// 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.
//
// This file implements a standalone host process for Me2Me.

#include <string>

#include "base/at_exit.h"
#include "base/bind.h"
#include "base/callback.h"
#include "base/command_line.h"
#include "base/debug/alias.h"
#include "base/file_util.h"
#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/message_loop/message_loop.h"
#include "base/single_thread_task_runner.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/synchronization/waitable_event.h"
#include "base/threading/thread.h"
#include "build/build_config.h"
#include "crypto/nss_util.h"
#include "ipc/ipc_channel.h"
#include "ipc/ipc_channel_proxy.h"
#include "ipc/ipc_listener.h"
#include "media/base/media.h"
#include "net/base/network_change_notifier.h"
#include "net/socket/client_socket_factory.h"
#include "net/socket/ssl_server_socket.h"
#include "net/url_request/url_fetcher.h"
#include "remoting/base/auto_thread_task_runner.h"
#include "remoting/base/breakpad.h"
#include "remoting/base/constants.h"
#include "remoting/base/rsa_key_pair.h"
#include "remoting/base/util.h"
#include "remoting/host/branding.h"
#include "remoting/host/chromoting_host.h"
#include "remoting/host/chromoting_host_context.h"
#include "remoting/host/chromoting_messages.h"
#include "remoting/host/config_file_watcher.h"
#include "remoting/host/desktop_environment.h"
#include "remoting/host/desktop_session_connector.h"
#include "remoting/host/dns_blackhole_checker.h"
#include "remoting/host/heartbeat_sender.h"
#include "remoting/host/host_change_notification_listener.h"
#include "remoting/host/host_config.h"
#include "remoting/host/host_event_logger.h"
#include "remoting/host/host_exit_codes.h"
#include "remoting/host/host_main.h"
#include "remoting/host/host_status_sender.h"
#include "remoting/host/ipc_constants.h"
#include "remoting/host/ipc_desktop_environment.h"
#include "remoting/host/ipc_host_event_logger.h"
#include "remoting/host/json_host_config.h"
#include "remoting/host/log_to_server.h"
#include "remoting/host/logging.h"
#include "remoting/host/me2me_desktop_environment.h"
#include "remoting/host/pairing_registry_delegate.h"
#include "remoting/host/policy_hack/policy_watcher.h"
#include "remoting/host/service_urls.h"
#include "remoting/host/session_manager_factory.h"
#include "remoting/host/signaling_connector.h"
#include "remoting/host/token_validator_factory_impl.h"
#include "remoting/host/usage_stats_consent.h"
#include "remoting/jingle_glue/network_settings.h"
#include "remoting/jingle_glue/xmpp_signal_strategy.h"
#include "remoting/protocol/me2me_host_authenticator_factory.h"
#include "remoting/protocol/pairing_registry.h"

#if defined(OS_POSIX)
#include <signal.h>
#include <sys/types.h>
#include <unistd.h>
#include "base/file_descriptor_posix.h"
#include "remoting/host/pam_authorization_factory_posix.h"
#include "remoting/host/posix/signal_handler.h"
#endif  // defined(OS_POSIX)

#if defined(OS_MACOSX)
#include "base/mac/scoped_cftyperef.h"
#endif  // defined(OS_MACOSX)

#if defined(OS_LINUX)
#include "remoting/host/audio_capturer_linux.h"
#endif  // defined(OS_LINUX)

#if defined(OS_WIN)
#include <commctrl.h>
#include "base/win/scoped_handle.h"
#include "remoting/host/win/session_desktop_environment.h"
#endif  // defined(OS_WIN)

#if defined(TOOLKIT_GTK)
#include "ui/gfx/gtk_util.h"
#endif  // defined(TOOLKIT_GTK)

namespace {

// This is used for tagging system event logs.
const char kApplicationName[] = "chromoting";

#if defined(OS_LINUX)
// The command line switch used to pass name of the pipe to capture audio on
// linux.
const char kAudioPipeSwitchName[] = "audio-pipe-name";
#endif  // defined(OS_LINUX)

// The command line switch used by the parent to request the host to signal it
// when it is successfully started.
const char kSignalParentSwitchName[] = "signal-parent";

// Value used for --host-config option to indicate that the path must be read
// from stdin.
const char kStdinConfigPath[] = "-";

void QuitMessageLoop(base::MessageLoop* message_loop) {
  message_loop->PostTask(FROM_HERE, base::MessageLoop::QuitClosure());
}

}  // namespace

namespace remoting {

class HostProcess
    : public ConfigFileWatcher::Delegate,
      public HeartbeatSender::Listener,
      public HostChangeNotificationListener::Listener,
      public IPC::Listener,
      public base::RefCountedThreadSafe<HostProcess> {
 public:
  HostProcess(scoped_ptr<ChromotingHostContext> context,
              int* exit_code_out);

  // ConfigFileWatcher::Delegate interface.
  virtual void OnConfigUpdated(const std::string& serialized_config) OVERRIDE;
  virtual void OnConfigWatcherError() OVERRIDE;

  // IPC::Listener implementation.
  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
  virtual void OnChannelError() OVERRIDE;

  // HeartbeatSender::Listener overrides.
  virtual void OnHeartbeatSuccessful() OVERRIDE;
  virtual void OnUnknownHostIdError() OVERRIDE;

  // HostChangeNotificationListener::Listener overrides.
  virtual void OnHostDeleted() OVERRIDE;

 private:
  enum HostState {
    // Host process has just been started. Waiting for config and policies to be
    // read from the disk.
    HOST_INITIALIZING,

