8 files changed, 2102 insertions, 0 deletions
diff --git a/netwerk/protocol/webtransport/WebTransportLog.h b/netwerk/protocol/webtransport/WebTransportLog.h
new file mode 100644
index 0000000000..99f211b893
--- /dev/null
+++ b/netwerk/protocol/webtransport/WebTransportLog.h
@@ -0,0 +1,21 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et 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 WebTransportLog_h
+#define WebTransportLog_h
+
+#include "mozilla/Logging.h"
+#include "mozilla/net/NeckoChild.h"
+
+namespace mozilla::net {
+extern LazyLogModule webTransportLog;
+}  // namespace mozilla::net
+
+#undef LOG
+#define LOG(args) \
+  MOZ_LOG(mozilla::net::webTransportLog, mozilla::LogLevel::Debug, args)
+
+#endif
diff --git a/netwerk/protocol/webtransport/WebTransportSessionProxy.cpp b/netwerk/protocol/webtransport/WebTransportSessionProxy.cpp
new file mode 100644
index 0000000000..d6091b9ab4
--- /dev/null
+++ b/netwerk/protocol/webtransport/WebTransportSessionProxy.cpp
@@ -0,0 +1,1198 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 "WebTransportLog.h"
+#include "Http3WebTransportSession.h"
+#include "Http3WebTransportStream.h"
+#include "WebTransportSessionProxy.h"
+#include "WebTransportStreamProxy.h"
+#include "nsIAsyncVerifyRedirectCallback.h"
+#include "nsIHttpChannel.h"
+#include "nsIHttpChannelInternal.h"
+#include "nsIRequest.h"
+#include "nsNetUtil.h"
+#include "nsProxyRelease.h"
+#include "nsSocketTransportService2.h"
+#include "mozilla/Logging.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/StaticPrefs_network.h"
+
+namespace mozilla::net {
+
+LazyLogModule webTransportLog("nsWebTransport");
+
+NS_IMPL_ISUPPORTS(WebTransportSessionProxy, WebTransportSessionEventListener,
+                  nsIWebTransport, nsIRedirectResultListener, nsIStreamListener,
+                  nsIChannelEventSink, nsIInterfaceRequestor);
+
+WebTransportSessionProxy::WebTransportSessionProxy()
+    : mMutex("WebTransportSessionProxy::mMutex"),
+      mTarget(GetMainThreadSerialEventTarget()) {
+  LOG(("WebTransportSessionProxy constructor"));
+}
+
+WebTransportSessionProxy::~WebTransportSessionProxy() {
+  if (OnSocketThread()) {
+    return;
+  }
+
+  MutexAutoLock lock(mMutex);
+  if ((mState != WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED) &&
+      (mState != WebTransportSessionProxyState::ACTIVE) &&
+      (mState != WebTransportSessionProxyState::SESSION_CLOSE_PENDING)) {
+    return;
+  }
+
+  MOZ_ASSERT(mState != WebTransportSessionProxyState::SESSION_CLOSE_PENDING,
+             "We can not be in the SESSION_CLOSE_PENDING state in destructor, "
+             "because should e an runnable  that holds reference to this"
+             "object.");
+
+  Unused << gSocketTransportService->Dispatch(NS_NewRunnableFunction(
+      "WebTransportSessionProxy::ProxyHttp3WebTransportSessionRelease",
+      [self{std::move(mWebTransportSession)}]() {}));
+}
+
+//-----------------------------------------------------------------------------
+// WebTransportSessionProxy::nsIWebTransport
+//-----------------------------------------------------------------------------
+
+nsresult WebTransportSessionProxy::AsyncConnect(
+    nsIURI* aURI, nsIPrincipal* aPrincipal, uint32_t aSecurityFlags,
+    WebTransportSessionEventListener* aListener) {
+  return AsyncConnectWithClient(aURI, aPrincipal, aSecurityFlags, aListener,
+                                Maybe<dom::ClientInfo>());
+}
+
+nsresult WebTransportSessionProxy::AsyncConnectWithClient(
+    nsIURI* aURI, nsIPrincipal* aPrincipal, uint32_t aSecurityFlags,
+    WebTransportSessionEventListener* aListener,
+    const Maybe<dom::ClientInfo>& aClientInfo) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  LOG(("WebTransportSessionProxy::AsyncConnect"));
+  {
+    MutexAutoLock lock(mMutex);
+    mListener = aListener;
+  }
+  auto cleanup = MakeScopeExit([self = RefPtr<WebTransportSessionProxy>(this)] {
+    MutexAutoLock lock(self->mMutex);
+    self->mListener->OnSessionClosed(0, ""_ns);  // TODO: find a better error.
+    self->mChannel = nullptr;
+    self->mListener = nullptr;
+    self->ChangeState(WebTransportSessionProxyState::DONE);
+  });
+
+  nsSecurityFlags flags = nsILoadInfo::SEC_COOKIES_OMIT | aSecurityFlags;
+  nsLoadFlags loadFlags = nsIRequest::LOAD_NORMAL |
+                          nsIRequest::LOAD_BYPASS_CACHE |
+                          nsIRequest::INHIBIT_CACHING;
+  nsresult rv = NS_ERROR_FAILURE;
+
+  if (aClientInfo.isSome()) {
+    rv = NS_NewChannel(getter_AddRefs(mChannel), aURI, aPrincipal,
+                       aClientInfo.ref(), Maybe<dom::ServiceWorkerDescriptor>(),
+                       flags, nsContentPolicyType::TYPE_WEB_TRANSPORT,
+                       /* aCookieJarSettings */ nullptr,
+                       /* aPerformanceStorage */ nullptr,
+                       /* aLoadGroup */ nullptr,
+                       /* aCallbacks */ this, loadFlags);
+  } else {
+    rv = NS_NewChannel(getter_AddRefs(mChannel), aURI, aPrincipal, flags,
+                       nsContentPolicyType::TYPE_WEB_TRANSPORT,
+                       /* aCookieJarSettings */ nullptr,
+                       /* aPerformanceStorage */ nullptr,
+                       /* aLoadGroup */ nullptr,
+                       /* aCallbacks */ this, loadFlags);
+  }
+
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // configure HTTP specific stuff
+  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(mChannel);
+  if (!httpChannel) {
+    mChannel = nullptr;
+    return NS_ERROR_ABORT;
+  }
+
+  {
+    MutexAutoLock lock(mMutex);
+    ChangeState(WebTransportSessionProxyState::NEGOTIATING);
+  }
+
+  // https://www.ietf.org/archive/id/draft-ietf-webtrans-http3-04.html#section-6
+  rv = httpChannel->SetRequestHeader("Sec-Webtransport-Http3-Draft02"_ns,
+                                     "1"_ns, false);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // To establish a WebTransport session with an origin origin, follow
+  // [WEB-TRANSPORT-HTTP3] section 3.3, with using origin, serialized and
+  // isomorphic encoded, as the `Origin` header of the request.
+  // https://www.w3.org/TR/webtransport/#protocol-concepts
+  nsAutoCString serializedOrigin;
+  if (NS_FAILED(aPrincipal->GetAsciiOrigin(serializedOrigin))) {
+    // origin/URI will be missing for system principals
+    // assign null origin
+    serializedOrigin = "null"_ns;
+  }
+
+  rv = httpChannel->SetRequestHeader("Origin"_ns, serializedOrigin, false);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsCOMPtr<nsIHttpChannelInternal> internalChannel =
+      do_QueryInterface(mChannel);
+  if (!internalChannel) {
+    mChannel = nullptr;
+    return NS_ERROR_ABORT;
+  }
+  Unused << internalChannel->SetWebTransportSessionEventListener(this);
+
+  rv = mChannel->AsyncOpen(this);
+  if (NS_SUCCEEDED(rv)) {
+    cleanup.release();
+  }
+  return rv;
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::RetargetTo(nsIEventTarget* aTarget) {
+  if (!aTarget) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  {
+    MutexAutoLock lock(mMutex);
+    LOG(("WebTransportSessionProxy::RetargetTo mState=%d", mState));
+    // RetargetTo should be only called after the session is ready.
