// Copyright 2013 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/setup/me2me_native_messaging_host.h"

#include <cstdint>
#include <memory>
#include <string>
#include <utility>

#include "base/bind.h"
#include "base/callback.h"
#include "base/command_line.h"
#include "base/json/json_reader.h"
#include "base/json/json_writer.h"
#include "base/logging.h"
#include "base/single_thread_task_runner.h"
#include "base/stl_util.h"
#include "base/strings/stringize_macros.h"
#include "base/time/time.h"
#include "base/values.h"
#include "build/build_config.h"
#include "google_apis/gaia/gaia_oauth_client.h"
#include "google_apis/google_api_keys.h"
#include "net/base/network_interfaces.h"
#include "remoting/base/auto_thread_task_runner.h"
#include "remoting/base/oauth_client.h"
#include "remoting/base/rsa_key_pair.h"
#include "remoting/host/chromoting_host_context.h"
#include "remoting/host/native_messaging/log_message_handler.h"
#include "remoting/host/pin_hash.h"
#include "remoting/protocol/pairing_registry.h"

#if defined(OS_WIN)
#include "remoting/host/win/elevated_native_messaging_host.h"
#endif  // defined(OS_WIN)

namespace {

#if defined(OS_WIN)
const int kElevatedHostTimeoutSeconds = 300;
#endif  // defined(OS_WIN)

// redirect_uri to use when authenticating service accounts (service account
// codes are obtained "out-of-band", i.e., not through an OAuth redirect).
const char* kServiceAccountRedirectUri = "oob";

// Features supported in addition to the base protocol.
const char* kSupportedFeatures[] = {
  "pairingRegistry",
  "oauthClient",
  "getRefreshTokenFromAuthCode",
};

// Helper to extract the "config" part of a message as a DictionaryValue.
// Returns nullptr on failure, and logs an error message.
std::unique_ptr<base::DictionaryValue> ConfigDictionaryFromMessage(
    std::unique_ptr<base::DictionaryValue> message) {
  std::unique_ptr<base::DictionaryValue> result;
  const base::DictionaryValue* config_dict;
  if (message->GetDictionary("config", &config_dict)) {
    result = config_dict->CreateDeepCopy();
  }
  return result;
}

}  // namespace

namespace remoting {

Me2MeNativeMessagingHost::Me2MeNativeMessagingHost(
    bool needs_elevation,
    intptr_t parent_window_handle,
    std::unique_ptr<ChromotingHostContext> host_context,
    scoped_refptr<DaemonController> daemon_controller,
    scoped_refptr<protocol::PairingRegistry> pairing_registry,
    std::unique_ptr<OAuthClient> oauth_client)
    : needs_elevation_(needs_elevation),
#if defined(OS_WIN)
      parent_window_handle_(parent_window_handle),
#endif
      host_context_(std::move(host_context)),
      daemon_controller_(daemon_controller),
      pairing_registry_(pairing_registry),
      oauth_client_(std::move(oauth_client)),
      weak_factory_(this) {
  weak_ptr_ = weak_factory_.GetWeakPtr();
}

Me2MeNativeMessagingHost::~Me2MeNativeMessagingHost() {
  DCHECK(task_runner()->BelongsToCurrentThread());
}

void Me2MeNativeMessagingHost::OnMessage(const std::string& message) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  auto response = std::make_unique<base::DictionaryValue>();
  std::unique_ptr<base::Value> message_value = base::JSONReader::Read(message);
  if (!message_value->is_dict()) {
    OnError("Received a message that's not a dictionary.");
    return;
  }

  std::unique_ptr<base::DictionaryValue> message_dict(
      static_cast<base::DictionaryValue*>(message_value.release()));

  // If the client supplies an ID, it will expect it in the response. This
  // might be a string or a number, so cope with both.
  const base::Value* id;
  if (message_dict->Get("id", &id))
    response->SetKey("id", id->Clone());

  std::string type;
  if (!message_dict->GetString("type", &type)) {
    OnError("'type' not found");
    return;
  }

  response->SetString("type", type + "Response");

