Native Messaging!

chrome/browser/extensions/native_message_process.cc

+// Copyright (c) 2012 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 "chrome/browser/extensions/native_message_process.h"
+
+#include <unistd.h>
+
+#include "base/command_line.h"
+#include "base/file_path.h"
+#include "base/json/json_reader.h"
+#include "base/json/json_writer.h"
+#include "base/logging.h"
+#include "base/path_service.h"
+#include "base/pickle.h"
+#include "base/process_util.h"
+#include "base/values.h"
+#include "chrome/browser/extensions/message_service.h"
+#include "chrome/common/chrome_paths.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace {
+
+// TODO(eriq): Figure out good values for these constants.
+const int kExitTimeoutMS = 100;
+const uint32 kMaxMessageDataLength = 4096;

[Matt Perry, 2012/08/09 02:13:00]

I imagine extensions will want much larger sizes, to pass things like image data
back and forth.

[eaugusti, 2012/08/13 23:22:34]

How about 10MB?

[Matt Perry, 2012/08/16 00:01:36]

SGTM

+const char kNativeClientDir[] = "Native Hosts";
+
+}  // namespace
+
+namespace extensions {
+
+NativeMessageProcess::MessageData::MessageData() {
+}
+
+NativeMessageProcess::MessageData::MessageData(MessageType message_type,
+                                               std::string message_data)
+      : type(message_type),
+        data(message_data) {
+}
+
+NativeMessageProcess::NativeMessageProcess(
+    MessageService* service,
+    int dest_port,
+    base::ProcessHandle handle,
+    int read_fd,
+    int write_fd,
+    bool is_send_message)
+    : service_(service),
+      dest_port_(dest_port),
+      handle_(handle),
+      watching_write_(false),
+      read_fd_(read_fd),
+      write_fd_(write_fd),
+      is_send_message_(is_send_message) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
+  scoped_read_fd_.reset(&read_fd_);
+  scoped_write_fd_.reset(&write_fd_);
+  // Always watch the read end.
+  MessageLoopForIO::current()->WatchFileDescriptor(read_fd_,
+                                                   true, /* persistent */
+                                                   MessageLoopForIO::WATCH_READ,
+                                                   &read_watcher_,
+                                                   this);
+}
+
+NativeMessageProcess::~NativeMessageProcess() {
+  read_watcher_.StopWatchingFileDescriptor();
+  write_watcher_.StopWatchingFileDescriptor();
+
+  // Close the fds now.
+  scoped_read_fd_.reset();
+  scoped_write_fd_.reset();
+
+  content::BrowserThread::PostTask(
+      content::BrowserThread::FILE,
+      FROM_HERE,
+      base::Bind(&NativeMessageProcess::KillProcess, handle_));
+}
+
+// static
+NativeMessageProcess* NativeMessageProcess::Create(
+    const std::string& native_app_name,
+    const std::string& connection_message,
+    MessageService* service,
+    int dest_port,
+    MessageType type) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
+
+  DCHECK(type == TYPE_SEND_MESSAGE_REQUEST || type == TYPE_CONNECT);
+
+  base::FileHandleMappingVector fd_map;
+
+  int read_pipe_fds[2];
+  if (HANDLE_EINTR(pipe(read_pipe_fds)) != 0) {
+    LOG(ERROR) << "Bad read pipe";
+    return NULL;
+  }
+  file_util::ScopedFD read_pipe_read_fd(&read_pipe_fds[0]);
+  file_util::ScopedFD read_pipe_write_fd(&read_pipe_fds[1]);
+  fd_map.push_back(std::make_pair(*read_pipe_write_fd, STDOUT_FILENO));
+
+  int write_pipe_fds[2];
+  if (HANDLE_EINTR(pipe(write_pipe_fds)) != 0) {
+    LOG(ERROR) << "Bad write pipe";
+    return NULL;
+  }
+  file_util::ScopedFD write_pipe_read_fd(&write_pipe_fds[0]);
+  file_util::ScopedFD write_pipe_write_fd(&write_pipe_fds[1]);
+  fd_map.push_back(std::make_pair(*write_pipe_read_fd, STDIN_FILENO));
+
+  FilePath client_path;
+  FilePath registered_client_dir;
+  CHECK(PathService::Get(chrome::DIR_USER_DATA, &registered_client_dir));
+  registered_client_dir = registered_client_dir.Append(kNativeClientDir);
+  client_path = registered_client_dir.Append(native_app_name);
+
+  // Make sure that the client is not trying to invoke something outside of the
+  // proper directory. Eg. '../../dangerous_something.exe'.
+  if (!file_util::ContainsPath(registered_client_dir, client_path)) {
+    LOG(ERROR) << "Paths are not accepted as native app names.";
+    return NULL;
+  }
+
+  CommandLine line(client_path);
+  base::ProcessHandle handle;
+  base::LaunchOptions options;
+  options.fds_to_remap = &fd_map;
+  if (!base::LaunchProcess(line, options, &handle)) {
+    LOG(ERROR) << "Error launching process";
+    return NULL;
+  }
+
+  // We will not be reading from the write pipe, nor writing from the read pipe.
+  write_pipe_read_fd.reset();
+  read_pipe_write_fd.reset();
+
+  NativeMessageProcess* process = new NativeMessageProcess(
+      service, dest_port, handle,
+      *read_pipe_read_fd.release(), *write_pipe_write_fd.release(),
+      type == TYPE_SEND_MESSAGE_REQUEST);
+
+  process->Send(type, connection_message);
+
+  return process;
+}
+
+void NativeMessageProcess::WatchWrite() {
+  CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
+  if (!MessageLoopForIO::current()->WatchFileDescriptor(
+      write_fd_, true, /* persistent */
+      MessageLoopForIO::WATCH_WRITE, &write_watcher_, this)) {
+    LOG(ERROR) << "Error watching for the FD.";
+  }
+}
+
+void NativeMessageProcess::Send(MessageType type, const std::string& json) {