    // Host is started and running.
    HOST_STARTED,

    // Host is being stopped and will need to be started again.
    HOST_STOPPING_TO_RESTART,

    // Host is being stopped.
    HOST_STOPPING,

    // Host has been stopped.
    HOST_STOPPED,

    // Allowed state transitions:
    //   INITIALIZING->STARTED
    //   INITIALIZING->STOPPED
    //   STARTED->STOPPING_TO_RESTART
    //   STARTED->STOPPING
    //   STOPPING_TO_RESTART->STARTED
    //   STOPPING_TO_RESTART->STOPPING
    //   STOPPING->STOPPED
    //   STOPPED->STARTED
    //
    // |host_| must be NULL in INITIALIZING and STOPPED states and not-NULL in
    // all other states.
  };

  friend class base::RefCountedThreadSafe<HostProcess>;
  virtual ~HostProcess();

  void StartOnNetworkThread();

#if defined(OS_POSIX)
  // Callback passed to RegisterSignalHandler() to handle SIGTERM events.
  void SigTermHandler(int signal_number);
#endif

  // Called to initialize resources on the UI thread.
  void StartOnUiThread();

  // Initializes IPC control channel and config file path from |cmd_line|.
  // Called on the UI thread.
  bool InitWithCommandLine(const CommandLine* cmd_line);

  // Called on the UI thread to start monitoring the configuration file.
  void StartWatchingConfigChanges();

  // Called on the network thread to set the host's Authenticator factory.
  void CreateAuthenticatorFactory();

  // Tear down resources that run on the UI thread.
  void ShutdownOnUiThread();

  // Applies the host config, returning true if successful.
  bool ApplyConfig(scoped_ptr<JsonHostConfig> config);

  void OnPolicyUpdate(scoped_ptr<base::DictionaryValue> policies);
  bool OnHostDomainPolicyUpdate(const std::string& host_domain);
  bool OnUsernamePolicyUpdate(bool curtain_required,
                              bool username_match_required);
  bool OnNatPolicyUpdate(bool nat_traversal_enabled);
  void OnCurtainPolicyUpdate(bool curtain_required);
  bool OnHostTalkGadgetPrefixPolicyUpdate(const std::string& talkgadget_prefix);
  bool OnHostTokenUrlPolicyUpdate(const GURL& token_url,
                                  const GURL& token_validation_url);
  bool OnPairingPolicyUpdate(bool pairing_enabled);

  void StartHost();

  void OnAuthFailed();

  void RestartHost();

  // Stops the host and shuts down the process with the specified |exit_code|.
  void ShutdownHost(HostExitCodes exit_code);

  void ScheduleHostShutdown();

  void ShutdownOnNetworkThread();

  // Crashes the process in response to a daemon's request. The daemon passes
  // the location of the code that detected the fatal error resulted in this
  // request.
  void OnCrash(const std::string& function_name,
               const std::string& file_name,
               const int& line_number);

  scoped_ptr<ChromotingHostContext> context_;

  // Created on the UI thread but used from the network thread.
  scoped_ptr<net::NetworkChangeNotifier> network_change_notifier_;

  // Accessed on the UI thread.
  scoped_ptr<IPC::ChannelProxy> daemon_channel_;

  // XMPP server/remoting bot configuration (initialized from the command line).
  XmppSignalStrategy::XmppServerConfig xmpp_server_config_;
  std::string directory_bot_jid_;

  // Created on the UI thread but used from the network thread.
  base::FilePath host_config_path_;
  std::string host_config_;
  scoped_ptr<DesktopEnvironmentFactory> desktop_environment_factory_;

  // Accessed on the network thread.
  HostState state_;

  scoped_ptr<ConfigFileWatcher> config_watcher_;

  std::string host_id_;
  protocol::SharedSecretHash host_secret_hash_;
  scoped_refptr<RsaKeyPair> key_pair_;
  std::string oauth_refresh_token_;
  std::string serialized_config_;
  std::string host_owner_;
  bool use_service_account_;
  scoped_ptr<policy_hack::PolicyWatcher> policy_watcher_;
  bool allow_nat_traversal_;
  std::string talkgadget_prefix_;
  bool allow_pairing_;

  bool curtain_required_;
  GURL token_url_;
  GURL token_validation_url_;

  scoped_ptr<XmppSignalStrategy> signal_strategy_;
  scoped_ptr<SignalingConnector> signaling_connector_;
  scoped_ptr<HeartbeatSender> heartbeat_sender_;
  scoped_ptr<HostStatusSender> host_status_sender_;
  scoped_ptr<HostChangeNotificationListener> host_change_notification_listener_;
  scoped_ptr<LogToServer> log_to_server_;
  scoped_ptr<HostEventLogger> host_event_logger_;

  scoped_ptr<ChromotingHost> host_;

  // Used to keep this HostProcess alive until it is shutdown.
  scoped_refptr<HostProcess> self_;

#if defined(REMOTING_MULTI_PROCESS)
  DesktopSessionConnector* desktop_session_connector_;
#endif  // defined(REMOTING_MULTI_PROCESS)

  int* exit_code_out_;
  bool signal_parent_;
};

HostProcess::HostProcess(scoped_ptr<ChromotingHostContext> context,
                         int* exit_code_out)
    : context_(context.Pass()),
      state_(HOST_INITIALIZING),
      use_service_account_(false),
      allow_nat_traversal_(true),
      allow_pairing_(true),
      curtain_required_(false),
#if defined(REMOTING_MULTI_PROCESS)
      desktop_session_connector_(NULL),
#endif  // defined(REMOTING_MULTI_PROCESS)
      self_(this),
      exit_code_out_(exit_code_out),
      signal_parent_(false) {
  StartOnUiThread();
}

