1 files changed, 404 insertions, 0 deletions
diff --git a/dom/messagechannel/MessagePortService.cpp b/dom/messagechannel/MessagePortService.cpp
new file mode 100644
index 0000000000..3b45102e75
--- /dev/null
+++ b/dom/messagechannel/MessagePortService.cpp
@@ -0,0 +1,404 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=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 "MessagePortService.h"
+#include "MessagePortParent.h"
+#include "mozilla/dom/RefMessageBodyService.h"
+#include "mozilla/dom/SharedMessageBody.h"
+#include "mozilla/dom/quota/CheckedUnsafePtr.h"
+#include "mozilla/ipc/BackgroundParent.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/Unused.h"
+#include "mozilla/WeakPtr.h"
+#include "nsTArray.h"
+
+using mozilla::ipc::AssertIsOnBackgroundThread;
+
+namespace mozilla::dom {
+
+namespace {
+
+StaticRefPtr<MessagePortService> gInstance;
+
+void AssertIsInMainProcess() {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_Default);
+}
+
+}  // namespace
+
+struct MessagePortService::NextParent {
+  uint32_t mSequenceID;
+  // MessagePortParent keeps the service alive, and we don't want a cycle.
+  WeakPtr<MessagePortParent> mParent;
+};
+
+}  // namespace mozilla::dom
+
+namespace mozilla::dom {
+
+class MessagePortService::MessagePortServiceData final {
+ public:
+  explicit MessagePortServiceData(const nsID& aDestinationUUID)
+      : mDestinationUUID(aDestinationUUID),
+        mSequenceID(1),
+        mParent(nullptr)
+        // By default we don't know the next parent.
+        ,
+        mWaitingForNewParent(true),
+        mNextStepCloseAll(false) {
+    MOZ_COUNT_CTOR(MessagePortServiceData);
+  }
+
+  MessagePortServiceData(const MessagePortServiceData& aOther) = delete;
+  MessagePortServiceData& operator=(const MessagePortServiceData&) = delete;
+
+  MOZ_COUNTED_DTOR(MessagePortServiceData)
+
+  nsID mDestinationUUID;
+
+  uint32_t mSequenceID;
+  CheckedUnsafePtr<MessagePortParent> mParent;
+
+  FallibleTArray<NextParent> mNextParents;
+  FallibleTArray<RefPtr<SharedMessageBody>> mMessages;
+
+  bool mWaitingForNewParent;
+  bool mNextStepCloseAll;
+};
+
+/* static */
+MessagePortService* MessagePortService::Get() {
+  AssertIsInMainProcess();
+  AssertIsOnBackgroundThread();
+
+  return gInstance;
+}
+
+/* static */
+MessagePortService* MessagePortService::GetOrCreate() {
+  AssertIsInMainProcess();
+  AssertIsOnBackgroundThread();
+
+  if (!gInstance) {
+    gInstance = new MessagePortService();
+  }
+
+  return gInstance;
+}
+
+bool MessagePortService::RequestEntangling(MessagePortParent* aParent,
+                                           const nsID& aDestinationUUID,
+                                           const uint32_t& aSequenceID) {
+  MOZ_ASSERT(aParent);
+  MessagePortServiceData* data;
+
+  // If we don't have a MessagePortServiceData, we must create 2 of them for
+  // both ports.
+  if (!mPorts.Get(aParent->ID(), &data)) {
+    // Create the MessagePortServiceData for the destination.
+    if (mPorts.Get(aDestinationUUID, nullptr)) {
+      MOZ_ASSERT(false, "The creation of the 2 ports should be in sync.");
+      return false;
+    }
+
+    mPorts.InsertOrUpdate(aDestinationUUID,
+                          MakeUnique<MessagePortServiceData>(aParent->ID()));
+
+    data = mPorts
+               .InsertOrUpdate(
+                   aParent->ID(),
+                   MakeUnique<MessagePortServiceData>(aDestinationUUID))
+               .get();
+  }
+
+  // This is a security check.
+  if (!data->mDestinationUUID.Equals(aDestinationUUID)) {
+    MOZ_ASSERT(false, "DestinationUUIDs do not match!");
+    CloseAll(aParent->ID());
+    return false;
+  }
+
+  if (aSequenceID < data->mSequenceID) {
+    MOZ_ASSERT(false, "Invalid sequence ID!");
+    CloseAll(aParent->ID());
+    return false;
+  }
+
+  if (aSequenceID == data->mSequenceID) {
+    if (data->mParent) {
+      MOZ_ASSERT(false, "Two ports cannot have the same sequenceID.");
+      CloseAll(aParent->ID());
+      return false;
+    }
+
+    // We activate this port, sending all the messages.
