endif
+
+  if (channel->mFlags & DATA_CHANNEL_FLAGS_OUT_OF_ORDER_ALLOWED) {
+    // Don't send unordered until this gets cleared
+    channel->mFlags |= DATA_CHANNEL_FLAGS_WAITING_ACK;
+  }
+
+  if (!(channel->mFlags & DATA_CHANNEL_FLAGS_EXTERNAL_NEGOTIATED)) {
+    if (!SendOpenRequestMessage(channel->mLabel, channel->mProtocol,
+                                stream,
+                                !!(channel->mFlags & DATA_CHANNEL_FLAGS_OUT_OF_ORDER_ALLOWED),
+                                channel->mPrPolicy, channel->mPrValue)) {
+      LOG(("SendOpenRequest failed, errno = %d", errno));
+      if (errno == EAGAIN || errno == EWOULDBLOCK) {
+        channel->mFlags |= DATA_CHANNEL_FLAGS_SEND_REQ;
+        // Note: we're locked, so there's no danger of a race with the
+        // buffer-threshold callback
+        return channel.forget();
+      } else {
+        if (channel->mFlags & DATA_CHANNEL_FLAGS_FINISH_OPEN) {
+          // We already returned the channel to the app.
+          NS_ERROR("Failed to send open request");
+          NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                                    DataChannelOnMessageAvailable::ON_CHANNEL_CLOSED, this,
+                                    channel)));
+        }
+        // If we haven't returned the channel yet, it will get destroyed when we exit
+        // this function.
+        mStreams[stream] = nullptr;
+        channel->mStream = INVALID_STREAM;
+        // we'll be destroying the channel
+        channel->mState = CLOSED;
+        return nullptr;
+      }
+      /* NOTREACHED */
+    }
+  }
+  // Either externally negotiated or we sent Open
+  channel->mState = OPEN;
+  channel->mReady = true;
+  // FIX?  Move into DOMDataChannel?  I don't think we can send it yet here
+  LOG(("%s: sending ON_CHANNEL_OPEN for %p", __FUNCTION__, channel.get()));
+  NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                            DataChannelOnMessageAvailable::ON_CHANNEL_OPEN, this,
+                            channel)));
+
+  return channel.forget();
+
+request_error_cleanup:
+  channel->mState = CLOSED;
+  if (channel->mFlags & DATA_CHANNEL_FLAGS_FINISH_OPEN) {
+    // We already returned the channel to the app.
+    NS_ERROR("Failed to request more streams");
+    NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                              DataChannelOnMessageAvailable::ON_CHANNEL_CLOSED, this,
+                              channel)));
+    return channel.forget();
+  }
+  // we'll be destroying the channel, but it never really got set up
+  // Alternative would be to RUN_ON_THREAD(channel.forget(),::Destroy,...) and
+  // Dispatch it to ourselves
+  return nullptr;
+}
+
+int32_t
+DataChannelConnection::SendMsgInternal(DataChannel *channel, const char *data,
+                                       size_t length, uint32_t ppid)
+{
+  uint16_t flags;
+  struct sctp_sendv_spa spa;
+  int32_t result;
+
+  NS_ENSURE_TRUE(channel->mState == OPEN || channel->mState == CONNECTING, 0);
+  NS_WARNING_ASSERTION(length > 0, "Length is 0?!");
+
+  // To avoid problems where an in-order OPEN is lost and an
+  // out-of-order data message "beats" it, require data to be in-order
+  // until we get an ACK.
+  if ((channel->mFlags & DATA_CHANNEL_FLAGS_OUT_OF_ORDER_ALLOWED) &&
+      !(channel->mFlags & DATA_CHANNEL_FLAGS_WAITING_ACK)) {
+    flags = SCTP_UNORDERED;
+  } else {
+    flags = 0;
+  }
+
+  spa.sendv_sndinfo.snd_ppid = htonl(ppid);
+  spa.sendv_sndinfo.snd_sid = channel->mStream;
+  spa.sendv_sndinfo.snd_flags = flags;
+  spa.sendv_sndinfo.snd_context = 0;
+  spa.sendv_sndinfo.snd_assoc_id = 0;
+  spa.sendv_flags = SCTP_SEND_SNDINFO_VALID;
+
+  if (channel->mPrPolicy != SCTP_PR_SCTP_NONE) {
+    spa.sendv_prinfo.pr_policy = channel->mPrPolicy;
+    spa.sendv_prinfo.pr_value = channel->mPrValue;
+    spa.sendv_flags |= SCTP_SEND_PRINFO_VALID;
+  }
+
+  // Note: Main-thread IO, but doesn't block!
+  // XXX FIX!  to deal with heavy overruns of JS trying to pass data in
+  // (more than the buffersize) queue data onto another thread to do the
+  // actual sends.  See netwerk/protocol/websocket/WebSocketChannel.cpp
+
+  // SCTP will return EMSGSIZE if the message is bigger than the buffer
+  // size (or EAGAIN if there isn't space)
+
+  // Avoid a race between buffer-full-failure (where we have to add the
+  // packet to the buffered-data queue) and the buffer-now-only-half-full
+  // callback, which happens on a different thread.  Otherwise we might
+  // fail here, then before we add it to the queue get the half-full
+  // callback, find nothing to do, then on this thread add it to the
+  // queue - which would sit there.  Also, if we later send more data, it
+  // would arrive ahead of the buffered message, but if the buffer ever
+  // got to 1/2 full, the message would get sent - but at a semi-random
+  // time, after other data it was supposed to be in front of.
+
+  // Must lock before empty check for similar reasons!
+  MutexAutoLock lock(mLock);
+  if (channel->mBufferedData.IsEmpty()) {
+    result = usrsctp_sendv(mSocket, data, length,
+                           nullptr, 0,
+                           (void *)&spa, (socklen_t)sizeof(struct sctp_sendv_spa),
+                           SCTP_SENDV_SPA, 0);
+    LOG(("Sent buffer (len=%u), result=%d", length, result));
+  } else {
+    // Fake EAGAIN if we're already buffering data
+    result = -1;
+    errno = EAGAIN;
+  }
+  if (result < 0) {
+    if (errno == EAGAIN || errno == EWOULDBLOCK) {
+
+      // queue data for resend!  And queue any further data for the stream until it is...
