Suspend (rather than shut down) the host upon policy errors.

remoting/host/remoting_me2me_host.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.
 //
 // This file implements a standalone host process for Me2Me.
 
 #include <string>
 
 #include "base/at_exit.h"
 #include "base/bind.h"
@@ skipping 129 matching lines @@
 const char kWindowIdSwitchName[] = "window-id";
 
 // Maximum time to wait for clean shutdown to occur, before forcing termination
 // of the process.
 const int kShutdownTimeoutSeconds = 15;
 
 // Maximum time to wait for reporting host-offline-reason to the service,
 // before continuing normal process shutdown.
 const int kHostOfflineReasonTimeoutSeconds = 10;
 
+// Host offline reasons not associated with shutting down the host process
+// and therefore not expressible through HostExitCodes enum.
+const char kHostOfflineBecauseOfRestarting[] = "RESTARTING";
+const char kHostOfflineBecauseOfPolicyReadError[] = "POLICY_READ_ERROR";
+
 }  // namespace
 
 namespace remoting {
 
 class HostProcess : public ConfigWatcher::Delegate,
                     public HostSignalingManager::Listener,
                     public HostChangeNotificationListener::Listener,
                     public IPC::Listener,
                     public base::RefCountedThreadSafe<HostProcess> {
  public:
@@ skipping 46 matching lines @@
     //   STARTED->STOPPING
     //   STOPPING_TO_RESTART->STARTED
     //   STOPPING_TO_RESTART->STOPPING
     //   STOPPING->STOPPED
     //   STOPPED->STARTED
     //
     // |host_| must be nullptr in INITIALIZING and STOPPED states and not
     // nullptr in all other states.
   };
 
+  enum PolicyState {
+    // Cannot start the host, because a valid policy has not been read yet.
+    POLICY_INITIALIZING,
+
+    // Policy was loaded successfully.
+    POLICY_LOADED,
+
+    // Policy error was detected, and we haven't yet sent out a
+    // host-offline-reason (i.e. because we haven't yet read the config).
+    POLICY_ERROR_REPORT_PENDING,
+
+    // Policy error was detected, and we have sent out a host-offline-reason.
+    POLICY_ERROR_REPORTED,
+  };
+
   friend class base::RefCountedThreadSafe<HostProcess>;
   ~HostProcess() override;
 
   void StartOnNetworkThread();
 
 #if defined(OS_POSIX)
   // Callback passed to RegisterSignalHandler() to handle SIGTERM events.
   void SigTermHandler(int signal_number);
 #endif
 
@@ skipping 12 matching lines @@
 
   // Tear down resources that run on the UI thread.
   void ShutdownOnUiThread();
 
   // Applies the host config, returning true if successful.
   bool ApplyConfig(const base::DictionaryValue& config);
 
   // Handles policy updates, by calling On*PolicyUpdate methods.
   void OnPolicyUpdate(scoped_ptr<base::DictionaryValue> policies);
   void OnPolicyError();
+  void ReportPolicyErrorAndRestartHost();
   void ApplyHostDomainPolicy();
   void ApplyUsernamePolicy();
   bool OnHostDomainPolicyUpdate(base::DictionaryValue* policies);
   bool OnUsernamePolicyUpdate(base::DictionaryValue* policies);
   bool OnNatPolicyUpdate(base::DictionaryValue* policies);
   bool OnRelayPolicyUpdate(base::DictionaryValue* policies);
   bool OnUdpPortPolicyUpdate(base::DictionaryValue* policies);
   bool OnCurtainPolicyUpdate(base::DictionaryValue* policies);
   bool OnHostTalkGadgetPrefixPolicyUpdate(base::DictionaryValue* policies);
   bool OnHostTokenUrlPolicyUpdate(base::DictionaryValue* policies);
   bool OnPairingPolicyUpdate(base::DictionaryValue* policies);
   bool OnGnubbyAuthPolicyUpdate(base::DictionaryValue* policies);
 
   scoped_ptr<HostSignalingManager> CreateHostSignalingManager();
 
   void StartHostIfReady();
   void StartHost();
 
   // Overrides for HostSignalingManager::Listener interface.
   void OnHeartbeatSuccessful() override;
   void OnUnknownHostIdError() override;
   void OnAuthFailed() override;
 
   void RestartHost();
 
   // Stops the host and shuts down the process with the specified |exit_code|.
   void ShutdownHost(HostExitCodes exit_code);
 