+    data->mParent = aParent;
+    data->mWaitingForNewParent = false;
+
+    // We want to ensure we clear data->mMessages even if we early return, while
+    // also ensuring that its contents remain alive until after array's contents
+    // are destroyed because of JSStructuredCloneData borrowing.  So we use
+    // Move to initialize things swapped and do it before we declare `array` so
+    // that reverse destruction order works for us.
+    FallibleTArray<RefPtr<SharedMessageBody>> messages(
+        std::move(data->mMessages));
+    nsTArray<MessageData> array;
+    if (!SharedMessageBody::FromSharedToMessagesParent(aParent->Manager(),
+                                                       messages, array)) {
+      CloseAll(aParent->ID());
+      return false;
+    }
+
+    // We can entangle the port.
+    if (!aParent->Entangled(std::move(array))) {
+      CloseAll(aParent->ID());
+      return false;
+    }
+
+    // If we were waiting for this parent in order to close this channel, this
+    // is the time to do it.
+    if (data->mNextStepCloseAll) {
+      CloseAll(aParent->ID());
+    }
+
+    return true;
+  }
+
+  // This new parent will be the next one when a Disentangle request is
+  // received from the current parent.
+  auto nextParent = data->mNextParents.AppendElement(mozilla::fallible);
+  if (!nextParent) {
+    CloseAll(aParent->ID());
+    return false;
+  }
+
+  nextParent->mSequenceID = aSequenceID;
+  nextParent->mParent = aParent;
+
+  return true;
+}
+
+bool MessagePortService::DisentanglePort(
+    MessagePortParent* aParent,
+    FallibleTArray<RefPtr<SharedMessageBody>> aMessages) {
+  MessagePortServiceData* data;
+  if (!mPorts.Get(aParent->ID(), &data)) {
+    MOZ_ASSERT(false, "Unknown MessagePortParent should not happen.");
+    return false;
+  }
+
+  if (data->mParent != aParent) {
+    MOZ_ASSERT(
+        false,
+        "DisentanglePort() should be called just from the correct parent.");
+    return false;
+  }
+
+  // Let's put the messages in the correct order. |aMessages| contains the
+  // unsent messages so they have to go first.
+  if (!aMessages.AppendElements(std::move(data->mMessages),
+                                mozilla::fallible)) {
+    return false;
+  }
+
+  ++data->mSequenceID;
+
+  // If we don't have a parent, we have to store the pending messages and wait.
+  uint32_t index = 0;
+  MessagePortParent* nextParent = nullptr;
+  for (; index < data->mNextParents.Length(); ++index) {
+    if (data->mNextParents[index].mSequenceID == data->mSequenceID) {
+      nextParent = data->mNextParents[index].mParent;
+      break;
+    }
+  }
+
+  // We didn't find the parent.
+  if (!nextParent) {
+    data->mMessages = std::move(aMessages);
+    data->mWaitingForNewParent = true;
+    data->mParent = nullptr;
+    return true;
+  }
+
+  data->mParent = nextParent;
+  data->mNextParents.RemoveElementAt(index);
+
+  nsTArray<MessageData> array;
+  if (!SharedMessageBody::FromSharedToMessagesParent(data->mParent->Manager(),
+                                                     aMessages, array)) {
+    return false;
+  }
+
+  Unused << data->mParent->Entangled(std::move(array));
+  return true;
+}
+
+bool MessagePortService::ClosePort(MessagePortParent* aParent) {
+  MessagePortServiceData* data;
+  if (!mPorts.Get(aParent->ID(), &data)) {
+    MOZ_ASSERT(false, "Unknown MessagePortParent should not happend.");
+    return false;
+  }
+
+  if (data->mParent != aParent) {
+    MOZ_ASSERT(false,
+               "ClosePort() should be called just from the correct parent.");
+    return false;
+  }
+
+  if (!data->mNextParents.IsEmpty()) {
+    MOZ_ASSERT(false,
+               "ClosePort() should be called when there are not next parents.");
+    return false;
+  }
+
+  // We don't want to send a message to this parent.