+    if (mState != WebTransportSessionProxyState::ACTIVE) {
+      return NS_ERROR_UNEXPECTED;
+    }
+
+    mTarget = aTarget;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::GetStats() { return NS_ERROR_NOT_IMPLEMENTED; }
+
+NS_IMETHODIMP
+WebTransportSessionProxy::CloseSession(uint32_t status,
+                                       const nsACString& reason) {
+  MutexAutoLock lock(mMutex);
+  MOZ_ASSERT(mTarget->IsOnCurrentThread());
+  mCloseStatus = status;
+  mReason = reason;
+  mListener = nullptr;
+  mPendingEvents.Clear();
+  switch (mState) {
+    case WebTransportSessionProxyState::INIT:
+    case WebTransportSessionProxyState::DONE:
+      return NS_ERROR_NOT_INITIALIZED;
+    case WebTransportSessionProxyState::NEGOTIATING:
+      mChannel->Cancel(NS_ERROR_ABORT);
+      mChannel = nullptr;
+      ChangeState(WebTransportSessionProxyState::DONE);
+      break;
+    case WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED:
+      mChannel->Cancel(NS_ERROR_ABORT);
+      mChannel = nullptr;
+      ChangeState(WebTransportSessionProxyState::SESSION_CLOSE_PENDING);
+      CloseSessionInternal();
+      break;
+    case WebTransportSessionProxyState::ACTIVE:
+      ChangeState(WebTransportSessionProxyState::SESSION_CLOSE_PENDING);
+      CloseSessionInternal();
+      break;
+    case WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING:
+      ChangeState(WebTransportSessionProxyState::DONE);
+      break;
+    case SESSION_CLOSE_PENDING:
+      break;
+  }
+  return NS_OK;
+}
+
+void WebTransportSessionProxy::CloseSessionInternalLocked() {
+  MutexAutoLock lock(mMutex);
+  CloseSessionInternal();
+}
+
+void WebTransportSessionProxy::CloseSessionInternal() {
+  if (!OnSocketThread()) {
+    mMutex.AssertCurrentThreadOwns();
+    RefPtr<WebTransportSessionProxy> self(this);
+    Unused << gSocketTransportService->Dispatch(NS_NewRunnableFunction(
+        "WebTransportSessionProxy::CallCloseWebTransportSession",
+        [self{std::move(self)}]() { self->CloseSessionInternalLocked(); }));
+    return;
+  }
+
+  mMutex.AssertCurrentThreadOwns();
+
+  RefPtr<Http3WebTransportSession> wt;
+  uint32_t closeStatus = 0;
+  nsCString reason;
+
+  if (mState == WebTransportSessionProxyState::SESSION_CLOSE_PENDING) {
+    MOZ_ASSERT(mWebTransportSession);
+    wt = mWebTransportSession;
+    mWebTransportSession = nullptr;
+    closeStatus = mCloseStatus;
+    reason = mReason;
+    ChangeState(WebTransportSessionProxyState::DONE);
+  } else {
+    MOZ_ASSERT(mState == WebTransportSessionProxyState::DONE);
+  }
+
+  if (wt) {
+    MutexAutoUnlock unlock(mMutex);
+    wt->CloseSession(closeStatus, reason);
+  }
+}
+
+class WebTransportStreamCallbackWrapper final {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(WebTransportStreamCallbackWrapper)
+
+  explicit WebTransportStreamCallbackWrapper(
+      nsIWebTransportStreamCallback* aCallback, bool aBidi)
+      : mCallback(aCallback),
+        mTarget(GetCurrentSerialEventTarget()),
+        mBidi(aBidi) {}
+
+  void CallOnError(nsresult aError) {
+    if (!mTarget->IsOnCurrentThread()) {
+      RefPtr<WebTransportStreamCallbackWrapper> self(this);
+      Unused << mTarget->Dispatch(NS_NewRunnableFunction(
+          "WebTransportStreamCallbackWrapper::CallOnError",
+          [self{std::move(self)}, error{aError}]() {
+            self->CallOnError(error);
+          }));
+      return;
+    }
+
+    LOG(("WebTransportStreamCallbackWrapper::OnError aError=0x%" PRIx32,
+         static_cast<uint32_t>(aError)));
+    Unused << mCallback->OnError(nsIWebTransport::INVALID_STATE_ERROR);
+  }
+
+  void CallOnStreamReady(WebTransportStreamProxy* aStream) {
+    if (!mTarget->IsOnCurrentThread()) {
+      RefPtr<WebTransportStreamCallbackWrapper> self(this);
+      RefPtr<WebTransportStreamProxy> stream = aStream;
+      Unused << mTarget->Dispatch(NS_NewRunnableFunction(
+          "WebTransportStreamCallbackWrapper::CallOnStreamReady",
+          [self{std::move(self)}, stream{std::move(stream)}]() {
+            self->CallOnStreamReady(stream);
+          }));
+      return;
+    }
+
+    if (mBidi) {
+      Unused << mCallback->OnBidirectionalStreamReady(aStream);
+      return;
+    }
+
+    Unused << mCallback->OnUnidirectionalStreamReady(aStream);
+  }
+
+ private:
+  virtual ~WebTransportStreamCallbackWrapper() {
+    NS_ProxyRelease(
+        "WebTransportStreamCallbackWrapper::~WebTransportStreamCallbackWrapper",
+        mTarget, mCallback.forget());
+  }
+
+  nsCOMPtr<nsIWebTransportStreamCallback> mCallback;
+  nsCOMPtr<nsIEventTarget> mTarget;
+  bool mBidi = false;
+};
+
+void WebTransportSessionProxy::CreateStreamInternal(
+    nsIWebTransportStreamCallback* callback, bool aBidi) {
+  mMutex.AssertCurrentThreadOwns();
+  LOG(
+      ("WebTransportSessionProxy::CreateStreamInternal %p "
+       "mState=%d, bidi=%d",
+       this, mState, aBidi));
+  switch (mState) {
+    case WebTransportSessionProxyState::INIT:
+    case WebTransportSessionProxyState::NEGOTIATING:
+    case WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED:
+    case WebTransportSessionProxyState::ACTIVE: {
+      RefPtr<WebTransportStreamCallbackWrapper> wrapper =
+          new WebTransportStreamCallbackWrapper(callback, aBidi);
+      if (mState == WebTransportSessionProxyState::ACTIVE &&
+          mWebTransportSession) {
+        DoCreateStream(wrapper, mWebTransportSession, aBidi);
+      } else {
+        LOG(
+            ("WebTransportSessionProxy::CreateStreamInternal %p "
+             " queue create stream event",
+             this));
+        auto task = [self = RefPtr{this}, wrapper{std::move(wrapper)},
+                     bidi(aBidi)](nsresult aStatus) {
+          if (NS_FAILED(aStatus)) {
+            wrapper->CallOnError(aStatus);
+            return;
+          }
+
+          self->DoCreateStream(wrapper, nullptr, bidi);
+        };
+        // TODO: we should do this properly in bug 1830362.
+        mPendingCreateStreamEvents.AppendElement(std::move(task));
+      }
+    } break;
+    case WebTransportSessionProxyState::SESSION_CLOSE_PENDING:
+    case WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING:
+    case WebTransportSessionProxyState::DONE: {
+      nsCOMPtr<nsIWebTransportStreamCallback> cb(callback);
+      NS_DispatchToCurrentThread(NS_NewRunnableFunction(
+          "WebTransportSessionProxy::CreateStreamInternal",
+          [cb{std::move(cb)}]() {
+            cb->OnError(nsIWebTransport::INVALID_STATE_ERROR);
+          }));
+    } break;
+  }
+}
+
+void WebTransportSessionProxy::DoCreateStream(
+    WebTransportStreamCallbackWrapper* aCallback,
+    Http3WebTransportSession* aSession, bool aBidi) {
+  if (!OnSocketThread()) {
+    RefPtr<WebTransportSessionProxy> self(this);
+    RefPtr<WebTransportStreamCallbackWrapper> wrapper(aCallback);
+    Unused << gSocketTransportService->Dispatch(NS_NewRunnableFunction(
+        "WebTransportSessionProxy::DoCreateStream",
+        [self{std::move(self)}, wrapper{std::move(wrapper)}, bidi(aBidi)]() {
+          self->DoCreateStream(wrapper, nullptr, bidi);
+        }));
+    return;
+  }
+
+  LOG(("WebTransportSessionProxy::DoCreateStream %p bidi=%d", this, aBidi));
+
+  RefPtr<Http3WebTransportSession> session = aSession;
+  // Having no session here means that this is called by dispatching tasks.
+  // The mState may be already changed, so we need to check it again.
+  if (!aSession) {
+    MutexAutoLock lock(mMutex);
+    switch (mState) {
+      case WebTransportSessionProxyState::INIT:
+      case WebTransportSessionProxyState::NEGOTIATING:
+      case WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED:
+        MOZ_ASSERT(false, "DoCreateStream called with invalid state");
+        aCallback->CallOnError(NS_ERROR_UNEXPECTED);
+        return;
+      case WebTransportSessionProxyState::ACTIVE: {
+        session = mWebTransportSession;
+      } break;
+      case WebTransportSessionProxyState::SESSION_CLOSE_PENDING:
+      case WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING:
+      case WebTransportSessionProxyState::DONE:
+        // Session is going to be closed.
+        aCallback->CallOnError(NS_ERROR_NOT_AVAILABLE);
+        return;
+    }
+  }
+
+  if (!session) {
+    MOZ_ASSERT_UNREACHABLE("This should not happen");
+    aCallback->CallOnError(NS_ERROR_UNEXPECTED);
+    return;
+  }
+
+  RefPtr<WebTransportStreamCallbackWrapper> wrapper(aCallback);
+  auto callback =
+      [wrapper{std::move(wrapper)}](
+          Result<RefPtr<Http3WebTransportStream>, nsresult>&& aResult) {
+        if (aResult.isErr()) {
+          wrapper->CallOnError(aResult.unwrapErr());
+          return;
+        }
+
+        RefPtr<Http3WebTransportStream> stream = aResult.unwrap();
+        RefPtr<WebTransportStreamProxy> streamProxy =
+            new WebTransportStreamProxy(stream);
+        wrapper->CallOnStreamReady(streamProxy);
+      };
+
+  if (aBidi) {
+    session->CreateOutgoingBidirectionalStream(std::move(callback));
+  } else {
+    session->CreateOutgoingUnidirectionalStream(std::move(callback));
+  }
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::CreateOutgoingUnidirectionalStream(
+    nsIWebTransportStreamCallback* callback) {
+  if (!callback) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  MutexAutoLock lock(mMutex);
+  CreateStreamInternal(callback, false);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::CreateOutgoingBidirectionalStream(
+    nsIWebTransportStreamCallback* callback) {
+  if (!callback) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  MutexAutoLock lock(mMutex);
+  CreateStreamInternal(callback, true);
+  return NS_OK;
+}
+
+void WebTransportSessionProxy::SendDatagramInternal(
+    const RefPtr<Http3WebTransportSession>& aSession, nsTArray<uint8_t>&& aData,
+    uint64_t aTrackingId) {
+  MOZ_ASSERT(OnSocketThread());
+
+  aSession->SendDatagram(std::move(aData), aTrackingId);
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::SendDatagram(const nsTArray<uint8_t>& aData,
+                                       uint64_t aTrackingId) {
+  RefPtr<Http3WebTransportSession> session;
+  {
+    MutexAutoLock lock(mMutex);
+    if (mState != WebTransportSessionProxyState::ACTIVE ||
+        !mWebTransportSession) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+    session = mWebTransportSession;
+  }
+
+  nsTArray<uint8_t> copied;
+  copied.Assign(aData);
+  if (!OnSocketThread()) {
+    return gSocketTransportService->Dispatch(NS_NewRunnableFunction(
+        "WebTransportSessionProxy::SendDatagramInternal",
+        [self = RefPtr{this}, session{std::move(session)},
+         data{std::move(copied)}, trackingId(aTrackingId)]() mutable {
+          self->SendDatagramInternal(session, std::move(data), trackingId);
+        }));
+  }
+
+  SendDatagramInternal(session, std::move(copied), aTrackingId);
+  return NS_OK;
+}
+
+void WebTransportSessionProxy::GetMaxDatagramSizeInternal(
+    const RefPtr<Http3WebTransportSession>& aSession) {
+  MOZ_ASSERT(OnSocketThread());
+
+  aSession->GetMaxDatagramSize();
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::GetMaxDatagramSize() {
+  RefPtr<Http3WebTransportSession> session;
+  {
+    MutexAutoLock lock(mMutex);
+    if (mState != WebTransportSessionProxyState::ACTIVE ||
+        !mWebTransportSession) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+    session = mWebTransportSession;
+  }
+
+  if (!OnSocketThread()) {
+    return gSocketTransportService->Dispatch(NS_NewRunnableFunction(
+        "WebTransportSessionProxy::GetMaxDatagramSizeInternal",
+        [self = RefPtr{this}, session{std::move(session)}]() {
+          self->GetMaxDatagramSizeInternal(session);
+        }));
+  }
+
+  GetMaxDatagramSizeInternal(session);
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// WebTransportSessionProxy::nsIStreamListener
+//-----------------------------------------------------------------------------
+
+NS_IMETHODIMP
+WebTransportSessionProxy::OnStartRequest(nsIRequest* aRequest) {
+  MOZ_ASSERT(NS_IsMainThread());
+  LOG(("WebTransportSessionProxy::OnStartRequest\n"));
+  nsCOMPtr<WebTransportSessionEventListener> listener;
+  nsAutoCString reason;
+  uint32_t closeStatus = 0;
+  {
+    MutexAutoLock lock(mMutex);
+    switch (mState) {
+      case WebTransportSessionProxyState::INIT:
+      case WebTransportSessionProxyState::DONE:
+      case WebTransportSessionProxyState::ACTIVE:
+      case WebTransportSessionProxyState::SESSION_CLOSE_PENDING:
+        MOZ_ASSERT(false, "OnStartRequest cannot be called in this state.");
+        break;
+      case WebTransportSessionProxyState::NEGOTIATING:
+      case WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING:
+        listener = mListener;
+        mListener = nullptr;
+        mChannel = nullptr;
+        reason = mReason;
+        closeStatus = mCloseStatus;
+        ChangeState(WebTransportSessionProxyState::DONE);
+        break;
+      case WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED: {
+        uint32_t status;
+
+        nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(mChannel);
+        if (!httpChannel ||
+            NS_FAILED(httpChannel->GetResponseStatus(&status)) ||
+            !(status >= 200 && status < 300)) {
+          listener = mListener;
+          mListener = nullptr;
+          mChannel = nullptr;
+          mReason = ""_ns;
+          reason = ""_ns;
+          mCloseStatus =
+              0;  // TODO: find a better error. Currently error code 0 is used
+          ChangeState(WebTransportSessionProxyState::SESSION_CLOSE_PENDING);
+          CloseSessionInternal();  // TODO: find a better error. Currently error
+                                   // code 0 is used.
