// 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 is the browser side of the resource dispatcher, it receives requests
// from the child process (i.e. [Renderer, Plugin, Worker]ProcessHost), and
// dispatches them to URLRequests. It then forwards the messages from the
// URLRequests back to the correct process for handling.
//
// See http://dev.chromium.org/developers/design-documents/multi-process-resource-loading

#ifndef CONTENT_BROWSER_LOADER_RESOURCE_DISPATCHER_HOST_IMPL_H_
#define CONTENT_BROWSER_LOADER_RESOURCE_DISPATCHER_HOST_IMPL_H_

#include <map>
#include <set>
#include <string>
#include <vector>

#include "base/basictypes.h"
#include "base/gtest_prod_util.h"
#include "base/memory/linked_ptr.h"
#include "base/memory/scoped_ptr.h"
#include "base/observer_list.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "content/browser/download/download_resource_handler.h"
#include "content/browser/loader/global_routing_id.h"
#include "content/browser/loader/resource_loader.h"
#include "content/browser/loader/resource_loader_delegate.h"
#include "content/browser/loader/resource_scheduler.h"
#include "content/common/content_export.h"
#include "content/common/resource_request_body.h"
#include "content/public/browser/child_process_data.h"
#include "content/public/browser/download_item.h"
#include "content/public/browser/download_url_parameters.h"
#include "content/public/browser/global_request_id.h"
#include "content/public/browser/notification_types.h"
#include "content/public/browser/resource_dispatcher_host.h"
#include "content/public/common/resource_type.h"
#include "ipc/ipc_message.h"
#include "net/base/request_priority.h"
#include "net/cookies/canonical_cookie.h"
#include "net/url_request/url_request.h"

class ResourceHandler;
struct ResourceHostMsg_Request;

namespace base {
class FilePath;
}

namespace net {
class URLRequestJobFactory;
}

namespace storage {
class ShareableFileReference;
}

namespace content {
class AppCacheService;
class AsyncRevalidationManager;
class NavigationURLLoaderImplCore;
class ResourceContext;
class ResourceDispatcherHostDelegate;
class ResourceMessageDelegate;
class ResourceMessageFilter;
class ResourceRequestInfoImpl;
class SaveFileManager;
class ServiceWorkerNavigationHandleCore;
class WebContentsImpl;
struct CommonNavigationParams;
struct DownloadSaveInfo;
struct NavigationRequestInfo;
struct Referrer;

class CONTENT_EXPORT ResourceDispatcherHostImpl
    : public ResourceDispatcherHost,
      public ResourceLoaderDelegate {
 public:
  ResourceDispatcherHostImpl();
  ~ResourceDispatcherHostImpl() override;

  // Returns the current ResourceDispatcherHostImpl. May return NULL if it
  // hasn't been created yet.
  static ResourceDispatcherHostImpl* Get();

  // ResourceDispatcherHost implementation:
  void SetDelegate(ResourceDispatcherHostDelegate* delegate) override;
  void SetAllowCrossOriginAuthPrompt(bool value) override;
  DownloadInterruptReason BeginDownload(
      scoped_ptr<net::URLRequest> request,
      const Referrer& referrer,
      bool is_content_initiated,
      ResourceContext* context,
      int child_id,
      int render_view_route_id,
      int render_frame_route_id,
      bool prefer_cache,
      bool do_not_prompt_for_login,
      scoped_ptr<DownloadSaveInfo> save_info,
      uint32 download_id,
      const DownloadStartedCallback& started_callback) override;
  void ClearLoginDelegateForRequest(net::URLRequest* request) override;
  void BlockRequestsForRoute(int child_id, int route_id) override;
  void ResumeBlockedRequestsForRoute(int child_id, int route_id) override;

  // Puts the resource dispatcher host in an inactive state (unable to begin
  // new requests).  Cancels all pending requests.
  void Shutdown();

  // Notify the ResourceDispatcherHostImpl of a new resource context.
  void AddResourceContext(ResourceContext* context);

  // Notify the ResourceDispatcherHostImpl of a resource context destruction.
  void RemoveResourceContext(ResourceContext* context);

