components/proximity_auth/messenger_impl.cc - chromium/src.git - Git at Google

 // 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 "components/proximity_auth/messenger_impl.h"

 #include <utility>

 #include "base/base64url.h"
 #include "base/bind.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/values.h"
 #include "components/cryptauth/connection.h"
 #include "components/cryptauth/secure_context.h"
 #include "components/cryptauth/wire_message.h"
 #include "components/proximity_auth/logging/logging.h"
 #include "components/proximity_auth/messenger_observer.h"
 #include "components/proximity_auth/remote_status_update.h"

 namespace proximity_auth {
 namespace {

 // The key names of JSON fields for messages sent between the devices.
 const char kTypeKey[] = "type";
 const char kNameKey[] = "name";
 const char kDataKey[] = "data";
 const char kEncryptedDataKey[] = "encrypted_data";

 // The types of messages that can be sent and received.
 const char kMessageTypeLocalEvent[] = "event";
 const char kMessageTypeRemoteStatusUpdate[] = "status_update";
 const char kMessageTypeDecryptRequest[] = "decrypt_request";
 const char kMessageTypeDecryptResponse[] = "decrypt_response";
 const char kMessageTypeUnlockRequest[] = "unlock_request";
 const char kMessageTypeUnlockResponse[] = "unlock_response";

 // The name for an unlock event originating from the local device.
 const char kUnlockEventName[] = "easy_unlock";

 // Messages sent and received from the iOS app when polling for it's lock screen
 // status.
 // TODO(tengs): Unify the iOS status update protocol with the existing Android
 // protocol, so we don't have this special case.
 const char kPollScreenState[] = "PollScreenState";
 const char kScreenUnlocked[] = "Screen Unlocked";
 const char kScreenLocked[] = "Screen Locked";
 const int kIOSPollingIntervalSeconds = 5;

 const char kEasyUnlockFeatureName[] = "easy_unlock";

 // Serializes the |value| to a JSON string and returns the result.
 std::string SerializeValueToJson(const base::Value& value) {
   std::string json;
   base::JSONWriter::Write(value, &json);
   return json;
 }

 // Returns the message type represented by the |message|. This is a convenience
 // wrapper that should only be called when the |message| is known to specify its
 // message type, i.e. this should not be called for untrusted input.
 std::string GetMessageType(const base::DictionaryValue& message) {
   std::string type;
   message.GetString(kTypeKey, &type);
   return type;
 }

 }  // namespace

 MessengerImpl::MessengerImpl(
     std::unique_ptr<cryptauth::Connection> connection,
     std::unique_ptr<cryptauth::SecureContext> secure_context)
     : connection_(std::move(connection)),
       secure_context_(std::move(secure_context)),
       weak_ptr_factory_(this) {
   DCHECK(connection_->IsConnected());
   connection_->AddObserver(this);

   // TODO(tengs): We need CryptAuth to report if the phone runs iOS or Android,
   // rather than relying on this heuristic.
   if (connection_->remote_device().bluetooth_address.empty())
     PollScreenStateForIOS();
 }

 MessengerImpl::~MessengerImpl() {
   if (connection_)
     connection_->RemoveObserver(this);
 }

 void MessengerImpl::AddObserver(MessengerObserver* observer) {
   observers_.AddObserver(observer);
 }

 void MessengerImpl::RemoveObserver(MessengerObserver* observer) {
   observers_.RemoveObserver(observer);
 }

 bool MessengerImpl::SupportsSignIn() const {
   // TODO(tengs): Support sign-in for Bluetooth LE protocol.
   return (secure_context_->GetProtocolVersion() ==
           cryptauth::SecureContext::PROTOCOL_VERSION_THREE_ONE) &&
          !connection_->remote_device().bluetooth_address.empty();
 }

 void MessengerImpl::DispatchUnlockEvent() {
   base::DictionaryValue message;
   message.SetString(kTypeKey, kMessageTypeLocalEvent);
   message.SetString(kNameKey, kUnlockEventName);
   queued_messages_.push_back(PendingMessage(message));
   ProcessMessageQueue();
 }