+        }
+        // The success cases will be handled in OnStopRequest.
+      } break;
+    }
+  }
+  if (listener) {
+    listener->OnSessionClosed(closeStatus, reason);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::OnDataAvailable(nsIRequest* aRequest,
+                                          nsIInputStream* aStream,
+                                          uint64_t aOffset, uint32_t aCount) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_RELEASE_ASSERT(
+      false, "WebTransportSessionProxy::OnDataAvailable should not be called");
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::OnStopRequest(nsIRequest* aRequest,
+                                        nsresult aStatus) {
+  MOZ_ASSERT(NS_IsMainThread());
+  mChannel = nullptr;
+  nsCOMPtr<WebTransportSessionEventListener> listener;
+  nsAutoCString reason;
+  uint32_t closeStatus = 0;
+  uint64_t sessionId;
+  bool succeeded = false;
+  nsTArray<std::function<void()>> pendingEvents;
+  nsTArray<std::function<void(nsresult)>> pendingCreateStreamEvents;
+  {
+    MutexAutoLock lock(mMutex);
+    switch (mState) {
+      case WebTransportSessionProxyState::INIT:
+      case WebTransportSessionProxyState::ACTIVE:
+      case WebTransportSessionProxyState::NEGOTIATING:
+        MOZ_ASSERT(false, "OnStopRequest cannot be called in this state.");
+        break;
+      case WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING:
+        reason = mReason;
+        closeStatus = mCloseStatus;
+        listener = mListener;
+        mListener = nullptr;
+        ChangeState(WebTransportSessionProxyState::DONE);
+        break;
+      case WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED:
+        if (NS_FAILED(aStatus)) {
+          listener = mListener;
+          mListener = nullptr;
+          mReason = ""_ns;
+          reason = ""_ns;
+          mCloseStatus = 0;
+          ChangeState(WebTransportSessionProxyState::SESSION_CLOSE_PENDING);
+          CloseSessionInternal();  // TODO: find a better error. Currently error
+                                   // code 0 is used.
+        } else {
+          succeeded = true;
+          sessionId = mSessionId;
+          listener = mListener;
+          ChangeState(WebTransportSessionProxyState::ACTIVE);
+        }
+        break;
+      case WebTransportSessionProxyState::SESSION_CLOSE_PENDING:
+      case WebTransportSessionProxyState::DONE:
+        break;
+    }
+    pendingEvents = std::move(mPendingEvents);
+    pendingCreateStreamEvents = std::move(mPendingCreateStreamEvents);
+    if (!pendingCreateStreamEvents.IsEmpty()) {
+      if (NS_SUCCEEDED(aStatus) &&
+          (mState == WebTransportSessionProxyState::DONE ||
+           mState == WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING ||
+           mState == WebTransportSessionProxyState::SESSION_CLOSE_PENDING)) {
+        aStatus = NS_ERROR_FAILURE;
+      }
+    }
+
+    mStopRequestCalled = true;
+  }
+
+  if (!pendingCreateStreamEvents.IsEmpty()) {
+    Unused << gSocketTransportService->Dispatch(NS_NewRunnableFunction(
+        "WebTransportSessionProxy::DispatchPendingCreateStreamEvents",
+        [pendingCreateStreamEvents = std::move(pendingCreateStreamEvents),
+         status(aStatus)]() {
+          for (const auto& event : pendingCreateStreamEvents) {
+            event(status);
+          }
+        }));
+  }  // otherwise let the CreateStreams just go away
+
+  if (listener) {
+    if (succeeded) {
+      listener->OnSessionReady(sessionId);
+      if (!pendingEvents.IsEmpty()) {
+        Unused << gSocketTransportService->Dispatch(NS_NewRunnableFunction(
+            "WebTransportSessionProxy::DispatchPendingEvents",
+            [pendingEvents = std::move(pendingEvents)]() {
+              for (const auto& event : pendingEvents) {
+                event();
+              }
+            }));
+      }
+    } else {
+      listener->OnSessionClosed(closeStatus,
+                                reason);  // TODO: find a better error.
+                                          // Currently error code 0 is used.
+    }
+  }
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// WebTransportSessionProxy::nsIChannelEventSink
+//-----------------------------------------------------------------------------
+
+NS_IMETHODIMP
+WebTransportSessionProxy::AsyncOnChannelRedirect(
+    nsIChannel* aOldChannel, nsIChannel* aNewChannel, uint32_t aFlags,
+    nsIAsyncVerifyRedirectCallback* callback) {
+  // Currently implementation we do not reach this part of the code
+  // as location headers are not forwarded by the http3 stack to the applicaion.
+  // Hence, the channel is aborted due to the location header check in
+  // nsHttpChannel::AsyncProcessRedirection This comment must be removed  after
+  // the  following neqo bug is resolved
+  // https://github.com/mozilla/neqo/issues/1364
+  if (!StaticPrefs::network_webtransport_redirect_enabled()) {
+    LOG(("Channel Redirects are disabled for WebTransport sessions"));
+    return NS_ERROR_ABORT;
+  }
+
+  nsCOMPtr<nsIURI> newURI;
+  nsresult rv = NS_GetFinalChannelURI(aNewChannel, getter_AddRefs(newURI));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = aNewChannel->GetURI(getter_AddRefs(newURI));
+  if (NS_FAILED(rv)) {
+    callback->OnRedirectVerifyCallback(rv);
+    return NS_OK;
+  }
+
+  // abort the request if redirecting to insecure context
+  if (!newURI->SchemeIs("https")) {
+    callback->OnRedirectVerifyCallback(NS_ERROR_ABORT);
+    return NS_OK;
+  }
+
+  // Assign to mChannel after we get notification about success of the
+  // redirect in OnRedirectResult.
+  mRedirectChannel = aNewChannel;
+
+  callback->OnRedirectVerifyCallback(NS_OK);
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// WebTransportSessionProxy::nsIRedirectResultListener
+//-----------------------------------------------------------------------------
+
+NS_IMETHODIMP
+WebTransportSessionProxy::OnRedirectResult(nsresult aStatus) {
+  if (NS_SUCCEEDED(aStatus) && mRedirectChannel) {
+    mChannel = mRedirectChannel;
+  }
+
+  mRedirectChannel = nullptr;
+
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// WebTransportSessionProxy::nsIInterfaceRequestor
+//-----------------------------------------------------------------------------
+
+NS_IMETHODIMP
+WebTransportSessionProxy::GetInterface(const nsIID& aIID, void** aResult) {
+  if (aIID.Equals(NS_GET_IID(nsIChannelEventSink))) {
+    NS_ADDREF_THIS();
+    *aResult = static_cast<nsIChannelEventSink*>(this);
+    return NS_OK;
+  }
+
+  if (aIID.Equals(NS_GET_IID(nsIRedirectResultListener))) {
+    NS_ADDREF_THIS();
+    *aResult = static_cast<nsIRedirectResultListener*>(this);
+    return NS_OK;
+  }
+
+  return NS_ERROR_NO_INTERFACE;
+}
+
+//-----------------------------------------------------------------------------
+// WebTransportSessionProxy::WebTransportSessionEventListener
+//-----------------------------------------------------------------------------
+
+// This function is called when the Http3WebTransportSession is ready. After
+// this call WebTransportSessionProxy is responsible for the
+// Http3WebTransportSession, i.e. it is responsible for closing it.
+// The listener of the WebTransportSessionProxy will be informed during
+// OnStopRequest call.
+NS_IMETHODIMP
+WebTransportSessionProxy::OnSessionReadyInternal(
+    Http3WebTransportSession* aSession) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  LOG(("WebTransportSessionProxy::OnSessionReadyInternal"));
+  MutexAutoLock lock(mMutex);
+  switch (mState) {
+    case WebTransportSessionProxyState::INIT:
+    case WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING:
+    case WebTransportSessionProxyState::ACTIVE:
+    case WebTransportSessionProxyState::SESSION_CLOSE_PENDING:
+    case WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED:
+      MOZ_ASSERT(false,
+                 "OnSessionReadyInternal cannot be called in this state.");
+      return NS_ERROR_ABORT;
+    case WebTransportSessionProxyState::NEGOTIATING:
+      mWebTransportSession = aSession;
+      mSessionId = aSession->StreamId();
+      ChangeState(WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED);
+      break;
+    case WebTransportSessionProxyState::DONE:
+      // The session has been canceled. We do not need to set
+      // mWebTransportSession.
