// 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 "extensions/browser/extension_function_dispatcher.h"

#include "base/bind.h"
#include "base/json/json_string_value_serializer.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "base/metrics/sparse_histogram.h"
#include "base/process/process.h"
#include "base/values.h"
#include "build/build_config.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/render_frame_host.h"
#include "content/public/browser/render_process_host.h"
#include "content/public/browser/render_view_host.h"
#include "content/public/browser/user_metrics.h"
#include "content/public/browser/web_contents.h"
#include "content/public/browser/web_contents_observer.h"
#include "content/public/common/result_codes.h"
#include "extensions/browser/api_activity_monitor.h"
#include "extensions/browser/extension_function_registry.h"
#include "extensions/browser/extension_message_filter.h"
#include "extensions/browser/extension_registry.h"
#include "extensions/browser/extension_system.h"
#include "extensions/browser/extensions_browser_client.h"
#include "extensions/browser/process_manager.h"
#include "extensions/browser/process_map.h"
#include "extensions/browser/quota_service.h"
#include "extensions/common/extension_api.h"
#include "extensions/common/extension_messages.h"
#include "extensions/common/extension_set.h"
#include "ipc/ipc_message.h"
#include "ipc/ipc_message_macros.h"

using content::BrowserThread;
using content::RenderViewHost;

namespace extensions {
namespace {

// Notifies the ApiActivityMonitor that an extension API function has been
// called. May be called from any thread.
void NotifyApiFunctionCalled(const std::string& extension_id,
                             const std::string& api_name,
                             scoped_ptr<base::ListValue> args,
                             content::BrowserContext* browser_context) {
  // The ApiActivityMonitor can only be accessed from the main (UI) thread. If
  // we're running on the wrong thread, re-dispatch from the main thread.
  if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
    BrowserThread::PostTask(BrowserThread::UI,
                            FROM_HERE,
                            base::Bind(&NotifyApiFunctionCalled,
                                       extension_id,
                                       api_name,
                                       base::Passed(&args),
                                       browser_context));
    return;
  }
  // The BrowserContext may become invalid after the task above is posted.
  if (!ExtensionsBrowserClient::Get()->IsValidContext(browser_context))
    return;

  ApiActivityMonitor* monitor =
      ExtensionsBrowserClient::Get()->GetApiActivityMonitor(browser_context);
  if (monitor)
    monitor->OnApiFunctionCalled(extension_id, api_name, args.Pass());
}

// Separate copy of ExtensionAPI used for IO thread extension functions. We need
// this because ExtensionAPI has mutable data. It should be possible to remove
// this once all the extension APIs are updated to the feature system.
struct Static {
  Static() : api(ExtensionAPI::CreateWithDefaultConfiguration()) {}
  scoped_ptr<ExtensionAPI> api;
};
base::LazyInstance<Static> g_global_io_data = LAZY_INSTANCE_INITIALIZER;

// Kills the specified process because it sends us a malformed message.
void KillBadMessageSender(base::ProcessHandle process) {
  NOTREACHED();
  content::RecordAction(base::UserMetricsAction("BadMessageTerminate_EFD"));
  if (process)
    base::KillProcess(process, content::RESULT_CODE_KILLED_BAD_MESSAGE, false);
}

void CommonResponseCallback(IPC::Sender* ipc_sender,
                            int routing_id,
                            base::ProcessHandle peer_process,
                            int request_id,
                            ExtensionFunction::ResponseType type,
                            const base::ListValue& results,
                            const std::string& error) {
  DCHECK(ipc_sender);

  if (type == ExtensionFunction::BAD_MESSAGE) {
    // The renderer has done validation before sending extension api requests.
    // Therefore, we should never receive a request that is invalid in a way
    // that JSON validation in the renderer should have caught. It could be an
    // attacker trying to exploit the browser, so we crash the renderer instead.
    LOG(ERROR) <<
        "Terminating renderer because of malformed extension message.";
    if (content::RenderProcessHost::run_renderer_in_process()) {
      // In single process mode it is better if we don't suicide but just crash.
      CHECK(false);
    } else {
      KillBadMessageSender(peer_process);
    }

    return;
  }

  ipc_sender->Send(new ExtensionMsg_Response(
      routing_id, request_id, type == ExtensionFunction::SUCCEEDED, results,
      error));
}

void IOThreadResponseCallback(
    const base::WeakPtr<ExtensionMessageFilter>& ipc_sender,
    int routing_id,
    int request_id,
    ExtensionFunction::ResponseType type,
    const base::ListValue& results,
    const std::string& error) {
  if (!ipc_sender.get())
    return;

