Introduce ChannelMojo

ipc/mojo/ipc_channel_mojo.cc

+// Copyright 2014 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 "ipc/mojo/ipc_channel_mojo.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/lazy_instance.h"
+#include "ipc/ipc_listener.h"
+#include "mojo/embedder/embedder.h"
+
+#if defined(OS_POSIX) && !defined(OS_NACL)
+#include "ipc/file_descriptor_set_posix.h"
+#endif
+
+namespace IPC {
+
+namespace {
+
+// IPC::Listener for bootstrap channels.
+// It should never receive any message.
+class NullListener : public Listener {
+ public:
+  virtual bool OnMessageReceived(const Message&) OVERRIDE {
+    NOTREACHED();
+    return false;
+  }
+
+  virtual void OnChannelConnected(int32 peer_pid) OVERRIDE {
+    NOTREACHED();
+  }
+
+  virtual void OnChannelError() OVERRIDE {
+    NOTREACHED();
+  }
+
+  virtual void OnBadMessageReceived(const Message& message) OVERRIDE {
+    NOTREACHED();
+  }
+};
+
+base::LazyInstance<NullListener> g_null_listener = LAZY_INSTANCE_INITIALIZER;
+
+class MojoChannelBuilder : public ChannelBuilder {
+ public:
+  MojoChannelBuilder(
+      ChannelHandle channel_handle,
+      Channel::Mode mode,
+      scoped_refptr<base::TaskRunner> io_thread_task_runner)
+      : channel_handle_(channel_handle),
+        mode_(mode),
+        io_thread_task_runner_(io_thread_task_runner) {
+  }
+
+  virtual std::string GetName() const OVERRIDE {
+    return channel_handle_.name;
+  }
+
+  virtual scoped_ptr<Channel> BuildChannel(Listener* listener) OVERRIDE {
+    return ChannelMojo::Create(
+        channel_handle_,
+        mode_,
+        listener,
+        io_thread_task_runner_).PassAs<Channel>();
+  }
+
+ private:
+  ChannelHandle channel_handle_;
+  Channel::Mode mode_;
+  scoped_refptr<base::TaskRunner> io_thread_task_runner_;
+};
+
+mojo::embedder::PlatformHandle ToPlatformHandle(
+    const ChannelHandle& handle) {
+#if defined(OS_POSIX) && !defined(OS_NACL)
+  return mojo::embedder::PlatformHandle(handle.socket.fd);
+#elif defined(OS_WIN)
+  return mojo::embedder::PlatformHandle(handle.pipe.handle);
+#else
+#error "Unsupported Platform!"
+#endif
+}
+
+//------------------------------------------------------------------------------
+
+// TODO(morrita): This should be built using higher-level Mojo construct
+// for clarify and extensibility.
+class HelloMessage {

[viettrungluu, 2014/07/17 15:11:54]

Why do you need to send any hello messages, etc.?

The existing IPC code does a hello dance only exists because of Windows XP
(which doesn't provide any API to selectively pass handles to child processes)
AFAIK, but there are ways around that. jschuh@ says that he's going to work on
such a workaround in the next few weeks.

[Hajime Morrita, 2014/07/17 18:32:12]

I'm using the magic header so that we can detect anyone else uses underlying
IPC::Channel accidentally. We might not need it.

We need some kind of handshake to pass another channel for sending IPC::Message
bytes though. I'd like to use the bootstrap channel as a control channel which
other Mojo-based services can use to establish their own MessagePipe. For
example, MojoApplicationHost can use that control channel to send its
bootstrapping pipe, instead using IPC::Message. Does this make sense?