  if (type == "hello") {
    ProcessHello(std::move(message_dict), std::move(response));
  } else if (type == "clearPairedClients") {
    ProcessClearPairedClients(std::move(message_dict), std::move(response));
  } else if (type == "deletePairedClient") {
    ProcessDeletePairedClient(std::move(message_dict), std::move(response));
  } else if (type == "getHostName") {
    ProcessGetHostName(std::move(message_dict), std::move(response));
  } else if (type == "getPinHash") {
    ProcessGetPinHash(std::move(message_dict), std::move(response));
  } else if (type == "generateKeyPair") {
    ProcessGenerateKeyPair(std::move(message_dict), std::move(response));
  } else if (type == "updateDaemonConfig") {
    ProcessUpdateDaemonConfig(std::move(message_dict), std::move(response));
  } else if (type == "getDaemonConfig") {
    ProcessGetDaemonConfig(std::move(message_dict), std::move(response));
  } else if (type == "getPairedClients") {
    ProcessGetPairedClients(std::move(message_dict), std::move(response));
  } else if (type == "getUsageStatsConsent") {
    ProcessGetUsageStatsConsent(std::move(message_dict), std::move(response));
  } else if (type == "startDaemon") {
    ProcessStartDaemon(std::move(message_dict), std::move(response));
  } else if (type == "stopDaemon") {
    ProcessStopDaemon(std::move(message_dict), std::move(response));
  } else if (type == "getDaemonState") {
    ProcessGetDaemonState(std::move(message_dict), std::move(response));
  } else if (type == "getHostClientId") {
    ProcessGetHostClientId(std::move(message_dict), std::move(response));
  } else if (type == "getCredentialsFromAuthCode") {
    ProcessGetCredentialsFromAuthCode(
        std::move(message_dict), std::move(response), true);
  } else if (type == "getRefreshTokenFromAuthCode") {
    ProcessGetCredentialsFromAuthCode(
        std::move(message_dict), std::move(response), false);
  } else {
    OnError("Unsupported request type: " + type);
  }
}

void Me2MeNativeMessagingHost::Start(Client* client) {
  DCHECK(task_runner()->BelongsToCurrentThread());
  client_ = client;
  log_message_handler_.reset(new LogMessageHandler(
      base::Bind(&Me2MeNativeMessagingHost::SendMessageToClient, weak_ptr_)));
}

scoped_refptr<base::SingleThreadTaskRunner>
Me2MeNativeMessagingHost::task_runner() const {
  return host_context_->ui_task_runner();
}

void Me2MeNativeMessagingHost::ProcessHello(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  response->SetString("version", STRINGIZE(VERSION));
  std::unique_ptr<base::ListValue> supported_features_list(
      new base::ListValue());
  supported_features_list->AppendStrings(std::vector<std::string>(
      kSupportedFeatures, kSupportedFeatures + base::size(kSupportedFeatures)));
  response->Set("supportedFeatures", std::move(supported_features_list));
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::ProcessClearPairedClients(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  if (needs_elevation_) {
    if (DelegateToElevatedHost(std::move(message)) != DELEGATION_SUCCESS) {
      SendBooleanResult(std::move(response), false);
    }
    return;
  }

  if (pairing_registry_.get()) {
    pairing_registry_->ClearAllPairings(
        base::Bind(&Me2MeNativeMessagingHost::SendBooleanResult, weak_ptr_,
                   base::Passed(&response)));
  } else {
    SendBooleanResult(std::move(response), false);
  }
}

void Me2MeNativeMessagingHost::ProcessDeletePairedClient(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  if (needs_elevation_) {
    if (DelegateToElevatedHost(std::move(message)) != DELEGATION_SUCCESS) {
      SendBooleanResult(std::move(response), false);
    }
    return;
  }

  std::string client_id;
  if (!message->GetString(protocol::PairingRegistry::kClientIdKey,
                          &client_id)) {
    OnError("'" + std::string(protocol::PairingRegistry::kClientIdKey) +
            "' string not found.");
    return;
  }

  if (pairing_registry_.get()) {
    pairing_registry_->DeletePairing(
        client_id, base::Bind(&Me2MeNativeMessagingHost::SendBooleanResult,
                              weak_ptr_, base::Passed(&response)));
  } else {
    SendBooleanResult(std::move(response), false);
  }
}

void Me2MeNativeMessagingHost::ProcessGetHostName(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  response->SetString("hostname", net::GetHostName());
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::ProcessGetPinHash(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  std::string host_id;
  if (!message->GetString("hostId", &host_id)) {
    std::string message_json;
    base::JSONWriter::Write(*message, &message_json);
    OnError("'hostId' not found: " + message_json);
    return;
  }
  std::string pin;
  if (!message->GetString("pin", &pin)) {
    std::string message_json;
    base::JSONWriter::Write(*message, &message_json);
    OnError("'pin' not found: " + message_json);
    return;
  }
  response->SetString("hash", MakeHostPinHash(host_id, pin));
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::ProcessGenerateKeyPair(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  scoped_refptr<RsaKeyPair> key_pair = RsaKeyPair::Generate();
  response->SetString("privateKey", key_pair->ToString());
  response->SetString("publicKey", key_pair->GetPublicKey());
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::ProcessUpdateDaemonConfig(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  if (needs_elevation_) {
    DelegationResult result = DelegateToElevatedHost(std::move(message));
    switch (result) {
      case DELEGATION_SUCCESS:
        return;  // Result will be returned by elevated host.
      case DELEGATION_CANCELLED:
        SendAsyncResult(std::move(response),
                        DaemonController::RESULT_CANCELLED);
        return;
      default:
        SendAsyncResult(std::move(response), DaemonController::RESULT_FAILED);
        return;
    }
  }