+      auto *buffered = new BufferedMsg(spa, data, length); // infallible malloc
+      channel->mBufferedData.AppendElement(buffered); // owned by mBufferedData array
+      channel->mFlags |= DATA_CHANNEL_FLAGS_SEND_DATA;
+      LOG(("Queued %u buffers (len=%u)", channel->mBufferedData.Length(), length));
+      return 0;
+    }
+    LOG(("error %d sending string", errno));
+  }
+  return result;
+}
+
+// Handles fragmenting binary messages
+int32_t
+DataChannelConnection::SendBinary(DataChannel *channel, const char *data,
+                                  size_t len,
+                                  uint32_t ppid_partial, uint32_t ppid_final)
+{
+  // Since there's a limit on network buffer size and no limits on message
+  // size, and we don't want to use EOR mode (multiple writes for a
+  // message, but all other streams are blocked until you finish sending
+  // this message), we need to add application-level fragmentation of large
+  // messages.  On a reliable channel, these can be simply rebuilt into a
+  // large message.  On an unreliable channel, we can't and don't know how
+  // long to wait, and there are no retransmissions, and no easy way to
+  // tell the user "this part is missing", so on unreliable channels we
+  // need to return an error if sending more bytes than the network buffers
+  // can hold, and perhaps a lower number.
+
+  // We *really* don't want to do this from main thread! - and SendMsgInternal
+  // avoids blocking.
+  // This MUST be reliable and in-order for the reassembly to work
+  if (len > DATA_CHANNEL_MAX_BINARY_FRAGMENT &&
+      channel->mPrPolicy == DATA_CHANNEL_RELIABLE &&
+      !(channel->mFlags & DATA_CHANNEL_FLAGS_OUT_OF_ORDER_ALLOWED)) {
+    int32_t sent=0;
+    uint32_t origlen = len;
+    LOG(("Sending binary message length %u in chunks", len));
+    // XXX check flags for out-of-order, or force in-order for large binary messages
+    while (len > 0) {
+      size_t sendlen = std::min<size_t>(len, DATA_CHANNEL_MAX_BINARY_FRAGMENT);
+      uint32_t ppid;
+      len -= sendlen;
+      ppid = len > 0 ? ppid_partial : ppid_final;
+      LOG(("Send chunk of %u bytes, ppid %u", sendlen, ppid));
+      // Note that these might end up being deferred and queued.
+      sent += SendMsgInternal(channel, data, sendlen, ppid);
+      data += sendlen;
+    }
+    LOG(("Sent %d buffers for %u bytes, %d sent immediately, %d buffers queued",
+         (origlen+DATA_CHANNEL_MAX_BINARY_FRAGMENT-1)/DATA_CHANNEL_MAX_BINARY_FRAGMENT,
+         origlen, sent,
+         channel->mBufferedData.Length()));
+    return sent;
+  }
+  NS_WARNING_ASSERTION(len <= DATA_CHANNEL_MAX_BINARY_FRAGMENT,
+                       "Sending too-large data on unreliable channel!");
+
+  // This will fail if the message is too large (default 256K)
+  return SendMsgInternal(channel, data, len, ppid_final);
+}
+
+class ReadBlobRunnable : public Runnable {
+public:
+  ReadBlobRunnable(DataChannelConnection* aConnection, uint16_t aStream,
+    nsIInputStream* aBlob) :
+    mConnection(aConnection),
+    mStream(aStream),
+    mBlob(aBlob)
+  {}
+
+  NS_IMETHOD Run() override {
+    // ReadBlob() is responsible to releasing the reference
+    DataChannelConnection *self = mConnection;
+    self->ReadBlob(mConnection.forget(), mStream, mBlob);
+    return NS_OK;
+  }
+
+private:
+  // Make sure the Connection doesn't die while there are jobs outstanding.
+  // Let it die (if released by PeerConnectionImpl while we're running)
+  // when we send our runnable back to MainThread.  Then ~DataChannelConnection
+  // can send the IOThread to MainThread to die in a runnable, avoiding
+  // unsafe event loop recursion.  Evil.
+  RefPtr<DataChannelConnection> mConnection;
+  uint16_t mStream;
+  // Use RefCount for preventing the object is deleted when SendBlob returns.
+  RefPtr<nsIInputStream> mBlob;
+};
+
+int32_t
+DataChannelConnection::SendBlob(uint16_t stream, nsIInputStream *aBlob)
+{
+  DataChannel *channel = mStreams[stream];
+  NS_ENSURE_TRUE(channel, 0);
+  // Spawn a thread to send the data
+  if (!mInternalIOThread) {
+    nsresult res = NS_NewThread(getter_AddRefs(mInternalIOThread));
+    if (NS_FAILED(res)) {
+      return -1;
+    }
+  }
+
+  mInternalIOThread->Dispatch(do_AddRef(new ReadBlobRunnable(this, stream, aBlob)), NS_DISPATCH_NORMAL);
+  return 0;
+}
+
+class DataChannelBlobSendRunnable : public Runnable
+{
+public:
+  DataChannelBlobSendRunnable(already_AddRefed<DataChannelConnection>& aConnection,
+                              uint16_t aStream)
+    : mConnection(aConnection)
+    , mStream(aStream) {}
+
+  ~DataChannelBlobSendRunnable() override
+  {
+    if (!NS_IsMainThread() && mConnection) {
+      MOZ_ASSERT(false);
+      // explicitly leak the connection if destroyed off mainthread
+      Unused << mConnection.forget().take();
+    }
+  }
+
+  NS_IMETHOD Run() override
+  {
+    ASSERT_WEBRTC(NS_IsMainThread());
+
+    mConnection->SendBinaryMsg(mStream, mData);
+    mConnection = nullptr;
+    return NS_OK;
+  }
+
+  // explicitly public so we can avoid allocating twice and copying
+  nsCString mData;
+
+private:
+  // Note: we can be destroyed off the target thread, so be careful not to let this
+  // get Released()ed on the temp thread!