 void MessengerImpl::RequestDecryption(const std::string& challenge) {
   if (!SupportsSignIn()) {
     PA_LOG(WARNING) << "Dropping decryption request, as remote device "
                     << "does not support protocol v3.1.";
     for (auto& observer : observers_)
       observer.OnDecryptResponse(std::string());
     return;
   }

   const std::string encrypted_message_data = challenge;
   std::string encrypted_message_data_base64;
   base::Base64UrlEncode(encrypted_message_data,
                         base::Base64UrlEncodePolicy::INCLUDE_PADDING,
                         &encrypted_message_data_base64);

   base::DictionaryValue message;
   message.SetString(kTypeKey, kMessageTypeDecryptRequest);
   message.SetString(kEncryptedDataKey, encrypted_message_data_base64);
   queued_messages_.push_back(PendingMessage(message));
   ProcessMessageQueue();
 }

 void MessengerImpl::RequestUnlock() {
   if (!SupportsSignIn()) {
     PA_LOG(WARNING) << "Dropping unlock request, as remote device does not "
                     << "support protocol v3.1.";
     for (auto& observer : observers_)
       observer.OnUnlockResponse(false);
     return;
   }

   base::DictionaryValue message;
   message.SetString(kTypeKey, kMessageTypeUnlockRequest);
   queued_messages_.push_back(PendingMessage(message));
   ProcessMessageQueue();
 }

 cryptauth::SecureContext* MessengerImpl::GetSecureContext() const {
   return secure_context_.get();
 }

 MessengerImpl::PendingMessage::PendingMessage() {}

 MessengerImpl::PendingMessage::PendingMessage(
     const base::DictionaryValue& message)
     : json_message(SerializeValueToJson(message)),
       type(GetMessageType(message)) {}

 MessengerImpl::PendingMessage::PendingMessage(const std::string& message)
     : json_message(message), type(std::string()) {}

 MessengerImpl::PendingMessage::~PendingMessage() {}

 void MessengerImpl::ProcessMessageQueue() {
   if (pending_message_ || queued_messages_.empty() ||
       connection_->is_sending_message())
     return;

   pending_message_.reset(new PendingMessage(queued_messages_.front()));
   queued_messages_.pop_front();

   secure_context_->Encode(pending_message_->json_message,
                           base::Bind(&MessengerImpl::OnMessageEncoded,
                                      weak_ptr_factory_.GetWeakPtr()));
 }

 void MessengerImpl::OnMessageEncoded(const std::string& encoded_message) {
   connection_->SendMessage(base::MakeUnique<cryptauth::WireMessage>(
       encoded_message, std::string(kEasyUnlockFeatureName)));
 }

 void MessengerImpl::OnMessageDecoded(const std::string& decoded_message) {
   // TODO(tengs): Unify the iOS status update protocol with the existing Android
   // protocol, so we don't have this special case.
   if (decoded_message == kScreenUnlocked || decoded_message == kScreenLocked) {
     RemoteStatusUpdate update;
     update.user_presence =
         (decoded_message == kScreenUnlocked ? USER_PRESENT : USER_ABSENT);
     update.secure_screen_lock_state = SECURE_SCREEN_LOCK_ENABLED;
     update.trust_agent_state = TRUST_AGENT_ENABLED;
     for (auto& observer : observers_)
       observer.OnRemoteStatusUpdate(update);
     pending_message_.reset();
     ProcessMessageQueue();
     return;
   }

   // The decoded message should be a JSON string.
   std::unique_ptr<base::Value> message_value =
       base::JSONReader::Read(decoded_message);
   if (!message_value || !message_value->IsType(base::Value::Type::DICTIONARY)) {
     PA_LOG(ERROR) << "Unable to parse message as JSON:\n" << decoded_message;
     return;
   }

   base::DictionaryValue* message;
   bool success = message_value->GetAsDictionary(&message);
   DCHECK(success);

   std::string type;
   if (!message->GetString(kTypeKey, &type)) {
     PA_LOG(ERROR) << "Missing '" << kTypeKey << "' key in message:\n "
                   << decoded_message;
     return;
   }