+      break;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::OnIncomingStreamAvailableInternal(
+    Http3WebTransportStream* aStream) {
+  nsCOMPtr<WebTransportSessionEventListener> listener;
+  {
+    MutexAutoLock lock(mMutex);
+
+    LOG(
+        ("WebTransportSessionProxy::OnIncomingStreamAvailableInternal %p "
+         "mState=%d "
+         "mStopRequestCalled=%d",
+         this, mState, mStopRequestCalled));
+    // Since OnSessionReady on the listener is called on the main thread,
+    // OnIncomingStreamAvailableInternal and OnSessionReady can be racy. If
+    // OnStopRequest is not called yet, OnIncomingStreamAvailableInternal needs
+    // to wait.
+    if (!mStopRequestCalled) {
+      mPendingEvents.AppendElement(
+          [self = RefPtr{this}, stream = RefPtr{aStream}]() {
+            self->OnIncomingStreamAvailableInternal(stream);
+          });
+      return NS_OK;
+    }
+
+    if (!mTarget->IsOnCurrentThread()) {
+      RefPtr<WebTransportSessionProxy> self(this);
+      RefPtr<Http3WebTransportStream> stream = aStream;
+      Unused << mTarget->Dispatch(NS_NewRunnableFunction(
+          "WebTransportSessionProxy::OnIncomingStreamAvailableInternal",
+          [self{std::move(self)}, stream{std::move(stream)}]() {
+            self->OnIncomingStreamAvailableInternal(stream);
+          }));
+      return NS_OK;
+    }
+
+    LOG(
+        ("WebTransportSessionProxy::OnIncomingStreamAvailableInternal %p "
+         "mState=%d mListener=%p",
+         this, mState, mListener.get()));
+    if (mState == WebTransportSessionProxyState::ACTIVE) {
+      listener = mListener;
+    }
+  }
+
+  if (!listener) {
+    // Session can be already closed.
+    return NS_OK;
+  }
+
+  RefPtr<WebTransportStreamProxy> streamProxy =
+      new WebTransportStreamProxy(aStream);
+  if (aStream->StreamType() == WebTransportStreamType::BiDi) {
+    Unused << listener->OnIncomingBidirectionalStreamAvailable(streamProxy);
+  } else {
+    Unused << listener->OnIncomingUnidirectionalStreamAvailable(streamProxy);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::OnIncomingBidirectionalStreamAvailable(
+    nsIWebTransportBidirectionalStream* aStream) {
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::OnIncomingUnidirectionalStreamAvailable(
+    nsIWebTransportReceiveStream* aStream) {
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::OnSessionReady(uint64_t ready) {
+  MOZ_ASSERT(false, "Should not b called");
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::OnSessionClosed(uint32_t status,
+                                          const nsACString& reason) {
+  MOZ_ASSERT(OnSocketThread(), "not on socket thread");
+  MutexAutoLock lock(mMutex);
+  LOG(
+      ("WebTransportSessionProxy::OnSessionClosed %p mState=%d "
+       "mStopRequestCalled=%d",
+       this, mState, mStopRequestCalled));
+  // Since OnSessionReady on the listener is called on the main thread,
+  // OnSessionClosed and OnSessionReady can be racy. If OnStopRequest is not
+  // called yet, OnSessionClosed needs to wait.
+  if (!mStopRequestCalled) {
+    nsCString closeReason(reason);
+    mPendingEvents.AppendElement(
+        [self = RefPtr{this}, status(status), closeReason(closeReason)]() {
+          Unused << self->OnSessionClosed(status, closeReason);
+        });
+    return NS_OK;
+  }
+
+  switch (mState) {
+    case WebTransportSessionProxyState::INIT:
+    case WebTransportSessionProxyState::NEGOTIATING:
+    case WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING:
+      MOZ_ASSERT(false, "OnSessionClosed cannot be called in this state.");
+      return NS_ERROR_ABORT;
+    case WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED:
+    case WebTransportSessionProxyState::ACTIVE: {
+      mCloseStatus = status;
+      mReason = reason;
+      mWebTransportSession = nullptr;
+      ChangeState(WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING);
+      CallOnSessionClosed();
+    } break;
+    case WebTransportSessionProxyState::SESSION_CLOSE_PENDING:
+      ChangeState(WebTransportSessionProxyState::DONE);
+      break;
+    case WebTransportSessionProxyState::DONE:
+      // The session has been canceled. We do not need to set
+      // mWebTransportSession.
+      break;
+  }
+  return NS_OK;
+}
+
+void WebTransportSessionProxy::CallOnSessionClosedLocked() {
+  MutexAutoLock lock(mMutex);
+  CallOnSessionClosed();
+}
+
+void WebTransportSessionProxy::CallOnSessionClosed() {
+  mMutex.AssertCurrentThreadOwns();
+
+  if (!mTarget->IsOnCurrentThread()) {
+    RefPtr<WebTransportSessionProxy> self(this);
+    Unused << mTarget->Dispatch(NS_NewRunnableFunction(
+        "WebTransportSessionProxy::CallOnSessionClosed",
+        [self{std::move(self)}]() { self->CallOnSessionClosedLocked(); }));
+    return;
+  }
+
+  MOZ_ASSERT(mTarget->IsOnCurrentThread());
+  nsCOMPtr<WebTransportSessionEventListener> listener;
+  nsAutoCString reason;
+  uint32_t closeStatus = 0;
+
+  switch (mState) {
+    case WebTransportSessionProxyState::INIT:
+    case WebTransportSessionProxyState::NEGOTIATING:
+    case WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED:
+    case WebTransportSessionProxyState::ACTIVE:
+    case WebTransportSessionProxyState::SESSION_CLOSE_PENDING:
+      MOZ_ASSERT(false, "CallOnSessionClosed cannot be called in this state.");
+      break;
+    case WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING:
+      listener = mListener;
+      mListener = nullptr;
+      reason = mReason;
+      closeStatus = mCloseStatus;
+      ChangeState(WebTransportSessionProxyState::DONE);
+      break;
+    case WebTransportSessionProxyState::DONE:
+      break;
+  }
+
+  if (listener) {
+    // Don't invoke the callback under the lock.
+    MutexAutoUnlock unlock(mMutex);
+    listener->OnSessionClosed(closeStatus, reason);
+  }
+}
+
+void WebTransportSessionProxy::ChangeState(
+    WebTransportSessionProxyState newState) {
+  mMutex.AssertCurrentThreadOwns();
+  LOG(("WebTransportSessionProxy::ChangeState %d -> %d [this=%p]", mState,
+       newState, this));
+  switch (newState) {
+    case WebTransportSessionProxyState::INIT:
+      MOZ_ASSERT(false, "Cannot change into INIT sate.");
+      break;
+    case WebTransportSessionProxyState::NEGOTIATING:
+      MOZ_ASSERT(mState == WebTransportSessionProxyState::INIT,
+                 "Only from INIT can be change into NEGOTIATING");
+      MOZ_ASSERT(mChannel);
+      MOZ_ASSERT(mListener);
+      break;
+    case WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED:
+      MOZ_ASSERT(
+          mState == WebTransportSessionProxyState::NEGOTIATING,
+          "Only from NEGOTIATING can be change into NEGOTIATING_SUCCEEDED");
+      MOZ_ASSERT(mChannel);
+      MOZ_ASSERT(mWebTransportSession);
+      MOZ_ASSERT(mListener);
+      break;
+    case WebTransportSessionProxyState::ACTIVE:
+      MOZ_ASSERT(mState == WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED,
+                 "Only from NEGOTIATING_SUCCEEDED can be change into ACTIVE");
+      MOZ_ASSERT(!mChannel);
+      MOZ_ASSERT(mWebTransportSession);
+      MOZ_ASSERT(mListener);
+      break;
+    case WebTransportSessionProxyState::SESSION_CLOSE_PENDING:
+      MOZ_ASSERT(
+          (mState == WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED) ||
+              (mState == WebTransportSessionProxyState::ACTIVE),
+          "Only from NEGOTIATING_SUCCEEDED and ACTIVE can be change into"
+          " SESSION_CLOSE_PENDING");
+      MOZ_ASSERT(!mChannel);
+      MOZ_ASSERT(mWebTransportSession);
+      MOZ_ASSERT(!mListener);
+      break;
+    case WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING:
+      MOZ_ASSERT(
+          (mState == WebTransportSessionProxyState::NEGOTIATING_SUCCEEDED) ||
+              (mState == WebTransportSessionProxyState::ACTIVE),
+          "Only from NEGOTIATING_SUCCEEDED and ACTIVE can be change into"
+          " CLOSE_CALLBACK_PENDING");
+      MOZ_ASSERT(!mWebTransportSession);
+      MOZ_ASSERT(mListener);
+      break;
+    case WebTransportSessionProxyState::DONE:
+      MOZ_ASSERT(
+          (mState == WebTransportSessionProxyState::NEGOTIATING) ||
+              (mState ==
+               WebTransportSessionProxyState::SESSION_CLOSE_PENDING) ||
+              (mState == WebTransportSessionProxyState::CLOSE_CALLBACK_PENDING),
+          "Only from NEGOTIATING, SESSION_CLOSE_PENDING and "
+          "CLOSE_CALLBACK_PENDING can be change into DONE");
+      MOZ_ASSERT(!mChannel);
+      MOZ_ASSERT(!mWebTransportSession);
+      MOZ_ASSERT(!mListener);
+      break;
+  }
+  mState = newState;
+}
+
+void WebTransportSessionProxy::NotifyDatagramReceived(
+    nsTArray<uint8_t>&& aData) {
+  nsCOMPtr<WebTransportSessionEventListener> listener;
+  {
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(mTarget->IsOnCurrentThread());
+
+    if (!mStopRequestCalled) {
+      CopyableTArray<uint8_t> copied(aData);
+      mPendingEvents.AppendElement(
+          [self = RefPtr{this}, data = std::move(copied)]() mutable {
+            self->NotifyDatagramReceived(std::move(data));
+          });
+      return;
+    }
+
+    if (mState != WebTransportSessionProxyState::ACTIVE || !mListener) {
+      return;
+    }
+    listener = mListener;
+  }
+
+  listener->OnDatagramReceived(aData);
+}
+
+NS_IMETHODIMP WebTransportSessionProxy::OnDatagramReceivedInternal(
+    nsTArray<uint8_t>&& aData) {
+  MOZ_ASSERT(OnSocketThread());
+
+  {
+    MutexAutoLock lock(mMutex);