HostProcess::~HostProcess() {
  // Verify that UI components have been torn down.
  DCHECK(!config_watcher_);
  DCHECK(!daemon_channel_);
  DCHECK(!desktop_environment_factory_);

  // We might be getting deleted on one of the threads the |host_context| owns,
  // so we need to post it back to the caller thread to safely join & delete the
  // threads it contains.  This will go away when we move to AutoThread.
  // |context_release()| will null |context_| before the method is invoked, so
  // we need to pull out the task-runner on which to call DeleteSoon first.
  scoped_refptr<base::SingleThreadTaskRunner> task_runner =
      context_->ui_task_runner();
  task_runner->DeleteSoon(FROM_HERE, context_.release());
}

bool HostProcess::InitWithCommandLine(const CommandLine* cmd_line) {
#if defined(REMOTING_MULTI_PROCESS)
  // Parse the handle value and convert it to a handle/file descriptor.
  std::string channel_name =
      cmd_line->GetSwitchValueASCII(kDaemonPipeSwitchName);

  int pipe_handle = 0;
  if (channel_name.empty() ||
      !base::StringToInt(channel_name, &pipe_handle)) {
    LOG(ERROR) << "Invalid '" << kDaemonPipeSwitchName
               << "' value: " << channel_name;
    return false;
  }

#if defined(OS_WIN)
  base::win::ScopedHandle pipe(reinterpret_cast<HANDLE>(pipe_handle));
  IPC::ChannelHandle channel_handle(pipe);
#elif defined(OS_POSIX)
  base::FileDescriptor pipe(pipe_handle, true);
  IPC::ChannelHandle channel_handle(channel_name, pipe);
#endif  // defined(OS_POSIX)

  // Connect to the daemon process.
  daemon_channel_.reset(new IPC::ChannelProxy(
      channel_handle,
      IPC::Channel::MODE_CLIENT,
      this,
      context_->network_task_runner()));
#else  // !defined(REMOTING_MULTI_PROCESS)
  // Connect to the daemon process.
  std::string channel_name =
      cmd_line->GetSwitchValueASCII(kDaemonPipeSwitchName);
  if (!channel_name.empty()) {
    daemon_channel_.reset(
        new IPC::ChannelProxy(channel_name,
                              IPC::Channel::MODE_CLIENT,
                              this,
                              context_->network_task_runner().get()));
  }

  if (cmd_line->HasSwitch(kHostConfigSwitchName)) {
    host_config_path_ = cmd_line->GetSwitchValuePath(kHostConfigSwitchName);

    // Read config from stdin if necessary.
    if (host_config_path_ == base::FilePath(kStdinConfigPath)) {
      char buf[4096];
      size_t len;
      while ((len = fread(buf, 1, sizeof(buf), stdin)) > 0) {
        host_config_.append(buf, len);
      }
    }
  } else {
    base::FilePath default_config_dir = remoting::GetConfigDir();
    host_config_path_ = default_config_dir.Append(kDefaultHostConfigFile);
  }

  if (host_config_path_ != base::FilePath(kStdinConfigPath) &&
      !base::PathExists(host_config_path_)) {
    LOG(ERROR) << "Can't find host config at " << host_config_path_.value();
    return false;
  }
#endif  // !defined(REMOTING_MULTI_PROCESS)

  // Ignore certificate requests - the host currently has no client certificate
  // support, so ignoring certificate requests allows connecting to servers that
  // request, but don't require, a certificate (optional client authentication).
  net::URLFetcher::SetIgnoreCertificateRequests(true);

  ServiceUrls* service_urls = ServiceUrls::GetInstance();
  bool xmpp_server_valid = net::ParseHostAndPort(
      service_urls->xmpp_server_address(),
      &xmpp_server_config_.host, &xmpp_server_config_.port);
  if (!xmpp_server_valid) {
    LOG(ERROR) << "Invalid XMPP server: " <<
        service_urls->xmpp_server_address();
    return false;
  }
  xmpp_server_config_.use_tls = service_urls->xmpp_server_use_tls();
  directory_bot_jid_ = service_urls->directory_bot_jid();

  signal_parent_ = cmd_line->HasSwitch(kSignalParentSwitchName);

  return true;
}

void HostProcess::OnConfigUpdated(
    const std::string& serialized_config) {
  if (!context_->network_task_runner()->BelongsToCurrentThread()) {
    context_->network_task_runner()->PostTask(FROM_HERE,
        base::Bind(&HostProcess::OnConfigUpdated, this, serialized_config));
    return;
  }

  // Filter out duplicates.
  if (serialized_config_ == serialized_config)
    return;