   // Remote status updates can be received out of the blue.
   if (type == kMessageTypeRemoteStatusUpdate) {
     HandleRemoteStatusUpdateMessage(*message);
     return;
   }

   // All other messages should only be received in response to a message that
   // the messenger sent.
   if (!pending_message_) {
     PA_LOG(WARNING) << "Unexpected message received:\n" << decoded_message;
     return;
   }

   std::string expected_type;
   if (pending_message_->type == kMessageTypeDecryptRequest)
     expected_type = kMessageTypeDecryptResponse;
   else if (pending_message_->type == kMessageTypeUnlockRequest)
     expected_type = kMessageTypeUnlockResponse;
   else
     NOTREACHED();  // There are no other message types that expect a response.

   if (type != expected_type) {
     PA_LOG(ERROR) << "Unexpected '" << kTypeKey << "' value in message. "
                   << "Expected '" << expected_type << "' but received '" << type
                   << "'.";
     return;
   }

   if (type == kMessageTypeDecryptResponse)
     HandleDecryptResponseMessage(*message);
   else if (type == kMessageTypeUnlockResponse)
     HandleUnlockResponseMessage(*message);
   else
     NOTREACHED();  // There are no other message types that expect a response.

   pending_message_.reset();
   ProcessMessageQueue();
 }

 void MessengerImpl::HandleRemoteStatusUpdateMessage(
     const base::DictionaryValue& message) {
   std::unique_ptr<RemoteStatusUpdate> status_update =
       RemoteStatusUpdate::Deserialize(message);
   if (!status_update) {
     PA_LOG(ERROR) << "Unexpected remote status update: " << message;
     return;
   }

   for (auto& observer : observers_)
     observer.OnRemoteStatusUpdate(*status_update);
 }

 void MessengerImpl::HandleDecryptResponseMessage(
     const base::DictionaryValue& message) {
   std::string base64_data;
   std::string decrypted_data;
   if (!message.GetString(kDataKey, &base64_data) || base64_data.empty()) {
     PA_LOG(ERROR) << "Decrypt response missing '" << kDataKey << "' value.";
   } else if (!base::Base64UrlDecode(
                  base64_data, base::Base64UrlDecodePolicy::REQUIRE_PADDING,
                  &decrypted_data)) {
     PA_LOG(ERROR) << "Unable to base64-decode decrypt response.";
   }

   for (auto& observer : observers_)
     observer.OnDecryptResponse(decrypted_data);
 }

 void MessengerImpl::HandleUnlockResponseMessage(
     const base::DictionaryValue& message) {
   for (auto& observer : observers_)
     observer.OnUnlockResponse(true);
 }

 void MessengerImpl::PollScreenStateForIOS() {
   if (!connection_->IsConnected())
     return;

   // Sends message requesting screen state.
   queued_messages_.push_back(PendingMessage(std::string(kPollScreenState)));
   ProcessMessageQueue();

   // Schedules the next message in |kPollingIntervalSeconds|.
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
       FROM_HERE, base::Bind(&MessengerImpl::PollScreenStateForIOS,
                             weak_ptr_factory_.GetWeakPtr()),
       base::TimeDelta::FromSeconds(kIOSPollingIntervalSeconds));
 }

 void MessengerImpl::OnConnectionStatusChanged(
     cryptauth::Connection* connection,
     cryptauth::Connection::Status old_status,
     cryptauth::Connection::Status new_status) {
   DCHECK_EQ(connection, connection_.get());
   if (new_status == cryptauth::Connection::DISCONNECTED) {
     PA_LOG(INFO) << "Secure channel disconnected...";
     connection_->RemoveObserver(this);
     for (auto& observer : observers_)
       observer.OnDisconnected();
     // TODO(isherman): Determine whether it's also necessary/appropriate to fire
     // this notification from the destructor.
   }
 }