+    if (!mTarget->IsOnCurrentThread()) {
+      return mTarget->Dispatch(NS_NewRunnableFunction(
+          "WebTransportSessionProxy::OnDatagramReceived",
+          [self = RefPtr{this}, data{std::move(aData)}]() mutable {
+            self->NotifyDatagramReceived(std::move(data));
+          }));
+    }
+  }
+
+  NotifyDatagramReceived(std::move(aData));
+  return NS_OK;
+}
+
+NS_IMETHODIMP WebTransportSessionProxy::OnDatagramReceived(
+    const nsTArray<uint8_t>& aData) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+void WebTransportSessionProxy::OnMaxDatagramSizeInternal(uint64_t aSize) {
+  nsCOMPtr<WebTransportSessionEventListener> listener;
+  {
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(mTarget->IsOnCurrentThread());
+
+    if (!mStopRequestCalled) {
+      mPendingEvents.AppendElement([self = RefPtr{this}, size(aSize)]() {
+        self->OnMaxDatagramSizeInternal(size);
+      });
+      return;
+    }
+
+    if (mState != WebTransportSessionProxyState::ACTIVE || !mListener) {
+      return;
+    }
+    listener = mListener;
+  }
+
+  listener->OnMaxDatagramSize(aSize);
+}
+
+NS_IMETHODIMP WebTransportSessionProxy::OnMaxDatagramSize(uint64_t aSize) {
+  MOZ_ASSERT(OnSocketThread());
+
+  {
+    MutexAutoLock lock(mMutex);
+    if (!mTarget->IsOnCurrentThread()) {
+      return mTarget->Dispatch(
+          NS_NewRunnableFunction("WebTransportSessionProxy::OnMaxDatagramSize",
+                                 [self = RefPtr{this}, size(aSize)] {
+                                   self->OnMaxDatagramSizeInternal(size);
+                                 }));
+    }
+  }
+
+  OnMaxDatagramSizeInternal(aSize);
+  return NS_OK;
+}
+
+void WebTransportSessionProxy::OnOutgoingDatagramOutComeInternal(
+    uint64_t aId, WebTransportSessionEventListener::DatagramOutcome aOutCome) {
+  nsCOMPtr<WebTransportSessionEventListener> listener;
+  {
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(mTarget->IsOnCurrentThread());
+    if (mState != WebTransportSessionProxyState::ACTIVE || !mListener) {
+      return;
+    }
+    listener = mListener;
+  }
+
+  listener->OnOutgoingDatagramOutCome(aId, aOutCome);
+}
+
+NS_IMETHODIMP
+WebTransportSessionProxy::OnOutgoingDatagramOutCome(
+    uint64_t aId, WebTransportSessionEventListener::DatagramOutcome aOutCome) {
+  MOZ_ASSERT(OnSocketThread());
+
+  {
+    MutexAutoLock lock(mMutex);
+    if (!mTarget->IsOnCurrentThread()) {
+      return mTarget->Dispatch(NS_NewRunnableFunction(
+          "WebTransportSessionProxy::OnOutgoingDatagramOutCome",
+          [self = RefPtr{this}, id(aId), outcome(aOutCome)] {
+            self->OnOutgoingDatagramOutComeInternal(id, outcome);
+          }));
+    }
+  }
+
+  OnOutgoingDatagramOutComeInternal(aId, aOutCome);
+  return NS_OK;
+}
+
+NS_IMETHODIMP WebTransportSessionProxy::OnStopSending(uint64_t aStreamId,
+                                                      nsresult aError) {
+  MOZ_ASSERT(OnSocketThread());
+  nsCOMPtr<WebTransportSessionEventListener> listener;
+  {
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(mTarget->IsOnCurrentThread());
+
+    if (mState != WebTransportSessionProxyState::ACTIVE || !mListener) {
+      return NS_OK;
+    }
+    listener = mListener;
+  }
+
+  listener->OnStopSending(aStreamId, aError);
+  return NS_OK;
+}
+
+NS_IMETHODIMP WebTransportSessionProxy::OnResetReceived(uint64_t aStreamId,
+                                                        nsresult aError) {
+  MOZ_ASSERT(OnSocketThread());
+  nsCOMPtr<WebTransportSessionEventListener> listener;
+  {
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(mTarget->IsOnCurrentThread());
+
+    if (mState != WebTransportSessionProxyState::ACTIVE || !mListener) {
+      return NS_OK;
+    }
+    listener = mListener;
+  }
+
+  listener->OnResetReceived(aStreamId, aError);
+  return NS_OK;
+}
+
+}  // namespace mozilla::net
diff --git a/netwerk/protocol/webtransport/WebTransportSessionProxy.h b/netwerk/protocol/webtransport/WebTransportSessionProxy.h
new file mode 100644
index 0000000000..1e8eacc60b
--- /dev/null
+++ b/netwerk/protocol/webtransport/WebTransportSessionProxy.h
@@ -0,0 +1,192 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 mozilla_net_WebTransportProxy_h
+#define mozilla_net_WebTransportProxy_h
+
+#include <functional>
+#include "nsIChannelEventSink.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIRedirectResultListener.h"
+#include "nsIStreamListener.h"
+#include "nsIWebTransport.h"
+
+/*
+ * WebTransportSessionProxy is introduced to enable the creation of a
+ * Http3WebTransportSession and coordination of actions that are performed on
+ * the main thread and on the socket thread.
+ *
+ * mChannel, mRedirectChannel, and mListener are used only on the main thread.
+ *
+ * mWebTransportSession is used only on the socket thread.
+ *
+ * mState and mSessionId are used on both threads, socket and main thread and it
+ * is only used with a lock.
+ *
+ *
+ * WebTransportSessionProxyState:
+ * - INIT: before AsyncConnect is called.
+ *
+ * - NEGOTIATING: It is set during AsyncConnect. During this state HttpChannel
+ *   is open but OnStartRequest has not been called yet. This state can
+ *   transfer into:
+ *    - NEGOTIATING_SUCCEEDED: when a Http3WebTransportSession has been
+ *      negotiated.
+ *    - DONE: when a WebTransport session has been canceled.
+ *
+ * - NEGOTIATING_SUCCEEDED: It is set during parsing of
+ *   Http3WebTransportSession response when the response has been successful.
+ *   mWebTransport is set to the Http3WebTransportSession at the same time the
+ *   session changes to this state. This state can transfer into:
+ *    - ACTIVE: during the OnStopRequest call if the WebTransport has not been
+ *      canceled or failed for other reason, e.g. a browser shutdown or content
+ *      blocking policies.
+ *    - SESSION_CLOSE_PENDING: if the WebTransport has been canceled via an API
+ *      call or content blocking policies. (the main thread initiated close).
+ *    - CLOSE_CALLBACK_PENDING: if Http3WebTransportSession has been canceled
+ *     due to a shutdown or a server closing a session. (the socket thread
+ *     initiated close).
+ *
+ * - ACTIVE: In this state the session is negotiated and ready to use. This
+ *   state can transfer into:
+ *    - SESSION_CLOSE_PENDING: if the WebTransport has been canceled via an API
+ *      call(nsIWebTransport::closeSession) or content blocking policies. (the
+ *      main thread initiated close).
+ *    - CLOSE_CALLBACK_PENDING: if Http3WebTransportSession has been canceled
+ *      due to a shutdown or a server closing a session. (the socket thread
+ *      initiated close).
+ *
+ * - CLOSE_CALLBACK_PENDING: This is the socket thread initiated close. In this
+ *   state, the Http3WebTransportSession has been closed and a
+ * CallOnSessionClosed call is dispatched to the main thread to call the
+ * appropriate listener.
+ *
+ * - SESSION_CLOSE_PENDING: This is the main thread initiated close. In this
+ * state, the WebTransport has been closed via an API call
+ *   (nsIWebTransport::closeSession) and a CloseSessionInternal call is
+ * dispatched to the socket thread to close the appropriate
+ * Http3WebTransportSession.
+ *
+ * - DONE: everything has been cleaned up on both threads.
+ *
+ *
+ * AsyncConnect creates mChannel on the main thread. Redirect callbacks are also
+ * performed on the main thread (mRedirectChannel set and access only on the
+ * main thread). Before this point, there are no activities on the socket thread
+ * and Http3WebTransportSession is nullptr. mChannel is going to create a
+ * nsHttpTransaction. The transaction will be dispatched on a nsAHttpConnection,
+ * i.e. currently only the HTTP/3 version is implemented, therefore this will be
+ * a HttpConnectionUDP and a Http3Session. The Http3Session creates a
+ * Http3WebTransportSession. Until a response is received
+ * Http3WebTransportSession is only accessed by Http3Session. During parsing of
+ * a successful received from a server on the socket thread,
+ * WebTransportSessionProxy::mWebTransportSession will take a reference to
+ * Http3WebTransportSession and mState will be set to NEGOTIATING_SUCCEEDED.
+ * From now on WebTransportSessionProxy is responsible for closing
+ * Http3WebTransportSession if the closing of the session is initiated on the
+ * main thread. OnStartRequest and OnStopRequest will be called on the main
+ * thread. The session negotiation can have 2 outcomes:
+ * - If both calls, i.e. OnStartRequest an OnStopRequest, indicate that the
+ * request has succeeded and mState is NEGOTIATING_SUCCEEDED, the
+ * mListener->OnSessionReady will be called during OnStopRequest.
+ * - Otherwise, mListener->OnSessionClosed will be called, the state transferred
+ * into SESSION_CLOSE_PENDING, and CloseSessionInternal will be dispatched to
+ * the socket thread.
+ *
+ * CloseSession is called on the main thread. If the session is already closed
+ * it returns an error. If the session is in state NEGOTIATING or
+ * NEGOTIATING_SUCCEEDED mChannel will be canceled. If the session is in state
+ * NEGOTIATING_SUCCEEDED or ACTIVE the state transferred into
+ * SESSION_CLOSE_PENDING, and CloseSessionInternal will be dispatched to the
+ * socket thread
+ *
+ * OnSessionReadyInternal is called on the socket thread. If mState is
+ * NEGOTIATING the state will be set to NEGOTIATING_SUCCEEDED and mWebTransport
+ * will be set to the newly negotiated Http3WebTransportSession. If mState is
+ * DONE, the Http3WebTransportSession will be close.