+  RefPtr<DataChannelConnection> mConnection;
+  uint16_t mStream;
+};
+
+void
+DataChannelConnection::ReadBlob(already_AddRefed<DataChannelConnection> aThis,
+                                uint16_t aStream, nsIInputStream* aBlob)
+{
+  // NOTE: 'aThis' has been forgotten by the caller to avoid releasing
+  // it off mainthread; if PeerConnectionImpl has released then we want
+  // ~DataChannelConnection() to run on MainThread
+
+  // XXX to do this safely, we must enqueue these atomically onto the
+  // output socket.  We need a sender thread(s?) to enqueue data into the
+  // socket and to avoid main-thread IO that might block.  Even on a
+  // background thread, we may not want to block on one stream's data.
+  // I.e. run non-blocking and service multiple channels.
+
+  // For now as a hack, send as a single blast of queued packets which may
+  // be deferred until buffer space is available.
+  uint64_t len;
+  nsCOMPtr<nsIThread> mainThread;
+  NS_GetMainThread(getter_AddRefs(mainThread));
+
+  // Must not let Dispatching it cause the DataChannelConnection to get
+  // released on the wrong thread.  Using WrapRunnable(RefPtr<DataChannelConnection>(aThis),...
+  // will occasionally cause aThis to get released on this thread.  Also, an explicit Runnable
+  // lets us avoid copying the blob data an extra time.
+  RefPtr<DataChannelBlobSendRunnable> runnable = new DataChannelBlobSendRunnable(aThis,
+                                                                                   aStream);
+  // avoid copying the blob data by passing the mData from the runnable
+  if (NS_FAILED(aBlob->Available(&len)) ||
+      NS_FAILED(NS_ReadInputStreamToString(aBlob, runnable->mData, len))) {
+    // Bug 966602:  Doesn't return an error to the caller via onerror.
+    // We must release DataChannelConnection on MainThread to avoid issues (bug 876167)
+    // aThis is now owned by the runnable; release it there
+    NS_ProxyRelease(mainThread, runnable.forget());
+    return;
+  }
+  aBlob->Close();
+  NS_DispatchToMainThread(runnable, NS_DISPATCH_NORMAL);
+}
+
+void
+DataChannelConnection::GetStreamIds(std::vector<uint16_t>* aStreamList)
+{
+  ASSERT_WEBRTC(NS_IsMainThread());
+  for (uint32_t i = 0; i < mStreams.Length(); ++i) {
+    if (mStreams[i]) {
+      aStreamList->push_back(mStreams[i]->mStream);
+    }
+  }
+}
+
+int32_t
+DataChannelConnection::SendMsgCommon(uint16_t stream, const nsACString &aMsg,
+                                     bool isBinary)
+{
+  ASSERT_WEBRTC(NS_IsMainThread());
+  // We really could allow this from other threads, so long as we deal with
+  // asynchronosity issues with channels closing, in particular access to
+  // mStreams, and issues with the association closing (access to mSocket).
+
+  const char *data = aMsg.BeginReading();
+  uint32_t len     = aMsg.Length();
+  DataChannel *channel;
+
+  LOG(("Sending %sto stream %u: %u bytes", isBinary ? "binary " : "", stream, len));
+  // XXX if we want more efficiency, translate flags once at open time
+  channel = mStreams[stream];
+  NS_ENSURE_TRUE(channel, 0);
+
+  if (isBinary)
+    return SendBinary(channel, data, len,
+                      DATA_CHANNEL_PPID_BINARY, DATA_CHANNEL_PPID_BINARY_LAST);
+  return SendBinary(channel, data, len,
+                    DATA_CHANNEL_PPID_DOMSTRING, DATA_CHANNEL_PPID_DOMSTRING_LAST);
+}
+
+void
+DataChannelConnection::Close(DataChannel *aChannel)
+{
+  MutexAutoLock lock(mLock);
+  CloseInt(aChannel);
+}
+
+// So we can call Close() with the lock already held
+// Called from someone who holds a ref via ::Close(), or from ~DataChannel
+void
+DataChannelConnection::CloseInt(DataChannel *aChannel)
+{
+  MOZ_ASSERT(aChannel);
+  RefPtr<DataChannel> channel(aChannel); // make sure it doesn't go away on us
+
+  mLock.AssertCurrentThreadOwns();
+  LOG(("Connection %p/Channel %p: Closing stream %u",
+       channel->mConnection.get(), channel.get(), channel->mStream));
+  // re-test since it may have closed before the lock was grabbed
+  if (aChannel->mState == CLOSED || aChannel->mState == CLOSING) {
+    LOG(("Channel already closing/closed (%u)", aChannel->mState));
+    if (mState == CLOSED && channel->mStream != INVALID_STREAM) {
+      // called from CloseAll()
+      // we're not going to hang around waiting any more
+      mStreams[channel->mStream] = nullptr;
+    }
+    return;
+  }
+  aChannel->mBufferedData.Clear();
+  if (channel->mStream != INVALID_STREAM) {
+    ResetOutgoingStream(channel->mStream);
+    if (mState == CLOSED) { // called from CloseAll()
+      // Let resets accumulate then send all at once in CloseAll()
+      // we're not going to hang around waiting
+      mStreams[channel->mStream] = nullptr;
+    } else {
+      SendOutgoingStreamReset();
+    }
+  }
+  aChannel->mState = CLOSING;
+  if (mState == CLOSED) {
+    // we're not going to hang around waiting
+    channel->StreamClosedLocked();
+  }
+  // At this point when we leave here, the object is a zombie held alive only by the DOM object
+}
+
+void DataChannelConnection::CloseAll()
+{
+  LOG(("Closing all channels (connection %p)", (void*) this));
+  // Don't need to lock here
+
+  // Make sure no more channels will be opened
+  {
+    MutexAutoLock lock(mLock);
+    mState = CLOSED;
+  }
+
+  // Close current channels
+  // If there are runnables, they hold a strong ref and keep the channel
+  // and/or connection alive (even if in a CLOSED state)
+  bool closed_some = false;
+  for (uint32_t i = 0; i < mStreams.Length(); ++i) {
+    if (mStreams[i]) {
+      mStreams[i]->Close();
+      closed_some = true;
+    }
+  }
+
+  // Clean up any pending opens for channels
+  RefPtr<DataChannel> channel;
+  while (nullptr != (channel = dont_AddRef(static_cast<DataChannel *>(mPending.PopFront())))) {
+    LOG(("closing pending channel %p, stream %u", channel.get(), channel->mStream));
+    channel->Close(); // also releases the ref on each iteration
+    closed_some = true;
+  }
+  // It's more efficient to let the Resets queue in shutdown and then
+  // SendOutgoingStreamReset() here.