+ public:
+  static Pickle CreateRequest(int32 pid) {
+    Pickle request;
+    request.WriteString(kHelloRequestMagic);
+    request.WriteInt(pid);
+    return request;
+  }
+
+  static bool ReadRequest(Pickle& pickle, int32* pid) {
+    PickleIterator iter(pickle);
+    std::string hello;
+    if (!iter.ReadString(&hello)) {
+      DLOG(WARNING) << "Failed to Read magic string.";
+      return false;
+    }
+
+    if (hello != kHelloRequestMagic) {
+      DLOG(WARNING) << "Magic mismatch:" << hello;
+      return false;
+    }
+
+    int read_pid;
+    if (!iter.ReadInt(&read_pid)) {
+      DLOG(WARNING) << "Failed to Read PID.";
+      return false;
+    }
+
+    *pid = read_pid;
+    return true;
+  }
+
+  static Pickle CreateResponse(int32 pid) {
+    Pickle request;
+    request.WriteString(kHelloResponseMagic);
+    request.WriteInt(pid);
+    return request;
+  }
+
+  static bool ReadResponse(Pickle& pickle, int32* pid) {
+    PickleIterator iter(pickle);
+    std::string hello;
+    if (!iter.ReadString(&hello)) {
+      DLOG(WARNING) << "Failed to read magic string.";
+      return false;
+    }
+
+    if (hello != kHelloResponseMagic) {
+      DLOG(WARNING) << "Magic mismatch:" << hello;
+      return false;
+    }
+
+    int read_pid;
+    if (!iter.ReadInt(&read_pid)) {
+      DLOG(WARNING) << "Failed to read PID.";
+      return false;
+    }
+
+    *pid = read_pid;
+    return true;
+  }
+
+ private:
+  static const char* kHelloRequestMagic;
+  static const char* kHelloResponseMagic;
+};
+
+const char* HelloMessage::kHelloRequestMagic = "MREQ";
+const char* HelloMessage::kHelloResponseMagic = "MRES";
+
+} // namespace
+
+//------------------------------------------------------------------------------
+
+// A MessagePipeReader implemenation for IPC::Message communication.
+class ChannelMojo::MessageReader : public internal::MessagePipeReader {
+ public:
+  MessageReader(ChannelMojo* owner)
+      : owner_(owner) { }
+
+  bool Send(scoped_ptr<Message> message);
+  virtual void OnMessageArrived() OVERRIDE;
+  virtual void OnPipeClosed() OVERRIDE;
+  virtual void OnPipeError(MojoResult error) OVERRIDE;
+
+ private:
+  ChannelMojo* owner_;
+};
+
+void ChannelMojo::MessageReader::OnMessageArrived() {
+  Message message(data_buffer().empty() ? "" : &data_buffer()[0],
+                  data_buffer().size());
+
+#if defined(OS_POSIX) && !defined(OS_NACL)
+  for (size_t i = 0; i < handle_buffer().size(); ++i) {
+    mojo::embedder::ScopedPlatformHandle platform_handle;
+    MojoResult unwrap_result = mojo::embedder::PassWrappedPlatformHandle(
+        handle_buffer()[i], &platform_handle);
+    if (unwrap_result != MOJO_RESULT_OK) {
+      DLOG(WARNING) << "Pipe failed to covert handles. Closing: "
+                    << unwrap_result;
+      CloseWithError(unwrap_result);
+      return;
+    }
+
+    bool ok = message.file_descriptor_set()->Add(platform_handle.release().fd);
+    DCHECK(ok);
+  }
+#else
+  DCHECK(handle_buffer_.empty());
+#endif
+
+  message.TraceMessageEnd();
+  owner_->OnMessageReceived(message);
+}
+
+void ChannelMojo::MessageReader::OnPipeClosed() {
+  if (!owner_)
+    return;
+  owner_->OnPipeClosed(this);
+  owner_ = NULL;
+}
+
+void ChannelMojo::MessageReader::OnPipeError(MojoResult error) {
+  if (!owner_)
+    return;
+  owner_->OnPipeError(this);
+}
+
+bool ChannelMojo::MessageReader::Send(scoped_ptr<Message> message) {
+  DCHECK(IsValid());
+
+  message->TraceMessageBegin();
+  std::vector<MojoHandle> handles;
+#if defined(OS_POSIX) && !defined(OS_NACL)
+  if (message->HasFileDescriptors()) {
+    FileDescriptorSet* fdset = message->file_descriptor_set();
+    for (size_t i = 0; i < fdset->size(); ++i) {