+ *
+ * OnSessionClosed is called on the socket thread. mState will be set to
+ * CLOSE_CALLBACK_PENDING and CallOnSessionClosed will be dispatched to the main
+ * thread.
+ *
+ * mWebTransport is set during states NEGOTIATING_SUCCEEDED, ACTIVE and
+ * SESSION_CLOSE_PENDING.
+ */
+
+namespace mozilla::net {
+
+class WebTransportStreamCallbackWrapper;
+
+class WebTransportSessionProxy final : public nsIWebTransport,
+                                       public WebTransportSessionEventListener,
+                                       public nsIStreamListener,
+                                       public nsIChannelEventSink,
+                                       public nsIRedirectResultListener,
+                                       public nsIInterfaceRequestor {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIWEBTRANSPORT
+  NS_DECL_WEBTRANSPORTSESSIONEVENTLISTENER
+  NS_DECL_NSIREQUESTOBSERVER
+  NS_DECL_NSISTREAMLISTENER
+  NS_DECL_NSICHANNELEVENTSINK
+  NS_DECL_NSIREDIRECTRESULTLISTENER
+  NS_DECL_NSIINTERFACEREQUESTOR
+
+  WebTransportSessionProxy();
+
+ private:
+  ~WebTransportSessionProxy();
+
+  void CloseSessionInternal();
+  void CloseSessionInternalLocked();
+  void CallOnSessionClosed();
+  void CallOnSessionClosedLocked();
+
+  enum WebTransportSessionProxyState {
+    INIT,
+    NEGOTIATING,
+    NEGOTIATING_SUCCEEDED,
+    ACTIVE,
+    CLOSE_CALLBACK_PENDING,
+    SESSION_CLOSE_PENDING,
+    DONE,
+  };
+  mozilla::Mutex mMutex;
+  WebTransportSessionProxyState mState MOZ_GUARDED_BY(mMutex) =
+      WebTransportSessionProxyState::INIT;
+  void ChangeState(WebTransportSessionProxyState newState);
+  void CreateStreamInternal(nsIWebTransportStreamCallback* callback,
+                            bool aBidi);
+  void DoCreateStream(WebTransportStreamCallbackWrapper* aCallback,
+                      Http3WebTransportSession* aSession, bool aBidi);
+  void SendDatagramInternal(const RefPtr<Http3WebTransportSession>& aSession,
+                            nsTArray<uint8_t>&& aData, uint64_t aTrackingId);
+  void NotifyDatagramReceived(nsTArray<uint8_t>&& aData);
+  void GetMaxDatagramSizeInternal(
+      const RefPtr<Http3WebTransportSession>& aSession);
+  void OnMaxDatagramSizeInternal(uint64_t aSize);
+  void OnOutgoingDatagramOutComeInternal(
+      uint64_t aId, WebTransportSessionEventListener::DatagramOutcome aOutCome);
+
+  nsCOMPtr<nsIChannel> mChannel;
+  nsCOMPtr<nsIChannel> mRedirectChannel;
+  nsCOMPtr<WebTransportSessionEventListener> mListener MOZ_GUARDED_BY(mMutex);
+  RefPtr<Http3WebTransportSession> mWebTransportSession MOZ_GUARDED_BY(mMutex);
+  uint64_t mSessionId MOZ_GUARDED_BY(mMutex) = UINT64_MAX;
+  uint32_t mCloseStatus MOZ_GUARDED_BY(mMutex) = 0;
+  nsCString mReason MOZ_GUARDED_BY(mMutex);
+  bool mStopRequestCalled MOZ_GUARDED_BY(mMutex) = false;
+  // This is used to store events happened before OnSessionReady.
+  // Note that these events will be dispatched to the socket thread.
+  nsTArray<std::function<void()>> mPendingEvents MOZ_GUARDED_BY(mMutex);
+  nsTArray<std::function<void(nsresult)>> mPendingCreateStreamEvents
+      MOZ_GUARDED_BY(mMutex);
+  nsCOMPtr<nsIEventTarget> mTarget MOZ_GUARDED_BY(mMutex);
+};
+
+}  // namespace mozilla::net
+
+#endif  // mozilla_net_WebTransportProxy_h
diff --git a/netwerk/protocol/webtransport/WebTransportStreamProxy.cpp b/netwerk/protocol/webtransport/WebTransportStreamProxy.cpp
new file mode 100644
index 0000000000..090b1cceb9
--- /dev/null
+++ b/netwerk/protocol/webtransport/WebTransportStreamProxy.cpp
@@ -0,0 +1,368 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 "WebTransportStreamProxy.h"
+
+#include "WebTransportLog.h"
+#include "Http3WebTransportStream.h"
+#include "nsProxyRelease.h"
+#include "nsSocketTransportService2.h"
+
+namespace mozilla::net {
+
+NS_IMPL_ADDREF(WebTransportStreamProxy)
+NS_IMPL_RELEASE(WebTransportStreamProxy)
+
+NS_INTERFACE_MAP_BEGIN(WebTransportStreamProxy)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIWebTransportReceiveStream)
+  NS_INTERFACE_MAP_ENTRY(nsIWebTransportReceiveStream)
+  NS_INTERFACE_MAP_ENTRY(nsIWebTransportSendStream)
+  NS_INTERFACE_MAP_ENTRY(nsIWebTransportBidirectionalStream)
+NS_INTERFACE_MAP_END
+
+WebTransportStreamProxy::WebTransportStreamProxy(
+    Http3WebTransportStream* aStream)
+    : mWebTransportStream(aStream) {
+  nsCOMPtr<nsIAsyncInputStream> inputStream;
+  nsCOMPtr<nsIAsyncOutputStream> outputStream;
+  mWebTransportStream->GetWriterAndReader(getter_AddRefs(outputStream),
+                                          getter_AddRefs(inputStream));
+  if (outputStream) {
+    mWriter = new AsyncOutputStreamWrapper(outputStream);
+  }
+  if (inputStream) {
+    mReader = new AsyncInputStreamWrapper(inputStream, mWebTransportStream);
+  }
+}
+
+WebTransportStreamProxy::~WebTransportStreamProxy() {
+  // mWebTransportStream needs to be destroyed on the socket thread.
+  NS_ProxyRelease("WebTransportStreamProxy::~WebTransportStreamProxy",
+                  gSocketTransportService, mWebTransportStream.forget());
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::SendStopSending(uint8_t aError) {
+  if (!OnSocketThread()) {
+    RefPtr<WebTransportStreamProxy> self(this);
+    return gSocketTransportService->Dispatch(
+        NS_NewRunnableFunction("WebTransportStreamProxy::SendStopSending",
+                               [self{std::move(self)}, error(aError)]() {
+                                 self->SendStopSending(error);
+                               }));
+  }
+
+  mWebTransportStream->SendStopSending(aError);
+  return NS_OK;
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::SendFin(void) {
+  if (!mWriter) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  mWriter->Close();
+
+  if (!OnSocketThread()) {
+    RefPtr<WebTransportStreamProxy> self(this);
+    return gSocketTransportService->Dispatch(NS_NewRunnableFunction(
+        "WebTransportStreamProxy::SendFin",
+        [self{std::move(self)}]() { self->mWebTransportStream->SendFin(); }));
+  }
+
+  mWebTransportStream->SendFin();
+  return NS_OK;
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::Reset(uint8_t aErrorCode) {
+  if (!mWriter) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  mWriter->Close();
+
+  if (!OnSocketThread()) {
+    RefPtr<WebTransportStreamProxy> self(this);
+    return gSocketTransportService->Dispatch(
+        NS_NewRunnableFunction("WebTransportStreamProxy::Reset",
+                               [self{std::move(self)}, error(aErrorCode)]() {
+                                 self->mWebTransportStream->Reset(error);
+                               }));
+  }
+
+  mWebTransportStream->Reset(aErrorCode);
+  return NS_OK;
+}
+
+namespace {
+
+class StatsCallbackWrapper : public nsIWebTransportStreamStatsCallback {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  explicit StatsCallbackWrapper(nsIWebTransportStreamStatsCallback* aCallback)
+      : mCallback(aCallback), mTarget(GetCurrentSerialEventTarget()) {}
+
+  NS_IMETHOD OnSendStatsAvailable(
+      nsIWebTransportSendStreamStats* aStats) override {
+    if (!mTarget->IsOnCurrentThread()) {
+      RefPtr<StatsCallbackWrapper> self(this);
+      nsCOMPtr<nsIWebTransportSendStreamStats> stats = aStats;
+      Unused << mTarget->Dispatch(NS_NewRunnableFunction(
+          "StatsCallbackWrapper::OnSendStatsAvailable",
+          [self{std::move(self)}, stats{std::move(stats)}]() {
+            self->OnSendStatsAvailable(stats);
+          }));
+      return NS_OK;
+    }
+
+    mCallback->OnSendStatsAvailable(aStats);
+    return NS_OK;
+  }
+
+  NS_IMETHOD OnReceiveStatsAvailable(
+      nsIWebTransportReceiveStreamStats* aStats) override {
+    if (!mTarget->IsOnCurrentThread()) {
+      RefPtr<StatsCallbackWrapper> self(this);
+      nsCOMPtr<nsIWebTransportReceiveStreamStats> stats = aStats;
+      Unused << mTarget->Dispatch(NS_NewRunnableFunction(
+          "StatsCallbackWrapper::OnReceiveStatsAvailable",
+          [self{std::move(self)}, stats{std::move(stats)}]() {
+            self->OnReceiveStatsAvailable(stats);
+          }));
+      return NS_OK;
+    }
+
+    mCallback->OnReceiveStatsAvailable(aStats);
+    return NS_OK;
+  }
+
+ private:
+  virtual ~StatsCallbackWrapper() {
+    NS_ProxyRelease("StatsCallbackWrapper::~StatsCallbackWrapper", mTarget,
+                    mCallback.forget());
+  }
+
+  nsCOMPtr<nsIWebTransportStreamStatsCallback> mCallback;
+  nsCOMPtr<nsIEventTarget> mTarget;
+};
+
+NS_IMPL_ISUPPORTS(StatsCallbackWrapper, nsIWebTransportStreamStatsCallback)
+
+}  // namespace
+
+NS_IMETHODIMP WebTransportStreamProxy::GetSendStreamStats(
+    nsIWebTransportStreamStatsCallback* aCallback) {
+  if (!OnSocketThread()) {
+    RefPtr<WebTransportStreamProxy> self(this);
+    nsCOMPtr<nsIWebTransportStreamStatsCallback> callback =
+        new StatsCallbackWrapper(aCallback);
+    return gSocketTransportService->Dispatch(NS_NewRunnableFunction(
+        "WebTransportStreamProxy::GetSendStreamStats",
+        [self{std::move(self)}, callback{std::move(callback)}]() {
+          self->GetSendStreamStats(callback);
+        }));
+  }
+
+  nsCOMPtr<nsIWebTransportSendStreamStats> stats =
+      mWebTransportStream->GetSendStreamStats();
+  aCallback->OnSendStatsAvailable(stats);
+  return NS_OK;
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::GetReceiveStreamStats(
+    nsIWebTransportStreamStatsCallback* aCallback) {
+  if (!OnSocketThread()) {
+    RefPtr<WebTransportStreamProxy> self(this);