+  if (closed_some) {
+    MutexAutoLock lock(mLock);
+    SendOutgoingStreamReset();
+  }
+}
+
+DataChannel::~DataChannel()
+{
+  // NS_ASSERTION since this is more "I think I caught all the cases that
+  // can cause this" than a true kill-the-program assertion.  If this is
+  // wrong, nothing bad happens.  A worst it's a leak.
+  NS_ASSERTION(mState == CLOSED || mState == CLOSING, "unexpected state in ~DataChannel");
+}
+
+void
+DataChannel::Close()
+{
+  if (mConnection) {
+    // ensure we don't get deleted
+    RefPtr<DataChannelConnection> connection(mConnection);
+    connection->Close(this);
+  }
+}
+
+// Used when disconnecting from the DataChannelConnection
+void
+DataChannel::StreamClosedLocked()
+{
+  mConnection->mLock.AssertCurrentThreadOwns();
+  ENSURE_DATACONNECTION;
+
+  LOG(("Destroying Data channel %u", mStream));
+  MOZ_ASSERT_IF(mStream != INVALID_STREAM,
+                !mConnection->FindChannelByStream(mStream));
+  mStream = INVALID_STREAM;
+  mState = CLOSED;
+  NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                                      DataChannelOnMessageAvailable::ON_CHANNEL_CLOSED,
+                                      mConnection, this)));
+  // We leave mConnection live until the DOM releases us, to avoid races
+}
+
+void
+DataChannel::ReleaseConnection()
+{
+  ASSERT_WEBRTC(NS_IsMainThread());
+  mConnection = nullptr;
+}
+
+void
+DataChannel::SetListener(DataChannelListener *aListener, nsISupports *aContext)
+{
+  MutexAutoLock mLock(mListenerLock);
+  mContext = aContext;
+  mListener = aListener;
+}
+
+// May be called from another (i.e. Main) thread!
+void
+DataChannel::AppReady()
+{
+  ENSURE_DATACONNECTION;
+
+  MutexAutoLock lock(mConnection->mLock);
+
+  mReady = true;
+  if (mState == WAITING_TO_OPEN) {
+    mState = OPEN;
+    NS_DispatchToMainThread(do_AddRef(new DataChannelOnMessageAvailable(
+                              DataChannelOnMessageAvailable::ON_CHANNEL_OPEN, mConnection,
+                              this)));
+    for (uint32_t i = 0; i < mQueuedMessages.Length(); ++i) {
+      nsCOMPtr<nsIRunnable> runnable = mQueuedMessages[i];
+      MOZ_ASSERT(runnable);
+      NS_DispatchToMainThread(runnable);
+    }
+  } else {
+    NS_ASSERTION(mQueuedMessages.IsEmpty(), "Shouldn't have queued messages if not WAITING_TO_OPEN");
+  }
+  mQueuedMessages.Clear();
+  mQueuedMessages.Compact();
+  // We never use it again...  We could even allocate the array in the odd
+  // cases we need it.
+}
+
+uint32_t
+DataChannel::GetBufferedAmountLocked() const
+{
+  size_t buffered = 0;
+
+  for (auto& buffer : mBufferedData) {
+    buffered += buffer->mLength;
+  }
+  // XXX Note: per Michael Tuexen, there's no way to currently get the buffered
+  // amount from the SCTP stack for a single stream.  It is on their to-do
+  // list, and once we import a stack with support for that, we'll need to
+  // add it to what we buffer.  Also we'll need to ask for notification of a per-
+  // stream buffer-low event and merge that into the handling of buffer-low
+  // (the equivalent to TCP_NOTSENT_LOWAT on TCP sockets)
+
+  if (buffered > UINT32_MAX) { // paranoia - >4GB buffered is very very unlikely
+    buffered = UINT32_MAX;
+  }
+  return buffered;
+}
+
+uint32_t
+DataChannel::GetBufferedAmountLowThreshold()
+{
+  return mBufferedThreshold;
+}
+
+// Never fire immediately, as it's defined to fire on transitions, not state
+void
+DataChannel::SetBufferedAmountLowThreshold(uint32_t aThreshold)
+{
+  mBufferedThreshold = aThreshold;
+}
+
+// Called with mLock locked!
+void
+DataChannel::SendOrQueue(DataChannelOnMessageAvailable *aMessage)
+{
+  if (!mReady &&
+      (mState == CONNECTING || mState == WAITING_TO_OPEN)) {
+    mQueuedMessages.AppendElement(aMessage);
+  } else {
+    NS_DispatchToMainThread(aMessage);
+  }
+}
+
+} // namespace mozilla
diff --git a/netwerk/sctp/datachannel/DataChannel.h b/netwerk/sctp/datachannel/DataChannel.h
new file mode 100644
index 000000000..84ab422fc
--- /dev/null
+++ b/netwerk/sctp/datachannel/DataChannel.h
@@ -0,0 +1,583 @@
+/* -*- 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 <string>
+#include <errno.h>
+#include "nsISupports.h"
+#include "nsCOMPtr.h"
+#include "mozilla/WeakPtr.h"
+#include "nsString.h"
+#include "nsThreadUtils.h"
+#include "nsTArray.h"
+#include "nsDeque.h"
+#include "nsIInputStream.h"
+#include "mozilla/Mutex.h"
+#include "DataChannelProtocol.h"
+#include "DataChannelListener.h"
+#ifdef SCTP_DTLS_SUPPORTED
+#include "mtransport/sigslot.h"
+#include "mtransport/transportflow.h"
+#include "mtransport/transportlayer.h"
+#include "mtransport/transportlayerdtls.h"
+#include "mtransport/transportlayerprsock.h"
+#endif
+
+#ifndef DATACHANNEL_LOG
+#define DATACHANNEL_LOG(args)
+#endif
+
+#ifndef EALREADY
+#define EALREADY  WSAEALREADY
+#endif
+
+extern "C" {
+  struct socket;
+  struct sctp_rcvinfo;
+}
+
+namespace mozilla {
+
+class DataChannelConnection;
+class DataChannel;
+class DataChannelOnMessageAvailable;
+
+// For queuing outgoing messages
+class BufferedMsg
+{
+public:
+  BufferedMsg(struct sctp_sendv_spa &spa,const char *data,
+              size_t length);
+  ~BufferedMsg();
+
+  struct sctp_sendv_spa *mSpa;
+  const char *mData;
+  size_t mLength;
+};
+
+// 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,
+             const void *data, size_t length)
+    : mStream(stream)
+    , mPpid(ppid)
+    , mLength(length)
+  {
+    mData = static_cast<char *>(moz_xmalloc(length)); // infallible
+    memcpy(mData, data, length);
+  }
+
+  ~QueuedDataMessage()
+  {
+    free(mData);
+  }
+
+  uint16_t mStream;
+  uint32_t mPpid;
+  size_t   mLength;
+  char     *mData;
+};
+
+// One per PeerConnection
+class DataChannelConnection
+#ifdef SCTP_DTLS_SUPPORTED
+  : public sigslot::has_slots<>
+#endif
+{
+  virtual ~DataChannelConnection();
+
+public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(DataChannelConnection)
+
+  class DataConnectionListener : public SupportsWeakPtr<DataConnectionListener>
+  {
+  public:
+    MOZ_DECLARE_WEAKREFERENCE_TYPENAME(DataChannelConnection::DataConnectionListener)
+    virtual ~DataConnectionListener() {}
+
+    // Called when a new DataChannel has been opened by the other side.