  std::unique_ptr<base::DictionaryValue> config_dict =
      ConfigDictionaryFromMessage(std::move(message));
  if (!config_dict) {
    OnError("'config' dictionary not found");
    return;
  }

  daemon_controller_->UpdateConfig(
      std::move(config_dict),
      base::Bind(&Me2MeNativeMessagingHost::SendAsyncResult, weak_ptr_,
                 base::Passed(&response)));
}

void Me2MeNativeMessagingHost::ProcessGetDaemonConfig(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  daemon_controller_->GetConfig(
      base::Bind(&Me2MeNativeMessagingHost::SendConfigResponse, weak_ptr_,
                 base::Passed(&response)));
}

void Me2MeNativeMessagingHost::ProcessGetPairedClients(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  if (pairing_registry_.get()) {
    pairing_registry_->GetAllPairings(
        base::Bind(&Me2MeNativeMessagingHost::SendPairedClientsResponse,
                   weak_ptr_, base::Passed(&response)));
  } else {
    std::unique_ptr<base::ListValue> no_paired_clients(new base::ListValue);
    SendPairedClientsResponse(std::move(response),
                              std::move(no_paired_clients));
  }
}

void Me2MeNativeMessagingHost::ProcessGetUsageStatsConsent(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  daemon_controller_->GetUsageStatsConsent(
      base::Bind(&Me2MeNativeMessagingHost::SendUsageStatsConsentResponse,
                 weak_ptr_, base::Passed(&response)));
}

void Me2MeNativeMessagingHost::ProcessStartDaemon(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  if (needs_elevation_) {
    DelegationResult result = DelegateToElevatedHost(std::move(message));
    switch (result) {
      case DELEGATION_SUCCESS:
        return;  // Result will be returned by elevated host.
      case DELEGATION_CANCELLED:
        SendAsyncResult(std::move(response),
                        DaemonController::RESULT_CANCELLED);
        return;
      default:
        SendAsyncResult(std::move(response), DaemonController::RESULT_FAILED);
        return;
    }
  }

  bool consent;
  if (!message->GetBoolean("consent", &consent)) {
    OnError("'consent' not found.");
    return;
  }

  std::unique_ptr<base::DictionaryValue> config_dict =
      ConfigDictionaryFromMessage(std::move(message));
  if (!config_dict) {
    OnError("'config' dictionary not found");
    return;
  }

  daemon_controller_->SetConfigAndStart(
      std::move(config_dict), consent,
      base::Bind(&Me2MeNativeMessagingHost::SendAsyncResult, weak_ptr_,
                 base::Passed(&response)));
}

void Me2MeNativeMessagingHost::ProcessStopDaemon(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  if (needs_elevation_) {
    DelegationResult result = DelegateToElevatedHost(std::move(message));
    switch (result) {
      case DELEGATION_SUCCESS:
        return;  // Result will be returned by elevated host.
      case DELEGATION_CANCELLED:
        SendAsyncResult(std::move(response),
                        DaemonController::RESULT_CANCELLED);
        return;
      default:
        SendAsyncResult(std::move(response), DaemonController::RESULT_FAILED);
        return;
    }
  }

  daemon_controller_->Stop(
      base::Bind(&Me2MeNativeMessagingHost::SendAsyncResult, weak_ptr_,
                 base::Passed(&response)));
}

void Me2MeNativeMessagingHost::ProcessGetDaemonState(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  DaemonController::State state = daemon_controller_->GetState();
  switch (state) {
    case DaemonController::STATE_NOT_IMPLEMENTED:
      response->SetString("state", "NOT_IMPLEMENTED");
      break;
    case DaemonController::STATE_STOPPED:
      response->SetString("state", "STOPPED");
      break;
    case DaemonController::STATE_STARTING:
      response->SetString("state", "STARTING");
      break;
    case DaemonController::STATE_STARTED:
      response->SetString("state", "STARTED");
      break;
    case DaemonController::STATE_STOPPING:
      response->SetString("state", "STOPPING");
      break;
    case DaemonController::STATE_UNKNOWN:
      response->SetString("state", "UNKNOWN");
      break;
  }
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::ProcessGetHostClientId(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  response->SetString("clientId", google_apis::GetOAuth2ClientID(
      google_apis::CLIENT_REMOTING_HOST));
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::ProcessGetCredentialsFromAuthCode(
    std::unique_ptr<base::DictionaryValue> message,
    std::unique_ptr<base::DictionaryValue> response,
    bool need_user_email) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  std::string auth_code;
  if (!message->GetString("authorizationCode", &auth_code)) {
    OnError("'authorizationCode' string not found.");
    return;
  }