  LOG(INFO) << "Processing new host configuration.";

  serialized_config_ = serialized_config;
  scoped_ptr<JsonHostConfig> config(new JsonHostConfig(base::FilePath()));
  if (!config->SetSerializedData(serialized_config)) {
    LOG(ERROR) << "Invalid configuration.";
    ShutdownHost(kInvalidHostConfigurationExitCode);
    return;
  }

  if (!ApplyConfig(config.Pass())) {
    LOG(ERROR) << "Failed to apply the configuration.";
    ShutdownHost(kInvalidHostConfigurationExitCode);
    return;
  }

  if (state_ == HOST_INITIALIZING) {
    // TODO(sergeyu): Currently OnPolicyUpdate() assumes that host config is
    // already loaded so PolicyWatcher has to be started here. Separate policy
    // loading from policy verifications and move |policy_watcher_|
    // initialization to StartOnNetworkThread().
    policy_watcher_.reset(
        policy_hack::PolicyWatcher::Create(context_->file_task_runner()));
    policy_watcher_->StartWatching(
        base::Bind(&HostProcess::OnPolicyUpdate, base::Unretained(this)));
  } else if (state_ == HOST_STARTED) {
    // TODO(sergeyu): Here we assume that PIN is the only part of the config
    // that may change while the service is running. Change ApplyConfig() to
    // detect other changes in the config and restart host if necessary here.
    CreateAuthenticatorFactory();
  }
}

void HostProcess::OnConfigWatcherError() {
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
  ShutdownHost(kInvalidHostConfigurationExitCode);
}

void HostProcess::StartOnNetworkThread() {
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

#if !defined(REMOTING_MULTI_PROCESS)
  if (host_config_path_ == base::FilePath(kStdinConfigPath)) {
    // Process config we've read from stdin.
    OnConfigUpdated(host_config_);
  } else {
    // Start watching the host configuration file.
    config_watcher_.reset(new ConfigFileWatcher(context_->network_task_runner(),
                                                context_->file_task_runner(),
                                                this));
    config_watcher_->Watch(host_config_path_);
  }
#endif  // !defined(REMOTING_MULTI_PROCESS)

#if defined(OS_POSIX)
  remoting::RegisterSignalHandler(
      SIGTERM,
      base::Bind(&HostProcess::SigTermHandler, base::Unretained(this)));
#endif  // defined(OS_POSIX)
}

#if defined(OS_POSIX)
void HostProcess::SigTermHandler(int signal_number) {
  DCHECK(signal_number == SIGTERM);
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
  LOG(INFO) << "Caught SIGTERM: Shutting down...";
  ShutdownHost(kSuccessExitCode);
}
#endif  // OS_POSIX

void HostProcess::CreateAuthenticatorFactory() {
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

  if (state_ != HOST_STARTED)
    return;

  std::string local_certificate = key_pair_->GenerateCertificate();
  if (local_certificate.empty()) {
    LOG(ERROR) << "Failed to generate host certificate.";
    ShutdownHost(kInitializationFailed);
    return;
  }

  scoped_refptr<protocol::PairingRegistry> pairing_registry = NULL;
  if (allow_pairing_) {
    pairing_registry = CreatePairingRegistry(context_->file_task_runner());
  }

  scoped_ptr<protocol::AuthenticatorFactory> factory;

  if (token_url_.is_empty() && token_validation_url_.is_empty()) {
    factory = protocol::Me2MeHostAuthenticatorFactory::CreateWithSharedSecret(
        host_owner_, local_certificate, key_pair_, host_secret_hash_,
        pairing_registry);

  } else if (token_url_.is_valid() && token_validation_url_.is_valid()) {
    scoped_ptr<protocol::ThirdPartyHostAuthenticator::TokenValidatorFactory>
        token_validator_factory(new TokenValidatorFactoryImpl(
            token_url_, token_validation_url_, key_pair_,
            context_->url_request_context_getter()));
    factory = protocol::Me2MeHostAuthenticatorFactory::CreateWithThirdPartyAuth(
        host_owner_, local_certificate, key_pair_,
        token_validator_factory.Pass());

  } else {
    // TODO(rmsousa): If the policy is bad the host should not go online. It
    // should keep running, but not connected, until the policies are fixed.
    // Having it show up as online and then reject all clients is misleading.
    LOG(ERROR) << "One of the third-party token URLs is empty or invalid. "
               << "Host will reject all clients until policies are corrected. "
               << "TokenUrl: " << token_url_ << ", "
               << "TokenValidationUrl: " << token_validation_url_;
    factory = protocol::Me2MeHostAuthenticatorFactory::CreateRejecting();
  }

#if defined(OS_POSIX)
  // On Linux and Mac, perform a PAM authorization step after authentication.
  factory.reset(new PamAuthorizationFactory(factory.Pass()));
#endif
  host_->SetAuthenticatorFactory(factory.Pass());

  host_->set_pairing_registry(pairing_registry);
}

// IPC::Listener implementation.
bool HostProcess::OnMessageReceived(const IPC::Message& message) {
  DCHECK(context_->ui_task_runner()->BelongsToCurrentThread());

#if defined(REMOTING_MULTI_PROCESS)
  bool handled = true;
  IPC_BEGIN_MESSAGE_MAP(HostProcess, message)
    IPC_MESSAGE_HANDLER(ChromotingDaemonMsg_Crash, OnCrash)
    IPC_MESSAGE_HANDLER(ChromotingDaemonNetworkMsg_Configuration,
                        OnConfigUpdated)
    IPC_MESSAGE_FORWARD(
        ChromotingDaemonNetworkMsg_DesktopAttached,
        desktop_session_connector_,
        DesktopSessionConnector::OnDesktopSessionAgentAttached)
    IPC_MESSAGE_FORWARD(ChromotingDaemonNetworkMsg_TerminalDisconnected,
                        desktop_session_connector_,
                        DesktopSessionConnector::OnTerminalDisconnected)
    IPC_MESSAGE_UNHANDLED(handled = false)
  IPC_END_MESSAGE_MAP()

  CHECK(handled) << "Received unexpected IPC type: " << message.type();
  return handled;

