[mojo] Ports EDK

mojo/edk/system/node_controller.cc

Index: mojo/edk/system/node_controller.cc
diff --git a/mojo/edk/system/node_controller.cc b/mojo/edk/system/node_controller.cc
new file mode 100644
index 0000000000000000000000000000000000000000..030cf47296ed8102d5d73814d451663b53a2bb64
--- /dev/null
+++ b/mojo/edk/system/node_controller.cc
@@ -0,0 +1,771 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "mojo/edk/system/node_controller.h"
+
+#include <algorithm>
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/message_loop/message_loop.h"
+#include "crypto/random.h"
+#include "mojo/edk/embedder/embedder_internal.h"
+#include "mojo/edk/embedder/platform_channel_pair.h"
+#include "mojo/edk/embedder/platform_support.h"
+#include "mojo/edk/system/core.h"
+#include "mojo/edk/system/ports_message.h"
+
+namespace mojo {
+namespace edk {
+
+namespace {
+
+template <typename T>
+void GenerateRandomName(T* out) { crypto::RandBytes(out, sizeof(T)); }
+
+ports::NodeName GetRandomNodeName() {
+  ports::NodeName name;
+  GenerateRandomName(&name);
+  return name;
+}
+
+// Used by NodeController to watch for shutdown. Since no IO can happen once
+// the IO thread is killed, the NodeController can cleanly drop all its peers
+// at that time.
+class ThreadDestructionObserver :
+    public base::MessageLoop::DestructionObserver {
+ public:
+  static void Create(scoped_refptr<base::TaskRunner> task_runner,
+                     const base::Closure& callback) {
+    if (task_runner->RunsTasksOnCurrentThread()) {
+      // Owns itself.
+      new ThreadDestructionObserver(callback);
+    } else {
+      task_runner->PostTask(FROM_HERE,
+                            base::Bind(&Create, task_runner, callback));
+    }
+  }
+
+ private:
+  explicit ThreadDestructionObserver(const base::Closure& callback)
+      : callback_(callback) {
+    base::MessageLoop::current()->AddDestructionObserver(this);
+  }
+
+  ~ThreadDestructionObserver() override {
+    base::MessageLoop::current()->RemoveDestructionObserver(this);
+  }
+
+  // base::MessageLoop::DestructionObserver:
+  void WillDestroyCurrentMessageLoop() override {
+    callback_.Run();
+    delete this;
+  }
+
+  const base::Closure callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadDestructionObserver);
+};
+
+}  // namespace
+
+NodeController::PendingPortRequest::PendingPortRequest() {}
+
+NodeController::PendingPortRequest::~PendingPortRequest() {}
+
+NodeController::ReservedPort::ReservedPort() {}
+
+NodeController::ReservedPort::~ReservedPort() {}
+
+NodeController::~NodeController() {}
+
+NodeController::NodeController(Core* core)
+    : core_(core),
+      name_(GetRandomNodeName()),
+      node_(new ports::Node(name_, this)) {
+  DVLOG(1) << "Initializing node " << name_;
+}
+
+void NodeController::SetIOTaskRunner(
+    scoped_refptr<base::TaskRunner> task_runner) {
+  io_task_runner_ = task_runner;
+  ThreadDestructionObserver::Create(
+      io_task_runner_,
+      base::Bind(&NodeController::DropAllPeers, base::Unretained(this)));
+}
+
+void NodeController::ConnectToChild(base::ProcessHandle process_handle,
+                                    ScopedPlatformHandle platform_handle) {
+  io_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&NodeController::ConnectToChildOnIOThread,
+                 base::Unretained(this),
+                 process_handle,
+                 base::Passed(&platform_handle)));
+}
+
+void NodeController::ConnectToParent(ScopedPlatformHandle platform_handle) {
+  io_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&NodeController::ConnectToParentOnIOThread,
+                 base::Unretained(this),
+                 base::Passed(&platform_handle)));
+}
+
+void NodeController::SetPortObserver(
+    const ports::PortRef& port,
+    const scoped_refptr<PortObserver>& observer) {
+  node_->SetUserData(port, observer);