+      MojoHandle wrapped_handle;
+      MojoResult wrap_result = CreatePlatformHandleWrapper(
+          mojo::embedder::ScopedPlatformHandle(
+              mojo::embedder::PlatformHandle(
+                  fdset->GetDescriptorAt(i))),
+          &wrapped_handle);
+      if (MOJO_RESULT_OK != wrap_result) {
+        DLOG(WARNING) << "Pipe failed to wrap handles. Closing: "
+                      << wrap_result;
+        CloseWithError(wrap_result);
+        return false;
+      }
+
+      handles.push_back(wrapped_handle);
+    }
+  }
+#endif
+  MojoResult write_result = MojoWriteMessage(
+      handle(),
+      message->data(), message->size(),
+      handles.empty() ? NULL : &handles[0], handles.size(),
+      MOJO_WRITE_MESSAGE_FLAG_NONE);
+  if (MOJO_RESULT_OK != write_result) {
+    CloseWithError(write_result);
+    return false;
+  }
+
+  return true;
+}
+
+//------------------------------------------------------------------------------
+
+// MessagePipeReader implemenation for control messages.
+// Actual message handling is implemented by sublcasses.
+class ChannelMojo::ControlReader : public internal::MessagePipeReader {
+ public:
+  ControlReader(ChannelMojo* owner)
+      : owner_(owner) { }
+
+  virtual bool Connect() { return true; }
+  virtual void OnPipeClosed() OVERRIDE;
+  virtual void OnPipeError(MojoResult error) OVERRIDE;
+
+ protected:
+  ChannelMojo* owner_;
+};
+
+void ChannelMojo::ControlReader::OnPipeClosed() {
+  if (!owner_)
+    return;
+  owner_->OnPipeClosed(this);
+  owner_ = NULL;
+}
+
+void ChannelMojo::ControlReader::OnPipeError(MojoResult error) {
+  if (!owner_)
+    return;
+  owner_->OnPipeError(this);
+}
+
+//------------------------------------------------------------------------------
+
+// ControlReader for server-side ChannelMojo.
+class ChannelMojo::ServerControlReader : public ChannelMojo::ControlReader {
+ public:
+  ServerControlReader(ChannelMojo* owner)
+      : ControlReader(owner) { }
+
+  virtual bool Connect() OVERRIDE;
+  virtual void OnMessageArrived() OVERRIDE;
+
+ private:
+  MojoResult SendHelloRequest();
+  MojoResult RespondHelloResponse();
+
+  mojo::ScopedMessagePipeHandle message_pipe_;
+};
+
+bool ChannelMojo::ServerControlReader::Connect() {
+  MojoResult result = SendHelloRequest();
+  if (result != MOJO_RESULT_OK) {
+    CloseWithError(result);
+    return false;
+  }
+
+  return true;
+}
+
+MojoResult ChannelMojo::ServerControlReader::SendHelloRequest() {
+  DCHECK(IsValid());
+  DCHECK(!message_pipe_.is_valid());
+
+  mojo::ScopedMessagePipeHandle self;
+  mojo::ScopedMessagePipeHandle peer;
+  MojoResult create_result = mojo::CreateMessagePipe(
+      NULL, &message_pipe_, &peer);
+  if (MOJO_RESULT_OK != create_result) {
+    DLOG(WARNING) << "mojo::CreateMessagePipe failed: " << create_result;
+    return create_result;
+  }
+
+  MojoHandle peer_to_send = peer.get().value();
+  Pickle request = HelloMessage::CreateRequest(owner_->GetSelfPID());
+  MojoResult write_result = MojoWriteMessage(
+      handle(),
+      request.data(), request.size(),
+      &peer_to_send, 1,
+      MOJO_WRITE_MESSAGE_FLAG_NONE);
+  if (MOJO_RESULT_OK != write_result) {
+    DLOG(WARNING) << "Writing Hello request failed: " << create_result;
+    return write_result;
+  }
+
+  // |peer| is sent and no longer owned by |this|.
+  (void)peer.release();
+  return MOJO_RESULT_OK;
+}
+
+MojoResult ChannelMojo::ServerControlReader::RespondHelloResponse() {
+  Pickle request(data_buffer_.empty() ? "" : data_buffer_.data(),
+                 data_buffer_.size());
+
+  int32 read_pid = 0;
+  if (!HelloMessage::ReadResponse(request, &read_pid)) {
+    DLOG(ERROR) << "Failed to parse Hello response.";