[Matt Perry, 2012/08/09 02:13:00]

What thread is this called on? Assuming the answer is anything but "FILE"
thread, there's some thread safety issues here. Touching any of these member
vars is not safe. You can probably just pass all this data over to the FILE
thread and do the updates there.

Have you seen ipc_channel_proxy.cc/h? That has to deal with issues like this. If
you can't use it directly, it may help to model it.

[eaugusti, 2012/08/13 23:22:34]

Done.

+  pending_messages_.push_back(MessageData(type, json));
+  if (!watching_write_) {
+    watching_write_ = true;
+    content::BrowserThread::PostTask(content::BrowserThread::FILE, FROM_HERE,
+        base::Bind(&NativeMessageProcess::WatchWrite, base::Unretained(this)));
+  }
+}
+
+void NativeMessageProcess::OnFileCanReadWithoutBlocking(int fd) {
+  CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
+
+  // Make sure that the fd given to us is the same one we started with.
+  CHECK_EQ(fd, read_fd_);
+
+  // If this is a sendMessage request, stop trying to read after the first
+  // message.
+  if (is_send_message_)
+    read_watcher_.StopWatchingFileDescriptor();
+
+  MessageData data;
+  if (!ReadMessage(fd, &data)) {
+    LOG(ERROR) << "Bad Read";
+    return;
+  }
+
+  service_->PostMessageFromRenderer(dest_port_, data.data);

[Matt Perry, 2012/08/09 02:13:00]

This must be called on the UI thread. Note you also have to deal with lifetime
issues (if you PostTask, |service| might be deleted by the time the Task runs).

[eaugusti, 2012/08/13 23:22:34]

Done.