 void MessengerImpl::OnMessageReceived(
     const cryptauth::Connection& connection,
     const cryptauth::WireMessage& wire_message) {
   secure_context_->Decode(wire_message.payload(),
                           base::Bind(&MessengerImpl::OnMessageDecoded,
                                      weak_ptr_factory_.GetWeakPtr()));
 }

 void MessengerImpl::OnSendCompleted(const cryptauth::Connection& connection,
                                     const cryptauth::WireMessage& wire_message,
                                     bool success) {
   if (!pending_message_) {
     PA_LOG(ERROR) << "Unexpected message sent.";
     return;
   }

   // In the common case, wait for a response from the remote device.
   // Don't wait if the message could not be sent, as there won't ever be a
   // response in that case. Likewise, don't wait for a response to local
   // event messages, as there is no response for such messages.
   if (success && pending_message_->type != kMessageTypeLocalEvent)
     return;

   // Notify observer of failure if sending the message fails.
   // For local events, we don't expect a response, so on success, we
   // notify observers right away.
   if (pending_message_->type == kMessageTypeDecryptRequest) {
     for (auto& observer : observers_)
       observer.OnDecryptResponse(std::string());
   } else if (pending_message_->type == kMessageTypeUnlockRequest) {
     for (auto& observer : observers_)
       observer.OnUnlockResponse(false);
   } else if (pending_message_->type == kMessageTypeLocalEvent) {
     for (auto& observer : observers_)
       observer.OnUnlockEventSent(success);
   } else {
     PA_LOG(ERROR) << "Message of unknown type '" << pending_message_->type
                   << "' sent.";
   }

   pending_message_.reset();
   ProcessMessageQueue();
 }

 }  // namespace proximity_auth
	// 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 "components/proximity_auth/messenger_impl.h"

	#include <utility>

	#include "base/base64url.h"
	#include "base/bind.h"
	#include "base/json/json_reader.h"
	#include "base/json/json_writer.h"
	#include "base/location.h"
	#include "base/memory/ptr_util.h"
	#include "base/threading/thread_task_runner_handle.h"
	#include "base/values.h"
	#include "components/cryptauth/connection.h"
	#include "components/cryptauth/secure_context.h"
	#include "components/cryptauth/wire_message.h"
	#include "components/proximity_auth/logging/logging.h"
	#include "components/proximity_auth/messenger_observer.h"
	#include "components/proximity_auth/remote_status_update.h"

	namespace proximity_auth {
	namespace {

	// The key names of JSON fields for messages sent between the devices.
	const char kTypeKey[] = "type";
	const char kNameKey[] = "name";
	const char kDataKey[] = "data";
	const char kEncryptedDataKey[] = "encrypted_data";

	// The types of messages that can be sent and received.
	const char kMessageTypeLocalEvent[] = "event";
	const char kMessageTypeRemoteStatusUpdate[] = "status_update";
	const char kMessageTypeDecryptRequest[] = "decrypt_request";
	const char kMessageTypeDecryptResponse[] = "decrypt_response";
	const char kMessageTypeUnlockRequest[] = "unlock_request";
	const char kMessageTypeUnlockResponse[] = "unlock_response";

	// The name for an unlock event originating from the local device.
	const char kUnlockEventName[] = "easy_unlock";

	// Messages sent and received from the iOS app when polling for it's lock screen
	// status.
	// TODO(tengs): Unify the iOS status update protocol with the existing Android
	// protocol, so we don't have this special case.
	const char kPollScreenState[] = "PollScreenState";
	const char kScreenUnlocked[] = "Screen Unlocked";
	const char kScreenLocked[] = "Screen Locked";
	const int kIOSPollingIntervalSeconds = 5;

	const char kEasyUnlockFeatureName[] = "easy_unlock";