+    return MOJO_RESULT_UNKNOWN;
+  }
+
+  base::ProcessId pid = static_cast<base::ProcessId>(read_pid);
+  owner_->set_peer_pid(pid);
+  owner_->OnConnected(message_pipe_.Pass());
+  return MOJO_RESULT_OK;
+}
+
+void ChannelMojo::ServerControlReader::OnMessageArrived() {
+  MojoResult result = RespondHelloResponse();
+  if (result != MOJO_RESULT_OK)
+    CloseWithError(result);
+}
+
+//------------------------------------------------------------------------------
+
+// ControlReader for client-side ChannelMojo.
+class ChannelMojo::ClientControlReader : public ChannelMojo::ControlReader {
+ public:
+  ClientControlReader(ChannelMojo* owner)
+      : ControlReader(owner) { }
+
+  virtual void OnMessageArrived() OVERRIDE;
+
+ private:
+  MojoResult RespondHelloRequest();
+};
+
+MojoResult ChannelMojo::ClientControlReader::RespondHelloRequest() {
+  DCHECK(IsValid());
+
+  if (handle_buffer_.size() != 1) {
+    DLOG(ERROR) << "Hello request doesn't contains required handle: "
+                << handle_buffer_.size();
+    return MOJO_RESULT_UNKNOWN;
+  }
+
+  mojo::ScopedMessagePipeHandle received_pipe(
+      (mojo::MessagePipeHandle(handle_buffer_[0])));
+
+  int32 read_request = 0;
+  Pickle request(data_buffer_.empty() ? "" : data_buffer_.data(),
+                 data_buffer_.size());
+  if (!HelloMessage::ReadRequest(request, &read_request)) {
+    DLOG(ERROR) << "Hello request has wrong magic.";
+    return MOJO_RESULT_UNKNOWN;
+  }
+
+  base::ProcessId pid = read_request;
+  Pickle response = HelloMessage::CreateResponse(owner_->GetSelfPID());
+  MojoResult write_result = MojoWriteMessage(
+      handle(),
+      response.data(), response.size(),
+      NULL, 0,
+      MOJO_WRITE_MESSAGE_FLAG_NONE);
+  if (MOJO_RESULT_OK != write_result) {
+    DLOG(ERROR) << "Writing Hello response failed: " << write_result;
+    return write_result;
+  }
+
+  owner_->set_peer_pid(pid);
+  owner_->OnConnected(received_pipe.Pass());
+  return MOJO_RESULT_OK;
+}
+
+void ChannelMojo::ClientControlReader::OnMessageArrived() {
+  MojoResult result = RespondHelloRequest();
+  if (result != MOJO_RESULT_OK) {
+    DLOG(ERROR) << "Failed to respond Hello request. Closing: "
+                << result;
+    CloseWithError(result);
+  }
+}
+
+// static
+scoped_ptr<ChannelMojo> ChannelMojo::Create(
+    scoped_ptr<Channel> bootstrap, Mode mode, Listener* listener,
+    scoped_refptr<base::TaskRunner> io_thread_task_runner) {
+  return make_scoped_ptr(new ChannelMojo(
+      bootstrap.Pass(), mode, listener, io_thread_task_runner));
+}
+
+// static
+scoped_ptr<ChannelMojo> ChannelMojo::Create(
+    const ChannelHandle &channel_handle, Mode mode, Listener* listener,
+    scoped_refptr<base::TaskRunner> io_thread_task_runner) {
+  return Create(
+      Channel::Create(channel_handle, mode, g_null_listener.Pointer()),
+      mode, listener, io_thread_task_runner);
+}
+
+// static
+scoped_ptr<ChannelBuilder> ChannelMojo::CreateBuilder(
+    const ChannelHandle &channel_handle, Mode mode,
+    scoped_refptr<base::TaskRunner> io_thread_task_runner) {
+  return make_scoped_ptr(
+      new MojoChannelBuilder(
+          channel_handle, mode,
+          io_thread_task_runner)).PassAs<ChannelBuilder>();
+}
+
+//------------------------------------------------------------------------------
+
+ChannelMojo::ChannelMojo(
+    scoped_ptr<Channel> bootstrap, Mode mode, Listener* listener,
+    scoped_refptr<base::TaskRunner> io_thread_task_runner)
+    : weak_factory_(this),
+      bootstrap_(bootstrap.Pass()),
+      mode_(mode), listener_(listener),
+      peer_pid_(base::kNullProcessId) {
+  DCHECK(mode_ == MODE_SERVER || mode_ == MODE_CLIENT);