+}
+
+void NodeController::ClosePort(const ports::PortRef& port) {
+  SetPortObserver(port, nullptr);
+  int rv = node_->ClosePort(port);
+  DCHECK_EQ(rv, ports::OK) << " Failed to close port: " << port.name();
+
+  AcceptIncomingMessages();
+}
+
+int NodeController::SendMessage(const ports::PortRef& port,
+                                scoped_ptr<PortsMessage>* message) {
+  ports::ScopedMessage ports_message(message->release());
+  int rv = node_->SendMessage(port, &ports_message);
+  if (rv != ports::OK) {
+    DCHECK(ports_message);
+    message->reset(static_cast<PortsMessage*>(ports_message.release()));
+  }
+
+  AcceptIncomingMessages();
+  return rv;
+}
+
+void NodeController::ReservePort(const std::string& token,
+                                 const ReservePortCallback& callback) {
+  ports::PortRef port;
+  node_->CreateUninitializedPort(&port);
+
+  DVLOG(2) << "Reserving port " << port.name() << "@" << name_ << " for token "
+           << token;
+
+  base::AutoLock lock(reserved_ports_lock_);
+  ReservedPort reservation;
+  reservation.local_port = port;
+  reservation.callback = callback;
+  reserved_ports_.insert(std::make_pair(token, reservation));
+}
+
+scoped_refptr<PlatformSharedBuffer> NodeController::CreateSharedBuffer(
+    size_t num_bytes) {
+  // TODO: Broker through the parent over a sync channel. :(
+  return internal::g_platform_support->CreateSharedBuffer(num_bytes);
+}
+
+void NodeController::ConnectToParentPort(const ports::PortRef& local_port,
+                                         const std::string& token,
+                                         const base::Closure& callback) {
+  io_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&NodeController::RequestParentPortConnectionOnIOThread,
+                 base::Unretained(this), local_port, token, callback));
+}
+
+void NodeController::ConnectReservedPorts(const std::string& token1,
+                                          const std::string& token2) {
+  ReservedPort port1;
+  ReservedPort port2;
+  {
+    base::AutoLock lock(reserved_ports_lock_);
+    auto it1 = reserved_ports_.find(token1);
+    if (it1 == reserved_ports_.end())
+      return;
+    auto it2 = reserved_ports_.find(token2);
+    if (it2 == reserved_ports_.end())
+      return;
+    port1 = it1->second;
+    port2 = it2->second;
+    reserved_ports_.erase(it1);
+    reserved_ports_.erase(it2);
+  }
+
+  node_->InitializePort(port1.local_port, name_, port2.local_port.name());
+  node_->InitializePort(port2.local_port, name_, port1.local_port.name());
+  port1.callback.Run(port1.local_port);
+  port2.callback.Run(port2.local_port);
+}
+
+void NodeController::RequestShutdown(const base::Closure& callback) {
+  {
+    base::AutoLock lock(shutdown_lock_);
+    shutdown_callback_ = callback;
+  }
+
+  AttemptShutdownIfRequested();
+}
+
+void NodeController::ConnectToChildOnIOThread(
+    base::ProcessHandle process_handle,
+    ScopedPlatformHandle platform_handle) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  scoped_refptr<NodeChannel> channel =
+      NodeChannel::Create(this, std::move(platform_handle), io_task_runner_);
+
+  ports::NodeName token;
+  GenerateRandomName(&token);
+
+  channel->SetRemoteNodeName(token);
+  channel->SetRemoteProcessHandle(process_handle);
+  channel->Start();
+  channel->AcceptChild(name_, token);
+
+  pending_children_.insert(std::make_pair(token, channel));
+}
+
+void NodeController::ConnectToParentOnIOThread(
+    ScopedPlatformHandle platform_handle) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  base::AutoLock lock(parent_lock_);
+  DCHECK(parent_name_ == ports::kInvalidNodeName);
+
+  // At this point we don't know the parent's name, so we can't yet insert it
+  // into our |peers_| map. That will happen as soon as we receive an
+  // AcceptChild message from them.