	// Serializes the \|value\| to a JSON string and returns the result.
	std::string SerializeValueToJson(const base::Value& value) {
	std::string json;
	base::JSONWriter::Write(value, &json);
	return json;
	}

	// Returns the message type represented by the \|message\|. This is a convenience
	// wrapper that should only be called when the \|message\| is known to specify its
	// message type, i.e. this should not be called for untrusted input.
	std::string GetMessageType(const base::DictionaryValue& message) {
	std::string type;
	message.GetString(kTypeKey, &type);
	return type;
	}

	} // namespace

	MessengerImpl::MessengerImpl(
	std::unique_ptr<cryptauth::Connection> connection,
	std::unique_ptr<cryptauth::SecureContext> secure_context)
	: connection_(std::move(connection)),
	secure_context_(std::move(secure_context)),
	weak_ptr_factory_(this) {
	DCHECK(connection_->IsConnected());
	connection_->AddObserver(this);

	// TODO(tengs): We need CryptAuth to report if the phone runs iOS or Android,
	// rather than relying on this heuristic.
	if (connection_->remote_device().bluetooth_address.empty())
	PollScreenStateForIOS();
	}

	MessengerImpl::~MessengerImpl() {
	if (connection_)
	connection_->RemoveObserver(this);
	}

	void MessengerImpl::AddObserver(MessengerObserver* observer) {
	observers_.AddObserver(observer);
	}

	void MessengerImpl::RemoveObserver(MessengerObserver* observer) {
	observers_.RemoveObserver(observer);
	}

	bool MessengerImpl::SupportsSignIn() const {
	// TODO(tengs): Support sign-in for Bluetooth LE protocol.
	return (secure_context_->GetProtocolVersion() ==
	cryptauth::SecureContext::PROTOCOL_VERSION_THREE_ONE) &&
	!connection_->remote_device().bluetooth_address.empty();
	}

	void MessengerImpl::DispatchUnlockEvent() {
	base::DictionaryValue message;
	message.SetString(kTypeKey, kMessageTypeLocalEvent);
	message.SetString(kNameKey, kUnlockEventName);
	queued_messages_.push_back(PendingMessage(message));
	ProcessMessageQueue();
	}

	void MessengerImpl::RequestDecryption(const std::string& challenge) {
	if (!SupportsSignIn()) {
	PA_LOG(WARNING) << "Dropping decryption request, as remote device "
	<< "does not support protocol v3.1.";
	for (auto& observer : observers_)
	observer.OnDecryptResponse(std::string());
	return;
	}

	const std::string encrypted_message_data = challenge;
	std::string encrypted_message_data_base64;
	base::Base64UrlEncode(encrypted_message_data,
	base::Base64UrlEncodePolicy::INCLUDE_PADDING,
	&encrypted_message_data_base64);

	base::DictionaryValue message;
	message.SetString(kTypeKey, kMessageTypeDecryptRequest);
	message.SetString(kEncryptedDataKey, encrypted_message_data_base64);
	queued_messages_.push_back(PendingMessage(message));
	ProcessMessageQueue();
	}

	void MessengerImpl::RequestUnlock() {
	if (!SupportsSignIn()) {
	PA_LOG(WARNING) << "Dropping unlock request, as remote device does not "
	<< "support protocol v3.1.";
	for (auto& observer : observers_)
	observer.OnUnlockResponse(false);
	return;
	}

	base::DictionaryValue message;
	message.SetString(kTypeKey, kMessageTypeUnlockRequest);
	queued_messages_.push_back(PendingMessage(message));
	ProcessMessageQueue();
	}

	cryptauth::SecureContext* MessengerImpl::GetSecureContext() const {
	return secure_context_.get();
	}

	MessengerImpl::PendingMessage::PendingMessage() {}

	MessengerImpl::PendingMessage::PendingMessage(
	const base::DictionaryValue& message)
	: json_message(SerializeValueToJson(message)),
	type(GetMessageType(message)) {}