-  // Private helper used by ShutdownHost method to initiate sending of
-  // host-offline-reason before continuing shutdown.
-  void SendOfflineReasonAndShutdownOnNetworkThread(HostExitCodes exit_code);
-
-  void ShutdownOnNetworkThread();
+  // Starts host shut down with an optional |host_offline_reason|.
+  void ShutdownOnNetworkThread(const std::string& host_offline_reason);
+  void OnHostOfflineReasonAck(bool success);
 
 #if defined(OS_WIN)
   // Initializes the pairing registry on Windows. This should be invoked on the
   // network thread.
   void InitializePairingRegistry(
       IPC::PlatformFileForTransit privileged_key,
       IPC::PlatformFileForTransit unprivileged_key);
 #endif  // defined(OS_WIN)
 
   // Crashes the process in response to a daemon's request. The daemon passes
@@ skipping 27 matching lines @@
   scoped_refptr<RsaKeyPair> key_pair_;
   std::string oauth_refresh_token_;
   std::string serialized_config_;
   std::string host_owner_;
   std::string host_owner_email_;
   bool use_service_account_;
   bool enable_vp9_;
   int64_t frame_recorder_buffer_size_;
 
   scoped_ptr<PolicyWatcher> policy_watcher_;
-  bool policies_loaded_;
+  PolicyState policy_state_;
   std::string host_domain_;
   bool host_username_match_required_;
   bool allow_nat_traversal_;
   bool allow_relay_;
   uint16 min_udp_port_;
   uint16 max_udp_port_;
   std::string talkgadget_prefix_;
   bool allow_pairing_;
 
   bool curtain_required_;
@@ skipping 35 matching lines @@
 };
 
 HostProcess::HostProcess(scoped_ptr<ChromotingHostContext> context,
                          int* exit_code_out,
                          ShutdownWatchdog* shutdown_watchdog)
     : context_(context.Pass()),
       state_(HOST_INITIALIZING),
       use_service_account_(false),
       enable_vp9_(false),
       frame_recorder_buffer_size_(0),
-      policies_loaded_(false),
+      policy_state_(POLICY_INITIALIZING),
       host_username_match_required_(false),
       allow_nat_traversal_(true),
       allow_relay_(true),
       min_udp_port_(0),
       max_udp_port_(0),
       allow_pairing_(true),
       curtain_required_(false),
       enable_gnubby_auth_(false),
       enable_window_capture_(false),
       window_id_(0),
@@ skipping 149 matching lines @@
     ShutdownHost(kInvalidHostConfigurationExitCode);
     return;
   }
 
   if (!ApplyConfig(*config)) {
     LOG(ERROR) << "Failed to apply the configuration.";
     ShutdownHost(kInvalidHostConfigurationExitCode);
     return;
   }
 
-  if (state_ == HOST_INITIALIZING) {
+  if (state_ == HOST_INITIALIZING || state_ == HOST_STOPPING_TO_RESTART) {
     StartHostIfReady();
   } else if (state_ == HOST_STARTED) {
-    DCHECK(policies_loaded_);
-
     // Reapply policies that could be affected by a new config.
+    DCHECK(policy_state_ == POLICY_LOADED);
     ApplyHostDomainPolicy();
     ApplyUsernamePolicy();
 
     // 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();
   }
 }
 
@@ skipping 404 matching lines @@
   // Note: UsernamePolicyUpdate must run after OnCurtainPolicyUpdate.
   restart_required |= OnUsernamePolicyUpdate(policies.get());
   restart_required |= OnNatPolicyUpdate(policies.get());
   restart_required |= OnRelayPolicyUpdate(policies.get());
   restart_required |= OnUdpPortPolicyUpdate(policies.get());
   restart_required |= OnHostTalkGadgetPrefixPolicyUpdate(policies.get());
   restart_required |= OnHostTokenUrlPolicyUpdate(policies.get());
   restart_required |= OnPairingPolicyUpdate(policies.get());
   restart_required |= OnGnubbyAuthPolicyUpdate(policies.get());
 
-  policies_loaded_ = true;
+  policy_state_ = POLICY_LOADED;
 
-  if (state_ == HOST_INITIALIZING) {
+  if (state_ == HOST_INITIALIZING || state_ == HOST_STOPPING_TO_RESTART) {
     StartHostIfReady();
   } else if (state_ == HOST_STARTED) {
     if (restart_required)
       RestartHost();
   }
 }
 
 void HostProcess::OnPolicyError() {
   if (!context_->network_task_runner()->BelongsToCurrentThread()) {
     context_->network_task_runner()->PostTask(
         FROM_HERE, base::Bind(&HostProcess::OnPolicyError, this));
     return;
   }
 