  CommonResponseCallback(ipc_sender.get(),
                         routing_id,
                         ipc_sender->PeerHandle(),
                         request_id,
                         type,
                         results,
                         error);
}

}  // namespace

class ExtensionFunctionDispatcher::UIThreadResponseCallbackWrapper
    : public content::WebContentsObserver {
 public:
  UIThreadResponseCallbackWrapper(
      const base::WeakPtr<ExtensionFunctionDispatcher>& dispatcher,
      RenderViewHost* render_view_host)
      : content::WebContentsObserver(
            content::WebContents::FromRenderViewHost(render_view_host)),
        dispatcher_(dispatcher),
        render_view_host_(render_view_host),
        weak_ptr_factory_(this) {
  }

  virtual ~UIThreadResponseCallbackWrapper() {
  }

  // content::WebContentsObserver overrides.
  virtual void RenderViewDeleted(
      RenderViewHost* render_view_host) OVERRIDE {
    DCHECK_CURRENTLY_ON(BrowserThread::UI);
    if (render_view_host != render_view_host_)
      return;

    if (dispatcher_.get()) {
      dispatcher_->ui_thread_response_callback_wrappers_
          .erase(render_view_host);
    }

    delete this;
  }

  ExtensionFunction::ResponseCallback CreateCallback(int request_id) {
    return base::Bind(
        &UIThreadResponseCallbackWrapper::OnExtensionFunctionCompleted,
        weak_ptr_factory_.GetWeakPtr(),
        request_id);
  }

 private:
  void OnExtensionFunctionCompleted(int request_id,
                                    ExtensionFunction::ResponseType type,
                                    const base::ListValue& results,
                                    const std::string& error) {
    CommonResponseCallback(
        render_view_host_, render_view_host_->GetRoutingID(),
        render_view_host_->GetProcess()->GetHandle(), request_id, type,
        results, error);
  }

  base::WeakPtr<ExtensionFunctionDispatcher> dispatcher_;
  content::RenderViewHost* render_view_host_;
  base::WeakPtrFactory<UIThreadResponseCallbackWrapper> weak_ptr_factory_;

  DISALLOW_COPY_AND_ASSIGN(UIThreadResponseCallbackWrapper);
};

WindowController*
ExtensionFunctionDispatcher::Delegate::GetExtensionWindowController() const {
  return NULL;
}

content::WebContents*
ExtensionFunctionDispatcher::Delegate::GetAssociatedWebContents() const {
  return NULL;
}

content::WebContents*
ExtensionFunctionDispatcher::Delegate::GetVisibleWebContents() const {
  return GetAssociatedWebContents();
}

void ExtensionFunctionDispatcher::GetAllFunctionNames(
    std::vector<std::string>* names) {
  ExtensionFunctionRegistry::GetInstance()->GetAllNames(names);
}

bool ExtensionFunctionDispatcher::OverrideFunction(
    const std::string& name, ExtensionFunctionFactory factory) {
  return ExtensionFunctionRegistry::GetInstance()->OverrideFunction(name,
                                                                    factory);
}

// static
void ExtensionFunctionDispatcher::DispatchOnIOThread(
    InfoMap* extension_info_map,
    void* profile_id,
    int render_process_id,
    base::WeakPtr<ExtensionMessageFilter> ipc_sender,
    int routing_id,
    const ExtensionHostMsg_Request_Params& params) {
  const Extension* extension =
      extension_info_map->extensions().GetByID(params.extension_id);

  ExtensionFunction::ResponseCallback callback(
      base::Bind(&IOThreadResponseCallback, ipc_sender, routing_id,
                 params.request_id));

  scoped_refptr<ExtensionFunction> function(
      CreateExtensionFunction(params,
                              extension,
                              render_process_id,
                              extension_info_map->process_map(),
                              g_global_io_data.Get().api.get(),
                              profile_id,
                              callback));
  if (!function.get())
    return;

  IOThreadExtensionFunction* function_io =
      function->AsIOThreadExtensionFunction();
  if (!function_io) {
    NOTREACHED();
    return;
  }
  function_io->set_ipc_sender(ipc_sender, routing_id);
  function_io->set_extension_info_map(extension_info_map);
  function->set_include_incognito(
      extension_info_map->IsIncognitoEnabled(extension->id()));

  if (!CheckPermissions(function.get(), extension, params, callback))
    return;