  gaia::OAuthClientInfo oauth_client_info = {
    google_apis::GetOAuth2ClientID(google_apis::CLIENT_REMOTING_HOST),
    google_apis::GetOAuth2ClientSecret(google_apis::CLIENT_REMOTING_HOST),
    kServiceAccountRedirectUri
  };

  oauth_client_->GetCredentialsFromAuthCode(
      oauth_client_info, auth_code, need_user_email, base::Bind(
          &Me2MeNativeMessagingHost::SendCredentialsResponse, weak_ptr_,
          base::Passed(&response)));
}

void Me2MeNativeMessagingHost::SendConfigResponse(
    std::unique_ptr<base::DictionaryValue> response,
    std::unique_ptr<base::DictionaryValue> config) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  if (config) {
    response->Set("config", std::move(config));
  } else {
    response->Set("config", std::make_unique<base::Value>());
  }
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::SendPairedClientsResponse(
    std::unique_ptr<base::DictionaryValue> response,
    std::unique_ptr<base::ListValue> pairings) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  response->Set("pairedClients", std::move(pairings));
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::SendUsageStatsConsentResponse(
    std::unique_ptr<base::DictionaryValue> response,
    const DaemonController::UsageStatsConsent& consent) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  response->SetBoolean("supported", consent.supported);
  response->SetBoolean("allowed", consent.allowed);
  response->SetBoolean("setByPolicy", consent.set_by_policy);
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::SendAsyncResult(
    std::unique_ptr<base::DictionaryValue> response,
    DaemonController::AsyncResult result) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  switch (result) {
    case DaemonController::RESULT_OK:
      response->SetString("result", "OK");
      break;
    case DaemonController::RESULT_FAILED:
      response->SetString("result", "FAILED");
      break;
    case DaemonController::RESULT_CANCELLED:
      response->SetString("result", "CANCELLED");
      break;
  }
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::SendBooleanResult(
    std::unique_ptr<base::DictionaryValue> response,
    bool result) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  response->SetBoolean("result", result);
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::SendCredentialsResponse(
    std::unique_ptr<base::DictionaryValue> response,
    const std::string& user_email,
    const std::string& refresh_token) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  if (!user_email.empty()) {
    response->SetString("userEmail", user_email);
  }
  response->SetString("refreshToken", refresh_token);
  SendMessageToClient(std::move(response));
}

void Me2MeNativeMessagingHost::SendMessageToClient(
    std::unique_ptr<base::Value> message) const {
  DCHECK(task_runner()->BelongsToCurrentThread());
  std::string message_json;
  base::JSONWriter::Write(*message, &message_json);
  client_->PostMessageFromNativeHost(message_json);
}

void Me2MeNativeMessagingHost::OnError(const std::string& error_message) {
  DCHECK(task_runner()->BelongsToCurrentThread());

  if (!error_message.empty()) {
    LOG(ERROR) << error_message;
  }

  // Trigger a host shutdown by sending an empty message.
  client_->CloseChannel(std::string());
}

#if defined(OS_WIN)

Me2MeNativeMessagingHost::DelegationResult
Me2MeNativeMessagingHost::DelegateToElevatedHost(
    std::unique_ptr<base::DictionaryValue> message) {
  DCHECK(task_runner()->BelongsToCurrentThread());
  DCHECK(needs_elevation_);

  if (!elevated_host_) {
    elevated_host_.reset(new ElevatedNativeMessagingHost(
        base::CommandLine::ForCurrentProcess()->GetProgram(),
        parent_window_handle_,
        /*elevate_process=*/true,
        base::TimeDelta::FromSeconds(kElevatedHostTimeoutSeconds),
        client_));
  }

  ProcessLaunchResult result = elevated_host_->EnsureElevatedHostCreated();
  if (result == PROCESS_LAUNCH_RESULT_SUCCESS) {
    elevated_host_->SendMessage(std::move(message));
  }

  switch (result) {
    case PROCESS_LAUNCH_RESULT_SUCCESS:
      return DELEGATION_SUCCESS;
    case PROCESS_LAUNCH_RESULT_CANCELLED:
      return DELEGATION_CANCELLED;
    case PROCESS_LAUNCH_RESULT_FAILED:
      return DELEGATION_FAILED;
  }
}

#else  // defined(OS_WIN)

Me2MeNativeMessagingHost::DelegationResult
Me2MeNativeMessagingHost::DelegateToElevatedHost(
    std::unique_ptr<base::DictionaryValue> message) {
  NOTREACHED();
  return DELEGATION_FAILED;
}

#endif  // !defined(OS_WIN)

}  // namespace remoting