#else  // !defined(REMOTING_MULTI_PROCESS)
  return false;
#endif  // !defined(REMOTING_MULTI_PROCESS)
}

void HostProcess::OnChannelError() {
  DCHECK(context_->ui_task_runner()->BelongsToCurrentThread());

  // Shutdown the host if the daemon process disconnects the IPC channel.
  context_->network_task_runner()->PostTask(
      FROM_HERE,
      base::Bind(&HostProcess::ShutdownHost, this, kSuccessExitCode));
}

void HostProcess::StartOnUiThread() {
  DCHECK(context_->ui_task_runner()->BelongsToCurrentThread());

  if (!InitWithCommandLine(CommandLine::ForCurrentProcess())) {
    // Shutdown the host if the command line is invalid.
    context_->network_task_runner()->PostTask(
        FROM_HERE, base::Bind(&HostProcess::ShutdownHost, this,
                              kUsageExitCode));
    return;
  }

#if defined(OS_LINUX)
  // If an audio pipe is specific on the command-line then initialize
  // AudioCapturerLinux to capture from it.
  base::FilePath audio_pipe_name = CommandLine::ForCurrentProcess()->
      GetSwitchValuePath(kAudioPipeSwitchName);
  if (!audio_pipe_name.empty()) {
    remoting::AudioCapturerLinux::InitializePipeReader(
        context_->audio_task_runner(), audio_pipe_name);
  }
#endif  // defined(OS_LINUX)

  // Create a desktop environment factory appropriate to the build type &
  // platform.
#if defined(OS_WIN)
  IpcDesktopEnvironmentFactory* desktop_environment_factory =
      new IpcDesktopEnvironmentFactory(
          context_->audio_task_runner(),
          context_->network_task_runner(),
          context_->video_capture_task_runner(),
          context_->network_task_runner(),
          daemon_channel_.get());
  desktop_session_connector_ = desktop_environment_factory;
#else  // !defined(OS_WIN)
  DesktopEnvironmentFactory* desktop_environment_factory =
      new Me2MeDesktopEnvironmentFactory(
          context_->network_task_runner(),
          context_->input_task_runner(),
          context_->ui_task_runner());
#endif  // !defined(OS_WIN)

  desktop_environment_factory_.reset(desktop_environment_factory);

  context_->network_task_runner()->PostTask(
      FROM_HERE,
      base::Bind(&HostProcess::StartOnNetworkThread, this));
}

void HostProcess::ShutdownOnUiThread() {
  DCHECK(context_->ui_task_runner()->BelongsToCurrentThread());

  // Tear down resources that need to be torn down on the UI thread.
  network_change_notifier_.reset();
  daemon_channel_.reset();
  desktop_environment_factory_.reset();

  // It is now safe for the HostProcess to be deleted.
  self_ = NULL;

#if defined(OS_LINUX)
  // Cause the global AudioPipeReader to be freed, otherwise the audio
  // thread will remain in-use and prevent the process from exiting.
  // TODO(wez): DesktopEnvironmentFactory should own the pipe reader.
  // See crbug.com/161373 and crbug.com/104544.
  AudioCapturerLinux::InitializePipeReader(NULL, base::FilePath());
#endif
}

// Overridden from HeartbeatSender::Listener
void HostProcess::OnUnknownHostIdError() {
  LOG(ERROR) << "Host ID not found.";
  ShutdownHost(kInvalidHostIdExitCode);
}

void HostProcess::OnHeartbeatSuccessful() {
  LOG(INFO) << "Host ready to receive connections.";
#if defined(OS_POSIX)
  if (signal_parent_) {
    kill(getppid(), SIGUSR1);
    signal_parent_ = false;
  }
#endif
}

void HostProcess::OnHostDeleted() {
  LOG(ERROR) << "Host was deleted from the directory.";
  ShutdownHost(kInvalidHostIdExitCode);
}

// Applies the host config, returning true if successful.
bool HostProcess::ApplyConfig(scoped_ptr<JsonHostConfig> config) {
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

  if (!config->GetString(kHostIdConfigPath, &host_id_)) {
    LOG(ERROR) << "host_id is not defined in the config.";
    return false;
  }

  std::string key_base64;
  if (!config->GetString(kPrivateKeyConfigPath, &key_base64)) {
    LOG(ERROR) << "Private key couldn't be read from the config file.";
    return false;
  }

  key_pair_ = RsaKeyPair::FromString(key_base64);
  if (!key_pair_.get()) {
    LOG(ERROR) << "Invalid private key in the config file.";
    return false;
  }

  std::string host_secret_hash_string;
  if (!config->GetString(kHostSecretHashConfigPath,
                         &host_secret_hash_string)) {
    host_secret_hash_string = "plain:";
  }

  if (!host_secret_hash_.Parse(host_secret_hash_string)) {
    LOG(ERROR) << "Invalid host_secret_hash.";
    return false;
  }