  // Force cancels any pending requests for the given |context|. This is
  // necessary to ensure that before |context| goes away, all requests
  // for it are dead.
  void CancelRequestsForContext(ResourceContext* context);

  // Returns true if the message was a resource message that was processed.
  bool OnMessageReceived(const IPC::Message& message,
                         ResourceMessageFilter* filter);

  // Initiates a save file from the browser process (as opposed to a resource
  // request from the renderer or another child process).
  void BeginSaveFile(const GURL& url,
                     const Referrer& referrer,
                     int save_item_id,
                     int save_package_id,
                     int child_id,
                     int render_view_route_id,
                     int render_frame_route_id,
                     ResourceContext* context);

  // Cancels the given request if it still exists.
  void CancelRequest(int child_id, int request_id);

  // Marks the request as "parked". This happens if a request is
  // redirected cross-site and needs to be resumed by a new render view.
  void MarkAsTransferredNavigation(const GlobalRequestID& id);

  // Cancels a request previously marked as being transferred, for use when a
  // navigation was cancelled.
  void CancelTransferringNavigation(const GlobalRequestID& id);

  // Resumes the request without transferring it to a new render view.
  void ResumeDeferredNavigation(const GlobalRequestID& id);

  // Returns the number of pending requests. This is designed for the unittests
  int pending_requests() const {
    return static_cast<int>(pending_loaders_.size());
  }

  // Intended for unit-tests only. Overrides the outstanding requests bound.
  void set_max_outstanding_requests_cost_per_process(int limit) {
    max_outstanding_requests_cost_per_process_ = limit;
  }
  void set_max_num_in_flight_requests_per_process(int limit) {
    max_num_in_flight_requests_per_process_ = limit;
  }
  void set_max_num_in_flight_requests(int limit) {
    max_num_in_flight_requests_ = limit;
  }

  // The average private bytes increase of the browser for each new pending
  // request. Experimentally obtained.
  static const int kAvgBytesPerOutstandingRequest = 4400;

  SaveFileManager* save_file_manager() const {
    return save_file_manager_.get();
  }

  // Called when a RenderViewHost is created.
  void OnRenderViewHostCreated(int child_id,
                               int route_id,
                               bool is_visible,
                               bool is_audible);

  // Called when a RenderViewHost is deleted.
  void OnRenderViewHostDeleted(int child_id, int route_id);

  // Called when a RenderViewHost starts or stops loading.
  void OnRenderViewHostSetIsLoading(int child_id,
                                    int route_id,
                                    bool is_loading);

  // Called when a RenderViewHost is hidden.
  void OnRenderViewHostWasHidden(int child_id, int route_id);

  // Called when a RenderViewHost is shown.
  void OnRenderViewHostWasShown(int child_id, int route_id);

  // Called when an AudioRenderHost starts or stops playing.
  void OnAudioRenderHostStreamStateChanged(int child_id,
                                           int route_id,
                                           bool is_playing);

  // Force cancels any pending requests for the given process.
  void CancelRequestsForProcess(int child_id);

  void OnUserGesture(WebContentsImpl* contents);

  // Retrieves a net::URLRequest.  Must be called from the IO thread.
  net::URLRequest* GetURLRequest(const GlobalRequestID& request_id);

  void RemovePendingRequest(int child_id, int request_id);

  // Cancels any blocked request for the specified route id.
  void CancelBlockedRequestsForRoute(int child_id, int route_id);

  // Maintains a collection of temp files created in support of
  // the download_to_file capability. Used to grant access to the
  // child process and to defer deletion of the file until it's
  // no longer needed.
  void RegisterDownloadedTempFile(
      int child_id, int request_id,
      const base::FilePath& file_path);
  void UnregisterDownloadedTempFile(int child_id, int request_id);

  // Needed for the sync IPC message dispatcher macros.
  bool Send(IPC::Message* message);

  // Indicates whether third-party sub-content can pop-up HTTP basic auth
  // dialog boxes.
  bool allow_cross_origin_auth_prompt();