  QuotaService* quota = extension_info_map->GetQuotaService();
  std::string violation_error = quota->Assess(extension->id(),
                                              function.get(),
                                              &params.arguments,
                                              base::TimeTicks::Now());
  if (violation_error.empty()) {
    scoped_ptr<base::ListValue> args(params.arguments.DeepCopy());
    NotifyApiFunctionCalled(extension->id(),
                            params.name,
                            args.Pass(),
                            static_cast<content::BrowserContext*>(profile_id));
    UMA_HISTOGRAM_SPARSE_SLOWLY("Extensions.FunctionCalls",
                                function->histogram_value());
    function->Run()->Execute();
  } else {
    function->OnQuotaExceeded(violation_error);
  }
}

ExtensionFunctionDispatcher::ExtensionFunctionDispatcher(
    content::BrowserContext* browser_context,
    Delegate* delegate)
    : browser_context_(browser_context),
      delegate_(delegate) {
}

ExtensionFunctionDispatcher::~ExtensionFunctionDispatcher() {
}

void ExtensionFunctionDispatcher::Dispatch(
    const ExtensionHostMsg_Request_Params& params,
    RenderViewHost* render_view_host) {
  UIThreadResponseCallbackWrapperMap::const_iterator
      iter = ui_thread_response_callback_wrappers_.find(render_view_host);
  UIThreadResponseCallbackWrapper* callback_wrapper = NULL;
  if (iter == ui_thread_response_callback_wrappers_.end()) {
    callback_wrapper = new UIThreadResponseCallbackWrapper(AsWeakPtr(),
                                                           render_view_host);
    ui_thread_response_callback_wrappers_[render_view_host] = callback_wrapper;
  } else {
    callback_wrapper = iter->second;
  }

  DispatchWithCallbackInternal(
      params, render_view_host, NULL,
      callback_wrapper->CreateCallback(params.request_id));
}

void ExtensionFunctionDispatcher::DispatchWithCallback(
    const ExtensionHostMsg_Request_Params& params,
    content::RenderFrameHost* render_frame_host,
    const ExtensionFunction::ResponseCallback& callback) {
  DispatchWithCallbackInternal(params, NULL, render_frame_host, callback);
}

void ExtensionFunctionDispatcher::DispatchWithCallbackInternal(
    const ExtensionHostMsg_Request_Params& params,
    RenderViewHost* render_view_host,
    content::RenderFrameHost* render_frame_host,
    const ExtensionFunction::ResponseCallback& callback) {
  DCHECK(render_view_host || render_frame_host);
  // TODO(yzshen): There is some shared logic between this method and
  // DispatchOnIOThread(). It is nice to deduplicate.
  ProcessMap* process_map = ProcessMap::Get(browser_context_);
  if (!process_map)
    return;

  ExtensionRegistry* registry = ExtensionRegistry::Get(browser_context_);
  const Extension* extension = registry->enabled_extensions().GetByID(
      params.extension_id);
  if (!extension) {
    extension =
        registry->enabled_extensions().GetHostedAppByURL(params.source_url);
  }

  int process_id = render_view_host ? render_view_host->GetProcess()->GetID() :
                                      render_frame_host->GetProcess()->GetID();
  scoped_refptr<ExtensionFunction> function(
      CreateExtensionFunction(params,
                              extension,
                              process_id,
                              *process_map,
                              ExtensionAPI::GetSharedInstance(),
                              browser_context_,
                              callback));
  if (!function.get())
    return;

  UIThreadExtensionFunction* function_ui =
      function->AsUIThreadExtensionFunction();
  if (!function_ui) {
    NOTREACHED();
    return;
  }
  if (render_view_host) {
    function_ui->SetRenderViewHost(render_view_host);
  } else {
    function_ui->SetRenderFrameHost(render_frame_host);
  }
  function_ui->set_dispatcher(AsWeakPtr());
  function_ui->set_browser_context(browser_context_);
  function->set_include_incognito(
      ExtensionsBrowserClient::Get()->CanExtensionCrossIncognito(
          extension, browser_context_));

  if (!CheckPermissions(function.get(), extension, params, callback))
    return;

  ExtensionSystem* extension_system = ExtensionSystem::Get(browser_context_);
  QuotaService* quota = extension_system->quota_service();
  std::string violation_error = quota->Assess(extension->id(),
                                              function.get(),
                                              &params.arguments,
                                              base::TimeTicks::Now());
  if (violation_error.empty()) {
    scoped_ptr<base::ListValue> args(params.arguments.DeepCopy());

    NotifyApiFunctionCalled(
        extension->id(), params.name, args.Pass(), browser_context_);
    UMA_HISTOGRAM_SPARSE_SLOWLY("Extensions.FunctionCalls",
                                function->histogram_value());
    function->Run()->Execute();
  } else {
    function->OnQuotaExceeded(violation_error);
  }

  // Note: do not access |this| after this point. We may have been deleted
  // if function->Run() ended up closing the tab that owns us.