+  bootstrap_parent_channel_ =
+      NodeChannel::Create(this, std::move(platform_handle), io_task_runner_);
+  bootstrap_parent_channel_->Start();
+}
+
+void NodeController::RequestParentPortConnectionOnIOThread(
+    const ports::PortRef& local_port,
+    const std::string& token,
+    const base::Closure& callback) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  scoped_refptr<NodeChannel> parent = GetParentChannel();
+  if (!parent) {
+    PendingPortRequest request;
+    request.token = token;
+    request.local_port = local_port;
+    request.callback = callback;
+    pending_port_requests_.push_back(request);
+    return;
+  }
+
+  pending_port_connections_.insert(std::make_pair(local_port.name(), callback));
+  parent->RequestPortConnection(local_port.name(), token);
+}
+
+scoped_refptr<NodeChannel> NodeController::GetPeerChannel(
+    const ports::NodeName& name) {
+  base::AutoLock lock(peers_lock_);
+  auto it = peers_.find(name);
+  if (it == peers_.end())
+    return nullptr;
+  return it->second;
+}
+
+scoped_refptr<NodeChannel> NodeController::GetParentChannel() {
+  ports::NodeName parent_name;
+  {
+    base::AutoLock lock(parent_lock_);
+    parent_name = parent_name_;
+  }
+  return GetPeerChannel(parent_name);
+}
+
+void NodeController::AddPeer(const ports::NodeName& name,
+                             scoped_refptr<NodeChannel> channel,
+                             bool start_channel) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  DCHECK(name != ports::kInvalidNodeName);
+  DCHECK(channel);
+
+  channel->SetRemoteNodeName(name);
+
+  base::AutoLock lock(peers_lock_);
+  if (peers_.find(name) != peers_.end()) {
+    // This can happen normally if two nodes race to be introduced to each
+    // other. The losing pipe will be silently closed and introduction should
+    // not be affected.
+    DVLOG(1) << "Ignoring duplicate peer name " << name;
+    return;
+  }
+
+  auto result = peers_.insert(std::make_pair(name, channel));
+  DCHECK(result.second);
+
+  DVLOG(2) << "Accepting new peer " << name << " on node " << name_;
+
+  if (start_channel)
+    channel->Start();
+
+  // Flush any queued message we need to deliver to this node.
+  OutgoingMessageQueue pending_messages;
+  auto it = pending_peer_messages_.find(name);
+  if (it != pending_peer_messages_.end()) {
+    auto& message_queue = it->second;
+    while (!message_queue.empty()) {
+      ports::ScopedMessage message = std::move(message_queue.front());
+      channel->PortsMessage(
+          static_cast<PortsMessage*>(message.get())->TakeChannelMessage());
+      message_queue.pop();
+    }
+    pending_peer_messages_.erase(it);
+  }
+}
+
+void NodeController::DropPeer(const ports::NodeName& name) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  {
+    base::AutoLock lock(peers_lock_);
+    auto it = peers_.find(name);
+
+    if (it != peers_.end()) {
+      ports::NodeName peer = it->first;
+      peers_.erase(it);
+      DVLOG(1) << "Dropped peer " << peer;
+    }
+
+    pending_peer_messages_.erase(name);
+    pending_children_.erase(name);
+  }
+
+  node_->LostConnectionToNode(name);
+}
+
+void NodeController::SendPeerMessage(const ports::NodeName& name,
+                                     ports::ScopedMessage message) {
+  PortsMessage* ports_message = static_cast<PortsMessage*>(message.get());
+
+#if defined(OS_WIN)
+  // If we're sending a message with handles and we're not the parent,
+  // relay the message through the parent.
+  if (ports_message->has_handles()) {
+    scoped_refptr<NodeChannel> parent = GetParentChannel();
+    if (parent) {
+      parent->RelayPortsMessage(name, ports_message->TakeChannelMessage());
+      return;
+    }
+  }
+#endif
+
+  scoped_refptr<NodeChannel> peer = GetPeerChannel(name);
+  if (peer) {
+    peer->PortsMessage(ports_message->TakeChannelMessage());
+    return;
+  }
+
+  // If we don't know who the peer is, queue the message for delivery. If this
+  // is the first message queued for the peer, we also ask the parent to
+  // introduce us to them.
+
+  bool needs_introduction = false;
+  {
+    base::AutoLock lock(peers_lock_);
+    auto& queue = pending_peer_messages_[name];
+    needs_introduction = queue.empty();
+    queue.emplace(std::move(message));
+  }
+
+  if (needs_introduction) {
+    scoped_refptr<NodeChannel> parent = GetParentChannel();
+    if (!parent) {
+      DVLOG(1) << "Dropping message for unknown peer: " << name;
+      return;
+    }
+    parent->RequestIntroduction(name);
+  }
+}
+
+void NodeController::AcceptIncomingMessages() {
+  std::queue<ports::ScopedMessage> messages;
+  for (;;) {
+    // TODO: We may need to be more careful to avoid starving the rest of the
+    // thread here. Revisit this if it turns out to be a problem. One
+    // alternative would be to schedule a task to continue pumping messages
+    // after flushing once.