+}
+
+void NativeMessageProcess::OnFileCanWriteWithoutBlocking(int fd) {
+  CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
+
+  // Make sure that the fd given to us is the same one we started with.
+  CHECK_EQ(fd, write_fd_);
+
+  write_watcher_.StopWatchingFileDescriptor();
+  watching_write_ = false;
+
+  while (!pending_messages_.empty()) {
+    WriteMessage(fd, pending_messages_.back());
+    pending_messages_.pop_back();
+  }
+}
+
+// TODO(eriq): Update doc: byte (type) -> uint32.
+bool NativeMessageProcess::WriteMessage(int fd, const MessageData& data) {
+  Pickle pickle;
+
+  // Pickles will always pad bytes to 32-bit alignment, so just use a unit32.
+  pickle.WriteUInt32(data.type);
+
+  // Pickles write the length of a string before it as a uint32.
+  pickle.WriteString(data.data);
+
+  // Make sure that the pickle doesn't do any unexpected padding.
+  DCHECK(8 + data.data.length() == pickle.payload_size());
+
+  if (!file_util::WriteFileDescriptor(
+        fd,
+        const_cast<const Pickle*>(&pickle)->payload(),
+        pickle.payload_size())) {
+    LOG(ERROR) << "Error writing message to the native client.";
+    return false;
+  }
+
+  return true;
+}
+
+bool NativeMessageProcess::ReadMessage(int fd, MessageData* message) {
+  char data[kMaxMessageDataLength];

[Matt Perry, 2012/08/09 02:13:00]

Better to heap-allocate this, especially if you up the max length. You can use a
std::string directly, and just resize it to the right size. That'll save you a
string copy down below, too.

[eaugusti, 2012/08/13 23:22:34]

Done.

+
+  // Read the type (uint32) and length (uint32).
+  errno = 0;
+  if (!file_util::ReadFromFD(fd, data, 8)) {
+    LOG(ERROR) << "Error reading the message type and length.";
+    return false;
+  }
+
+  Pickle pickle;
+  pickle.WriteBytes(data, 8);
+  PickleIterator pickle_it(pickle);
+  uint32 type;
+  uint32 data_length;
+  if (!pickle_it.ReadUInt32(&type) || !pickle_it.ReadUInt32(&data_length)) {
+    LOG(ERROR) << "Error getting the message type and length from the pickle.";
+    return false;
+  }
+
+  if (type < 0 || type >= NUM_MESSAGE_TYPES) {
+    LOG(ERROR) << type << " is not a valid message type.";
+    return false;
+  }
+
+  if ((is_send_message_ && (type != TYPE_SEND_MESSAGE_RESPONSE)) ||
+      (!is_send_message_ && (type != TYPE_CONNECT_MESSAGE))) {
+    LOG(ERROR) << "Recieved a message of type " << type << ". "
+               << "Expecting a message of type "
+               << (is_send_message_ ? TYPE_SEND_MESSAGE_RESPONSE :
+                                      TYPE_CONNECT_MESSAGE);
+    return false;
+  }
+  message->type = static_cast<MessageType>(type);
+
+  if (data_length > kMaxMessageDataLength) {
+    LOG(ERROR) << data_length << " is too large for the length of a message. "
+               << "Max message size is " << kMaxMessageDataLength;
+    return false;
+  }
+
+  if (!file_util::ReadFromFD(fd, data, data_length)) {
+    LOG(ERROR) << "Error reading the json data.";
+    return false;
+  }
+  std::string read_data(data, data_length);
+  message->data.swap(read_data);
+
+  return true;
+}
+
+// static
+void NativeMessageProcess::KillProcess(base::ProcessHandle handle) {

[Matt Perry, 2012/08/09 02:13:00]

This is a little draconian. Why do we need to be so adamant about killing the
process quickly? Can we do this on a worker thread and make the timeout much
longer? What does ChildProcessLauncher do?

[Aaron Boodman, 2012/08/09 18:36:12]

I don't think we need to kill it all. We can just release our file descriptors
and let the other side shut down as it wants.

[eaugusti, 2012/08/13 23:22:34]

Aaron and I were talking about it, and how about we first close the pipes and
then wait ~5secs until we try and kill it.

FYI: ChildProcessLauncher does base::KillProcess() followed immediately by
base::EnsureProcessTerminated().

+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
+  int exit_code = 0;
+  if (!base::WaitForExitCodeWithTimeout(
+        handle,
+        &exit_code,
+        base::TimeDelta::FromMilliseconds(kExitTimeoutMS))) {
+    // Kill the process.
+    if (!base::KillProcess(handle,
+                           -1, /* error exit code */
+                           false /* Don't wait for the process to exit */)) {
+      // Really kill the process.
+      base::EnsureProcessTerminated(handle);
+    }
+  }
+}
+
+}  // namespace extensions