  ResourceDispatcherHostDelegate* delegate() {
    return delegate_;
  }

  // Must be called after the ResourceRequestInfo has been created
  // and associated with the request.
  // |id| should be |content::DownloadItem::kInvalidId| to request automatic
  // assignment. This is marked virtual so it can be overriden in testing.
  virtual scoped_ptr<ResourceHandler> CreateResourceHandlerForDownload(
      net::URLRequest* request,
      bool is_content_initiated,
      bool must_download,
      uint32 id,
      scoped_ptr<DownloadSaveInfo> save_info,
      const DownloadUrlParameters::OnStartedCallback& started_cb);

  // Called to determine whether the response to |request| should be intercepted
  // and handled as a stream. Streams are used to pass direct access to a
  // resource response to another application (e.g. a web page) without being
  // handled by the browser itself. If the request should be intercepted as a
  // stream, a StreamResourceHandler is returned which provides access to the
  // response. |plugin_path| is the path to the plugin which is handling the
  // URL request. This may be empty if there is no plugin handling the request.
  //
  // This function must be called after the ResourceRequestInfo has been created
  // and associated with the request. If |payload| is set to a non-empty value,
  // the caller must send it to the old resource handler instead of cancelling
  // it.
  virtual scoped_ptr<ResourceHandler> MaybeInterceptAsStream(
      const base::FilePath& plugin_path,
      net::URLRequest* request,
      ResourceResponse* response,
      std::string* payload);

  ResourceScheduler* scheduler() { return scheduler_.get(); }

  // Called by a ResourceHandler when it's ready to start reading data and
  // sending it to the renderer. Returns true if there are enough file
  // descriptors available for the shared memory buffer. If false is returned,
  // the request should cancel.
  bool HasSufficientResourcesForRequest(net::URLRequest* request);

  // Called by a ResourceHandler after it has finished its request and is done
  // using its shared memory buffer. Frees up that file descriptor to be used
  // elsewhere.
  void FinishedWithResourcesForRequest(net::URLRequest* request);

  // PlzNavigate: Begins a request for NavigationURLLoader. |loader| is the
  // loader to attach to the leaf resource handler.
  void BeginNavigationRequest(
      ResourceContext* resource_context,
      const NavigationRequestInfo& info,
      NavigationURLLoaderImplCore* loader,
      ServiceWorkerNavigationHandleCore* service_worker_handle_core);

  // Turns on stale-while-revalidate support, regardless of command-line flags
  // or experiment status. For unit tests only.
  void EnableStaleWhileRevalidateForTesting();

 private:
  friend class ResourceDispatcherHostTest;

  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest,
                           TestBlockedRequestsProcessDies);
  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest,
                           CalculateApproximateMemoryCost);
  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest,
                           DetachableResourceTimesOut);
  FRIEND_TEST_ALL_PREFIXES(ResourceDispatcherHostTest,
                           TestProcessCancelDetachableTimesOut);

  struct OustandingRequestsStats {
    int memory_cost;
    int num_requests;
  };

  friend class ShutdownTask;
  friend class ResourceMessageDelegate;

  // Information about status of a ResourceLoader.
  struct LoadInfo {
    GURL url;
    net::LoadStateWithParam load_state;
    uint64 upload_position;
    uint64 upload_size;
  };

  // Map from ProcessID+RouteID pair to the "most interesting" LoadState.
  typedef std::map<GlobalRoutingID, LoadInfo> LoadInfoMap;

  // ResourceLoaderDelegate implementation:
  ResourceDispatcherHostLoginDelegate* CreateLoginDelegate(
      ResourceLoader* loader,
      net::AuthChallengeInfo* auth_info) override;
  bool HandleExternalProtocol(ResourceLoader* loader, const GURL& url) override;
  void DidStartRequest(ResourceLoader* loader) override;
  void DidReceiveRedirect(ResourceLoader* loader, const GURL& new_url) override;
  void DidReceiveResponse(ResourceLoader* loader) override;
  void DidFinishLoading(ResourceLoader* loader) override;