	MessengerImpl::PendingMessage::PendingMessage(const std::string& message)
	: json_message(message), type(std::string()) {}

	MessengerImpl::PendingMessage::~PendingMessage() {}

	void MessengerImpl::ProcessMessageQueue() {
	if (pending_message_ \|\| queued_messages_.empty() \|\|
	connection_->is_sending_message())
	return;

	pending_message_.reset(new PendingMessage(queued_messages_.front()));
	queued_messages_.pop_front();

	secure_context_->Encode(pending_message_->json_message,
	base::Bind(&MessengerImpl::OnMessageEncoded,
	weak_ptr_factory_.GetWeakPtr()));
	}

	void MessengerImpl::OnMessageEncoded(const std::string& encoded_message) {
	connection_->SendMessage(base::MakeUnique<cryptauth::WireMessage>(
	encoded_message, std::string(kEasyUnlockFeatureName)));
	}

	void MessengerImpl::OnMessageDecoded(const std::string& decoded_message) {
	// TODO(tengs): Unify the iOS status update protocol with the existing Android
	// protocol, so we don't have this special case.
	if (decoded_message == kScreenUnlocked \|\| decoded_message == kScreenLocked) {
	RemoteStatusUpdate update;
	update.user_presence =
	(decoded_message == kScreenUnlocked ? USER_PRESENT : USER_ABSENT);
	update.secure_screen_lock_state = SECURE_SCREEN_LOCK_ENABLED;
	update.trust_agent_state = TRUST_AGENT_ENABLED;
	for (auto& observer : observers_)
	observer.OnRemoteStatusUpdate(update);
	pending_message_.reset();
	ProcessMessageQueue();
	return;
	}

	// The decoded message should be a JSON string.
	std::unique_ptr<base::Value> message_value =
	base::JSONReader::Read(decoded_message);
	if (!message_value \|\| !message_value->IsType(base::Value::Type::DICTIONARY)) {
	PA_LOG(ERROR) << "Unable to parse message as JSON:\n" << decoded_message;
	return;
	}

	base::DictionaryValue* message;
	bool success = message_value->GetAsDictionary(&message);
	DCHECK(success);

	std::string type;
	if (!message->GetString(kTypeKey, &type)) {
	PA_LOG(ERROR) << "Missing '" << kTypeKey << "' key in message:\n "
	<< decoded_message;
	return;
	}

	// Remote status updates can be received out of the blue.
	if (type == kMessageTypeRemoteStatusUpdate) {
	HandleRemoteStatusUpdateMessage(*message);
	return;
	}

	// All other messages should only be received in response to a message that
	// the messenger sent.
	if (!pending_message_) {
	PA_LOG(WARNING) << "Unexpected message received:\n" << decoded_message;
	return;
	}

	std::string expected_type;
	if (pending_message_->type == kMessageTypeDecryptRequest)
	expected_type = kMessageTypeDecryptResponse;
	else if (pending_message_->type == kMessageTypeUnlockRequest)
	expected_type = kMessageTypeUnlockResponse;
	else
	NOTREACHED(); // There are no other message types that expect a response.

	if (type != expected_type) {
	PA_LOG(ERROR) << "Unexpected '" << kTypeKey << "' value in message. "
	<< "Expected '" << expected_type << "' but received '" << type
	<< "'.";
	return;
	}

	if (type == kMessageTypeDecryptResponse)
	HandleDecryptResponseMessage(*message);
	else if (type == kMessageTypeUnlockResponse)
	HandleUnlockResponseMessage(*message);
	else
	NOTREACHED(); // There are no other message types that expect a response.