  // Check if extension was uninstalled by management.uninstall.
  if (!registry->enabled_extensions().GetByID(params.extension_id))
    return;

  // We only adjust the keepalive count for UIThreadExtensionFunction for
  // now, largely for simplicity's sake. This is OK because currently, only
  // the webRequest API uses IOThreadExtensionFunction, and that API is not
  // compatible with lazy background pages.
  extension_system->process_manager()->IncrementLazyKeepaliveCount(extension);
}

void ExtensionFunctionDispatcher::OnExtensionFunctionCompleted(
    const Extension* extension) {
  ExtensionSystem::Get(browser_context_)->process_manager()->
      DecrementLazyKeepaliveCount(extension);
}

// static
bool ExtensionFunctionDispatcher::CheckPermissions(
    ExtensionFunction* function,
    const Extension* extension,
    const ExtensionHostMsg_Request_Params& params,
    const ExtensionFunction::ResponseCallback& callback) {
  if (!function->HasPermission()) {
    LOG(ERROR) << "Extension " << extension->id() << " does not have "
               << "permission to function: " << params.name;
    SendAccessDenied(callback);
    return false;
  }
  return true;
}

namespace {

// Only COMPONENT hosted apps may call extension APIs, and they are limited
// to just the permissions they explicitly request. They should not have access
// to extension APIs like eg chrome.runtime, chrome.windows, etc. that normally
// are available without permission.
// TODO(mpcomplete): move this to ExtensionFunction::HasPermission (or remove
// it altogether).
bool AllowHostedAppAPICall(const Extension& extension,
                           const GURL& source_url,
                           const std::string& function_name) {
  if (extension.location() != Manifest::COMPONENT)
    return false;

  if (!extension.web_extent().MatchesURL(source_url))
    return false;

  // Note: Not BLESSED_WEB_PAGE_CONTEXT here because these component hosted app
  // entities have traditionally been treated as blessed extensions, for better
  // or worse.
  Feature::Availability availability =
      ExtensionAPI::GetSharedInstance()->IsAvailable(
          function_name, &extension, Feature::BLESSED_EXTENSION_CONTEXT,
          source_url);
  return availability.is_available();
}

}  // namespace


// static
ExtensionFunction* ExtensionFunctionDispatcher::CreateExtensionFunction(
    const ExtensionHostMsg_Request_Params& params,
    const Extension* extension,
    int requesting_process_id,
    const ProcessMap& process_map,
    ExtensionAPI* api,
    void* profile_id,
    const ExtensionFunction::ResponseCallback& callback) {
  if (!extension) {
    LOG(ERROR) << "Specified extension does not exist.";
    SendAccessDenied(callback);
    return NULL;
  }

  // Most hosted apps can't call APIs.
  bool allowed = true;
  if (extension->is_hosted_app())
    allowed = AllowHostedAppAPICall(*extension, params.source_url, params.name);

  // Privileged APIs can only be called from the process the extension
  // is running in.
  if (allowed && !api->IsAvailableInUntrustedContext(params.name, extension))
    allowed = process_map.Contains(extension->id(), requesting_process_id);

  if (!allowed) {
    LOG(ERROR) << "Extension API call disallowed - name:" << params.name
               << " pid:" << requesting_process_id
               << " from URL " << params.source_url.spec();
    SendAccessDenied(callback);
    return NULL;
  }

  ExtensionFunction* function =
      ExtensionFunctionRegistry::GetInstance()->NewFunction(params.name);
  if (!function) {
    LOG(ERROR) << "Unknown Extension API - " << params.name;
    SendAccessDenied(callback);
    return NULL;
  }

  function->SetArgs(&params.arguments);
  function->set_source_url(params.source_url);
  function->set_request_id(params.request_id);
  function->set_has_callback(params.has_callback);
  function->set_user_gesture(params.user_gesture);
  function->set_extension(extension);
  function->set_profile_id(profile_id);
  function->set_response_callback(callback);
  function->set_source_tab_id(params.source_tab_id);

  return function;
}

// static
void ExtensionFunctionDispatcher::SendAccessDenied(
    const ExtensionFunction::ResponseCallback& callback) {
  base::ListValue empty_list;
  callback.Run(ExtensionFunction::FAILED, empty_list,
               "Access to extension API denied.");
}

}  // namespace extensions