+    nsCOMPtr<nsIWebTransportStreamStatsCallback> callback =
+        new StatsCallbackWrapper(aCallback);
+    return gSocketTransportService->Dispatch(NS_NewRunnableFunction(
+        "WebTransportStreamProxy::GetReceiveStreamStats",
+        [self{std::move(self)}, callback{std::move(callback)}]() {
+          self->GetReceiveStreamStats(callback);
+        }));
+  }
+
+  nsCOMPtr<nsIWebTransportReceiveStreamStats> stats =
+      mWebTransportStream->GetReceiveStreamStats();
+  aCallback->OnReceiveStatsAvailable(stats);
+  return NS_OK;
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::GetHasReceivedFIN(
+    bool* aHasReceivedFIN) {
+  *aHasReceivedFIN = mWebTransportStream->RecvDone();
+  return NS_OK;
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::GetInputStream(
+    nsIAsyncInputStream** aOut) {
+  if (!mReader) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  RefPtr<AsyncInputStreamWrapper> stream = mReader;
+  stream.forget(aOut);
+  return NS_OK;
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::GetOutputStream(
+    nsIAsyncOutputStream** aOut) {
+  if (!mWriter) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  RefPtr<AsyncOutputStreamWrapper> stream = mWriter;
+  stream.forget(aOut);
+  return NS_OK;
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::GetStreamId(uint64_t* aId) {
+  *aId = mWebTransportStream->StreamId();
+  return NS_OK;
+}
+
+//------------------------------------------------------------------------------
+// WebTransportStreamProxy::AsyncInputStreamWrapper
+//------------------------------------------------------------------------------
+
+NS_IMPL_ISUPPORTS(WebTransportStreamProxy::AsyncInputStreamWrapper,
+                  nsIInputStream, nsIAsyncInputStream)
+
+WebTransportStreamProxy::AsyncInputStreamWrapper::AsyncInputStreamWrapper(
+    nsIAsyncInputStream* aStream, Http3WebTransportStream* aWebTransportStream)
+    : mStream(aStream), mWebTransportStream(aWebTransportStream) {}
+
+WebTransportStreamProxy::AsyncInputStreamWrapper::~AsyncInputStreamWrapper() =
+    default;
+
+void WebTransportStreamProxy::AsyncInputStreamWrapper::MaybeCloseStream() {
+  if (!mWebTransportStream->RecvDone()) {
+    return;
+  }
+
+  uint64_t available = 0;
+  Unused << Available(&available);
+  if (available) {
+    // Don't close the InputStream if there's unread data available, since it
+    // would be lost. We exit above unless we know no more data will be received
+    // for the stream.
+    return;
+  }
+
+  LOG(
+      ("AsyncInputStreamWrapper::MaybeCloseStream close stream due to FIN "
+       "stream=%p",
+       mWebTransportStream.get()));
+  Close();
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncInputStreamWrapper::Close() {
+  return mStream->CloseWithStatus(NS_BASE_STREAM_CLOSED);
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncInputStreamWrapper::Available(
+    uint64_t* aAvailable) {
+  return mStream->Available(aAvailable);
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncInputStreamWrapper::StreamStatus() {
+  return mStream->StreamStatus();
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncInputStreamWrapper::Read(
+    char* aBuf, uint32_t aCount, uint32_t* aResult) {
+  LOG(("WebTransportStreamProxy::AsyncInputStreamWrapper::Read %p", this));
+  nsresult rv = mStream->Read(aBuf, aCount, aResult);
+  MaybeCloseStream();
+  return rv;
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncInputStreamWrapper::ReadSegments(
+    nsWriteSegmentFun aWriter, void* aClosure, uint32_t aCount,
+    uint32_t* aResult) {
+  LOG(("WebTransportStreamProxy::AsyncInputStreamWrapper::ReadSegments %p",
+       this));
+  nsresult rv = mStream->ReadSegments(aWriter, aClosure, aCount, aResult);
+  MaybeCloseStream();
+  return rv;
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncInputStreamWrapper::IsNonBlocking(
+    bool* aResult) {
+  return mStream->IsNonBlocking(aResult);
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncInputStreamWrapper::CloseWithStatus(
+    nsresult aStatus) {
+  return mStream->CloseWithStatus(aStatus);
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncInputStreamWrapper::AsyncWait(
+    nsIInputStreamCallback* aCallback, uint32_t aFlags,
+    uint32_t aRequestedCount, nsIEventTarget* aEventTarget) {
+  return mStream->AsyncWait(aCallback, aFlags, aRequestedCount, aEventTarget);
+}
+
+//------------------------------------------------------------------------------
+// WebTransportStreamProxy::AsyncOutputStreamWrapper
+//------------------------------------------------------------------------------
+
+NS_IMPL_ISUPPORTS(WebTransportStreamProxy::AsyncOutputStreamWrapper,
+                  nsIOutputStream, nsIAsyncOutputStream)
+
+WebTransportStreamProxy::AsyncOutputStreamWrapper::AsyncOutputStreamWrapper(
+    nsIAsyncOutputStream* aStream)
+    : mStream(aStream) {}
+
+WebTransportStreamProxy::AsyncOutputStreamWrapper::~AsyncOutputStreamWrapper() =
+    default;
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncOutputStreamWrapper::Flush() {
+  return mStream->Flush();
+}
+
+NS_IMETHODIMP
+WebTransportStreamProxy::AsyncOutputStreamWrapper::StreamStatus() {
+  return mStream->StreamStatus();
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncOutputStreamWrapper::Write(
+    const char* aBuf, uint32_t aCount, uint32_t* aResult) {
+  return mStream->Write(aBuf, aCount, aResult);
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncOutputStreamWrapper::WriteFrom(
+    nsIInputStream* aFromStream, uint32_t aCount, uint32_t* aResult) {
+  return mStream->WriteFrom(aFromStream, aCount, aResult);
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncOutputStreamWrapper::WriteSegments(
+    nsReadSegmentFun aReader, void* aClosure, uint32_t aCount,
+    uint32_t* aResult) {
+  return mStream->WriteSegments(aReader, aClosure, aCount, aResult);
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncOutputStreamWrapper::AsyncWait(
+    nsIOutputStreamCallback* aCallback, uint32_t aFlags,
+    uint32_t aRequestedCount, nsIEventTarget* aEventTarget) {
+  return mStream->AsyncWait(aCallback, aFlags, aRequestedCount, aEventTarget);
+}
+
+NS_IMETHODIMP
+WebTransportStreamProxy::AsyncOutputStreamWrapper::CloseWithStatus(
+    nsresult aStatus) {
+  return mStream->CloseWithStatus(aStatus);
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncOutputStreamWrapper::Close() {
+  return mStream->Close();
+}
+
+NS_IMETHODIMP WebTransportStreamProxy::AsyncOutputStreamWrapper::IsNonBlocking(
+    bool* aResult) {
+  return mStream->IsNonBlocking(aResult);
+}
+
+}  // namespace mozilla::net
diff --git a/netwerk/protocol/webtransport/WebTransportStreamProxy.h b/netwerk/protocol/webtransport/WebTransportStreamProxy.h
new file mode 100644
index 0000000000..972eac3f05
--- /dev/null
+++ b/netwerk/protocol/webtransport/WebTransportStreamProxy.h
@@ -0,0 +1,83 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 mozilla_net_WebTransportStreamProxy_h
+#define mozilla_net_WebTransportStreamProxy_h
+
+#include "nsIAsyncInputStream.h"
+#include "nsIAsyncOutputStream.h"
+#include "nsIWebTransportStream.h"
+#include "nsCOMPtr.h"
+
+namespace mozilla::net {
+
+class Http3WebTransportStream;
+
+class WebTransportStreamProxy final
+    : public nsIWebTransportReceiveStream,
+      public nsIWebTransportSendStream,
+      public nsIWebTransportBidirectionalStream {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  explicit WebTransportStreamProxy(Http3WebTransportStream* aStream);
+
+  NS_IMETHOD SendStopSending(uint8_t aError) override;
+  NS_IMETHOD SendFin() override;
+  NS_IMETHOD Reset(uint8_t aErrorCode) override;
+  NS_IMETHOD GetSendStreamStats(
+      nsIWebTransportStreamStatsCallback* aCallback) override;
+  NS_IMETHOD GetReceiveStreamStats(
+      nsIWebTransportStreamStatsCallback* aCallback) override;
+
+  NS_IMETHOD GetHasReceivedFIN(bool* aHasReceivedFIN) override;
+
+  NS_IMETHOD GetInputStream(nsIAsyncInputStream** aOut) override;
+  NS_IMETHOD GetOutputStream(nsIAsyncOutputStream** aOut) override;
+
+  NS_IMETHOD GetStreamId(uint64_t* aId) override;
+
+ private:
+  virtual ~WebTransportStreamProxy();
+
+  class AsyncInputStreamWrapper : public nsIAsyncInputStream {
+   public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+    NS_DECL_NSIINPUTSTREAM
+    NS_DECL_NSIASYNCINPUTSTREAM
+
+    AsyncInputStreamWrapper(nsIAsyncInputStream* aStream,
+                            Http3WebTransportStream* aWebTransportStream);
+
+   private:
+    virtual ~AsyncInputStreamWrapper();
+    void MaybeCloseStream();
+
+    nsCOMPtr<nsIAsyncInputStream> mStream;
+    RefPtr<Http3WebTransportStream> mWebTransportStream;
+  };
+
+  class AsyncOutputStreamWrapper : public nsIAsyncOutputStream {
+   public:
+    NS_DECL_THREADSAFE_ISUPPORTS
+    NS_DECL_NSIOUTPUTSTREAM
+    NS_DECL_NSIASYNCOUTPUTSTREAM
+
+    explicit AsyncOutputStreamWrapper(nsIAsyncOutputStream* aStream);
+
+   private:
+    virtual ~AsyncOutputStreamWrapper();
+
+    nsCOMPtr<nsIAsyncOutputStream> mStream;
+  };
+
+  RefPtr<Http3WebTransportStream> mWebTransportStream;
+  RefPtr<AsyncOutputStreamWrapper> mWriter;
+  RefPtr<AsyncInputStreamWrapper> mReader;
+};
+
+}  // namespace mozilla::net
+
+#endif
diff --git a/netwerk/protocol/webtransport/moz.build b/netwerk/protocol/webtransport/moz.build
new file mode 100644
index 0000000000..ef0f6705ab
--- /dev/null
+++ b/netwerk/protocol/webtransport/moz.build
@@ -0,0 +1,34 @@
+# -*- 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/.