+    virtual void NotifyDataChannel(already_AddRefed<DataChannel> channel) = 0;
+  };
+
+  explicit DataChannelConnection(DataConnectionListener *listener);
+
+  bool Init(unsigned short aPort, uint16_t aNumStreams, bool aUsingDtls);
+  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);
+
+#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
+  // Connect using a TransportFlow (DTLS) channel
+  void SetEvenOdd();
+  bool ConnectViaTransportFlow(TransportFlow *aFlow, uint16_t localport, uint16_t remoteport);
+  void CompleteConnect(TransportFlow *flow, TransportLayer::State state);
+  void SetSignals();
+#endif
+
+  typedef enum {
+    RELIABLE=0,
+    PARTIAL_RELIABLE_REXMIT = 1,
+    PARTIAL_RELIABLE_TIMED = 2
+  } Type;
+
+  MOZ_MUST_USE
+  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 Close(DataChannel *aChannel);
+  // CloseInt() must be called with mLock held
+  void CloseInt(DataChannel *aChannel);
+  void CloseAll();
+
+  int32_t SendMsg(uint16_t stream, const nsACString &aMsg)
+    {
+      return SendMsgCommon(stream, aMsg, false);
+    }
+  int32_t SendBinaryMsg(uint16_t stream, const nsACString &aMsg)
+    {
+      return SendMsgCommon(stream, aMsg, true);
+    }
+  int32_t 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
+  int ReceiveCallback(struct socket* sock, void *data, size_t datalen,
+                      struct sctp_rcvinfo rcv, int32_t flags);
+
+  // Find out state
+  enum {
+    CONNECTING = 0U,
+    OPEN = 1U,
+    CLOSING = 2U,
+    CLOSED = 3U
+  };
+  uint16_t GetReadyState() { MutexAutoLock lock(mLock); return mState; }
+
+  friend class DataChannel;
+  Mutex  mLock;
+
+  void ReadBlob(already_AddRefed<DataChannelConnection> aThis, uint16_t aStream, nsIInputStream* aBlob);
+
+  void GetStreamIds(std::vector<uint16_t>* aStreamList);
+
+  bool SendDeferredMessages();
+
+protected:
+  friend class DataChannelOnMessageAvailable;
+  // Avoid cycles with PeerConnectionImpl
+  // Use from main thread only as WeakPtr is not threadsafe
+  WeakPtr<DataConnectionListener> mListener;
+
+private:
+  friend class DataChannelConnectRunnable;
+
+#ifdef SCTP_DTLS_SUPPORTED
+  static void DTLSConnectThread(void *data);
+  int SendPacket(unsigned char data[], size_t len, bool release);
+  void SctpDtlsInput(TransportFlow *flow, const unsigned char *data, size_t len);
+  static int SctpDtlsOutput(void *addr, void *buffer, size_t length, uint8_t tos, uint8_t set_df);
+#endif
+  DataChannel* FindChannelByStream(uint16_t stream);
+  uint16_t FindFreeStream();
+  bool RequestMoreStreams(int32_t aNeeded = 16);
+  int32_t SendControlMessage(void *msg, uint32_t len, uint16_t stream);
+  int32_t SendOpenRequestMessage(const nsACString& label, const nsACString& protocol,
+                                 uint16_t stream,
+                                 bool unordered, uint16_t prPolicy, uint32_t prValue);
+  int32_t SendOpenAckMessage(uint16_t stream);
+  int32_t SendMsgInternal(DataChannel *channel, const char *data,
+                          size_t length, uint32_t ppid);
+  int32_t SendBinary(DataChannel *channel, const char *data,
+                     size_t len, uint32_t ppid_partial, uint32_t ppid_final);
+  int32_t SendMsgCommon(uint16_t stream, const nsACString &aMsg, bool isBinary);
+
+  void DeliverQueuedData(uint16_t stream);
+
+  already_AddRefed<DataChannel> OpenFinish(already_AddRefed<DataChannel>&& aChannel);
+
+  void ProcessQueuedOpens();
+  void ClearResets();
+  void SendOutgoingStreamReset();
+  void ResetOutgoingStream(uint16_t stream);
+  void HandleOpenRequestMessage(const struct rtcweb_datachannel_open_request *req,
+                                size_t length,
+                                uint16_t stream);
+  void HandleOpenAckMessage(const struct rtcweb_datachannel_ack *ack,
+                            size_t length, uint16_t stream);
+  void HandleUnknownMessage(uint32_t ppid, size_t length, uint16_t stream);
+  void HandleDataMessage(uint32_t ppid, const void *buffer, size_t length, uint16_t stream);
+  void HandleMessage(const void *buffer, size_t length, uint32_t ppid, uint16_t stream);
+  void HandleAssociationChangeEvent(const struct sctp_assoc_change *sac);
+  void HandlePeerAddressChangeEvent(const struct sctp_paddr_change *spc);
+  void HandleRemoteErrorEvent(const struct sctp_remote_error *sre);
+  void HandleShutdownEvent(const struct sctp_shutdown_event *sse);
+  void HandleAdaptationIndication(const struct sctp_adaptation_event *sai);
+  void HandleSendFailedEvent(const struct sctp_send_failed_event *ssfe);
+  void HandleStreamResetEvent(const struct sctp_stream_reset_event *strrst);
+  void HandleStreamChangeEvent(const struct sctp_stream_change_event *strchg);
+  void HandleNotification(const union sctp_notification *notif, size_t n);
+
+#ifdef SCTP_DTLS_SUPPORTED
+  bool IsSTSThread() {
+    bool on = false;
+    if (mSTS) {
+      mSTS->IsOnCurrentThread(&on);
+    }
+    return on;
+  }
+#endif
+
+  // Exists solely for proxying release of the TransportFlow to the STS thread
+  static void ReleaseTransportFlow(RefPtr<TransportFlow> aFlow) {}
+
+  // Data:
+  // NOTE: while this array will auto-expand, increases in the number of
+  // channels available from the stack must be negotiated!