-  ShutdownHost(kInvalidHostConfigurationExitCode);
+  if (policy_state_ != POLICY_ERROR_REPORTED) {
+    policy_state_ = POLICY_ERROR_REPORT_PENDING;
+    if (state_ == HOST_INITIALIZING) {
+      StartHostIfReady();
+    } else if (state_ == HOST_STARTED) {
+      ReportPolicyErrorAndRestartHost();
+    }
+  }
+}
+
+void HostProcess::ReportPolicyErrorAndRestartHost() {
+  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
+  DCHECK_EQ(policy_state_, POLICY_ERROR_REPORT_PENDING);
+
+  LOG(INFO) << "Restarting the host due to policy errors.";
+
+  policy_state_ = POLICY_ERROR_REPORTED;
+  state_ = HOST_STOPPING_TO_RESTART;
+
+  ShutdownOnNetworkThread(kHostOfflineBecauseOfPolicyReadError);
 }
 
 void HostProcess::ApplyHostDomainPolicy() {
   if (state_ != HOST_STARTED)
     return;
 
   HOST_LOG << "Policy sets host domain: " << host_domain_;
 
   if (!host_domain_.empty()) {
     // If the user does not have a Google email, their client JID will not be
@@ skipping 281 matching lines @@
 }
 
 scoped_ptr<HostSignalingManager> HostProcess::CreateHostSignalingManager() {
   DCHECK(!host_id_.empty());  // |ApplyConfig| should already have been run.
 
   scoped_ptr<OAuthTokenGetter::OAuthCredentials> oauth_credentials(
       new OAuthTokenGetter::OAuthCredentials(xmpp_server_config_.username,
                                              oauth_refresh_token_,
                                              use_service_account_));
 
-  return HostSignalingManager::Create(this, context_->network_task_runner(),
-                                      context_->url_request_context_getter(),
-                                      xmpp_server_config_, talkgadget_prefix_,
-                                      host_id_, key_pair_, directory_bot_jid_,
-                                      oauth_credentials.Pass());
+  return HostSignalingManager::Create(
+      this, context_->url_request_context_getter(), xmpp_server_config_,
+      talkgadget_prefix_, host_id_, key_pair_, directory_bot_jid_,
+      oauth_credentials.Pass());
 }
 
 void HostProcess::StartHostIfReady() {
   DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
-  DCHECK_EQ(state_, HOST_INITIALIZING);
+  DCHECK((state_ == HOST_INITIALIZING) || (state_ == HOST_STOPPING_TO_RESTART));
 
   // Start the host if both the config and the policies are loaded.
-  if (!serialized_config_.empty() && policies_loaded_)
-    StartHost();
+  if (!serialized_config_.empty()) {
+    if (policy_state_ == POLICY_LOADED) {
+      StartHost();
+    } else if (policy_state_ == POLICY_ERROR_REPORT_PENDING) {
+      ReportPolicyErrorAndRestartHost();
+    }
+  }
 }
 
 void HostProcess::StartHost() {
   DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
   DCHECK(!host_);
   DCHECK(!host_signaling_manager_);
 
   DCHECK(state_ == HOST_INITIALIZING || state_ == HOST_STOPPING_TO_RESTART ||
          state_ == HOST_STOPPED)
       << "state_ = " << state_;
@@ skipping 80 matching lines @@
 
 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::SendOfflineReasonAndShutdownOnNetworkThread(
-    HostExitCodes exit_code) {
-  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
-  DCHECK(host_signaling_manager_);
-  host_signaling_manager_.release()->SendHostOfflineReasonAndDelete(
-      ExitCodeToString(exit_code),
-      base::TimeDelta::FromSeconds(kHostOfflineReasonTimeoutSeconds));
-  ShutdownOnNetworkThread();
+  ShutdownOnNetworkThread(kHostOfflineBecauseOfRestarting);
 }
 
 void HostProcess::ShutdownHost(HostExitCodes exit_code) {
   DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
 
   *exit_code_out_ = exit_code;
+  std::string host_offline_reason = ExitCodeToString(exit_code);
 
   switch (state_) {
     case HOST_INITIALIZING:
-      state_ = HOST_STOPPING;
-      DCHECK(!host_signaling_manager_);
-      host_signaling_manager_ = CreateHostSignalingManager();
-      SendOfflineReasonAndShutdownOnNetworkThread(exit_code);
-      break;
-
     case HOST_STARTED:
       state_ = HOST_STOPPING;
-      SendOfflineReasonAndShutdownOnNetworkThread(exit_code);
+      ShutdownOnNetworkThread(host_offline_reason);
       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;
   }
 }
 