+
+with Files("**"):
+    BUG_COMPONENT = ("Core", "Networking: WebTransport")
+
+XPIDL_SOURCES += [
+    "nsIWebTransport.idl",
+    "nsIWebTransportStream.idl",
+]
+
+XPIDL_MODULE = "necko_webtransport"
+
+EXPORTS.mozilla.net += [
+    "WebTransportSessionProxy.h",
+    "WebTransportStreamProxy.h",
+]
+
+UNIFIED_SOURCES += [
+    "WebTransportSessionProxy.cpp",
+    "WebTransportStreamProxy.cpp",
+]
+
+FINAL_LIBRARY = "xul"
+
+LOCAL_INCLUDES += [
+    "/netwerk/base",
+    "/netwerk/protocol/http",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
diff --git a/netwerk/protocol/webtransport/nsIWebTransport.idl b/netwerk/protocol/webtransport/nsIWebTransport.idl
new file mode 100644
index 0000000000..2740236daa
--- /dev/null
+++ b/netwerk/protocol/webtransport/nsIWebTransport.idl
@@ -0,0 +1,122 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 "nsISupports.idl"
+#include "nsIURI.idl"
+#include "nsIPrincipal.idl"
+
+interface WebTransportSessionEventListener;
+interface nsIWebTransportStreamCallback;
+interface nsIWebTransportBidirectionalStream;
+interface nsIWebTransportSendStream;
+interface nsIWebTransportReceiveStream;
+
+%{C++
+namespace mozilla::dom {
+class ClientInfo;
+}
+namespace mozilla::net {
+class Http3WebTransportSession;
+class Http3WebTransportStream;
+}
+%}
+
+[ptr] native Http3WebTransportSessionPtr(mozilla::net::Http3WebTransportSession);
+[ptr] native Http3WebTransportStreamPtr(mozilla::net::Http3WebTransportStream);
+native Datagram(nsTArray<uint8_t>&&);
+[ref] native const_MaybeClientInfoRef(const mozilla::Maybe<mozilla::dom::ClientInfo>);
+
+[builtinclass, scriptable, uuid(c20d6e77-8cb1-4838-a88d-fff826080aa3)]
+interface nsIWebTransport : nsISupports {
+  cenum WebTransportError : 16 {
+    UNKNOWN_ERROR,
+    INVALID_STATE_ERROR,
+  };
+
+  // When called, perform steps in "Initialization WebTransport over HTTP".
+  void asyncConnect(in nsIURI aURI,
+                    in nsIPrincipal aLoadingPrincipal,
+                    in unsigned long aSecurityFlags,
+                    in WebTransportSessionEventListener aListener);
+
+  void asyncConnectWithClient(in nsIURI aURI,
+                    in nsIPrincipal aLoadingPrincipal,
+                    in unsigned long aSecurityFlags,
+                    in WebTransportSessionEventListener aListener,
+                    in const_MaybeClientInfoRef aClientInfo);
+
+  // Asynchronously get states.
+  void getStats();
+
+  // Close the session.
+  void closeSession(in uint32_t aErrorCode,
+                    in ACString aReason);
+
+  // Create and open a new WebTransport stream.
+  void createOutgoingBidirectionalStream(in nsIWebTransportStreamCallback aListener);
+  void createOutgoingUnidirectionalStream(in nsIWebTransportStreamCallback aListener);
+
+  void sendDatagram(in Array<uint8_t> aData, in uint64_t aTrackingId);
+
+  void getMaxDatagramSize();
+
+  // This can be only called after onSessionReady().
+  // After this point, we can retarget the underlying WebTransportSessionProxy
+  // object off main thread.
+  [noscript] void retargetTo(in nsIEventTarget aTarget);
+};
+
+// Events related to a WebTransport session.
+[scriptable, uuid(0e3cb269-f318-43c8-959e-897f57894b71)]
+interface WebTransportSessionEventListener : nsISupports {
+  // This is used to let the consumer of nsIWebTransport know that the
+  // underlying WebTransportSession object is ready to use.
+  void onSessionReady(in uint64_t aSessionId);
+  // This is used internally to pass the reference of WebTransportSession
+  // object to WebTransportSessionProxy.
+  void onSessionReadyInternal(in Http3WebTransportSessionPtr aSession);
+  void onSessionClosed(in uint32_t aErrorCode,
+                       in ACString aReason);
+
+  // When a new stream has been received.
+  void onIncomingBidirectionalStreamAvailable(in nsIWebTransportBidirectionalStream aStream);
+  void onIncomingUnidirectionalStreamAvailable(in nsIWebTransportReceiveStream aStream);
+
+  // This is used internally to pass the reference of Http3WebTransportStream
+  // object to WebTransportSessionProxy.
+  void onIncomingStreamAvailableInternal(in Http3WebTransportStreamPtr aStream);
+
+  void onStopSending(in uint64_t aStreamId, in nsresult aError);
+  void onResetReceived(in uint64_t aStreamId, in nsresult aError);
+
+  // When a new datagram has been received.
+  void onDatagramReceived(in Array<uint8_t> aData);
+
+  // This is used internally to pass the datagram to WebTransportSessionProxy.
+  void onDatagramReceivedInternal(in Datagram aData);
+
+  void onMaxDatagramSize(in uint64_t aSize);
+
+  cenum DatagramOutcome: 32 {
+    UNKNOWN               = 0,
+    DROPPED_TOO_MUCH_DATA = 1,
+    SENT                  = 2,
+  };
+
+  void onOutgoingDatagramOutCome(
+    in uint64_t aId,
+    in WebTransportSessionEventListener_DatagramOutcome aOutCome);
+
+  // void onStatsAvailable(in WebTransportStats aStats);
+};
+
+// This interface is used as a callback when creating an outgoing
+// unidirectional or bidirectional stream.
+[scriptable, uuid(c6eeff1d-599b-40a8-9157-c7a40c3d51a2)]
+interface nsIWebTransportStreamCallback : nsISupports {
+  void onBidirectionalStreamReady(in nsIWebTransportBidirectionalStream aStream);
+  void onUnidirectionalStreamReady(in nsIWebTransportSendStream aStream);
+  void onError(in uint8_t aError);
+};
diff --git a/netwerk/protocol/webtransport/nsIWebTransportStream.idl b/netwerk/protocol/webtransport/nsIWebTransportStream.idl
new file mode 100644
index 0000000000..c620b213ee
--- /dev/null
+++ b/netwerk/protocol/webtransport/nsIWebTransportStream.idl
@@ -0,0 +1,84 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 "nsISupports.idl"
+
+interface nsIAsyncInputStream;
+interface nsIAsyncOutputStream;
+interface nsIInputStreamCallback;
+interface nsIEventTarget;
+
+%{C++
+namespace mozilla {
+class TimeStamp;
+}
+%}
+
+native TimeStamp(mozilla::TimeStamp);
+
+[builtinclass, scriptable, uuid(ccc3e685-8411-48f0-8b3e-ff6d1fae4809)]
+interface nsIWebTransportSendStreamStats : nsISupports {
+  [noscript] readonly attribute TimeStamp timestamp;
+  readonly attribute unsigned long long bytesSent;
+  readonly attribute unsigned long long bytesAcknowledged;
+};
+
+[builtinclass, scriptable, uuid(43ce1145-30ef-41a7-b97d-fa797f7f7d18)]
+interface nsIWebTransportReceiveStreamStats : nsISupports {
+  [noscript] readonly attribute TimeStamp timestamp;
+  readonly attribute unsigned long long bytesReceived;
+};
+
+[scriptable, uuid(9c1df3f5-bf04-46b6-9977-eb6389076db8)]
+interface nsIWebTransportStreamStatsCallback : nsISupports {
+  void onSendStatsAvailable(in nsIWebTransportSendStreamStats aStats);
+  void onReceiveStatsAvailable(in nsIWebTransportReceiveStreamStats aStats);
+};
+
+[builtinclass, scriptable, uuid(d461b235-6291-4817-adcc-a2a3b3dfc10b)]
+interface nsIWebTransportReceiveStream : nsISupports {
+  // Sends the STOP_SENDING on the stream.
+  void sendStopSending(in uint8_t aError);
+
+  void getReceiveStreamStats(
+    in nsIWebTransportStreamStatsCallback aCallback);
+
+  // When true, this indicates that FIN had been received.
+  readonly attribute boolean hasReceivedFIN;
+  readonly attribute nsIAsyncInputStream inputStream;
+  readonly attribute uint64_t streamId;
+};
+
+[builtinclass, scriptable, uuid(804f245c-52ea-403c-8a78-f751533bdd70)]
+interface nsIWebTransportSendStream : nsISupports {
+  // Sends the FIN on the stream.
+  void sendFin();
+
+  // Reset the stream with the specified error code.
+  void reset(in uint8_t aErrorCode);
+
+  void getSendStreamStats(in nsIWebTransportStreamStatsCallback aCallback);
+  readonly attribute nsIAsyncOutputStream outputStream;
+  readonly attribute uint64_t streamId;
+};
+
+[builtinclass, scriptable, uuid(f9ecb509-36db-4689-97d6-137639a08750)]
+interface nsIWebTransportBidirectionalStream : nsISupports {
+  // Sends the STOP_SENDING on the stream.
+  void sendStopSending(in uint8_t aError);
+
+  // Sends the FIN on the stream.
+  void sendFin();
+
+  // Reset the stream with the specified error code.
+  void reset(in uint8_t aErrorCode);
+
+  // When true, this indicates that FIN had been received.
+  readonly attribute boolean hasReceivedFIN;
+
+  readonly attribute nsIAsyncInputStream inputStream;
+  readonly attribute nsIAsyncOutputStream outputStream;
+  readonly attribute uint64_t streamId;
+};