  // An init helper that runs on the IO thread.
  void OnInit();

  // A shutdown helper that runs on the IO thread.
  void OnShutdown();

  // Helper function for regular and download requests.
  void BeginRequestInternal(scoped_ptr<net::URLRequest> request,
                            scoped_ptr<ResourceHandler> handler);

  void StartLoading(ResourceRequestInfoImpl* info,
                    const linked_ptr<ResourceLoader>& loader);

  // We keep track of how much memory each request needs and how many requests
  // are issued by each renderer. These are known as OustandingRequestStats.
  // Memory limits apply to all requests sent to us by the renderers. There is a
  // limit for each renderer. File descriptor limits apply to requests that are
  // receiving their body. These are known as in-flight requests. There is a
  // global limit that applies for the browser process. Each render is allowed
  // to use up to a fraction of that.

  // Returns the OustandingRequestsStats for |info|'s renderer, or an empty
  // struct if that renderer has no outstanding requests.
  OustandingRequestsStats GetOutstandingRequestsStats(
      const ResourceRequestInfoImpl& info);

  // Updates |outstanding_requests_stats_map_| with the specified |stats| for
  // the renderer that made the request in |info|.
  void UpdateOutstandingRequestsStats(const ResourceRequestInfoImpl& info,
                                      const OustandingRequestsStats& stats);

  // Called every time an outstanding request is created or deleted. |count|
  // indicates whether the request is new or deleted. |count| must be 1 or -1.
  OustandingRequestsStats IncrementOutstandingRequestsMemory(
      int count,
      const ResourceRequestInfoImpl& info);

  // Called when an in flight request allocates or releases a shared memory
  // buffer. |count| indicates whether the request is issuing or finishing.
  // |count| must be 1 or -1.
  OustandingRequestsStats IncrementOutstandingRequestsCount(
      int count,
      ResourceRequestInfoImpl* info);

  // Estimate how much heap space |request| will consume to run.
  static int CalculateApproximateMemoryCost(net::URLRequest* request);

  // Force cancels any pending requests for the given route id.  This method
  // acts like CancelRequestsForProcess when route_id is -1.
  void CancelRequestsForRoute(int child_id, int route_id);

  // The list of all requests that we have pending. This list is not really
  // optimized, and assumes that we have relatively few requests pending at once
  // since some operations require brute-force searching of the list.
  //
  // It may be enhanced in the future to provide some kind of prioritization
  // mechanism. We should also consider a hashtable or binary tree if it turns
  // out we have a lot of things here.
  typedef std::map<GlobalRequestID, linked_ptr<ResourceLoader> > LoaderMap;

  // Deletes the pending request identified by the iterator passed in.
  // This function will invalidate the iterator passed in. Callers should
  // not rely on this iterator being valid on return.
  void RemovePendingLoader(const LoaderMap::iterator& iter);

  // This function returns true if the LoadInfo of |a| is "more interesting"
  // than the LoadInfo of |b|.  The load that is currently sending the larger
  // request body is considered more interesting.  If neither request is
  // sending a body (Neither request has a body, or any request that has a body
  // is not currently sending the body), the request that is further along is
  // considered more interesting.
  //
  // This takes advantage of the fact that the load states are an enumeration
  // listed in the order in which they usually occur during the lifetime of a
  // request, so states with larger numeric values are generally further along
  // toward completion.
  //
  // For example, by this measure "tranferring data" is a more interesting state
  // than "resolving host" because when transferring data something is being
  // done that corresponds to changes that the user might observe, whereas
  // waiting for a host name to resolve implies being stuck.
  static bool LoadInfoIsMoreInteresting(const LoadInfo& a, const LoadInfo& b);

  // Used to marshal calls to LoadStateChanged from the IO to UI threads.  All
  // are done as a single callback to avoid spamming the UI thread.
  static void UpdateLoadInfoOnUIThread(scoped_ptr<LoadInfoMap> info_map);

  // Gets the most interesting LoadInfo for each GlobalRoutingID.
  scoped_ptr<LoadInfoMap> GetLoadInfoForAllRoutes();