+  bool mAllocateEven;
+  AutoTArray<RefPtr<DataChannel>,16> mStreams;
+  nsDeque mPending; // Holds addref'ed DataChannel's -- careful!
+  // holds data that's come in before a channel is open
+  nsTArray<nsAutoPtr<QueuedDataMessage>> mQueuedData;
+
+  // Streams pending reset
+  AutoTArray<uint16_t,4> mStreamsResetting;
+
+  struct socket *mMasterSocket; // accessed from STS thread
+  struct socket *mSocket; // cloned from mMasterSocket on successful Connect on STS thread
+  uint16_t mState; // Protected with mLock
+
+#ifdef SCTP_DTLS_SUPPORTED
+  RefPtr<TransportFlow> mTransportFlow;
+  nsCOMPtr<nsIEventTarget> mSTS;
+#endif
+  uint16_t mLocalPort; // Accessed from connect thread
+  uint16_t mRemotePort;
+  bool mUsingDtls;
+
+  nsCOMPtr<nsIThread> mInternalIOThread;
+};
+
+#define ENSURE_DATACONNECTION \
+  do { MOZ_ASSERT(mConnection); if (!mConnection) { return; } } while (0)
+
+#define ENSURE_DATACONNECTION_RET(x) \
+  do { MOZ_ASSERT(mConnection); if (!mConnection) { return (x); } } while (0)
+
+class DataChannel {
+public:
+  enum {
+    CONNECTING = 0U,
+    OPEN = 1U,
+    CLOSING = 2U,
+    CLOSED = 3U,
+    WAITING_TO_OPEN = 4U
+  };
+
+  DataChannel(DataChannelConnection *connection,
+              uint16_t stream,
+              uint16_t state,
+              const nsACString& label,
+              const nsACString& protocol,
+              uint16_t policy, uint32_t value,
+              uint32_t flags,
+              DataChannelListener *aListener,
+              nsISupports *aContext)
+    : mListenerLock("netwerk::sctp::DataChannel")
+    , mListener(aListener)
+    , mContext(aContext)
+    , mConnection(connection)
+    , mLabel(label)
+    , mProtocol(protocol)
+    , mState(state)
+    , mReady(false)
+    , mStream(stream)
+    , mPrPolicy(policy)
+    , mPrValue(value)
+    , mFlags(flags)
+    , mIsRecvBinary(false)
+    , mBufferedThreshold(0) // default from spec
+    {
+      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);
+
+  // Send a string
+  bool SendMsg(const nsACString &aMsg)
+    {
+      ENSURE_DATACONNECTION_RET(false);
+
+      if (mStream != INVALID_STREAM)
+        return (mConnection->SendMsg(mStream, aMsg) >= 0);
+      else
+        return false;
+    }
+
+  // Send a binary message (TypedArray)
+  bool SendBinaryMsg(const nsACString &aMsg)
+    {
+      ENSURE_DATACONNECTION_RET(false);
+
+      if (mStream != INVALID_STREAM)
+        return (mConnection->SendBinaryMsg(mStream, aMsg) >= 0);
+      else
+        return false;
+    }
+
+  // Send a binary blob
+  bool SendBinaryStream(nsIInputStream *aBlob, uint32_t msgLen)
+    {
+      ENSURE_DATACONNECTION_RET(false);
+
+      if (mStream != INVALID_STREAM)
+        return (mConnection->SendBlob(mStream, aBlob) == 0);
+      else
+        return false;
+    }
+
+  uint16_t GetType() { return mPrPolicy; }
+
+  bool GetOrdered() { return !(mFlags & DATA_CHANNEL_FLAGS_OUT_OF_ORDER_ALLOWED); }
+
+  // Amount of data buffered to send
+  uint32_t GetBufferedAmount()
+  {
+    if (!mConnection) {
+      return 0;
+    }
+
+    MutexAutoLock lock(mConnection->mLock);
+    return GetBufferedAmountLocked();
+  }
+
+
+  // Trigger amount for generating BufferedAmountLow events
+  uint32_t GetBufferedAmountLowThreshold();
+  void SetBufferedAmountLowThreshold(uint32_t aThreshold);
+
+  // Find out state
+  uint16_t GetReadyState()
+    {
+      if (mConnection) {
+        MutexAutoLock lock(mConnection->mLock);
+        if (mState == WAITING_TO_OPEN)
+          return CONNECTING;
+        return mState;
+      }
+      return CLOSED;
+    }
+
+  void GetLabel(nsAString& aLabel) { CopyUTF8toUTF16(mLabel, aLabel); }
+  void GetProtocol(nsAString& aProtocol) { CopyUTF8toUTF16(mProtocol, aProtocol); }
+  uint16_t GetStream() { return mStream; }
+
+  void AppReady();
+
+  void SendOrQueue(DataChannelOnMessageAvailable *aMessage);
+
+protected:
+  Mutex mListenerLock; // protects mListener and mContext
+  DataChannelListener *mListener;
+  nsCOMPtr<nsISupports> mContext;
+
+private:
+  friend class DataChannelOnMessageAvailable;
+  friend class DataChannelConnection;
+
+  nsresult AddDataToBinaryMsg(const char *data, uint32_t size);
+  uint32_t GetBufferedAmountLocked() const;
+
+  RefPtr<DataChannelConnection> mConnection;
+  nsCString mLabel;
+  nsCString mProtocol;
+  uint16_t mState;
+  bool     mReady;
+  uint16_t mStream;
+  uint16_t mPrPolicy;
+  uint32_t mPrValue;
+  uint32_t mFlags;
+  uint32_t mId;
+  bool mIsRecvBinary;
+  size_t mBufferedThreshold;
+  nsCString mRecvBuffer;
+  nsTArray<nsAutoPtr<BufferedMsg>> mBufferedData; // GUARDED_BY(mConnection->mLock)