+  mojo::ScopedMessagePipeHandle control_pipe
+      = mojo::embedder::CreateChannel(
+          mojo::embedder::ScopedPlatformHandle(
+              ToPlatformHandle(bootstrap_->TakePipeHandle())),
+          io_thread_task_runner,
+          base::Bind(&ChannelMojo::DidCreateChannel, base::Unretained(this)),
+          io_thread_task_runner);
+
+  // MessagePipeReader, that is crated in InitOnIOThread(), should live only in
+  // IO thread, but IPC::Channel can be instantiated outside of it.
+  // So we move the creation to the appropriate thread.
+  if (base::MessageLoopProxy::current() == io_thread_task_runner) {
+    InitOnIOThread(control_pipe.Pass());
+  } else {
+    io_thread_task_runner->PostTask(
+        FROM_HERE,
+        base::Bind(&ChannelMojo::InitOnIOThread,
+                   weak_factory_.GetWeakPtr(),
+                   base::Passed(control_pipe.Pass())));
+  }
+}
+
+ChannelMojo::~ChannelMojo() {
+  Close();
+}
+
+void ChannelMojo::InitOnIOThread(mojo::ScopedMessagePipeHandle control_pipe) {
+  control_reader_ = CreateControlReader();
+  control_reader_->SetPipe(control_pipe.Pass());
+}
+
+scoped_ptr<ChannelMojo::ControlReader> ChannelMojo::CreateControlReader() {
+  if (MODE_SERVER == mode_) {
+    return make_scoped_ptr(
+        new ServerControlReader(this)).PassAs<ControlReader>();
+  }
+
+  DCHECK(mode_ == MODE_CLIENT);
+  return make_scoped_ptr(
+      new ClientControlReader(this)).PassAs<ControlReader>();
+}
+
+bool ChannelMojo::Connect() {
+  DCHECK(!message_reader_);
+  return control_reader_->Connect();
+}
+
+void ChannelMojo::Close() {
+  control_reader_.reset();
+  message_reader_.reset();
+}
+
+void ChannelMojo::OnConnected(mojo::ScopedMessagePipeHandle pipe) {
+  message_reader_ = make_scoped_ptr(new MessageReader(this));
+  message_reader_->SetPipe(pipe.Pass());
+
+  for (size_t i = 0; i < pending_messages_.size(); ++i) {
+    message_reader_->Send(make_scoped_ptr(pending_messages_[i]));
+    pending_messages_[i] = NULL;
+  }
+
+  pending_messages_.clear();
+
+  listener_->OnChannelConnected(GetPeerPID());
+}
+
+void ChannelMojo::OnPipeClosed(internal::MessagePipeReader* reader) {
+  Close();
+}
+
+void ChannelMojo::OnPipeError(internal::MessagePipeReader* reader) {
+  listener_->OnChannelError();
+}
+
+
+bool ChannelMojo::Send(Message* message) {
+  if (!message_reader_) {
+    pending_messages_.push_back(message);
+    return true;
+  }
+
+  return message_reader_->Send(make_scoped_ptr(message));
+}
+
+base::ProcessId ChannelMojo::GetPeerPID() const {
+  return peer_pid_;
+}
+
+base::ProcessId ChannelMojo::GetSelfPID() const {
+  return bootstrap_->GetSelfPID();
+}
+
+ChannelHandle ChannelMojo::TakePipeHandle() {
+  return bootstrap_->TakePipeHandle();
+}
+
+void ChannelMojo::DidCreateChannel(mojo::embedder::ChannelInfo*) {
+  // TODO(morrita): I'm not sure what should be done here.
+  // Apparently there is no way to delete ChannelInfo and it will leak.

[viettrungluu, 2014/07/17 15:11:54]

See DestroyChannelOnIOThread(), which for some reason is missing a comment.
Oops.

[Hajime Morrita, 2014/07/17 18:32:12]

Oh I see. Problem solved!

+  // Mojo Embedder API needs some way to release it.
+}
+
+void ChannelMojo::OnMessageReceived(Message& message) {
+  listener_->OnMessageReceived(message);
+  if (message.dispatch_error())
+    listener_->OnBadMessageReceived(message);
+}
+
+#if defined(OS_POSIX) && !defined(OS_NACL)
+int ChannelMojo::GetClientFileDescriptor() const {
+  return bootstrap_->GetClientFileDescriptor();
+}
+
+int ChannelMojo::TakeClientFileDescriptor() {
+  return bootstrap_->TakeClientFileDescriptor();
+}
+#endif  // defined(OS_POSIX) && !defined(OS_NACL)
+
+}  // namespace IPC