  // Use an XMPP connection to the Talk network for session signalling.
  if (!config->GetString(kXmppLoginConfigPath, &xmpp_server_config_.username) ||
      !(config->GetString(kXmppAuthTokenConfigPath,
                          &xmpp_server_config_.auth_token) ||
        config->GetString(kOAuthRefreshTokenConfigPath,
                          &oauth_refresh_token_))) {
    LOG(ERROR) << "XMPP credentials are not defined in the config.";
    return false;
  }

  if (!oauth_refresh_token_.empty()) {
    // SignalingConnector is responsible for getting OAuth token.
    xmpp_server_config_.auth_token = "";
    xmpp_server_config_.auth_service = "oauth2";
  } else if (!config->GetString(kXmppAuthServiceConfigPath,
                                &xmpp_server_config_.auth_service)) {
    // For the me2me host, we default to ClientLogin token for chromiumsync
    // because earlier versions of the host had no HTTP stack with which to
    // request an OAuth2 access token.
    xmpp_server_config_.auth_service = kChromotingTokenDefaultServiceName;
  }

  if (config->GetString(kHostOwnerConfigPath, &host_owner_)) {
    // Service account configs have a host_owner, different from the xmpp_login.
    use_service_account_ = true;
  } else {
    // User credential configs only have an xmpp_login, which is also the owner.
    host_owner_ = xmpp_server_config_.username;
    use_service_account_ = false;
  }
  return true;
}

void HostProcess::OnPolicyUpdate(scoped_ptr<base::DictionaryValue> policies) {
  // TODO(rmsousa): Consolidate all On*PolicyUpdate methods into this one.
  // TODO(sergeyu): Currently polices are verified only when they are loaded.
  // Separate policy loading from policy verifications - this will allow to
  // check policies again later, e.g. when host config changes.

  if (!context_->network_task_runner()->BelongsToCurrentThread()) {
    context_->network_task_runner()->PostTask(FROM_HERE, base::Bind(
        &HostProcess::OnPolicyUpdate, this, base::Passed(&policies)));
    return;
  }

  bool restart_required = false;
  bool bool_value;
  std::string string_value;
  if (policies->GetString(policy_hack::PolicyWatcher::kHostDomainPolicyName,
                          &string_value)) {
    restart_required |= OnHostDomainPolicyUpdate(string_value);
  }
  bool curtain_required = false;
  if (policies->GetBoolean(
          policy_hack::PolicyWatcher::kHostRequireCurtainPolicyName,
          &curtain_required)) {
    OnCurtainPolicyUpdate(curtain_required);
  }
  if (policies->GetBoolean(
      policy_hack::PolicyWatcher::kHostMatchUsernamePolicyName,
      &bool_value)) {
    restart_required |= OnUsernamePolicyUpdate(curtain_required, bool_value);
  }
  if (policies->GetBoolean(policy_hack::PolicyWatcher::kNatPolicyName,
                           &bool_value)) {
    restart_required |= OnNatPolicyUpdate(bool_value);
  }
  if (policies->GetString(
          policy_hack::PolicyWatcher::kHostTalkGadgetPrefixPolicyName,
          &string_value)) {
    restart_required |= OnHostTalkGadgetPrefixPolicyUpdate(string_value);
  }
  std::string token_url_string, token_validation_url_string;
  if (policies->GetString(
          policy_hack::PolicyWatcher::kHostTokenUrlPolicyName,
          &token_url_string) &&
      policies->GetString(
          policy_hack::PolicyWatcher::kHostTokenValidationUrlPolicyName,
          &token_validation_url_string)) {
    restart_required |= OnHostTokenUrlPolicyUpdate(
        GURL(token_url_string), GURL(token_validation_url_string));
  }
  if (policies->GetBoolean(
          policy_hack::PolicyWatcher::kHostAllowClientPairing,
          &bool_value)) {
    restart_required |= OnPairingPolicyUpdate(bool_value);
  }

  if (state_ == HOST_INITIALIZING) {
    StartHost();
  } else if (state_ == HOST_STARTED && restart_required) {
    RestartHost();
  }
}

bool HostProcess::OnHostDomainPolicyUpdate(const std::string& host_domain) {
  // Returns true if the host has to be restarted after this policy update.
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

  LOG(INFO) << "Policy sets host domain: " << host_domain;

  if (!host_domain.empty() &&
      !EndsWith(host_owner_, std::string("@") + host_domain, false)) {
    ShutdownHost(kInvalidHostDomainExitCode);
  }
  return false;
}

bool HostProcess::OnUsernamePolicyUpdate(bool curtain_required,
                                         bool host_username_match_required) {
  // Returns false: never restart the host after this policy update.
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

  if (host_username_match_required) {
    LOG(INFO) << "Policy requires host username match.";
    std::string username = GetUsername();
    bool shutdown = username.empty() ||
        !StartsWithASCII(host_owner_, username + std::string("@"),
                         false);

#if defined(OS_MACOSX)
    // On Mac, we run as root at the login screen, so the username won't match.
    // However, there's no need to enforce the policy at the login screen, as
    // the client will have to reconnect if a login occurs.
    if (shutdown && getuid() == 0) {
      shutdown = false;
    }
#endif

    // Curtain-mode on Windows presents the standard OS login prompt to the user
    // for each connection, removing the need for an explicit user-name matching
    // check.
#if defined(OS_WIN) && defined(REMOTING_RDP_SESSION)
    if (curtain_required)
      return false;
#endif  // defined(OS_WIN) && defined(REMOTING_RDP_SESSION)

    // Shutdown the host if the username does not match.
    if (shutdown) {
      LOG(ERROR) << "The host username does not match.";
      ShutdownHost(kUsernameMismatchExitCode);
    }
  } else {
    LOG(INFO) << "Policy does not require host username match.";
  }

  return false;
}

bool HostProcess::OnNatPolicyUpdate(bool nat_traversal_enabled) {
  // Returns true if the host has to be restarted after this policy update.
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

  if (allow_nat_traversal_ != nat_traversal_enabled) {
    if (nat_traversal_enabled)
      LOG(INFO) << "Policy enables NAT traversal.";
    else
      LOG(INFO) << "Policy disables NAT traversal.";
    allow_nat_traversal_ = nat_traversal_enabled;
    return true;
  }
  return false;
}

void HostProcess::OnCurtainPolicyUpdate(bool curtain_required) {
  // Returns true if the host has to be restarted after this policy update.
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