+  nsTArray<nsCOMPtr<nsIRunnable>> mQueuedMessages;
+};
+
+// 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_CHANNEL_OPEN,
+    ON_CHANNEL_CLOSED,
+    ON_DATA,
+    BUFFER_LOW_THRESHOLD,
+    NO_LONGER_BUFFERED,
+  };  /* types */
+
+  DataChannelOnMessageAvailable(int32_t     aType,
+                                DataChannelConnection *aConnection,
+                                DataChannel *aChannel,
+                                nsCString   &aData,  // XXX this causes inefficiency
+                                int32_t     aLen)
+    : mType(aType),
+      mChannel(aChannel),
+      mConnection(aConnection),
+      mData(aData),
+      mLen(aLen) {}
+
+  DataChannelOnMessageAvailable(int32_t     aType,
+                                DataChannel *aChannel)
+    : mType(aType),
+      mChannel(aChannel) {}
+  // XXX is it safe to leave mData/mLen 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)
+    : mType(aType),
+      mChannel(aChannel),
+      mConnection(aConnection) {}
+
+  // for ON_CONNECTION/ON_DISCONNECTED
+  DataChannelOnMessageAvailable(int32_t     aType,
+                                DataChannelConnection *aConnection)
+    : 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:
+      case ON_CHANNEL_OPEN:
+      case ON_CHANNEL_CLOSED:
+      case BUFFER_LOW_THRESHOLD:
+      case NO_LONGER_BUFFERED:
+        {
+          MutexAutoLock lock(mChannel->mListenerLock);
+          if (!mChannel->mListener) {
+            DATACHANNEL_LOG(("DataChannelOnMessageAvailable (%d) with null Listener!",mType));
+            return NS_OK;
+          }
+
+          switch (mType) {
+            case ON_DATA:
+              if (mLen < 0) {
+                mChannel->mListener->OnMessageAvailable(mChannel->mContext, mData);
+              } else {
+                mChannel->mListener->OnBinaryMessageAvailable(mChannel->mContext, mData);
+              }
+              break;
+            case ON_CHANNEL_OPEN:
+              mChannel->mListener->OnChannelConnected(mChannel->mContext);
+              break;
+            case ON_CHANNEL_CLOSED:
+              mChannel->mListener->OnChannelClosed(mChannel->mContext);
+              break;
+            case BUFFER_LOW_THRESHOLD:
+              mChannel->mListener->OnBufferLow(mChannel->mContext);
+              break;
+            case NO_LONGER_BUFFERED:
+              mChannel->mListener->NotBuffered(mChannel->mContext);
+              break;
+          }
+          break;
+        }
+      case ON_DISCONNECTED:
+        // If we've disconnected, make sure we close all the streams - from mainthread!
+        mConnection->CloseAll();
+        MOZ_FALLTHROUGH;
+      case ON_CHANNEL_CREATED:
+      case ON_CONNECTION:
+        // WeakPtr - only used/modified/nulled from MainThread so we can use a WeakPtr here
+        if (!mConnection->mListener) {
+          DATACHANNEL_LOG(("DataChannelOnMessageAvailable (%d) with null Listener",mType));
+          return NS_OK;
+        }
+        switch (mType) {
+          case ON_CHANNEL_CREATED:
+            // important to give it an already_AddRefed pointer!
+            mConnection->mListener->NotifyDataChannel(mChannel.forget());
+            break;
+          default:
+            break;
+        }
+        break;
+    }
+    return NS_OK;
+  }
+
+private:
+  ~DataChannelOnMessageAvailable() {}
+
+  int32_t                           mType;
+  // XXX should use union
+  RefPtr<DataChannel>             mChannel;
+  RefPtr<DataChannelConnection>   mConnection;
+  nsCString                         mData;
+  int32_t                           mLen;
+};
+
+}
+
+#endif  // NETWERK_SCTP_DATACHANNEL_DATACHANNEL_H_
diff --git a/netwerk/sctp/datachannel/DataChannelListener.h b/netwerk/sctp/datachannel/DataChannelListener.h
new file mode 100644
index 000000000..f48aac10b
--- /dev/null
+++ b/netwerk/sctp/datachannel/DataChannelListener.h
@@ -0,0 +1,45 @@
+/* -*- 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_DATACHANNELLISTENER_H_
+#define NETWERK_SCTP_DATACHANNEL_DATACHANNELLISTENER_H_
+
+#include "nsISupports.h"
+#include "nsString.h"
+
+namespace mozilla {
+
+// Implemented by consumers of a Channel to receive messages.
+// Can't nest it in DataChannelConnection because C++ doesn't allow forward
+// refs to embedded classes
+class DataChannelListener {
+public:
+  virtual ~DataChannelListener() {}
+
+  // Called when a DOMString message is received.
+  virtual nsresult OnMessageAvailable(nsISupports *aContext,
+                                      const nsACString& message) = 0;
+
+  // Called when a binary message is received.