  // Checks all pending requests and updates the load info if necessary.
  void UpdateLoadInfo();

  // Resumes or cancels (if |cancel_requests| is true) any blocked requests.
  void ProcessBlockedRequestsForRoute(int child_id,
                                      int route_id,
                                      bool cancel_requests);

  void OnRequestResource(int routing_id,
                         int request_id,
                         const ResourceHostMsg_Request& request_data);
  void OnSyncLoad(int request_id,
                  const ResourceHostMsg_Request& request_data,
                  IPC::Message* sync_result);

  // Update the ResourceRequestInfo and internal maps when a request is
  // transferred from one process to another.
  void UpdateRequestForTransfer(int child_id,
                                int route_id,
                                int request_id,
                                const ResourceHostMsg_Request& request_data,
                                const linked_ptr<ResourceLoader>& loader);

  void BeginRequest(int request_id,
                    const ResourceHostMsg_Request& request_data,
                    IPC::Message* sync_result,  // only valid for sync
                    int route_id);  // only valid for async

  // Creates a ResourceHandler to be used by BeginRequest() for normal resource
  // loading.
  scoped_ptr<ResourceHandler> CreateResourceHandler(
      net::URLRequest* request,
      const ResourceHostMsg_Request& request_data,
      IPC::Message* sync_result,
      int route_id,
      int process_type,
      int child_id,
      ResourceContext* resource_context);

  // Wraps |handler| in the standard resource handlers for normal resource
  // loading and navigation requests. This adds MimeTypeResourceHandler and
  // ResourceThrottles.
  scoped_ptr<ResourceHandler> AddStandardHandlers(
      net::URLRequest* request,
      ResourceType resource_type,
      ResourceContext* resource_context,
      AppCacheService* appcache_service,
      int child_id,
      int route_id,
      scoped_ptr<ResourceHandler> handler);

  void OnDataDownloadedACK(int request_id);
  void OnCancelRequest(int request_id);
  void OnReleaseDownloadedFile(int request_id);
  void OnDidChangePriority(int request_id,
                           net::RequestPriority new_priority,
                           int intra_priority_value);

  // Creates ResourceRequestInfoImpl for a download or page save.
  // |download| should be true if the request is a file download.
  ResourceRequestInfoImpl* CreateRequestInfo(
      int child_id,
      int render_view_route_id,
      int render_frame_route_id,
      bool download,
      ResourceContext* context);

  // Relationship of resource being authenticated with the top level page.
  enum HttpAuthRelationType {
    HTTP_AUTH_RELATION_TOP,            // Top-level page itself
    HTTP_AUTH_RELATION_SAME_DOMAIN,    // Sub-content from same domain
    HTTP_AUTH_RELATION_BLOCKED_CROSS,  // Blocked Sub-content from cross domain
    HTTP_AUTH_RELATION_ALLOWED_CROSS,  // Allowed Sub-content per command line
    HTTP_AUTH_RELATION_LAST
  };

  HttpAuthRelationType HttpAuthRelationTypeOf(const GURL& request_url,
                                              const GURL& first_party);

  // Returns whether the URLRequest identified by |transferred_request_id| is
  // currently in the process of being transferred to a different renderer.
  // This happens if a request is redirected cross-site and needs to be resumed
  // by a new render view.
  bool IsTransferredNavigation(
      const GlobalRequestID& transferred_request_id) const;

  ResourceLoader* GetLoader(const GlobalRequestID& id) const;
  ResourceLoader* GetLoader(int child_id, int request_id) const;

  // Registers |delegate| to receive resource IPC messages targeted to the
  // specified |id|.
  void RegisterResourceMessageDelegate(const GlobalRequestID& id,
                                       ResourceMessageDelegate* delegate);
  void UnregisterResourceMessageDelegate(const GlobalRequestID& id,
                                         ResourceMessageDelegate* delegate);

  int BuildLoadFlagsForRequest(const ResourceHostMsg_Request& request_data,
                               int child_id,
                               bool is_sync_load);

  LoaderMap pending_loaders_;