+
+    {
+      base::AutoLock lock(messages_lock_);
+      if (incoming_messages_.empty())
+        break;
+      std::swap(messages, incoming_messages_);
+    }
+
+    while (!messages.empty()) {
+      node_->AcceptMessage(std::move(messages.front()));
+      messages.pop();
+    }
+  }
+  AttemptShutdownIfRequested();
+}
+
+void NodeController::DropAllPeers() {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  {
+    base::AutoLock lock(parent_lock_);
+    if (bootstrap_parent_channel_) {
+      bootstrap_parent_channel_->ShutDown();
+      bootstrap_parent_channel_ = nullptr;
+    }
+  }
+
+  std::vector<scoped_refptr<NodeChannel>> all_peers;
+  {
+    base::AutoLock lock(peers_lock_);
+    for (const auto& peer : peers_)
+      all_peers.push_back(peer.second);
+    for (const auto& peer : pending_children_)
+      all_peers.push_back(peer.second);
+    peers_.clear();
+    pending_children_.clear();
+    pending_peer_messages_.clear();
+  }
+
+  for (const auto& peer : all_peers)
+    peer->ShutDown();
+
+  if (destroy_on_io_thread_shutdown_)
+    delete this;
+}
+
+void NodeController::GenerateRandomPortName(ports::PortName* port_name) {
+  GenerateRandomName(port_name);
+}
+
+void NodeController::AllocMessage(size_t num_header_bytes,
+                                  ports::ScopedMessage* message) {
+  message->reset(new PortsMessage(num_header_bytes, 0, 0, nullptr));
+}
+
+void NodeController::ForwardMessage(const ports::NodeName& node,
+                                    ports::ScopedMessage message) {
+  if (node == name_) {
+    // NOTE: We need to avoid re-entering the Node instance within
+    // ForwardMessage. Because ForwardMessage is only ever called
+    // (synchronously) in response to Node's ClosePort, SendMessage, or
+    // AcceptMessage, we flush the queue after calling any of those methods.
+    base::AutoLock lock(messages_lock_);
+    incoming_messages_.emplace(std::move(message));
+  } else {
+    SendPeerMessage(node, std::move(message));
+  }
+}
+
+void NodeController::PortStatusChanged(const ports::PortRef& port) {
+  scoped_refptr<ports::UserData> user_data;
+  node_->GetUserData(port, &user_data);
+
+  PortObserver* observer = static_cast<PortObserver*>(user_data.get());
+  if (observer) {
+    observer->OnPortStatusChanged();
+  } else {
+    DVLOG(2) << "Ignoring status change for " << port.name() << " because it "
+             << "doesn't have an observer.";
+  }
+}
+
+void NodeController::OnAcceptChild(const ports::NodeName& from_node,
+                                   const ports::NodeName& parent_name,
+                                   const ports::NodeName& token) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  scoped_refptr<NodeChannel> parent;
+  {
+    base::AutoLock lock(parent_lock_);
+    if (!bootstrap_parent_channel_ || parent_name_ != ports::kInvalidNodeName) {
+      DLOG(ERROR) << "Unexpected AcceptChild message from " << from_node;
+      DropPeer(from_node);
+      return;
+    }
+
+    parent_name_ = parent_name;
+    parent = bootstrap_parent_channel_;
+    bootstrap_parent_channel_ = nullptr;
+  }
+
+  parent->AcceptParent(token, name_);
+  for (const auto& request : pending_port_requests_) {
+    pending_port_connections_.insert(
+        std::make_pair(request.local_port.name(), request.callback));
+    parent->RequestPortConnection(request.local_port.name(), request.token);
+  }
+  pending_port_requests_.clear();
+
+  DVLOG(1) << "Child " << name_ << " accepting parent " << parent_name;
+
+  AddPeer(parent_name_, parent, false /* start_channel */);
+}
+
+void NodeController::OnAcceptParent(const ports::NodeName& from_node,
+                                    const ports::NodeName& token,
+                                    const ports::NodeName& child_name) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  auto it = pending_children_.find(from_node);
+  if (it == pending_children_.end() || token != from_node) {
+    DLOG(ERROR) << "Received unexpected AcceptParent message from "
+                << from_node;
+    DropPeer(from_node);
+    return;
+  }
+
+  scoped_refptr<NodeChannel> channel = it->second;
+  pending_children_.erase(it);
+
+  DCHECK(channel);
+
+  DVLOG(1) << "Parent " << name_ << " accepted child " << child_name;
+
+  AddPeer(child_name, channel, false /* start_channel */);
+}
+