+  data->mParent = nullptr;
+
+  CloseAll(aParent->ID());
+  return true;
+}
+
+void MessagePortService::CloseAll(const nsID& aUUID, bool aForced) {
+  MessagePortServiceData* data;
+  if (!mPorts.Get(aUUID, &data)) {
+    MaybeShutdown();
+    return;
+  }
+
+  if (data->mParent) {
+    data->mParent->Close();
+    data->mParent = nullptr;
+  }
+
+  for (const auto& nextParent : data->mNextParents) {
+    MessagePortParent* const parent = nextParent.mParent;
+    if (parent) {
+      parent->CloseAndDelete();
+    }
+  }
+  data->mNextParents.Clear();
+
+  nsID destinationUUID = data->mDestinationUUID;
+
+  // If we have informations about the other port and that port has some
+  // pending messages to deliver but the parent has not processed them yet,
+  // because its entangling request didn't arrive yet), we cannot close this
+  // channel.
+  MessagePortServiceData* destinationData;
+  if (!aForced && mPorts.Get(destinationUUID, &destinationData) &&
+      !destinationData->mMessages.IsEmpty() &&
+      destinationData->mWaitingForNewParent) {
+    MOZ_ASSERT(!destinationData->mNextStepCloseAll);
+    destinationData->mNextStepCloseAll = true;
+    return;
+  }
+
+  mPorts.Remove(aUUID);
+
+  CloseAll(destinationUUID, aForced);
+
+  // CloseAll calls itself recursively and it can happen that it deletes
+  // itself. Before continuing we must check if we are still alive.
+  if (!gInstance) {
+    return;
+  }
+
+  MOZ_ASSERT(!mPorts.Contains(aUUID));
+
+  MaybeShutdown();
+}
+
+// This service can be dismissed when there are not active ports.
+void MessagePortService::MaybeShutdown() {
+  if (mPorts.Count() == 0) {
+    gInstance = nullptr;
+  }
+}
+
+bool MessagePortService::PostMessages(
+    MessagePortParent* aParent,
+    FallibleTArray<RefPtr<SharedMessageBody>> aMessages) {
+  MessagePortServiceData* data;
+  if (!mPorts.Get(aParent->ID(), &data)) {
+    MOZ_ASSERT(false, "Unknown MessagePortParent should not happend.");
+    return false;
+  }
+
+  if (data->mParent != aParent) {
+    MOZ_ASSERT(false,
+               "PostMessages() should be called just from the correct parent.");
+    return false;
+  }
+
+  MOZ_ALWAYS_TRUE(mPorts.Get(data->mDestinationUUID, &data));
+
+  if (!data->mMessages.AppendElements(std::move(aMessages),
+                                      mozilla::fallible)) {
+    return false;
+  }
+
+  // If the parent can send data to the child, let's proceed.
+  if (data->mParent && data->mParent->CanSendData()) {
+    {
+      nsTArray<MessageData> messages;
+      if (!SharedMessageBody::FromSharedToMessagesParent(
+              data->mParent->Manager(), data->mMessages, messages)) {
+        return false;
+      }
+
+      Unused << data->mParent->SendReceiveData(messages);
+    }
+    // `messages` borrows the underlying JSStructuredCloneData so we need to
+    // avoid destroying the `mMessages` until after we've destroyed `messages`.
+    data->mMessages.Clear();
+  }
+
+  return true;
+}
+
+void MessagePortService::ParentDestroy(MessagePortParent* aParent) {
+  // This port has already been destroyed.
+  MessagePortServiceData* data;
+  if (!mPorts.Get(aParent->ID(), &data)) {
+    return;
+  }
+
+  if (data->mParent != aParent) {
+    // We don't want to send a message to this parent.
+    for (uint32_t i = 0; i < data->mNextParents.Length(); ++i) {
+      if (aParent == data->mNextParents[i].mParent) {
+        data->mNextParents.RemoveElementAt(i);
+        break;
+      }
+    }
+  }
+
+  CloseAll(aParent->ID());
+}
+
+bool MessagePortService::ForceClose(const nsID& aUUID,
+                                    const nsID& aDestinationUUID,
+                                    const uint32_t& aSequenceID) {
+  MessagePortServiceData* data;
+  if (!mPorts.Get(aUUID, &data)) {
+    NS_WARNING("Unknown MessagePort in ForceClose()");
+    // There is nothing to close so we are ok.
+    return true;
+  }
+
+  if (!data->mDestinationUUID.Equals(aDestinationUUID) ||
+      data->mSequenceID != aSequenceID) {
+    NS_WARNING("DestinationUUID and/or sequenceID do not match.");
+    return false;
+  }
+
+  CloseAll(aUUID, true);
+  return true;
+}
+
+}  // namespace mozilla::dom