-void HostProcess::ShutdownOnNetworkThread() {
+void HostProcess::ShutdownOnNetworkThread(
+    const std::string& host_offline_reason) {
   DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
 
+  // Shut down most host subsystems ...
   host_.reset();
   host_event_logger_.reset();
   host_status_logger_.reset();
-  host_signaling_manager_.reset();
   host_change_notification_listener_.reset();
 
+  // ... but before shutting down |host_signaling_manager_|, check if we still
+  // need it for sending a |host_offline_reason| first.
+  if (!host_offline_reason.empty() && serialized_config_.empty()) {

[Wez, 2015/02/12 21:07:07]

This would read more clearly as:

if (!host_offline_reason.empty()) {
  if (!serialized_config_.empty()) {
    ... send offline reason and return ...
  } else {
    .. error message ...
  }
}

... shut down ALL da things ...

[Łukasz Anforowicz, 2015/02/12 22:51:13]

Done.

+    HOST_LOG << "SendHostOfflineReason( " << host_offline_reason << ") "
+             << "not possible without a config...";
+  } else if (!host_offline_reason.empty()) {
+    if (!host_signaling_manager_) {
+      host_signaling_manager_ = CreateHostSignalingManager();
+    }
+
+    host_signaling_manager_->SendHostOfflineReason(
+        host_offline_reason,
+        base::TimeDelta::FromSeconds(kHostOfflineReasonTimeoutSeconds),
+        base::Bind(&HostProcess::OnHostOfflineReasonAck,
+                   base::Unretained(this)));
+    return;  // Shutdown will resume after OnHostOfflineReasonAck.
+  }
+  host_signaling_manager_.reset();
+
   if (state_ == HOST_STOPPING_TO_RESTART) {
-    StartHost();
+    StartHostIfReady();
   } else if (state_ == HOST_STOPPING) {
     state_ = HOST_STOPPED;
 
     shutdown_watchdog_->SetExitCode(*exit_code_out_);
     shutdown_watchdog_->Arm();
 
     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::OnHostOfflineReasonAck(bool success) {
+  DCHECK(context_->network_task_runner()->BelongsToCurrentThread());
+
+  if (success) {
+    HOST_LOG << "SendHostOfflineReason: succeeded";
+  } else {
+    HOST_LOG << "SendHostOfflineReason: timed out";
+  }
+
+  ShutdownOnNetworkThread(std::string());

[Wez, 2015/02/12 21:07:07]

Now that I see this written out, it seems less clear than splitting
ShutdownOnNetworkThread() and ShutdownOnNetworkThreadWithReason(). WDYT?

[Łukasz Anforowicz, 2015/02/12 22:51:13]

I think I like it better this way.  

If we have a pair of functions, then one of these functions (ContinueShutdown)
is not really callable from anywhere other than Shutdown + OnAck.  If we want to
make ContinueShutdown callable separately (and name it
ShutdownOnNetworkThread[WithoutReason]) then it has to duplicate the code that
resets the 4 members (host, host_event_logger, ...) or we have to move this code
to yet another method.

OTOH, there are 2 things that bother me about the current approach:
1) a bit complicated logic (3 levels of nesting! :-) for figuring out when to
call SendHostOfflineReason (i.e. have to check host_offline_reason.empty(),
host_signaling_manager_ not null, serializer_config_.empty).
2) the whole ShutdownOnNetworkThread got a bit long

But I think this is still ok.  ShutdownOnNetworkThread is not that difficult to
follow (and I think surely not more difficult than having to understand how 2 or
3 methods work together / which one of them can be invoked standalone vs only
from the other one).

[Łukasz Anforowicz, 2015/02/13 20:41:00]

Actually, when addressing Sergey's feedback (and trying to clean-up state
transitions in general) I went ahead with 2 functions in patchset #4.  I think
things are in a better shape right now (better than baseline + better than the
1st two patchsets).

+}
+
 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.
@@ skipping 45 matching lines @@
       base::TimeDelta::FromSeconds(kShutdownTimeoutSeconds));
   new HostProcess(context.Pass(), &exit_code, &shutdown_watchdog);
 
   // Run the main (also UI) message loop until the host no longer needs it.
   message_loop.Run();
 
   return exit_code;
 }
 
 }  // namespace remoting