#if defined(OS_MACOSX)
  if (curtain_required) {
    // When curtain mode is in effect on Mac, the host process runs in the
    // user's switched-out session, but launchd will also run an instance at
    // the console login screen.  Even if no user is currently logged-on, we
    // can't support remote-access to the login screen because the current host
    // process model disconnects the client during login, which would leave
    // the logged in session un-curtained on the console until they reconnect.
    //
    // TODO(jamiewalch): Fix this once we have implemented the multi-process
    // daemon architecture (crbug.com/134894)
    if (getuid() == 0) {
      LOG(ERROR) << "Running the host in the console login session is yet not "
                    "supported.";
      ShutdownHost(kLoginScreenNotSupportedExitCode);
      return;
    }
  }
#endif

  if (curtain_required_ != curtain_required) {
    if (curtain_required)
      LOG(INFO) << "Policy requires curtain-mode.";
    else
      LOG(INFO) << "Policy does not require curtain-mode.";
    curtain_required_ = curtain_required;
    if (host_)
      host_->SetEnableCurtaining(curtain_required_);
  }
}

bool HostProcess::OnHostTalkGadgetPrefixPolicyUpdate(
    const std::string& talkgadget_prefix) {
  // Returns true if the host has to be restarted after this policy update.
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

  if (talkgadget_prefix != talkgadget_prefix_) {
    LOG(INFO) << "Policy sets talkgadget prefix: " << talkgadget_prefix;
    talkgadget_prefix_ = talkgadget_prefix;
    return true;
  }
  return false;
}

bool HostProcess::OnHostTokenUrlPolicyUpdate(
    const GURL& token_url,
    const GURL& token_validation_url) {
  // Returns true if the host has to be restarted after this policy update.
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

  if (token_url_ != token_url ||
      token_validation_url_ != token_validation_url) {
    LOG(INFO) << "Policy sets third-party token URLs: "
              << "TokenUrl: " << token_url << ", "
              << "TokenValidationUrl: " << token_validation_url;

    token_url_ = token_url;
    token_validation_url_ = token_validation_url;
    return true;
  }

  return false;
}

bool HostProcess::OnPairingPolicyUpdate(bool allow_pairing) {
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

  if (allow_pairing_ == allow_pairing)
    return false;

  if (allow_pairing)
    LOG(INFO) << "Policy enables client pairing.";
  else
    LOG(INFO) << "Policy disables client pairing.";
  allow_pairing_ = allow_pairing;
  return true;
}

void HostProcess::StartHost() {
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
  DCHECK(!host_);
  DCHECK(!signal_strategy_.get());
  DCHECK(state_ == HOST_INITIALIZING || state_ == HOST_STOPPING_TO_RESTART ||
         state_ == HOST_STOPPED) << state_;
  state_ = HOST_STARTED;

  signal_strategy_.reset(
      new XmppSignalStrategy(net::ClientSocketFactory::GetDefaultFactory(),
                             context_->url_request_context_getter(),
                             xmpp_server_config_));

  scoped_ptr<DnsBlackholeChecker> dns_blackhole_checker(
      new DnsBlackholeChecker(context_->url_request_context_getter(),
                              talkgadget_prefix_));

  // Create a NetworkChangeNotifier for use by the signaling connector.
  network_change_notifier_.reset(net::NetworkChangeNotifier::Create());

  signaling_connector_.reset(new SignalingConnector(
      signal_strategy_.get(),
      context_->url_request_context_getter(),
      dns_blackhole_checker.Pass(),
      base::Bind(&HostProcess::OnAuthFailed, this)));

  if (!oauth_refresh_token_.empty()) {
    scoped_ptr<SignalingConnector::OAuthCredentials> oauth_credentials(
        new SignalingConnector::OAuthCredentials(
            xmpp_server_config_.username, oauth_refresh_token_,
            use_service_account_));
    signaling_connector_->EnableOAuth(oauth_credentials.Pass());
  }

  NetworkSettings network_settings(
      allow_nat_traversal_ ?
      NetworkSettings::NAT_TRAVERSAL_ENABLED :
      NetworkSettings::NAT_TRAVERSAL_DISABLED);
  if (!allow_nat_traversal_) {
    network_settings.min_port = NetworkSettings::kDefaultMinPort;
    network_settings.max_port = NetworkSettings::kDefaultMaxPort;
  }

  host_.reset(new ChromotingHost(
      signal_strategy_.get(),
      desktop_environment_factory_.get(),
      CreateHostSessionManager(network_settings,
                               context_->url_request_context_getter()),
      context_->audio_task_runner(),
      context_->input_task_runner(),
      context_->video_capture_task_runner(),
      context_->video_encode_task_runner(),
      context_->network_task_runner(),
      context_->ui_task_runner()));

  // TODO(simonmorris): Get the maximum session duration from a policy.
#if defined(OS_LINUX)
  host_->SetMaximumSessionDuration(base::TimeDelta::FromHours(20));
#endif

  heartbeat_sender_.reset(new HeartbeatSender(
      this, host_id_, signal_strategy_.get(), key_pair_,
      directory_bot_jid_));

  host_status_sender_.reset(new HostStatusSender(
      host_id_, signal_strategy_.get(), key_pair_, directory_bot_jid_));

  host_change_notification_listener_.reset(new HostChangeNotificationListener(
      this, host_id_, signal_strategy_.get(), directory_bot_jid_));

  log_to_server_.reset(
      new LogToServer(host_->AsWeakPtr(), ServerLogEntry::ME2ME,
                      signal_strategy_.get(), directory_bot_jid_));

