[Chromoting] Moving common logic responsible for launching child processes to WorkerProcessLauncher…

remoting/host/win/worker_process_launcher.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 "remoting/host/win/worker_process_launcher.h"
+
+#include <windows.h>
+#include <sddl.h>
+#include <limits>
+
+#include "base/base_switches.h"
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/logging.h"
+#include "base/single_thread_task_runner.h"
+#include "base/process_util.h"
+#include "base/rand_util.h"
+#include "base/stringprintf.h"
+#include "base/utf_string_conversions.h"
+#include "base/win/scoped_handle.h"
+#include "ipc/ipc_channel_proxy.h"
+#include "ipc/ipc_message.h"
+
+using base::win::ScopedHandle;
+
+namespace {
+
+// Match the pipe name prefix used by Chrome IPC channels so that the client
+// could use Chrome IPC APIs instead of connecting manually.
+const char kChromePipeNamePrefix[] = "\\\\.\\pipe\\chrome.";
+
+} // namespace
+
+namespace remoting {
+
+WorkerProcessLauncher::Delegate::~Delegate() {
+}
+
+WorkerProcessLauncher::WorkerProcessLauncher(
+    Delegate* delegate,
+    const base::Closure& stopped_callback,
+    scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
+    scoped_refptr<base::SingleThreadTaskRunner> ipc_task_runner)
+    : Stoppable(main_task_runner, stopped_callback),
+      delegate_(delegate),
+      main_task_runner_(main_task_runner),
+      ipc_task_runner_(ipc_task_runner) {
+}
+
+WorkerProcessLauncher::~WorkerProcessLauncher() {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+}
+
+void WorkerProcessLauncher::Start(const std::string& pipe_sddl) {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+  DCHECK(ipc_channel_.get() == NULL);
+  DCHECK(!pipe_.IsValid());
+  DCHECK(!process_exit_event_.IsValid());
+  DCHECK(process_watcher_.GetWatchedObject() == NULL);
+
+  std::string channel_name = GenerateRandomChannelId();
+  if (CreatePipeForIpcChannel(channel_name, pipe_sddl, &pipe_)) {
+    // Wrap the pipe into an IPC channel.
+    ipc_channel_.reset(new IPC::ChannelProxy(
+        IPC::ChannelHandle(pipe_),
+        IPC::Channel::MODE_SERVER,
+        this,
+        ipc_task_runner_));
+
+    // Launch the process and attach an object watcher to the returned process
+    // handle so that we get notified if the process terminates.
+    if (delegate_->DoLaunchProcess(channel_name, &process_exit_event_)) {
+      if (process_watcher_.StartWatching(process_exit_event_, this)) {
+        return;
+      }
+
+      delegate_->DoKillProcess(CONTROL_C_EXIT);
+    }
+  }
+
+  Stop();
+}
+
+void WorkerProcessLauncher::Send(IPC::Message* message) {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+
+  ipc_channel_->Send(message);
+}
+
+void WorkerProcessLauncher::OnObjectSignaled(HANDLE object) {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+  DCHECK(process_watcher_.GetWatchedObject() == NULL);
+
+  Stop();
+}
+
+bool WorkerProcessLauncher::OnMessageReceived(const IPC::Message& message) {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+  DCHECK(ipc_channel_.get() != NULL);
+  DCHECK(pipe_.IsValid());
+  DCHECK(process_exit_event_.IsValid());
+
+  return delegate_->OnMessageReceived(message);
+}
+
+void WorkerProcessLauncher::OnChannelConnected(int32 peer_pid) {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+  DCHECK(ipc_channel_.get() != NULL);
+  DCHECK(pipe_.IsValid());
+  DCHECK(process_exit_event_.IsValid());
+
+  // Get the actual peer's PID (i.e. reported by the OS) instead of the PID
+  // reported by the peer itself (|peer_pid|).
+  DWORD actual_peer_pid;
+  if (!GetNamedPipeClientProcessId(pipe_, &actual_peer_pid)) {
+    LOG_GETLASTERROR(ERROR) << "Failed to query the peer's PID";
+    Stop();
+    return;
+  }
+
+  delegate_->OnChannelConnected(actual_peer_pid);
+}
+
+void WorkerProcessLauncher::OnChannelError() {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+  DCHECK(ipc_channel_.get() != NULL);
+  DCHECK(pipe_.IsValid());
+  DCHECK(process_exit_event_.IsValid());
+
+  Stop();
+}
+
+void WorkerProcessLauncher::DoStop() {
+  DCHECK(main_task_runner_->BelongsToCurrentThread());
+
+  ipc_channel_.reset();
+  pipe_.Close();
+
+  // Kill the process if it has been started already.
+  if (process_watcher_.GetWatchedObject() != NULL) {
+    delegate_->DoKillProcess(CONTROL_C_EXIT);
+    return;
+  }
+
+  DCHECK(ipc_channel_.get() == NULL);
+  DCHECK(!pipe_.IsValid());
+  DCHECK(process_watcher_.GetWatchedObject() == NULL);
+
+  process_exit_event_.Close();
+  CompleteStopping();
+}
+
+// Creates the server end of the Chromoting IPC channel.
+bool WorkerProcessLauncher::CreatePipeForIpcChannel(
+    const std::string& channel_name,
+    const std::string& pipe_sddl,
+    ScopedHandle* pipe_out) {
+  // Create security descriptor for the channel.
+  SECURITY_ATTRIBUTES security_attributes;
+  security_attributes.nLength = sizeof(security_attributes);
+  security_attributes.bInheritHandle = FALSE;
+
+  ULONG security_descriptor_length = 0;
+  if (!ConvertStringSecurityDescriptorToSecurityDescriptor(
+          UTF8ToUTF16(pipe_sddl).c_str(),
+          SDDL_REVISION_1,
+          reinterpret_cast<PSECURITY_DESCRIPTOR*>(
+              &security_attributes.lpSecurityDescriptor),
+          &security_descriptor_length)) {
+    LOG_GETLASTERROR(ERROR) <<
+        "Failed to create a security descriptor for the Chromoting IPC channel";
+    return false;
+  }
+
+  // Convert the channel name to the pipe name.
+  std::string pipe_name(kChromePipeNamePrefix);
+  pipe_name.append(channel_name);
+
+  // Create the server end of the pipe. This code should match the code in
+  // IPC::Channel with exception of passing a non-default security descriptor.
+  base::win::ScopedHandle pipe;
+  pipe.Set(CreateNamedPipe(
+      UTF8ToUTF16(pipe_name).c_str(),
+      PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED | FILE_FLAG_FIRST_PIPE_INSTANCE,
+      PIPE_TYPE_BYTE | PIPE_READMODE_BYTE,
+      1,
+      IPC::Channel::kReadBufferSize,
+      IPC::Channel::kReadBufferSize,
+      5000,
+      &security_attributes));
+  if (!pipe.IsValid()) {
+    LOG_GETLASTERROR(ERROR) <<
+        "Failed to create the server end of the Chromoting IPC channel";
+    LocalFree(security_attributes.lpSecurityDescriptor);
+    return false;
+  }
+
+  LocalFree(security_attributes.lpSecurityDescriptor);
+
+  *pipe_out = pipe.Pass();
+  return true;
+}
+
+// N.B. Copied from src/content/common/child_process_host_impl.cc
+std::string WorkerProcessLauncher::GenerateRandomChannelId() {
+  return base::StringPrintf("%d.%p.%d",
+                            base::GetCurrentProcId(), this,
+                            base::RandInt(0, std::numeric_limits<int>::max()));
+}
+
+} // namespace remoting