	pending_message_.reset();
	ProcessMessageQueue();
	}

	void MessengerImpl::HandleRemoteStatusUpdateMessage(
	const base::DictionaryValue& message) {
	std::unique_ptr<RemoteStatusUpdate> status_update =
	RemoteStatusUpdate::Deserialize(message);
	if (!status_update) {
	PA_LOG(ERROR) << "Unexpected remote status update: " << message;
	return;
	}

	for (auto& observer : observers_)
	observer.OnRemoteStatusUpdate(*status_update);
	}

	void MessengerImpl::HandleDecryptResponseMessage(
	const base::DictionaryValue& message) {
	std::string base64_data;
	std::string decrypted_data;
	if (!message.GetString(kDataKey, &base64_data) \|\| base64_data.empty()) {
	PA_LOG(ERROR) << "Decrypt response missing '" << kDataKey << "' value.";
	} else if (!base::Base64UrlDecode(
	base64_data, base::Base64UrlDecodePolicy::REQUIRE_PADDING,
	&decrypted_data)) {
	PA_LOG(ERROR) << "Unable to base64-decode decrypt response.";
	}

	for (auto& observer : observers_)
	observer.OnDecryptResponse(decrypted_data);
	}

	void MessengerImpl::HandleUnlockResponseMessage(
	const base::DictionaryValue& message) {
	for (auto& observer : observers_)
	observer.OnUnlockResponse(true);
	}

	void MessengerImpl::PollScreenStateForIOS() {
	if (!connection_->IsConnected())
	return;

	// Sends message requesting screen state.
	queued_messages_.push_back(PendingMessage(std::string(kPollScreenState)));
	ProcessMessageQueue();

	// Schedules the next message in \|kPollingIntervalSeconds\|.
	base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
	FROM_HERE, base::Bind(&MessengerImpl::PollScreenStateForIOS,
	weak_ptr_factory_.GetWeakPtr()),
	base::TimeDelta::FromSeconds(kIOSPollingIntervalSeconds));
	}

	void MessengerImpl::OnConnectionStatusChanged(
	cryptauth::Connection* connection,
	cryptauth::Connection::Status old_status,
	cryptauth::Connection::Status new_status) {
	DCHECK_EQ(connection, connection_.get());
	if (new_status == cryptauth::Connection::DISCONNECTED) {
	PA_LOG(INFO) << "Secure channel disconnected...";
	connection_->RemoveObserver(this);
	for (auto& observer : observers_)
	observer.OnDisconnected();
	// TODO(isherman): Determine whether it's also necessary/appropriate to fire
	// this notification from the destructor.
	}
	}

	void MessengerImpl::OnMessageReceived(
	const cryptauth::Connection& connection,
	const cryptauth::WireMessage& wire_message) {
	secure_context_->Decode(wire_message.payload(),
	base::Bind(&MessengerImpl::OnMessageDecoded,
	weak_ptr_factory_.GetWeakPtr()));
	}

	void MessengerImpl::OnSendCompleted(const cryptauth::Connection& connection,
	const cryptauth::WireMessage& wire_message,
	bool success) {
	if (!pending_message_) {
	PA_LOG(ERROR) << "Unexpected message sent.";
	return;
	}

	// In the common case, wait for a response from the remote device.
	// Don't wait if the message could not be sent, as there won't ever be a
	// response in that case. Likewise, don't wait for a response to local
	// event messages, as there is no response for such messages.
	if (success && pending_message_->type != kMessageTypeLocalEvent)
	return;

	// Notify observer of failure if sending the message fails.
	// For local events, we don't expect a response, so on success, we
	// notify observers right away.
	if (pending_message_->type == kMessageTypeDecryptRequest) {
	for (auto& observer : observers_)
	observer.OnDecryptResponse(std::string());
	} else if (pending_message_->type == kMessageTypeUnlockRequest) {
	for (auto& observer : observers_)
	observer.OnUnlockResponse(false);
	} else if (pending_message_->type == kMessageTypeLocalEvent) {
	for (auto& observer : observers_)
	observer.OnUnlockEventSent(success);
	} else {
	PA_LOG(ERROR) << "Message of unknown type '" << pending_message_->type
	<< "' sent.";
	}

	pending_message_.reset();
	ProcessMessageQueue();
	}

	} // namespace proximity_auth