+  virtual nsresult OnBinaryMessageAvailable(nsISupports *aContext,
+                                            const nsACString& message) = 0;
+
+  // Called when the channel is connected
+  virtual nsresult OnChannelConnected(nsISupports *aContext) = 0;
+
+  // Called when the channel is closed
+  virtual nsresult OnChannelClosed(nsISupports *aContext) = 0;
+
+  // Called when the BufferedAmount drops below the BufferedAmountLowThreshold
+  virtual nsresult OnBufferLow(nsISupports *aContext) = 0;
+
+  // Called when the BufferedAmount drops to 0
+  virtual nsresult NotBuffered(nsISupports *aContext) = 0;
+};
+
+}
+
+#endif
diff --git a/netwerk/sctp/datachannel/DataChannelLog.h b/netwerk/sctp/datachannel/DataChannelLog.h
new file mode 100644
index 000000000..07c8ad78b
--- /dev/null
+++ b/netwerk/sctp/datachannel/DataChannelLog.h
@@ -0,0 +1,20 @@
+/* -*- 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 DataChannelLog_h
+#define DataChannelLog_h
+
+#include "base/basictypes.h"
+#include "mozilla/Logging.h"
+
+namespace mozilla {
+extern mozilla::LazyLogModule gDataChannelLog;
+}
+
+#undef LOG
+#define LOG(args) MOZ_LOG(mozilla::gDataChannelLog, mozilla::LogLevel::Debug, args)
+
+#endif
diff --git a/netwerk/sctp/datachannel/DataChannelProtocol.h b/netwerk/sctp/datachannel/DataChannelProtocol.h
new file mode 100644
index 000000000..74fbe581c
--- /dev/null
+++ b/netwerk/sctp/datachannel/DataChannelProtocol.h
@@ -0,0 +1,80 @@
+/* -*- 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_DATACHANNELPROTOCOL_H_
+#define NETWERK_SCTP_DATACHANNEL_DATACHANNELPROTOCOL_H_
+
+#if defined(__GNUC__)
+#define SCTP_PACKED __attribute__((packed))
+#elif defined(_MSC_VER)
+#pragma pack (push, 1)
+#define SCTP_PACKED
+#else
+#error "Unsupported compiler"
+#endif
+
+// Duplicated in fsm.def
+#define WEBRTC_DATACHANNEL_STREAMS_DEFAULT 256
+
+#define DATA_CHANNEL_PPID_CONTROL        50
+#define DATA_CHANNEL_PPID_BINARY         52
+#define DATA_CHANNEL_PPID_BINARY_LAST    53
+#define DATA_CHANNEL_PPID_DOMSTRING      54
+#define DATA_CHANNEL_PPID_DOMSTRING_LAST 51
+
+#define DATA_CHANNEL_MAX_BINARY_FRAGMENT 0x4000
+
+#define DATA_CHANNEL_FLAGS_SEND_REQ             0x00000001
+#define DATA_CHANNEL_FLAGS_SEND_RSP             0x00000002
+#define DATA_CHANNEL_FLAGS_SEND_ACK             0x00000004
+#define DATA_CHANNEL_FLAGS_OUT_OF_ORDER_ALLOWED 0x00000008
+#define DATA_CHANNEL_FLAGS_SEND_DATA            0x00000010
+#define DATA_CHANNEL_FLAGS_FINISH_OPEN          0x00000020
+#define DATA_CHANNEL_FLAGS_FINISH_RSP           0x00000040
+#define DATA_CHANNEL_FLAGS_EXTERNAL_NEGOTIATED  0x00000080
+#define DATA_CHANNEL_FLAGS_WAITING_ACK          0x00000100
+
+#define INVALID_STREAM (0xFFFF)
+// max is 0xFFFF: Streams 0 to 0xFFFE = 0xFFFF streams
+#define MAX_NUM_STREAMS (2048)
+
+struct rtcweb_datachannel_open_request {
+  uint8_t  msg_type; // DATA_CHANNEL_OPEN
+  uint8_t  channel_type;  
+  int16_t  priority;
+  uint32_t reliability_param;
+  uint16_t label_length;
+  uint16_t protocol_length;
+  char     label[1]; // (and protocol) keep VC++ happy...
+} SCTP_PACKED;
+
+struct rtcweb_datachannel_ack {
+  uint8_t  msg_type; // DATA_CHANNEL_ACK
+} SCTP_PACKED;
+
+/* msg_type values: */
+/* 0-1 were used in an early version of the protocol with 3-way handshakes */
+#define DATA_CHANNEL_ACK                      2
+#define DATA_CHANNEL_OPEN_REQUEST             3
+
+/* channel_type values: */
+#define DATA_CHANNEL_RELIABLE                 0x00
+#define DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT  0x01
+#define DATA_CHANNEL_PARTIAL_RELIABLE_TIMED   0x02
+
+#define DATA_CHANNEL_RELIABLE_UNORDERED                0x80
+#define DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED 0x81
+#define DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED  0x82
+
+#define ERR_DATA_CHANNEL_ALREADY_OPEN   1
+#define ERR_DATA_CHANNEL_NONE_AVAILABLE 2
+
+#if defined(_MSC_VER)
+#pragma pack (pop)
+#undef SCTP_PACKED
+#endif
+
+#endif
diff --git a/netwerk/sctp/datachannel/moz.build b/netwerk/sctp/datachannel/moz.build
new file mode 100644
index 000000000..fc59da229
--- /dev/null
+++ b/netwerk/sctp/datachannel/moz.build
@@ -0,0 +1,40 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+EXPORTS.mozilla.net += [
+    'DataChannel.h',
+    'DataChannelListener.h',
+    'DataChannelProtocol.h'
+]
+
+SOURCES += [
+    'DataChannel.cpp',
+]
+
+include('/ipc/chromium/chromium-config.mozbuild')
+
+FINAL_LIBRARY = 'xul'
+
+LOCAL_INCLUDES += [
+    '/media/mtransport',
+    '/netwerk/sctp/src',
+]
+
+DEFINES['INET'] = 1
+DEFINES['SCTP_DEBUG'] = 1
+
+if CONFIG['OS_TARGET'] != 'Android':
+    DEFINES['INET6'] = 1
+
+if CONFIG['OS_TARGET'] == 'WINNT':
+    DEFINES['__Userspace_os_Windows'] = 1
+else:
+    DEFINES['__Userspace_os_%s' % CONFIG['OS_TARGET']] = 1
+
+NO_PGO = True # Don't PGO
+
+if CONFIG['GNU_CXX']:
+    CXXFLAGS += ['-Wno-error=shadow']