+void NodeController::OnPortsMessage(Channel::MessagePtr channel_message) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  void* data;
+  size_t num_data_bytes;
+  NodeChannel::GetPortsMessageData(
+      channel_message.get(), &data, &num_data_bytes);
+
+  size_t num_header_bytes, num_payload_bytes, num_ports_bytes;
+  ports::Message::Parse(data,
+                        num_data_bytes,
+                        &num_header_bytes,
+                        &num_payload_bytes,
+                        &num_ports_bytes);
+
+  CHECK(channel_message);
+  ports::ScopedMessage message(
+      new PortsMessage(num_header_bytes,
+                       num_payload_bytes,
+                       num_ports_bytes,
+                       std::move(channel_message)));
+
+  node_->AcceptMessage(std::move(message));
+  AcceptIncomingMessages();
+  AttemptShutdownIfRequested();
+}
+
+void NodeController::OnRequestPortConnection(
+    const ports::NodeName& from_node,
+    const ports::PortName& connector_port_name,
+    const std::string& token) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  DVLOG(2) << "Node " << name_ << " received RequestPortConnection for token "
+           << token << " and port " << connector_port_name << "@" << from_node;
+
+  ReservePortCallback callback;
+  ports::PortRef local_port;
+  {
+    base::AutoLock lock(reserved_ports_lock_);
+    auto it = reserved_ports_.find(token);
+    if (it == reserved_ports_.end()) {
+      DVLOG(1) << "Ignoring request to connect to port for unknown token "
+               << token;
+      return;
+    }
+    local_port = it->second.local_port;
+    callback = it->second.callback;
+    reserved_ports_.erase(it);
+  }
+
+  DCHECK(!callback.is_null());
+
+  scoped_refptr<NodeChannel> peer = GetPeerChannel(from_node);
+  if (!peer) {
+    DVLOG(1) << "Ignoring request to connect to port from unknown node "
+             << from_node;
+    return;
+  }
+
+  // This reserved port should not have been initialized yet.
+  CHECK_EQ(ports::OK, node_->InitializePort(local_port, from_node,
+                                            connector_port_name));
+
+  peer->ConnectToPort(local_port.name(), connector_port_name);
+  callback.Run(local_port);
+}
+
+void NodeController::OnConnectToPort(
+    const ports::NodeName& from_node,
+    const ports::PortName& connector_port_name,
+    const ports::PortName& connectee_port_name) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  DVLOG(2) << "Node " << name_ << " received ConnectToPort for local port "
+           << connectee_port_name << " to port " << connector_port_name << "@"
+           << from_node;
+
+  ports::PortRef connectee_port;
+  int rv = node_->GetPort(connectee_port_name, &connectee_port);
+  if (rv != ports::OK) {
+    DLOG(ERROR) << "Ignoring ConnectToPort for unknown port "
+                << connectee_port_name;
+    return;
+  }
+
+  // It's OK if this port has already been initialized. This message is only
+  // sent by the remote peer to ensure the port is ready before it starts
+  // us sending messages to it.
+  ports::PortStatus port_status;
+  rv = node_->GetStatus(connectee_port, &port_status);
+  if (rv == ports::OK) {
+    DVLOG(1) << "Ignoring ConnectToPort for already-initialized port "
+             << connectee_port_name;
+    return;
+  }
+
+  CHECK_EQ(ports::OK, node_->InitializePort(connectee_port, from_node,
+                                            connector_port_name));
+
+  auto it = pending_port_connections_.find(connectee_port_name);
+  DCHECK(it != pending_port_connections_.end());
+  it->second.Run();
+  pending_port_connections_.erase(it);
+}
+
+void NodeController::OnRequestIntroduction(const ports::NodeName& from_node,
+                                           const ports::NodeName& name) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  scoped_refptr<NodeChannel> requestor = GetPeerChannel(from_node);
+  if (from_node == name || name == ports::kInvalidNodeName || !requestor) {
+    DLOG(ERROR) << "Rejecting invalid OnRequestIntroduction message from "
+                << from_node;
+    DropPeer(from_node);
+    return;
+  }
+
+  if (GetParentChannel() != nullptr) {
+    DLOG(ERROR) << "Non-parent node cannot introduce peers to each other.";
+    return;
+  }
+
+  scoped_refptr<NodeChannel> new_friend = GetPeerChannel(name);
+  if (!new_friend) {
+    // We don't know who they're talking about!