  // Collection of temp files downloaded for child processes via
  // the download_to_file mechanism. We avoid deleting them until
  // the client no longer needs them.
  typedef std::map<int, scoped_refptr<storage::ShareableFileReference> >
      DeletableFilesMap;  // key is request id
  typedef std::map<int, DeletableFilesMap>
      RegisteredTempFiles;  // key is child process id
  RegisteredTempFiles registered_temp_files_;

  // A timer that periodically calls UpdateLoadInfo while pending_loaders_ is
  // not empty and at least one RenderViewHost is loading.
  scoped_ptr<base::RepeatingTimer> update_load_states_timer_;

  // We own the save file manager.
  scoped_refptr<SaveFileManager> save_file_manager_;

  // Request ID for browser initiated requests. request_ids generated by
  // child processes are counted up from 0, while browser created requests
  // start at -2 and go down from there. (We need to start at -2 because -1 is
  // used as a special value all over the resource_dispatcher_host for
  // uninitialized variables.) This way, we no longer have the unlikely (but
  // observed in the real world!) event where we have two requests with the same
  // request_id_.
  int request_id_;

  // True if the resource dispatcher host has been shut down.
  bool is_shutdown_;

  typedef std::vector<linked_ptr<ResourceLoader> > BlockedLoadersList;
  typedef std::map<GlobalRoutingID, BlockedLoadersList*> BlockedLoadersMap;
  BlockedLoadersMap blocked_loaders_map_;

  // Maps the child_ids to the approximate number of bytes
  // being used to service its resource requests. No entry implies 0 cost.
  typedef std::map<int, OustandingRequestsStats> OutstandingRequestsStatsMap;
  OutstandingRequestsStatsMap outstanding_requests_stats_map_;

  // |num_in_flight_requests_| is the total number of requests currently issued
  // summed across all renderers.
  int num_in_flight_requests_;

  // |max_num_in_flight_requests_| is the upper bound on how many requests
  // can be in flight at once. It's based on the maximum number of file
  // descriptors open per process. We need a global limit for the browser
  // process.
  int max_num_in_flight_requests_;

  // |max_num_in_flight_requests_| is the upper bound on how many requests
  // can be issued at once. It's based on the maximum number of file
  // descriptors open per process. We need a per-renderer limit so that no
  // single renderer can hog the browser's limit.
  int max_num_in_flight_requests_per_process_;

  // |max_outstanding_requests_cost_per_process_| is the upper bound on how
  // many outstanding requests can be issued per child process host.
  // The constraint is expressed in terms of bytes (where the cost of
  // individual requests is given by CalculateApproximateMemoryCost).
  // The total number of outstanding requests is roughly:
  //   (max_outstanding_requests_cost_per_process_ /
  //       kAvgBytesPerOutstandingRequest)
  int max_outstanding_requests_cost_per_process_;

  // Time of the last user gesture. Stored so that we can add a load
  // flag to requests occurring soon after a gesture to indicate they
  // may be because of explicit user action.
  base::TimeTicks last_user_gesture_time_;

  // Used during IPC message dispatching so that the handlers can get a pointer
  // to the source of the message.
  ResourceMessageFilter* filter_;

  ResourceDispatcherHostDelegate* delegate_;

  bool allow_cross_origin_auth_prompt_;

  // AsyncRevalidationManager is non-NULL if and only if
  // stale-while-revalidate is enabled.
  scoped_ptr<AsyncRevalidationManager> async_revalidation_manager_;

  // http://crbug.com/90971 - Assists in tracking down use-after-frees on
  // shutdown.
  std::set<const ResourceContext*> active_resource_contexts_;

  typedef std::map<GlobalRequestID,
                   base::ObserverList<ResourceMessageDelegate>*> DelegateMap;
  DelegateMap delegate_map_;

  scoped_ptr<ResourceScheduler> scheduler_;

  DISALLOW_COPY_AND_ASSIGN(ResourceDispatcherHostImpl);
};

}  // namespace content

#endif  // CONTENT_BROWSER_LOADER_RESOURCE_DISPATCHER_HOST_IMPL_H_