  // Set up repoting the host status notifications.
#if defined(REMOTING_MULTI_PROCESS)
  host_event_logger_.reset(
      new IpcHostEventLogger(host_->AsWeakPtr(), daemon_channel_.get()));
#else  // !defined(REMOTING_MULTI_PROCESS)
  host_event_logger_ =
      HostEventLogger::Create(host_->AsWeakPtr(), kApplicationName);
#endif  // !defined(REMOTING_MULTI_PROCESS)

  host_->SetEnableCurtaining(curtain_required_);
  host_->Start(host_owner_);

  CreateAuthenticatorFactory();
}

void HostProcess::OnAuthFailed() {
  ShutdownHost(kInvalidOauthCredentialsExitCode);
}

void HostProcess::RestartHost() {
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
  DCHECK_EQ(state_, HOST_STARTED);

  state_ = HOST_STOPPING_TO_RESTART;
  ShutdownOnNetworkThread();
}

void HostProcess::ShutdownHost(HostExitCodes exit_code) {
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

  *exit_code_out_ = exit_code;

  switch (state_) {
    case HOST_INITIALIZING:
      state_ = HOST_STOPPING;
      ShutdownOnNetworkThread();
      break;

    case HOST_STARTED:
      state_ = HOST_STOPPING;
      host_status_sender_->SendOfflineStatus(exit_code);
      ScheduleHostShutdown();
      break;

    case HOST_STOPPING_TO_RESTART:
      state_ = HOST_STOPPING;
      break;

    case HOST_STOPPING:
    case HOST_STOPPED:
      // Host is already stopped or being stopped. No action is required.
      break;
  }
}

// TODO(weitaosu): shut down the host once we get an ACK for the offline status
//                  XMPP message.
void HostProcess::ScheduleHostShutdown() {
  // Delay the shutdown by 2 second to allow SendOfflineStatus to complete.
  context_->network_task_runner()->PostDelayedTask(
      FROM_HERE,
      base::Bind(&HostProcess::ShutdownOnNetworkThread, base::Unretained(this)),
      base::TimeDelta::FromSeconds(2));
}

void HostProcess::ShutdownOnNetworkThread() {
  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());

  host_.reset();
  host_event_logger_.reset();
  log_to_server_.reset();
  heartbeat_sender_.reset();
  host_status_sender_.reset();
  host_change_notification_listener_.reset();
  signaling_connector_.reset();
  signal_strategy_.reset();
  network_change_notifier_.reset();

  if (state_ == HOST_STOPPING_TO_RESTART) {
    StartHost();
  } else if (state_ == HOST_STOPPING) {
    state_ = HOST_STOPPED;

    if (policy_watcher_.get()) {
      base::WaitableEvent done_event(true, false);
      policy_watcher_->StopWatching(&done_event);
      done_event.Wait();
      policy_watcher_.reset();
    }

    config_watcher_.reset();

    // Complete the rest of shutdown on the main thread.
    context_->ui_task_runner()->PostTask(
        FROM_HERE,
        base::Bind(&HostProcess::ShutdownOnUiThread, this));
  } else {
    // This method is only called in STOPPING_TO_RESTART and STOPPING states.
    NOTREACHED();
  }
}

void HostProcess::OnCrash(const std::string& function_name,
                          const std::string& file_name,
                          const int& line_number) {
  char message[1024];
  base::snprintf(message, sizeof(message),
                 "Requested by %s at %s, line %d.",
                 function_name.c_str(), file_name.c_str(), line_number);
  base::debug::Alias(message);

  // The daemon requested us to crash the process.
  CHECK(false) << message;
}

int HostProcessMain() {
#if defined(TOOLKIT_GTK)
  // Required for any calls into GTK functions, such as the Disconnect and
  // Continue windows, though these should not be used for the Me2Me case
  // (crbug.com/104377).
  gfx::GtkInitFromCommandLine(*CommandLine::ForCurrentProcess());
#endif  // TOOLKIT_GTK

  // Enable support for SSL server sockets, which must be done while still
  // single-threaded.
  net::EnableSSLServerSockets();

  // Ensures runtime specific CPU features are initialized.
  media::InitializeCPUSpecificMediaFeatures();

  // Create the main message loop and start helper threads.
  base::MessageLoop message_loop(base::MessageLoop::TYPE_UI);
  scoped_ptr<ChromotingHostContext> context =
      ChromotingHostContext::Create(new AutoThreadTaskRunner(
          message_loop.message_loop_proxy(), base::MessageLoop::QuitClosure()));
  if (!context)
    return kInitializationFailed;

  // Create & start the HostProcess using these threads.
  // TODO(wez): The HostProcess holds a reference to itself until Shutdown().
  // Remove this hack as part of the multi-process refactoring.
  int exit_code = kSuccessExitCode;
  new HostProcess(context.Pass(), &exit_code);

  // Run the main (also UI) message loop until the host no longer needs it.
  message_loop.Run();

  return exit_code;
}

}  // namespace remoting

#if !defined(OS_WIN)
int main(int argc, char** argv) {
  return remoting::HostMain(argc, argv);
}
#endif  // !defined(OS_WIN)