+    requestor->Introduce(name, ScopedPlatformHandle());
+  } else {
+    PlatformChannelPair new_channel;
+    requestor->Introduce(name, new_channel.PassServerHandle());
+    new_friend->Introduce(from_node, new_channel.PassClientHandle());
+  }
+}
+
+void NodeController::OnIntroduce(const ports::NodeName& from_node,
+                                 const ports::NodeName& name,
+                                 ScopedPlatformHandle channel_handle) {
+  DCHECK(io_task_runner_->RunsTasksOnCurrentThread());
+
+  {
+    base::AutoLock lock(parent_lock_);
+    if (from_node != parent_name_) {
+      DLOG(ERROR) << "Received unexpected Introduce message from node "
+                  << from_node;
+      DropPeer(from_node);
+      return;
+    }
+  }
+
+  if (!channel_handle.is_valid()) {
+    DLOG(ERROR) << "Could not be introduced to peer " << name;
+    base::AutoLock lock(peers_lock_);
+    pending_peer_messages_.erase(name);
+    return;
+  }
+
+  scoped_refptr<NodeChannel> channel =
+      NodeChannel::Create(this, std::move(channel_handle), io_task_runner_);
+
+  DVLOG(1) << "Adding new peer " << name << " via parent introduction.";
+  AddPeer(name, channel, true /* start_channel */);
+}
+
+#if defined(OS_WIN)
+void NodeController::OnRelayPortsMessage(const ports::NodeName& from_node,
+                                         base::ProcessHandle from_process,
+                                         const ports::NodeName& destination,
+                                         Channel::MessagePtr message) {
+  scoped_refptr<NodeChannel> parent = GetParentChannel();
+  if (parent) {
+    // Only the parent should be asked to relay a message.
+    DLOG(ERROR) << "Non-parent refusing to relay message.";
+    DropPeer(from_node);
+    return;
+  }
+
+  // The parent should always know which process this came from.
+  DCHECK(from_process != base::kNullProcessHandle);
+
+  // Duplicate the handles to this (the parent) process. If the message is
+  // destined for another child process, the handles will be duplicated to
+  // that process before going out (see NodeChannel::WriteChannelMessage).
+  //
+  // TODO: We could avoid double-duplication.
+  for (size_t i = 0; i < message->num_handles(); ++i) {
+    BOOL result = DuplicateHandle(
+        from_process, message->handles()[i].handle,
+        base::GetCurrentProcessHandle(),
+        reinterpret_cast<HANDLE*>(message->handles() + i),
+        0, FALSE, DUPLICATE_SAME_ACCESS | DUPLICATE_CLOSE_SOURCE);
+    DCHECK(result);
+  }
+  if (destination == name_) {
+    // Great, we can deliver this message locally.
+    OnPortsMessage(std::move(message));
+    return;
+  }
+
+  scoped_refptr<NodeChannel> peer = GetPeerChannel(destination);
+  if (peer)
+    peer->PortsMessage(std::move(message));
+  else
+    DLOG(ERROR) << "Dropping relay message for unknown node " << destination;
+}
+#endif
+
+void NodeController::OnChannelError(const ports::NodeName& from_node) {
+  if (io_task_runner_->RunsTasksOnCurrentThread()) {
+    DropPeer(from_node);
+  } else {
+    io_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&NodeController::DropPeer, base::Unretained(this),
+                   from_node));
+  }
+}
+
+void NodeController::DestroyOnIOThreadShutdown() {
+  destroy_on_io_thread_shutdown_ = true;
+}
+
+void NodeController::AttemptShutdownIfRequested() {
+  base::Closure callback;
+  {
+    base::AutoLock lock(shutdown_lock_);
+    if (shutdown_callback_.is_null())
+      return;
+    if (!node_->CanShutdownCleanly(true /* allow_local_ports */)) {
+      DVLOG(2) << "Unable to cleanly shut down node " << name_ << ".";
+      return;
+    }
+    callback = shutdown_callback_;
+    shutdown_callback_.Reset();
+  }
+
+  DCHECK(!callback.is_null());
+
+  callback.Run();
+}
+
+}  // namespace edk
+}  // namespace mojo